3D Bioplotter Research Papers

Displaying all papers about Gelatin (85 results)

3D Printing of Cytocompatible Graphene/Alginate Scaffolds for Mimetic Tissue Constructs

Frontiers in Bioengineering and Biotechnology 2020 Volume 8, Article 824

Tissue engineering, based on a combination of 3D printing, biomaterials blending and stem cell technology, offers the potential to establish customized, transplantable autologous implants using a patient‘s own cells. Graphene, as a two-dimensional (2D) version of carbon, has shown great potential for tissue engineering. Here, we describe a novel combination of graphene with 3D printed alginate (Alg)-based scaffolds for human adipose stem cell (ADSC) support and osteogenic induction. Alg printing was enabled through addition of gelatin (Gel) that was removed after printing, and the 3D structure was then coated with graphene oxide (GO). GO was chemically reduced with a biocompatible…

Optimization of Biomanufacturing process for Tissue Engineering applications

University of Brescia 2024 Thesis
R. Rovetta

In recent years, tissue engineering has experienced significant advancements, mostly driven by the emergence of additive manufacturing technologies and the integration of biomaterials and cells. This advanced technique enables the creation of intricate structures with diverse components and properties, specifically designed for use in biomedical applications. The primary benefit of this technology is its ability to be customised, which helps minimise post-operative difficulties for patients with orthopaedic diseases and those undergoing tissue transplants. For this purpose, the essential components can be synthesised by the patient’s own cells. However, there are still other obstacles that need to be addressed in order…

3D bioprinting of thermosensitive inks based on gelatin, hyaluronic acid, and fibrinogen: reproducibility and role of printing parameters

Bioprinting 2024 Volume 39, Article e00338

Thermosensitive inks are considered an attractive option for the 3D bioprinting of different tissue types, yet comprehensive information on their reliability, preparation, and properties remains lacking. This paper addresses this gap by presenting a twofold aim: firstly, characterizing the preparation, rheology, and printing aspects of two inks that have demonstrated success in skeletal muscle tissue engineering both in vitro and in vivo. The first ink is composed of fibrinogen, gelatin, hyaluronic acid, and glycerol, while the second is a sacrificial ink made of gelatin, hyaluronic acid, and glycerol. Secondly, from this analysis, we demonstrate how thermosensitive and multicomponent inks can…

Sustainable highly stretchable and tough gelatin-alkali lignin hydrogels for scaffolding and 3D printing applications

Materials Today Communications 2024 Volume 39, Article 108875

Hydrogels and bioinks obtained from gelatin (Gel) generally present poor mechanical properties and require a series of time-consuming and stepwise chemical processes to exhibit improved elasticity and resistance to fatigue. Alkali lignin (AL) is an underutilized by-product of the paper and pulp industry. It is a widely available and inexpensive biomaterial that presents enormous potential for high-value applications owing to its ease of chemical modification and unique naturally occurring polyaromatic structure. This work aims to develop different GelAL hydrogel formulations with a single-step method that are innovative and sustainable. The results obtained from the mechanical, rheological, and degradation studies of…

3D bioprinted mesenchymal stem cell laden scaffold enhances subcutaneous vascularization for delivery of cell therapy

Biomedical Microdevices 2024 Volume 26, Issue 3, Article 29

Subcutaneous delivery of cell therapy is an appealing minimally-invasive strategy for the treatment of various diseases. However, the subdermal site is poorly vascularized making it inadequate for supporting engraftment, viability, and function of exogenous cells. In this study, we developed a 3D bioprinted scaffold composed of alginate/gelatin (Alg/Gel) embedded with mesenchymal stem cells (MSCs) to enhance vascularization and tissue ingrowth in a subcutaneous microenvironment. We identified bio-ink crosslinking conditions that optimally recapitulated the mechanical properties of subcutaneous tissue. We achieved controlled degradation of the Alg/Gel scaffold synchronous with host tissue ingrowth and remodeling. Further, in a rat model, the Alg/Gel…

Three-dimensional printing hydrogel scaffold with bioactivity and shape-adaptability for potential application in irregular bone defect regeneration

Journal of Applied Polymer Science 2022 Volume 139, Issue 35, Article e52831

Complex shaped bone defects that need to be filled are very common in clinic. But after filling, gaps are inevitably left between substitutes and host bone due to the poor conformability of preformed implants, hence hindering bone regeneration. Therefore, based on our previous study, we here used the bioink (named PPG) composed of polyurethane, polyacrylamide, and gelatin with optimized composition ratio to three-dimensionally (3D) print an inorganic/organic composite hydrogel scaffold with self-expandability to fill irregular bone defects and bioactivity to accelerate bone healing through adjusting the content of bioactive ceramic (BC). The results indicated that, the 3D printed BC/PPG scaffold…

Development of mechanical characterization method of hydrogel scaffolds using synchrotron propagation-based imaging

University of Saskatchewan 2023 Thesis
N. Li

Hydrogel-based scaffolds have been widely used in soft tissue regeneration due to their biocompatible and tissue-like environment for maintaining cellular functions and tissue regeneration. Understanding the mechanical properties and internal microstructure of hydrogel-based scaffold, once implanted, is imperative in many tissue engineering applications and longitude studies. Notably, this has been challenging to date as various conventional characterization methods by, for example, mechanical testing (for mechanical properties) and microscope (for internal microstructure) are destructive as they require removing scaffolds from the implantation site and processing samples for characterization. Synchrotron propagation-based imaging – computed tomography (PBI-CT) is feasible and promising for non-destructive…

Alginate Gelatin

Switch-on mode of bioenergetic channels regulated by curcumin-loaded 3D composite scaffold to steer bone regeneration

Chemical Engineering Journal 2023 Volume 452, Part 1, Article 139165

Metabolic energy to steer osteoblastic differentiation of bone marrow mesenchymal stem cells (BMSCs) could be a promising therapeutic target for bone tissue engineering (BTE), but prior knowledge of this issue is limited. To address bone defects with BTE, we customized a three-dimensional (3D)-printed composite scaffold (Cur@MS) to allow the controlled release of curcumin, which could facilitate the “switch-on” mode of Glucose transporter 1 (GLUT1) in BMSCs. Consequently, bioenergetic channels, i.e. glucose uptake, were “switched on” to activate GLUT1-RUNX2 crosstalk, which was closely orchestrated with bone regeneration. Furthermore, curcumin-induced cholesterol/lipid raft (Cho/LR) was a “sensor” to trigger the “switch” (GLUT1) by…

Carboxymethyl cellulose-agarose-gelatin: A thermoresponsive triad bioink composition to fabricate volumetric soft tissue constructs

SLAS Technology 2023 Volume 28, Issue 3, Pages 183–198

Polysaccharide based hydrogels have been predominantly utilized as ink materials for 3D bioprinting due to biocompatibility and cell responsive features. However, most hydrogels require extensive crosslinking due to poor mechanical properties leading to limited printability. To improve printability without using cytotoxic crosslinkers, thermoresponsive bioinks could be developed. Agarose is a thermoresponsive polysaccharide with upper critical solution temperature (UCST) for sol-gel transition at 35–37 °C. Therefore, we hypothesized that a triad of carboxymethyl cellulose(C)–agarose(A)–gelatin(G) could be a suitable thermoresponsive ink for printing since they undergo instantaneous gelation without any addition of crosslinkers after bioprinting. The blend of agarose-carboxymethyl cellulose was mixed with…

Optimization of the modular reinforced bone scaffold for customized alveolar bone defects

Materials Letters 2023 Volume 331, Article 133413

A modular reinforced bone scaffold with enhanced mechanical properties has recently been developed by our group. It includes: 1) A load-bearing module: a skeleton which is made of a slowly degradable material, undertaking mechanical necessities of the scaffold, and 2) A bio-reactive module: a porous and biodegradable component undertaking biological necessities of the scaffold. The load-bearing module is placed into the bio-reactive module to reinforce it. This paper is dedicated to optimizing the load-bearing module for a certain customized alveolar bone defect. More specifically, a 3D-printed skeleton, made of polycaprolactone (PCL), is optimized based on the boundary conditions of the…

A self-healing nanocomposite double network bacterial nanocellulose/gelatin hydrogel for three dimensional printing

Carbohydrate Polymers 2023 Volume 313, Article 120879

Extrusion-based three-dimensional (3D) printing of gelatin is important for additive manufactured tissue engineering scaffolds, but gelatin’s thermal instability has remained an ongoing challenge. The gelatin tends to suddenly collapse at mild temperatures, which is a significant limitation for using it at physiological temperature of 37 °C. Hence, fabrication of a thermo-processable gelatin hydrogel adapted for extrusion-based additive manufacturing is still a challenge. To achieve this, a self-healing nanocomposite double-network (ncDN) gelatin hydrogel was fabricated with high thermo-processability, shear-thinning, mechanical strength, self-healing, self-recovery, and biocompatibility. To do this, amino group-rich gelatin was first created by combining gelatin with carboxyl methyl chitosan.…

Enhanced bone regeneration by low-intensity pulsed ultrasound and lipid microbubbles on PLGA/TCP 3D-printed scaffolds

BMC Biotechnology 2023 Volume 23, Article 13

Background To investigate the effect of low-intensity pulsed ultrasound (LIPUS) combined with lipid microbubbles on the proliferation and bone regeneration of bone marrow mesenchymal stem cells (BMSCs) in poly (lactic-glycolic acid copolymer) (PLGA)/α-tricalcium phosphate (TCP) 3D-printed scaffolds. Methods BMSCs were irradiated with different LIPUS parameters and microbubble concentrations, and the best acoustic excitation parameters were selected. The expression of type I collagen and the activity of alkaline phosphatase were detected. Alizarin red staining was used to evaluate the calcium salt production during osteogenic differentiation. Results BMSCs proliferation was the most significant under the condition of 0.5% (v/v) lipid microbubble concentration,…

3D-bioprinting of aortic valve interstitial cells: impact of hydrogel and printing parameters on cell viability

Biomedical Materials 2023 Volume 18, Article 015004

Calcific aortic valve disease (CAVD) is a frequent cardiac pathology in the aging society. Although valvular interstitial cells (VICs) seem to play a crucial role, mechanisms of CAVD are not fully understood. Development of tissue-engineered cellular models by 3D-bioprinting may help to further investigate underlying mechanisms of CAVD. VIC were isolated from ovine aortic valves and cultured in Dulbecco’s modified Eagle’s Medium (DMEM). VIC of passages six to ten were dissolved in a hydrogel consisting of 2% alginate and 8% gelatin with a concentration of 2 × 106 VIC ml−1. Cell-free and VIC-laden hydrogels were printed with an extrusion-based 3D-bioprinter…

3D printing-based full-scale human brain for diverse applications

Brain-X 2023 Volume 1, Issue 1, Article e5

Surgery is the most frequent treatment for patients with brain tumors. The construction of full-scale human brain models, which is still challenging to realize via current manufacturing techniques, can effectively train surgeons before brain tumor surgeries. This paper aims to develop a set of three-dimensional (3D) printing approaches to fabricate customized full-scale human brain models for surgery training as well as specialized brain patches for wound healing after surgery. First, a brain patch designed to fit a wound’s shape and size can be easily printed in and collected from a stimuli-responsive yield-stress support bath. Then, an inverse 3D printing strategy,…

Evaluation of Bioprinting Process by RSM Training

International Symposium on Industrial Engineering and Automation 2023 Pages 523-533

Bioprinting is one of the newest but mostly studied additive manufacturing processes of the last decade. Despite the huge amount of literature on this topic, a huge amount of aspects still have to be fully investigated. Precisely, each 3D printing process is characterized by a low stability and difficult replicability, in relation to conventional processes. For this reason, research on process control and optimization is one of the trending aspects nowadays. In this work, the Response Surface Methodology (RSM) approach is applied to 3D printing of hydrogel for biomedical applications and specifically of biocompatible hydrogels for cell-laden direct bioprinting purposes.…

Alginate Gelatin

Low-density tissue scaffold imaging by synchrotron radiation propagation-based imaging computed tomography with helical acquisition mode

Journal of Synchrotron Radiation 2023 Volume 30, Pages 417-429

Visualization of low-density tissue scaffolds made from hydro­gels is important yet challenging in tissue engineering and regenerative medicine (TERM). For this, synchrotron radiation propagation-based imaging computed tomography (SR-PBI-CT) has great potential, but is limited due to the ring artifacts commonly observed in SR-PBI-CT images. To address this issue, this study focuses on the integration of SR-PBI-CT and helical acquisition mode (i.e. SR-PBI-HCT) to visualize hydro­gel scaffolds. The influence of key imaging parameters on the image quality of hydro­gel scaffolds was investigated, including the helical pitch (p), photon energy (E) and the number of acquisition projections per rotation/revolution (Np), and, on…

3D-Printed Soft Membrane for Periodontal Guided Tissue Regeneration

Materials 2023 Volume 16, Issue 4, Article 1364

Objectives: The current study aimed to perform an in vivo examination using a critical-size periodontal canine model to investigate the capability of a 3D-printed soft membrane for guided tissue regeneration (GTR). This membrane is made of a specific composition of gelatin, elastin, and sodium hyaluronate that was fine-tuned and fully characterized in vitro in our previous study. The value of this composition is its potential to be employed as a suitable replacement for collagen, which is the main component of conventional GTR membranes, to overcome the cost issue with collagen. Methods: Critical-size dehiscence defects were surgically created on the buccal…

3D bioprinting optimization of human mesenchymal stromal cell laden gelatin-alginate-collagen bioink

Biomedical Materials 2022 Volume 18, Article 015016

3D bioprinting technology has gained increased attention in the regenerative medicine and tissue engineering communities over the past decade with their attempts to create functional living tissues and organs de novo. While tissues such as skin, bone, and cartilage have been successfully fabricated using 3D bioprinting, there are still many technical and process driven challenges that must be overcome before a complete tissue engineered solution is realized. Although there may never be a single adopted bioprinting process in the scientific community, adherence to optimized bioprinting protocols could reduce variability and improve precision with the goal of ensuring high quality printed…

Development of a modular reinforced bone tissue engineering scaffold with enhanced mechanical properties

Materials Letters 2022 Volume 318, Article 132170

A modular design composed of 3D-printed polycaprolactone (PCL) as the load-bearing module, and dual porosity gelatin foam as the bio-reactive module, was developed and characterized in this study. Surface treatment of the PCL module through aminolysis-aldehyde process was found to yield a stronger interface bonding compared to NaOH hydrolysis, and therefore was used in the fabrication procedure. The modular scaffold was shown to significantly improve the mechanical properties of the gelatin foam. Both compressive modulus and ultimate strength was found to increase over 10 times when the modular design was employed. The bio-reactive module i.e., gelatin foam, presented a dual…

3D bioprinting of multilayered scaffolds with spatially differentiated ADMSCs for rotator cuff tendon-to-bone interface regeneration

Applied Materials Today 2022 Volume 27, Article 101510

Regeneration of the gradient structure of the tendon-to-bone interface is still a significant clinical challenge. This study reports a novel therapeutic method combining three-dimensional (3D) bioprinting and melt electrospinning writing techniques to regenerate a functional tendon-to-bone interface. We generated biomimetic multilayered scaffolds with 3D-bioprinted pre-differentiated autologous adipose-derived mesenchymal stem cells (ADMSC), which recapitulated compositional and cellular structures of the interface. The hydrogel-based bioinks offered high cell viability and proliferative capability for rabbit ADMSCs. The hydrogels with pre-differentiated (into tenogenic, chondrogenic, and osteogenic lineages) or undifferentiated rabbit ADMSCs were 3D-bioprinted into zonal-specific constructs to mimic the structure of the tendon-to-bone interface.…

An Oral 3D Printed PLGA-Tocopherol PEG Succinate Nanocomposite Hydrogel for High-Dose Methotrexate Delivery in Maintenance Chemotherapy

Biomedicines 2022 Volume 10, Issue 7, Article 1470

High-dose methotrexate (HDMTX) is one of the chemotherapeutic agents used to treat a variety of cancers in both adults and children. However, the toxicity associated with HDMTX has resulted in the spread of infections and treatment interruption. Further, poor bioavailability due to efflux pump activities mediated by P-glycoprotein has also been linked to poor therapeutic effects of methotrexate following oral administrations. D-α-Tocopheryl poly-ethylene glycol 1000 succinate (TPGS) is known to improve the bioavailability of poorly soluble drugs by inhibiting P-gp efflux activities, thus enhancing cellular uptake. Therefore, to achieve improved bioavailability for MTX, this study aimed to design and develop…

Three-Dimensional Bio-Printed Cardiac Patch for Sustained Delivery of Extracellular Vesicles from the Interface

Gels 2022 Volume 8, Issue 12, Article 769

Cardiac tissue engineering has emerged as a promising strategy to treat infarcted cardiac tissues by replacing the injured region with an ex vivo fabricated functional cardiac patch. Nevertheless, integration of the transplanted patch with the host tissue is still a burden, limiting its clinical application. Here, a bi-functional, 3D bio-printed cardiac patch (CP) design is proposed, composed of a cell-laden compartment at its core and an extracellular vesicle (EV)-laden compartment at its shell for better integration of the CP with the host tissue. Alginate-based bioink solutions were developed for each compartment and characterized rheologically, examined for printability and their effect…

3D printing of gelatin/chitosan biodegradable hybrid hydrogel: Critical issues due to the crosslinking reaction, degradation phenomena and process parameters

Bioprinting 2021 Volume 24, Article e00170

Hydrogel materials are being investigated for application as scaffolds in tissue engineering owing to their many advantages, such as high water content, softness and flexibility similar to many soft tissues, tuneable physical, chemical, and biological properties, excellent biocompatibility and biodegradability, and extensive framework for cell proliferation and survival. During the past decade, because of the great versatility offered in terms of processing approach, material selection, and customization, 3D printing has become a leading technology used to fabricate hydrogel scaffolds. Furthermore, high reproducibility and unparalleled control over structural and compositional characteristics make additive manufacturing the preferred technology for the fabrication of…

Biologically Enhanced Starch Bio-Ink for Promoting 3D Cell Growth

Advanced Materials Technologies 2021 Volue 6, Issue 12, Article 2100551

The excellent rheological property has legitimated the suitability of starch hydrogel for extrusion-based 3D printing. However, the inability to promote cell attachment and migration has precluded the non-modified starch hydrogel from direct applications in the biomedical field. Herein, a novel 3D printable nanocomposite starch hydrogel is developed with highly enhanced biocompatibility for promoting 3D cell growth, by formulating with gelatin nanoparticles and collagen. The rheological evaluation reveals the shear-thinning and thixotropic properties of the starch-based hydrogel, as well as the combinatorial effect of collagen and gelatin nanoparticles on maintaining printability and 3D shape fidelity. The homogeneous microporous structure with abundant…

Tunable Microgel-Templated Porogel (MTP) Bioink for 3D Bioprinting Applications

Advanced Healthcare Materials 2022 Volume 11, Issue 8, Article 2200027

Micropores are essential for tissue engineering to ensure adequate mass transportation for embedded cells. Despite the considerable progress made by advanced 3D bioprinting technologies, it remains challenging to engineer micropores of 100 µm or smaller in cell-laden constructs. Here, a microgel-templated porogel (MTP) bioink platform is reported to introduce controlled microporosity in 3D bioprinted hydrogels in the presence of living cells. Templated gelatin microgels are fabricated with varied sizes (≈10, ≈45, and ≈100 µm) and mixed with photo-crosslinkable formulations to make composite MTP bioinks. The addition of microgels significantly enhances the shear-thinning and self-healing viscoelastic properties and thus the printability of bioinks…

3D bioprinting of tissue units with mesenchymal stem cells, retaining their proliferative and differentiating potential, in polyphosphate-containing bio-ink

Biofabrication 2022 Volume 14, Number 1, Article 015016

The three-dimensional (3D)-printing processes reach increasing recognition as important fabrication techniques to meet the growing demands in tissue engineering. However, it is imperative to fabricate 3D tissue units, which contain cells that have the property to be regeneratively active. In most bio-inks, a metabolic energy-providing component is missing. Here a formulation of a bio-ink is described, which is enriched with polyphosphate (polyP), a metabolic energy providing physiological polymer. The bio-ink composed of a scaffold (N,O-carboxymethyl chitosan), a hydrogel (alginate) and a cell adhesion matrix (gelatin) as well as polyP substantially increases the viability and the migration propensity of mesenchymal stem…

3D printed gelatin-genipin scaffolds for temporomandibular joint cartilage regeneration

Biomedical Physics & Engineering Express 2021 Volume 7, Number 5, Article 055025

Gelatin has emerged as a biocompatible polymer with high printability in scaffold-based tissue engineering. The aim of the current study was to investigate the potential of genipin-crosslinked 3D printed gelatin scaffolds for temporomandibular joint (TMJ) cartilage regeneration. Crosslinking with genipin increased the stability and mechanical properties, without any cytotoxic effects. Chondrogenic differentiation of human bone marrow-derived mesenchymal stem cells (hBMSC) on the scaffolds were compared to cell pellets and spheres. Although hBMSC seeded scaffolds showed a lower expression of chondrogenesis-related genes compared to cell pellets and spheres, they demonstrated a significantly reduced expression of collagen (COL) 10, suggesting a decreased…

3D-Printing Biodegradable PU/PAAM/Gel Hydrogel Scaffold with High Flexibility and Self-Adaptibility to Irregular Defects for Nonload-Bearing Bone Regeneration

Bioconjugate Chemistry 2021 Volume 32, Issue 8, Pages 1915-1925

A three-dimensional (3D) printed biodegradable hydrogel scaffold with a strong self-expanding ability to conform to the contour of irregular bone defects and be closely adjacent to host tissues is reported herein. The scaffold has a triple cross-linked network structure consisting of photo-cross-linked polyacrylamide (PAAM) and polyurethane (PU) as the primary IPN network and chemical cross-linked gelatin (Gel) as the secondary network, which confers the scaffold with good mechanical properties. The addition of PU in the polymerization process of acrylamide (AAM) can improve the ultraviolet (UV) photocuring efficiency of the hydrogel and incorporate abundant hydrogen bonds between the PAAM copolymer chain…

Novel Perspectives in Non-Invasive Diagnosis of Ailments through Analysis of Mechanical Wave Motion

Doctoral Thesis 2021 University of Illinois at Chicago
H. Palnitkar

The central theme of this dissertation is the observation that mechanical waves propagate and scatter at different velocities in biological tissues due to a difference in local material properties (such as viscosity and stiffness), due to the presence of inhomogeneities such as a blood vessel, an axon or a muscle filament. These scattered waves contain information about the characteristic stiffness, viscosity and the mechanical property inhomogeneity of the tissues through which they propagate; this information can aid in non-invasive diagnosis of disease and injury using novel quantitative techniques such as Insonification, Percussion and 1-Norm using Magnetic Resonance Elastography (MRE). The…

Development of bioinks for 3D printing microporous, sintered calcium phosphate scaffolds

Tissue Engineering Constructs and Cell Substrates 2021 Volume 32, Article number: 94

Beta-tricalcium phosphate (β-TCP)-based bioinks were developed to support direct-ink 3D printing-based manufacturing of macroporous scaffolds. Binding of the gelatin:β-TCP ink compositions was optimized by adding carboxymethylcellulose (CMC) to maximize the β-TCP content while maintaining printability. Post-sintering, the gelatin:β-TCP:CMC inks resulted in uniform grain size, uniform shrinkage of the printed structure, and included microporosity within the ceramic. The mechanical properties of the inks improved with increasing β-TCP content. The gelatin:β-TCP:CMC ink (25:75 gelatin:β-TCP and 3% CMC) optimized for mechanical strength was used to 3D print several architectures of macroporous scaffolds by varying the print nozzle tip diameter and pore spacing during…

Microengineered perfusable 3D-bioprinted glioblastoma model for in vivo mimicry of tumor microenvironment

Science Advances 2021 Volume 7, Issue 34, Article eabi9119

Many drugs show promising results in laboratory research but eventually fail clinical trials. We hypothesize that one main reason for this translational gap is that current cancer models are inadequate. Most models lack the tumor-stroma interactions, which are essential for proper representation of cancer complexed biology. Therefore, we recapitulated the tumor heterogenic microenvironment by creating fibrin glioblastoma bioink consisting of patient-derived glioblastoma cells, astrocytes, and microglia. In addition, perfusable blood vessels were created using a sacrificial bioink coated with brain pericytes and endothelial cells. We observed similar growth curves, drug response, and genetic signature of glioblastoma cells grown in our…

MicroRNA-activated hydrogel scaffold generated by 3D printing accelerates bone regeneration

Bioactive Materials 2022 Volume 10, Pages 1-14

Bone defects remain a major threat to human health and bone tissue regeneration has become a prominent clinical demand worldwide. The combination of microRNA (miRNA) therapy with 3D printed scaffolds has always posed a challenge. It can mimic physiological bone healing processes, in which a biodegradable scaffold is gradually replaced by neo-tissue, and the sustained release of miRNA plays a vital role in creating an optimal osteogenic microenvironment, thus achieving promising bone repair outcomes. However, the balance between two key factors – scaffold degradation behavior and miRNA release profile – on osteogenesis and bone formation is still poorly understood. Herein,…

Spatial alignment of 3D printed scaffolds modulates genotypic expression in pre-osteoblasts

Materials Letters 2020 Volume 276, Article 128189

3D printing, an advent from rapid prototyping technology is emerging as a suitable solution for various regenerative engineering applications. In this study, blended gelatin-sodium alginate 3D printed scaffolds with different pore geometries were developed by altering the spatial alignment of even layered struts in the scaffolds. A significant difference in compression modulus and osteogenic expression due to the difference in spatial printing was demonstrated. Pore geometry was found to be more dominant than the compressive modulus of the scaffold in regulating osteogenic gene expression. A shift in pore geometry by at least 45° was critical for significant increase in osteogenic…

The performance of 3D bioscaffolding based on a human periodontal ligament stem cell printing technique

Journal of Biomedical Materials Research Part A 2021 Volume 109, Issue 7, Pages 1209-1219

Bone tissue plays an important role in supporting and protecting the structure and function of the human body. Bone defects are a common source of injury and there are many reconstruction challenges in clinical practice. However, 3D bioprinting of scaffolds provides a promising solution. Hydrogels have emerged as biomaterials with good biocompatibility and are now widely used as cell-loaded materials for bioprinting. This study involved three steps: First, sodium alginate (SA), gelatin (Gel), and nano-hydroxyapatite (na-HA) were mixed into a hydrogel and its rheological properties assessed to identify the optimum slurry for printing. Second, SA/Gel/na-HA bioscaffolds were printed using 3D…

Dual-crosslinked 3D printed gelatin scaffolds with potential for temporomandibular joint cartilage regeneration

Biomedical Materials 2021 Volume 16, Number 3, Article 035026

A promising alternative to current treatment options for degenerative conditions of the temporomandibular joint (TMJ) is cartilage tissue engineering, using 3D printed scaffolds and mesenchymal stem cells. Gelatin, with its inherent biocompatibility and printability has been proposed as a scaffold biomaterial, but because of its thermoreversible properties, rapid degradation and inadequate strength it must be crosslinked to be stable in physiological conditions. The aim of this study was to identify non-toxic and effective crosslinking methods intended to improve the physical properties of 3D printed gelatin scaffolds for cartilage regeneration. Dehydrothermal (DHT), ribose glycation and dual crosslinking with both DHT and…

Hierarchical patterning via dynamic sacrificial printing of stimuli-responsive hydrogels

Biofabrication 2020 Volume 12, Number 3, Article 035007

Inspired by stimuli-tailored dynamic processes that spatiotemporally create structural and functional diversity in biology, a new hierarchical patterning strategy is proposed to induce the emergence of complex multidimensional structures via dynamic sacrificial printing of stimuli-responsive hydrogels. Using thermally responsive gelatin (Gel) and pH-responsive chitosan (Chit) as proof-of-concept materials, we demonstrate that the initially printed sacrificial material (Gel/Chit-H+ hydrogel with a single gelatin network) can be converted dynamically into non-sacrificial material (Gel/Chit-H+–Citr hydrogel with gelatin and an electrostatic citrate–chitosan dual network) under stimulus cues (citrate ions). Complex hierarchical structures and functions can be created by controlling either the printing patterns of…

A powerful combination in designing polymeric scaffolds: 3D bioprinting and cryogelation

International Journal of Polymeric Materials and Polymeric Biomaterials 2020 Volume 71, Issue 4, Pages 278-290

Three-dimensional (3D) bioprinting technologies have great attention in different researching areas such as tissue engineering, medicine, etc. due to its maximum mimetic property of natural biomaterials by providing cell combination, growth factors, and other biomaterials. Bioprinting of tissues, organs, or drug delivery systems emerged layer-by-layer deposition of bioinks. 3D bioprinting technique has some complexity such as choice of bioink combination, cell type, growth, and differentiation. In this study, a composite material in 3D bioprinting studies has been developed for biofabrication of the cell carrying scaffolds namely cryogenic scaffolds. Cryogenic scaffolds are highly elastic and have a continuous interconnected macroporous structure…

Bioprinting and In Vitro Characterization of an Egg White-Based Cardiac Patch for Myocardial Infarction

University of Saskatchewan 2021 Dissertation
Y. Delkash

Myocardial infarction (MI) or heart attack occurs when the bloodstream to the heart is blocked, which may destroy a part of the heart muscle (or myocardium) and form perdurable scarred tissue. The infarcted myocardial muscle nowadays has no revival treatments, and also transplantation is limited as an option. Tissue engineering has the potential to restore myocardial function after an MI by fabricating tailored tissues for treatment. For tissue engineering, three-dimensional (3D) bioprinting is a fabrication method to create 3D constructs with living cells, which would be impossible by other traditional methods. Although various biomaterials, biologically-derived or synthetic, are available, only…

A 3D printed graphene electrode device for enhanced and scalable stem cell culture, osteoinduction and tissue building

Materials & Design 2021 Volume 201, Article 109473

Bone related diseases and disorders increasingly impact human health. Electrical stimulation (ES) has been shown to promote osteogenesis and healing of bone defects. Graphene, is an electrically conductive and biocompatible material with good mechanical properties (strength with flexibility), and therefore shows significant promise as a cell-compatible electrode for ES. Graphene-based scaffolds may therefore be used for 3D cell and tissue support, including 3D osteoinduction. We have fabricated 3D graphene electrode structures to provide ES to human adipose stem cells (ADSCs). The assemblies support ADSC growth and differentiation, with ES augmenting proliferation and osteogenesis. Our findings expand our previous work on…

Three-dimensional biofabrication of an aragonite-enriched self-hardening bone graft substitute and assessment of its osteogenicity in vitro and in vivo

Biomaterials Translational 2020 Volume 1, Issue 1, Pages 69-81

A self-hardening three-dimensional (3D)-porous composite bone graft consisting of 65 wt% hydroxyapatite (HA) and 35 wt% aragonite was fabricated using a 3D-Bioplotter®. New tetracalcium phosphate and dicalcium phosphate anhydrous/aragonite/gelatine paste formulae were developed to overcome the phase separation of the liquid and solid components. The mechanical properties, porosity, height and width stability of the end products were optimised through a systematic analysis of the fabrication processing parameters including printing pressure, printing speed and distance between strands. The resulting 3D-printed bone graft was confirmed to be a mixture of HA and aragonite by X-ray diffraction, Fourier transform infrared spectroscopy and energy…

A tri-component knee plug for the 3rd generation of autologous chondrocyte implantation

Scientific Reports 2020 Volume 10, Article number: 17048

Here, we report a newly designed knee plug to be used in the 3rd generation of Autologous Chondrocyte Implantation (ACI) in order to heal the damaged knee cartilage. It is composed of three components: The first component (Bone Portion) is a 3D printed hard scaffold with large pores (~ 850 µm), made by hydroxyapatite and β-tricalcium phosphate to accommodate the bony parts underneath the knee cartilage. It is a cylinder with a diameter of 20 mm and height of 7.5 mm, with a slight dome shape on top. The plug also comprises a Cartilage Portion (component 2) which is a 3D…

Three dimensional printed bioglass/gelatin/alginate composite scaffolds with promoted mechanical strength, biomineralization, cell responses and osteogenesis

Journal of Materials Science: Materials in Medicine 2020 Volume 31, Article 77

In this study, porous bioglass/gelatin/alginate bone tissue engineering scaffolds were fabricated by three-dimensional printing. The compressive strength and in vitro biomineralization properties of the bioglass–gelatin–alginate scaffolds (BG/Gel/SA scaffolds) were significantly improved with the increase of bioglass content until 30% weight percentage followed by a rapid decline in strength. In addition, the cells attach and spread on the BG/Gel/SA scaffolds surfaces represents good adhesion and biocompatibility. Furthermore, the cells (rat bone marrow mesenchymal stem cells, mBMSCs) proliferation and osteogenic differentiation on the BG/Gel/SA scaffolds were also promoted with the increase of bioglass content. Overall, the adding of bioglass in Gel/SA scaffolds…

Expanding and optimizing 3D bioprinting capabilities using complementary network bioinks

Science Advances 2020 Volume 6, Article eabc5529

A major challenge in three-dimensional (3D) bioprinting is the limited number of bioinks that fulfill the physicochemical requirements of printing while also providing a desirable environment for encapsulated cells. Here, we address this limitation by temporarily stabilizing bioinks with a complementary thermo-reversible gelatin network. This strategy enables the effective printing of biomaterials that would typically not meet printing requirements, with instrument parameters and structural output largely independent of the base biomaterial. This approach is demonstrated across a library of photocrosslinkable bioinks derived from natural and synthetic polymers, including gelatin, hyaluronic acid, chondroitin sulfate, dextran, alginate, chitosan, heparin, and poly(ethylene glycol).…

Bioprinting and in vitro characterization of alginate dialdehyde–gelatin hydrogel bio-ink

Bio-Design and Manufacturing 2020 Volume 3, Pages 48–59

Cell-laden cardiac patches have recently been emerging to renew cellular sources for myocardial infarction (MI, commonly know as a heart attack) repair. However, the fabrication of cell-laden patches with porous structure remains challenging due to the limitations of currently available hydrogels and existing processing techniques. The present study utilized a bioprinting technique to fabricate hydrogel patches and characterize them in terms of printability, mechanical and biological properties. Cell-laden hydrogel (or bio-ink) was formulated from alginate dialdehyde (ADA) and gelatin (GEL) to improve the printability, degradability as well as bioactivity. Five groups of hydrogel compositions were designed to investigate the influence…

Three-dimensional printing of chemically crosslinked gelatin hydrogels for adipose tissue engineering

Biofabrication 2020 Volume 12, Number 2, Article 025001

Despite their outstanding potential and the success that has already been achieved with three-dimensional (3D) printed hydrogel scaffolds, there has been little investigation into their application in the regeneration of damaged or missing adipose tissue (AT). Due to their macroscopic shape, microarchitecture, extracellular matrix-mimicking structure, degradability and soft tissue biomimetic mechanical properties, 3D printed hydrogel scaffolds have great potential for use in aesthetic, structural and functional restoration of AT. Here, we propose a simple and cost-effective 3D printing strategy using gelatin-based ink to fabricate scaffolds suitable for AT engineering. The ink, successfully printed here for the first time, was prepared…

Experimental Investigation and Optimal 3D Bioprinting Parameters of SA-Gel Porous Cartilage Scaffold

Applied Sciences 2020 Volume 10, Article 768

The main aim of this paper is to achieve the suitable SA-GEL (sodium alginate and gelatin) porous cartilage scaffold by 3D printing technology with optimal prediction parameters. Firstly, the characteristics of SA-GEL were analyzed, the influence of calcium chloride on the gel was explored, and the optimal cross-linking concentration and gelation temperature were determined. Secondly, a prediction model of the extrusion line width of SA-GEL was established, in which the printing pressure, the moving speed of the needle and the fiber interval were the important parameters affecting the printing performance of the SA-GEL composite material. Thirdly, the SA-GEL composite scaffolds…

3D printable Polycaprolactone-gelatin blends characterized for in vitro osteogenic potency

Reactive and Functional Polymers 2020 Volume 146, Article 104445

Synthetic polycaprolactone (PCL) was modified with various concentrations of gelatin (GL) to enhance its physical properties and biological activity for bone regeneration. A novel trisolvent mixture has been used to mix PCL and GL that were fabricated as scaffolds using 3D plotting. The scaffolds were characterized for their mechanical properties, hydrophilicity and swelling ability. In addition, the structure and morphology of the printed scaffolds were analyzed by Fourier-Transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and microcomputed tomography (μCT). Attachment, proliferation and osteogenic differentiation of rat bone marrow stromal cells (BMSC) cultured on the printed scaffolds were…

Double dynamic cellulose nanocomposite hydrogels with environmentally adaptive self-healing and pH-tuning properties

Cellulose 2020 Volume 27, Pages 1407–1422

Dynamic hydrogels are prepared by either dynamic covalent bonds or supramolecular chemistry. Herein, we develop a dynamic hydrogel by combining both dynamic covalent bonds and supramolecular chemistry that exhibits environmentally adaptive self-healing and pH-tuning properties. To do so, we prepared a gelatin–nanopolysaccharide mixed hydrogel containing pyrogallol/catechol groups and trivalent metal ions. The as-prepared hydrogels are able to heal damage inflicted on them under acidic (pH 3 and 6), neutral (pH 7), and basic (pH 9) environments. The mechanism of healing at acidic and neutral pHs is dominated by coordination bonds between pyrogallol/catechol groups of tannic acid and ferric ions, whilst…

Printability of 3D Printed Hydrogel Scaffolds: Influence of Hydrogel Composition and Printing Parameters

Applied Sciences 2020 Volume 10, Issue 1, Article 292

Extrusion-based bioprinting of hydrogel scaffolds is challenging due to printing-related issues, such as the lack of capability to precisely print or deposit hydrogels onto three-dimensional (3D) scaffolds as designed. Printability is an index to measure the difference between the designed and fabricated scaffold in the printing process, which, however, is still under-explored. While studies have been reported on printing hydrogel scaffolds from one or more hydrogels, there is limited knowledge on the printability of hydrogels and their printing processes. This paper presented our study on the printability of 3D printed hydrogel scaffolds, with a focus on identifying the influence of…

Void‐Free 3D Bioprinting for In Situ Endothelialization and Microfluidic Perfusion

Advanced Functional Materials 2020 Volume 30, Issue 1, Article 1908349

Two major challenges of 3D bioprinting are the retention of structural fidelity and efficient endothelialization for tissue vascularization. Both of these issues are addressed by introducing a versatile 3D bioprinting strategy, in which a templating bioink is deposited layer‐by‐layer alongside a matrix bioink to establish void‐free multimaterial structures. After crosslinking the matrix phase, the templating phase is sacrificed to create a well‐defined 3D network of interconnected tubular channels. This void‐free 3D printing (VF‐3DP) approach circumvents the traditional concerns of structural collapse, deformation, and oxygen inhibition, moreover, it can be readily used to print materials that are widely considered “unprintable.” By…

3D printing of silk fibroin-based hybrid scaffold treated with platelet rich plasma for bone tissue engineering

Bioactive Materials 2019 Volume 4, Pages 256-260

3D printing/bioprinting are promising techniques to fabricate scaffolds with well controlled and patient-specific structures and architectures for bone tissue engineering. In this study, we developed a composite bioink consisting of silk fibroin (SF), gelatin (GEL), hyaluronic acid (HA), and tricalcium phosphate (TCP) and 3D bioprinted the silk fibroin-based hybrid scaffolds. The 3D bioprinted scaffolds with dual crosslinking were further treated with human platelet-rich plasma (PRP) to generate PRP coated scaffolds. Live/Dead and MTT assays demonstrated that PRP treatment could obviously promote the cell growth and proliferation of human adipose derived mesenchymal stem cells (HADMSC). In addition, the treatment of PRP…

Design of a new 3D‐printed joint plug

Asia‐Pacific Journal of Chemical Engineering 2019 Volume 14, Issue 6, Article e2360

This paper introduces a kit of parts as a novel three‐dimensional (3D)–printed joint plug, in which each of the parts function cooperatively to treat cartilage damage in joints of the human body (e.g., hips, wrists, elbow, knee, and ankle). Three required and one optional parts are involved in this plug. The first part is a 3D‐printed hard scaffold (bone portion) to accommodate bone cells, and the second is a 3D‐printed soft scaffold (cartilage portion) overlying the bone portion to accommodate chondrocytes. The third part of joint plug is a permeable membrane, termed film, to cover the entire plug to provide…

Employing PEG crosslinkers to optimize cell viability in gel phase bioinks and tailor post printing mechanical properties

Acta Biomaterialia 2019 Volume 99, Pages 121-132

The field of 3D bioprinting has rapidly grown, yet the fundamental ability to manipulate material properties has been challenging with current bioink methods. Here, we change bioink properties using our PEG cross-linking (PEGX) bioink method with the objective of optimizing cell viability while retaining control of mechanical properties of the final bioprinted construct. First, we investigate cytocompatible, covalent cross-linking chemistries for bioink synthesis (e.g. Thiol Michael type addition and bioorthogonal inverse electron demand Diels-Alder reaction). We demonstrate these reactions are compatible with the bioink method, which results in high cell viability. The PEGX method is then exploited to optimize extruded…

3D printed HUVECs/MSCs cocultures impact cellular interactions and angiogenesis depending on cell-cell distance

Biomaterials 2019 Volume 222, Article 119423

Vascularization is a crucial process during the growth and development of bone 1, yet it remains one of the main challenges in the reconstruction of large bone defects. The use of in vitro coculture of human umbilical vein endothelial cells (HUVECs) and human mesenchymal stem cells (hMSCs) has been one of the most explored options. Both cell types secrete specific growth factors that are mutually beneficial, and studies suggested that cell-cell communication and paracrine secretion could be affected by a number of factors. However, little is known about the effect of cell patterning and the distance between cell populations on…

An investigation into the relationship between inhomogeneity and wave shapes in phantoms and ex vivo skeletal muscle using Magnetic Resonance Elastography and finite element analysis

Journal of the Mechanical Behavior of Biomedical Materials 2019 Volume 98, Pages 108-120

Soft biological tissues such as skeletal muscle and brain white matter can be inhomogeneous and anisotropic due to the presence of fibers. Unlike biological tissue, phantoms with known microstructure and defined mechanical properties enable a quantitative assessment and systematic investigation of the influence of inhomogeneities on the nature of shear wave propagation. This study introduces a mathematical measure for the wave shape, which the authors call as the 1-Norm, to determine the conditions under which homogenization may be a valid approach. This is achieved through experimentation using the Magnetic Resonance Elastography technique on 3D printed inhomogeneous fiber phantoms as well…

Bacterial cellulose nanofibers promote stress and fidelity of 3D-printed silk based hydrogel scaffold with hierarchical pores

Carbohydrate Polymers 2019 Volume 221, Pages 146-156

One of the latest trends in the regenerative medicine is the development of 3D-printing hydrogel scaffolds with biomimetic structures for tissue regeneration and organ reconstruction. However, it has been practically difficult to achieve a highly biomimetic hydrogel scaffolds with proper mechanical properties matching the natural tissue. Here, bacterial cellulose nanofibers (BCNFs) were applied to improve the structural resolution and enhance mechanical properties of silk fibroin (SF)/gelatin composite hydrogel scaffolds. The SF-based hydrogel scaffolds with hierarchical pores were fabricated via 3D-printing followed by lyophilization. Results showed that the tensile strength of printed sample increased significantly with the addition of BCNFs in…

Carbon Nanodots Doped Super-paramagnetic Iron Oxide Nanoparticles for Multimodal Bioimaging and Osteochondral Tissue Regeneration via External Magnetic Actuation

ACS Biomaterials Science & Engineering 2019 Volume 5, Issue 7, Pages 3549-3560

Super-paramagnetic iron oxide nanoparticles (SPIONs) have multiple theranostics applications such as T2 contrast agent in magnetic resonance imaging (MRI) and electromagnetic manipulations in biomedical devices, sensors, and regenerative medicines. However, SPIONs suffer from the limitation of free radical generation, and this has a certain limitation in its applicability in tissue imaging and regeneration applications. In the current study, we developed a simple hydrothermal method to prepare carbon quantum dots (CD) doped SPIONs (FeCD) from easily available precursors. The nanoparticles are observed to be cytocompatible, hemocompatible, and capable of scavenging free radicals in vitro. They also have been observed to be…

Effects of 3-dimensional Bioprinting Alginate/ Gelatin Hydrogel Scaffold Extract on Proliferation and Differentiation of Human Dental Pulp Stem Cells

Journal of Endodontics 2019 Volume 45, Issue 6, Pages 706-715

Abrasive flow machining (AFM) is a nontraditional surface finishing method that finishes complex surface by pushing the abrasive media flow through the workpiece surface. The entrance effect that the material removal increases at the entrance of changing the cross-sectional flow channel is a difficult problem for AFM. In this paper, the effects of media rheological properties on the entrance effect are discussed. To explore the effects of the media’s viscoelasticity on the entrance effect, two sets of media with different viscoelasticity properties are adopted to study their rheological and machining performances in the designed flow channel with a contraction area.…

Printability and Cell Viability in Bioprinting Alginate Dialdehyde- Gelatin Scaffolds

ACS Biomaterials Science & Engineering 2019 Volume 5, Issue 6, Pages 2976-2987

Three-dimensional (3D) bioprinting is a promising technique used to fabricate scaffolds from hydrogels with living cells. However, the printability of hydrogels in bioprinting has not been adequately studied. The aim of this study was to quantitatively characterize the printability and cell viability of alginate dialdehyde (ADA)-gelatin (Gel) hydrogels for bioprinting. ADA-Gel hydrogels of various concentrations were synthesized and characterized using Fourier transform infrared spectroscopy, along with rheological tests for measuring storage and loss moduli. Scaffolds (with an area of 11 × 11 mm) of 1, 2, and 13 layers were fabricated from ADA-Gel hydrogels using a 3D-bioplotter under printing conditions…

Implantable Nanotube Sensor Platform for Rapid Analyte Detection

Macromolecular Bioscience 2019 Volume 19, Issue 6, Article 1800469

The use of nanoparticles within living systems is a growing field, but the long‐term effects of introducing nanoparticles to a biological system are unknown. If nanoparticles remain localized after in vivo implantation unanticipated side effects due to unknown biodistribution can be avoided. Unfortunately, stabilization and retention of nanoparticles frequently alters their function.1 In this work multiple hydrogel platforms are developed to look at long‐term localization of nanoparticle sensors with the goal of developing a sensor platform that will stabilize and localize the nanoparticles without altering their function. Two different hydrogel platforms are presented, one with a liquid core of sensors…

Indirect 3D bioprinting and characterization of alginate scaffolds for potential nerve tissue engineering applications

Journal of the Mechanical Behavior of Biomedical Materials 2019 Volume 93, Pages 183-193

Low-concentration hydrogels have favorable properties for many cell functions in tissue engineering but are considerably limited from a scaffold fabrication point of view due to poor three-dimensional (3D) printability. Here, we developed an indirect-bioprinting process for alginate scaffolds and characterized the potential of these scaffolds for nerve tissue engineering applications. The indirect-bioprinting process involves (1) printing a sacrificial framework from gelatin, (2) impregnating the framework with low-concentration alginate, and (3) removing the gelatin framework by an incubation process, thus forming low-concentration alginate scaffolds. The scaffolds were characterized by compression testing, swelling, degradation, and morphological and biological assessment of incorporated or…

Anisotropic composite material phantom to improve skeletal muscle characterization using magnetic resonance elastography

Journal of the Mechanical Behavior of Biomedical Materials 2019 Volume 89, Pages 199-208

The presence and progression of neuromuscular pathology, including spasticity, Duchenne’s muscular dystrophy and hyperthyroidism, has been correlated with changes in the intrinsic mechanical properties of skeletal muscle tissue. Tools for noninvasively measuring and monitoring these properties, such as Magnetic Resonance Elastography (MRE), could benefit basic research into understanding neuromuscular pathologies, as well as translational research to develop therapies, by providing a means of assessing and tracking their efficacy. Dynamic elastography methods for noninvasive measurement of tissue mechanical properties have been under development for nearly three decades. Much of the technological development to date, for both Ultrasound (US)-based and Magnetic Resonance…

Gelatin Imaging

Doping of Carbon Quantum Dots (CDs) in Calcium Phosphate Nanorods for Inducing Ectopic Chondrogenesis via Activation of the HIF-α/SOX‑9 Pathway

ACS Omega 2019 Volume 4, Issue 1, Pages 374-386

Calcium phosphate (CaPs)-based nanostructures are mostly known to induce osteogenic differentiation of mesenchymal stem cells (MSCs). However, in the current study, doping of carbon quantum dots into calcium phosphate nanorods (C-CaPs) has been observed to affect the differentiation pathway and enhanced the expression of chondrogenic genes instead of osteogenic ones. Here, we report a microwave-assisted single-step synthesis and doping of carbon dot into calcium phosphate nanorods and their ectopic chondrogenicity in a rodent subcutaneous model. High-resolution transmission electron microscopy, X-ray powder diffraction, and X-ray photoelectron spectroscopy studies show that the doping of carbon dots results in p-type semiconductor-like structure formation…

Anisotropic Composite Material Phantom Tested Using Magnetic Resonance Elastography

Proceedings of the Sixteenth International Tissue Elasticity Conference 2018 Page 22

Background: The presence and progression of neuromuscular pathologies, including spasticity, dystrophy and hyperthyroidism, have been correlated with changes in the intrinsic mechanical properties of skeletal muscle tissue. Tools of noninvasively measuring and monitoring these properties, such as Magnetic Resonance Elastography (MRE), could benefit basic research into understanding neuromuscular pathologies, as well as translational research to develop therapies, by providing a means of assessing and tracking their efficacy. While various approaches have been proposed in the literature [1,2], there is not yet an accepted standard for the identification of the mechanical properties of anisotropic and viscoelastic tissues through MRE; advances in…

Gelatin Imaging

Mechanically robust cryogels with injectability and bioprinting supportability for adipose tissue engineering

Acta Biomaterialia 2018 Volume 74, Pages 131-142

Bioengineered adipose tissues have gained increased interest as a promising alternative to autologous tissue flaps and synthetic adipose fillers for soft tissue augmentation and defect reconstruction in clinic. Although many scaffolding materials and biofabrication methods have been investigated for adipose tissue engineering in the last decades, there are still challenges to recapitulate the appropriate adipose tissue microenvironment, maintain volume stability, and induce vascularization to achieve long-term function and integration. In the present research, we fabricated cryogels consisting of methacrylated gelatin, methacrylated hyaluronic acid, and 4arm poly(ethylene glycol) acrylate (PEG-4A) by using cryopolymerization. The cryogels were repeatedly injectable and stretchable, and…

Stable gelatin-based phantom materials with tunable x-ray attenuation properties and 3D printability for x-ray imaging

Physics in Medicine & Biology 2018 Volume 63, Number 9, Article 09NT01

We report a novel method for developing gelatin-based phantom materials for transmission x-ray imaging with high stability at room temperature and tunable x-ray attenuation properties. This is achieved by efficiently cross-linking gelatin in a glycerin solution with only 10% water by volume and systematically decreasing their x-ray attenuation coefficients by doping with microbubbles that are originally designed to be used as lightweight additives for paints and crack fillers. For demonstration, we mimic breast glandular and adipose tissues by using such gelatin materials and also study the feasibility of 3D printing them based on the extrusion-based technique. Results from x-ray spectroscopy…

3D-printed thick structured gelatin membrane for engineering of heterogeneous tissues

Materials Letters 2018 Volume 217, Pages 39-43

Although biological membranes may look like a 2D assembly, they often have complex structures in their 3rd dimension. Using layer-by-layer assembly, 3D-printing can offer an advanced and unique approach for the fabrication of such models. However, printing of some widely used hydrogels, such as gelatin, encounters experimental difficulties due to their rheological properties. In this paper, we (a) discuss the complexities involved in printing gelatin, (b) offer a reproducible approach to overcome such difficulties, and (c) present the detailed design criteria and the production process of such 3D-printed gelatin membranes by exemplifying scaffolds suitable for growth of full-thickness oral mucosa…

3D-printed gelatin scaffolds of differing pore geometry modulate hepatocyte function and gene expression

Acta Biomaterialia 2018 Volume 69, Pages 63-70

Three dimensional (3D) printing is highly amenable to the fabrication of tissue-engineered organs of a repetitive microstructure such as the liver. The creation of uniform and geometrically repetitive tissue scaffolds can also allow for the control over cellular aggregation and nutrient diffusion. However, the effect of differing geometries, while controlling for pore size, has yet to be investigated in the context of hepatocyte function. In this study, we show the ability to precisely control pore geometry of 3D-printed gelatin scaffolds. An undifferentiated hepatocyte cell line (HUH7) demonstrated high viability and proliferation when seeded on 3D-printed scaffolds of two different geometries.…

Effects of tunable, 3D-bioprinted hydrogels on human brown adipocyte behavior and metabolic function

Acta Biomaterialia 2018 Volume 71, Pages 486-495

Obesity and its related health complications cause billions of dollars in healthcare costs annually in the United States, and there are yet to be safe and long-lasting anti-obesity approaches. Using brown adipose tissue (BAT) is a promising approach, as it uses fats for energy expenditure. However, the effect of the microenvironment on human thermogenic brown adipogenesis and how to generate clinically relevant sized and functioning BAT are still unknown. In our current study, we evaluated the effects of endothelial growth medium exposure on brown adipogenesis of human brown adipose progenitors (BAP). We found that pre-exposing BAP to angiogenic factors promoted…

[Gelatin/alginate hydrogel scaffolds prepared by 3D bioprinting promotes cell adhesion and proliferation of human dental pulp cells in vitro]

Nan Fang Yi Ke Da Xue Xue Bao (Journal of Southern Medical University) 2017 Volume 37, Issue 5, Pages 668-672

OBJECTIVE: To evaluate the cytotoxicity of gelatin/alginate hydrogel scaffolds prepared by 3D bioprinting in human dental pulp cells (HDPCs) and compare the cell adhesion and proliferation of the cells seeded in the biomaterial using two different methods. METHODS: HDPCs isolated by tissue block culture and enzyme digestion were cultured and passaged. Gelatin/alginate hydrogel scaffolds were printed using a bioplotter, and the cytotoxicity of the aqueous extracts of the scaffold material was tested in the third passage of HDPCs using cell counting kit-8. Scanning electron microscopy and trypan blue were used to assess the adhesion and proliferation of the cells seeded…

A bioprosthetic ovary created using 3D printed microporous scaffolds restores ovarian function in sterilized mice

Nature Communications 2017 Volume 88, Article number 15261

Emerging additive manufacturing techniques enable investigation of the effects of pore geometry on cell behavior and function. Here, we 3D print microporous hydrogel scaffolds to test how varying pore geometry, accomplished by manipulating the advancing angle between printed layers, affects the survival of ovarian follicles. 30° and 60° scaffolds provide corners that surround follicles on multiple sides while 90° scaffolds have an open porosity that limits follicle–scaffold interaction. As the amount of scaffold interaction increases, follicle spreading is limited and survival increases. Follicle-seeded scaffolds become highly vascularized and ovarian function is fully restored when implanted in surgically sterilized mice. Moreover,…

Osteogenic Differentiation of Three-Dimensional Bioprinted Constructs Consisting of Human Adipose-Derived Stem Cells In Vitro and In Vivo

PloS One 2016 Volume 11, Issue 6, e0157214

Here, we aimed to investigate osteogenic differentiation of human adipose-derived stem cells (hASCs) in three-dimensional (3D) bioprinted tissue constructs in vitro and in vivo. A 3D Bio-plotter dispensing system was used for building 3D constructs. Cell viability was determined using live/dead cell staining. After 7 and 14 days of culture, real-time quantitative polymerase chain reaction (PCR) was performed to analyze the expression of osteogenesis-related genes (RUNX2, OSX, and OCN). Western blotting for RUNX2 and immunofluorescent staining for OCN and RUNX2 were also performed. At 8 weeks after surgery, osteoids secreted by osteogenically differentiated cells were assessed by hematoxylin-eosin (H&E) staining,…

[Osteogenesis of human adipose-derived mesenchymal stem cells-biomaterial mixture in vivo after 3D bio-printing]

Journal of Peking University. Health Sciences 2016 Volume 48, Issue 1, Pages 45-50

To construct human adipose-derived mesenchymal stem cells (hASCs)-biomaterial mixture 3D bio-printing body and detect its osteogenesis in vivo, and to establish a guideline of osteogenesis in vivo by use of 3D bio-printing technology preliminarily.P4 hASCs were used as seed cells, whose osteogenic potential in vitro was tested by alkaline phosphatase (ALP) staining and alizarin red staining after 14 d of osteogenic induction. The cells were added into 20 g/L sodium alginate and 80 g/L gelatin mixture (cell density was 1×10(6)/mL), and the cell-sodium alginate-gelatin mixture was printed by Bioplotter 3D bio-printer (Envision company, Germany), in which the cells’survival rate was…

3D Printing of Porous Alginate/gelatin Hydrogel Scaffolds and Their Mechanical Property Characterization

International Journal of Polymeric Materials and Polymeric Biomaterials 2017 Volume 66, Issue 6, Pages 299-306

Hydrogel scaffolds with well-defined internal structure and interconnected porosity are important for tissue engineering. 3D Bioplotting technique supplemented with thermal/submerged ionic crosslinking process was used to fabricate hydrogel scaffolds. Six scaffold geometries were fabricated and their influence on mechanical performance was investigated. 0/90-0.8 group with the lowest porosity showed the highest Young’s modulus while the Shift group showed the lowest Young’s modulus. Same trend has also been observed for the dynamic modulus of each group. Results demonstrated that the mechanical performance of hydrogel scaffolds can be tuned by changing the internal structure parameters including strands orientation and spacing between strands.

Alginate Gelatin

3D Bioplotting of Gelatin/Alginate Scaffolds for Tissue Engineering: Influence of Crosslinking Degree and Pore Architecture on Physicochemical Properties

Journal of Materials Science & Technology 2016 Volume 32, Issue 9, Pages 889–900

Gelatin/Alginate hydrogels were engineered for bioplotting in tissue engineering. One major drawback of hydrogel scaffolds is the lack of adequate mechanical properties. In this study, using a bioplotter, we constructed the scaffolds with different pore architectures by deposition of gelatin/alginate hydrogels layer-by-layer. The scaffolds with different crosslinking degree were obtained by post-crosslinking methods. Their physicochemical properties, as well as cell viability, were assessed. Different crosslinking methods had little influence on scaffold architecture, porosity, pore size and distribution. By contrast, the water absorption ability, degradation rate and mechanical properties of the scaffolds were dramatically affected by treatment with various concentrations of…

A Multimaterial Bioink Method for 3D Printing Tunable, Cell-Compatible Hydrogels

Advanced Materials 2015 Volume 27, Issue 9, Pages 1607–1614

A multimaterial bio-ink method using polyethylene glycol crosslinking is presented for expanding the biomaterial palette required for 3D bioprinting of more mimetic and customizable tissue and organ constructs. Lightly crosslinked, soft hydrogels are produced from precursor solutions of various materials and 3D printed. Rheological and biological characterizations are presented, and the promise of this new bio-ink synthesis strategy is discussed.

Modular Small Diameter Vascular Grafts with Bioactive Functionalities

PloS One 2015 Volume 10, Issue 7, Article e0133632

We report the fabrication of a novel type of artificial small diameter blood vessels, termed biomimetic tissue-engineered blood vessels (bTEBV), with a modular composition. They are composed of a hydrogel scaffold consisting of two negatively charged natural polymers, alginate and a modified chitosan, N,O-carboxymethyl chitosan (N,O-CMC). Into this biologically inert scaffold two biofunctionally active biopolymers are embedded, inorganic polyphosphate (polyP) and silica, as well as gelatin which exposes the cell recognition signal, Arg-Gly-Asp (RGD). These materials can be hardened by exposure to Ca2+ through formation of Ca2+ bridges between the polyanions, alginate, N,O-CMC, and polyP (alginate-Ca2+-N,O-CMC-polyP). The bTEBV are formed…

Fabrication of novel Si-doped Hydroxyapatite/Gelatine scaffolds by rapid prototyping for drug delivery and bone regeneration

Acta Biomaterialia 2015 Volume 15, Pages 200–209

Porous 3-D scaffolds consisting of gelatine and Si-doped hydroxyapatite were fabricated at room temperature by rapid prototyping. Microscopic characterization revealed a highly homogeneous structure, showing the pre-designed porosity (macroporosity) and a lesser in-rod porosity (microporosity). The mechanical properties of such scaffolds are close to those of trabecular bone of the same density. The biological behavior of these hybrid scaffolds is greater than that of pure ceramic scaffolds without gelatine, increasing pre-osteoblastic MC3T3-E1 cell differentiation (matrix mineralization and gene expression). Since the fabrication process of these structures was carried out at mild conditions, an antibiotic (vancomycin) was incorporated in the slurry…

Effect of Bioglass on Growth and Biomineralization of SaOS-2 Cells in Hydrogel after 3D Cell Bioprinting

PloS One 2014 Volume 9, Issue 11, Article e112497

We investigated the effect of bioglass (bioactive glass) on growth and mineralization of bone-related SaOS-2 cells, encapsulated into a printable and biodegradable alginate/gelatine hydrogel. The hydrogel was supplemented either with polyphosphate (polyP), administered as polyP•Ca2+-complex, or silica, or as biosilica that had been enzymatically prepared from ortho-silicate by silicatein. These hydrogels, together with SaOS-2 cells, were bioprinted to computer-designed scaffolds. The results revealed that bioglass (nano)particles, with a size of 55 nm and a molar ratio of SiO2∶CaO∶P2O5 of 55∶40∶5, did not affect the growth of the encapsulated cells. If silica, biosilica, or polyP•Ca2+-complex is co-added to the cell-containing alginate/gelatin…

Engineering a morphogenetically active hydrogel for bioprinting of bioartificial tissue derived from human osteoblast-like SaOS-2 cells

Biomaterials 2014 Volume 35, Issue 31, Pages 8810–8819

Sodium alginate hydrogel, stabilized with gelatin, is a suitable, biologically inert matrix that can be used for encapsulating and 3D bioprinting of bone-related SaOS-2 cells. However, the cells, embedded in this matrix, remain in a non-proliferating state. Here we show that addition of an overlay onto the bioprinted alginate/gelatine/SaOS-2 cell scaffold, consisting of agarose and the calcium salt of polyphosphate [polyP·Ca2+-complex], resulted in a marked increase in cell proliferation. In the presence of 100 μm polyP·Ca2+-complex, the cells proliferate with a generation time of approximately 47–55 h. In addition, the hardness of the alginate/gelatin hydrogel substantially increases in the presence…

Layered Gradient Nonwovens of In Situ Crosslinked Electrospun Collagenous Nanofibers Used as Modular Scaffold Systems for Soft Tissue Regeneration

Advanced Functional Materials 2013 Volume 23, Issue 26, Pages 3277-3285

In a versatile modular scaffold system, gradient nonwovens of in situ crosslinked gelatin nanofibers (CGN), fabricated by reactive electrospinning, are laminated with perforated layers and nonwovens of thermoplastic non-crosslinked biodegradable polyesters. The addition of glyoxal to a gelatin solution in a non-toxic solvent mixture consisting of acetic acid, ethyl acetate, and water (5:3:2 w/w/w) enables the in situ crosslinking of gelatin nanofibers during electrospinning. The use of this fluorine-free crosslinking system eliminates the need of post-treatment crosslinking and purification steps typical for conventional CGN scaffolds. The slowly progressing crosslinking of the dissolved gelatin in the presence of glyoxal increases the…

Thermal imaging analysis of 3D biological agarose matrices

International Journal of Medical Engineering and Informatics 2011 Volume 3, Issue 2, Pages 167-179

Advances in rapid prototyping have allowed for the construction of biocompatible materials (hydrogels) to be used in regenerative medicine. Within this area of construction inherent problems arise due to the mechanical instability of such materials that are temperature dependent. This research paper describes a thermal imaging analysis used to circumvent needle blockage when using an RP technology called bioplotting, used for extruding high temperature hydrogels, where agarose was the experimental biomaterial. The investigation describes how we have overcome these inherent problems through thermal imaging analysis, allowing us to accurately construct 3D biological matrices that have satisfied the in-vitro cell requirements…

Construction of 3D biological matrices using rapid prototyping technology

Rapid Prototyping Journal 2009 Volume 15, Issue 3, Pages 204 - 210

Purpose Hydrogels with low viscosities tend to be difficult to use in constructing tissue engineering (TE) scaffolds used to replace or restore damaged tissue, due to the length of time it takes for final gelation to take place resulting in the scaffolds collapsing due to their mechanical instability. However, recent advances in rapid prototyping have allowed for a new technology called bioplotting to be developed, which aims to circumvent these inherent problems. This paper aims to present details of the process. Design/methodology/approach The paper demonstrates how by using the bioplotting technique complex 3D geometrical scaffolds with accurate feature sizes and…

Formed 3D Bio-Scaffolds via Rapid Prototyping Technology

IFMBE Proceedings 2009 Volume 22, Pages 2200-2204

The construction of biomaterial scaffolds for cell seeding is now seen as the most common approach for producing artificial tissue as compared with cell self-assembly and Acellular matrix techniques. This paper describes the use of synthetic and natural polymeric material shaped into 3D biological matrices by using Rapid Prototyping (RP) technology. Recent advances in RP technology have greatly enhanced the range of biomaterials that can now be constructed into scaffolds, also allowing for maximized control of the pore size and architecture. Bioplotting is one such method which allows the dispensing of various biomaterials into a media bath which has similar…

Rapid prototyping of scaffolds derived from thermoreversible hydrogels and tailored for applications in tissue engineering

Biomaterials 2002 Volume 23, Issue 23, Pages 4437-4447

In the year 2000 a new rapid prototyping (RP) technology was developed at the Freiburg Materials Research Center to meet the demands for desktop fabrication of scaffolds useful in tissue engineering. A key feature of this RP technology is the three-dimensional (3D) dispensing of liquids and pastes in liquid media. In contrast to conventional RP systems, mainly focused on melt processing, the 3D dispensing RP process (3D plotting) can apply a much larger variety of synthetic as well as natural materials, including aqueous solutions and pastes, to fabricate scaffolds for application in tissue engineering. For the first time, hydrogel scaffolds…