3D Bioplotter Research Papers

Engineered grafts constitute an alternative to autologous transplant for repairing severe peripheral nerve injuries. However, current clinically available solutions have substantial limitations and are not suited for the repair of long nerve defects. A novel design of nerve conduit is presented here, which consists of a chitosan porous matrix embedding a 3D-printed poly-ε-caprolactone mesh. These materials are selected due to their high biocompatibility, safe degradability, and ability to support the nerve regeneration process. The proposed design allows high control over geometrical features, pores morphology, compression resistance, and bending stiffness, yielding tunable and easy-to-manipulate grafts. The conduits are tested in chronic…

Decellularized extracellular matrix hydrogel (dECM-G) has demonstrated its significant tissue-specificity, high biocompatibility, and versatile utilities in tissue engineering. However, the low mechanical stability and fast degradation are major drawbacks for its application in three-dimensional (3D) printing. Herein, we report a hybrid hydrogel system consisting of dECM-Gs and photocrosslinkable gelatin methacrylate (GelMA), which resulted in significantly improved printability and structural fidelity. These premixed hydrogels retained high bioactivity and tissue-specificity due to their containing dECM-Gs. More specifically, it was realized that the hydrogel containing dECM-G derived from porcine peripheral nerves (GelMA/pDNM-G) effectively facilitated neurite growth and Schwann cell migration from two-dimensional cultured…

The efficiency of nerve guide conduits (NGCs) in repairing peripheral nerve injury is not high enough yet to be a substitute for autografts and is still insufficient for clinical use. To improve this efficiency, 3D electrospun scaffolds (3D/E) of poly(l-lactide-co-ε-caprolactone) (PLCL) and poly(l-lactide-co-glycolide) (PLGA) were designed and fabricated by the combination of 3D printing and electrospinning techniques, resulting in an ideal porous architecture for NGCs. Polypyrrole (PPy) was deposited on PLCL and PLGA scaffolds to enhance biocompatibility for nerve recovery. The designed pore architecture of these “PLCL-3D/E” and “PLGA-3D/E” scaffolds exhibited a combination of nano- and microscale structures. The mean…

The integration of multiscale micro- and macroenvironment has been demonstrated as a critical role in designing biomimetic scaffolds for peripheral nerve tissue regeneration. While it remains a remarkable challenge for developing a biomimetic multiscale scaffold for enhancing 3D neuronal maturation and outgrowth. Herein, we present a 3D bioprinted multiscale scaffold based on a modular bioink for integrating the 3D micro- and macroenvironment of native nerve tissue. Gelatin methacryloyl (GelMA)/Chitosan Microspheres (GC-MSs) were prepared by a microfluidic approach, and the effect of these microspheres on enhancing neurite outgrowth and elongation of PC12 cells was demonstrated. The 3D multiscale composite scaffolds were…

The classic cell culture involves the use of support in two dimensions, such as a well plate or a Petri dish, that allows the culture of different types of cells. However, this technique does not mimic the natural microenvironment where the cells are exposed to. To solve that, three-dimensional bioprinting techniques were implemented, which involves the use of biopolymers and/or synthetic materials and cells. Because of a lack of information between data sources, the objective of this review paper is, to sum up, all the available information on the topic of bioprinting and to help researchers with the problematics with…

3D bioprinting techniques have been attracting attention for tissue scaffold fabrication in nerve tissue engineering applications. However, due to the inherent complexity of nerve tissues, bioprinting scaffolds that can appropriately promote the regeneration of damaged tissues is still challenging. This paper presents our study on bioprinting Schwann cell-laden scaffolds from low-viscosity hydrogel compositions including RGD modified alginate, hyaluronic acid and fibrin, with a focus on investigating the printability of hydrogel compositions and characterizing the functions of printed scaffolds for potential use in nerve tissue regeneration. We assessed the rheological properties of hydrogel precursors via temperature, time and shear rate sweeps,…

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…

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…

Information from the brain travels back and forth along peripheral nerves in the form of electrical impulses generated by neurons and these impulses have repetitive patterns. Schwann cells in peripheral nerves receive molecular signals from axons to coordinate the process of myelination. There is evidence, however, that non-molecular signals play an important role in myelination in the form of patterned electrical impulses generated by neuronal activity. The role of patterned electrical impulses has been investigated in the literature using co-cultures of neurons and myelinating cells. The co-culturing method, however, prevents the uncoupling of the direct effect of patterned electrical impulses…

Peripheral nerve tissue requires appropriate biochemical and physical cues to guide the regeneration process after injury. Bioprinted peptide-conjugated sodium alginate (PCSA) scaffolds have the potential to provide physical and biochemical cues simultaneously. Such scaffolds need characterisation in terms of printability, mechanical stability, and biological performance to refine and improve application in nerve tissue regeneration. In this study, it was hypothesized that 3D scaffold printed with low concentrated multiple PCSA precursor would be supportive for axon outgrowth. Therefore, a 2% (w/v) alginate precursor was conjugated with either arginine-glycine-aspartate (RGD) or tyrosine-isoleucine-glycine-serine-arginine (YIGSR) peptides, or a mixture of RGD and YIGSR (1:2)…

When a biomaterial solution containing living cells is subject to bioprinting, the cells experience process-induced stresses, including shear and extensional stresses. These process-induced stresses breach cell membranes and can lead to cell damage, thus reducing cell viability and functioning within the printed constructs. Studies have been conducted to determine the influence of shear stress on cell damage; however, the effect of extensional stress has been typically ignored in the literature until the recently collected evidence of its importance. This paper presents a novel method to characterize and quantify the cell damage caused by both shear and extensional stresses in bioprinting.…

Three-dimensional bioprinting of biomaterials shows great potential for producing cell-encapsulated scaffolds to repair nerves after injury or disease. For this, preparation of biomaterials and bioprinting itself are critical to create scaffolds with both biological and mechanical properties appropriate for nerve regeneration, yet remain unachievable. This paper presents our study on bioprinting Schwann cell-encapsulated scaffolds using composite hydrogels of alginate, fibrin, hyaluronic acid, and/or RGD peptide, for nerve tissue engineering applications. For the preparation of composite hydrogels, suitable hydrogel combinations were identified and prepared by adjusting the concentration of fibrin based on the morphological spreading of Schwann cells. In bioprinting, the…

Three-dimensional (3D) printing is an emerging technology for the fabrication of scaffolds to repair/replace damaged tissue/organs in tissue engineering. This paper presents our study on 3D printed alginate scaffolds treated with phosphate buffered saline (PBS) and polyethyleneimine (PEI) coating and their impacts on the surface morphology and cellular response of the printed scaffolds. In our study, sterile alginate was prepared by means of the freeze-drying method and then, used to prepare the hydrogel for 3D printing into calcium chloride, forming 3D scaffolds. Scaffolds were treated with PBS for a time period of two days and seven days, respectively, and PEI…

The blood clotting protein fibrin contains cell-binding domains, providing potential advantage for the fabrication of tissue repair scaffolds and for live cell encapsulation. However, fabrication of fibrin scaffolds with encapsulated cells using three dimensional (3D) printing has proven challenging due to the mechanical difficulties of fabricating protein hydrogel scaffolds with defined microstructure. For example, extrusion based 3D printing of fibrin is generally unfeasible because of the low viscosity of precursor fibrinogen solution. Here we describe a novel technique for bioprinting of fibrin scaffolds by extruding fibrinogen solution into thrombin solution, utilizing hyaluronic acid (HA) and polyvinyl alcohol (PVA) to increase…

Recently alginate-based tissue repair scaffolds fabricated using 3D printing techniques have been extensively examined for use in tissue engineering applications. However, their physical and mechanical properties are unfavorable for many tissue engineering applications because these properties are poorly controlled during the fabrication process. Some improvement of alginate gel properties can be realized by addition of hyaluronic acid (HA), and this may also improve the ability of cells to interact with the gel. Here, we report improvement of the physical properties of alginate–HA gel scaffolds by the addition of the polycation polyethyleneimine (PEI) during the fabrication process in order to stabilize…

Bioplotting is an emerging freeform scaffold fabrication technique useful for creating artificial tissue scaffolds containing living cells. Simultaneous maintenance of scaffold structural integrity and cell viability is a challenging task. In this article, we present strategies developed to bioplot alginate-based three-dimensional tissue scaffolds containing hyaluronic acid and living Schwann cells for potential use in peripheral nerve tissue engineering. The fabrication platform, upon which the scaffold is created, was coated with the polycation polyethylenimine to immobilize the first layer of the scaffold on the platform. Each layer was then dispensed into a bath containing calcium chloride to cross-link the alginate, polyvinyl…

Artificial tissue engineering scaffolds can potentially provide support and guidance for the regrowth of severed axons following nerve injury. In this study, a hybrid biomaterial composed of alginate and hyaluronic acid (HA) was synthesized and characterized in terms of its suitability for covalent modification, biocompatibility for living Schwann cells and feasibility to construct three dimensional (3D) scaffolds. Carbodiimide mediated amide formation for the purpose of covalent crosslinking of the HA was carried out in the presence of calciumions that ionically crosslink alginate. Amide formation was found to be dependent on the concentrations of carbodiimide and calcium chloride. The double-crosslinked composite…

Nerve conduits for peripheral nerve repair have progressed from simple silicon tubes to complex engineered scaffolds. Recent advances in scaffold fabrication have enabled the incorporation of neurotrophins, extracellular matrix components and various cells into scaffolds for enhanced biologic properties. Bioplotting is one of the emerging methods, where the scaffold material, in form of a solution, is dispensed from a needle, layer by layer forming a three-dimensional structure. It enables the use of a wide range of materials, ranging from synthetic polymers (like polycaprolactone, polyglycolic acid, etc.) to naturally occurring polymers like alginate, chitosan, etc. Notably, the use of hydrogels gives…

Spinal cord injury (SCI) represents a major world health problem. Therefore it is urgent to develop novel strategies that can specifically target it. We have previously shown that the implantation of starch-based scaffolds (SPCL) aimed for spine stabilization on SCI animals leads to motor skills improvements. Therefore, we hypothesize that the combination of these scaffolds with relevant cell populations for SCI repair will, most likely, lead to further improvements. Therefore, in this work, the ability of SPCL scaffolds to support the 3D culture of olfactory ensheathing cells (OECs) and Schwann cells (SCs) was studied and characterized. The results demonstrate for…