Bioprinting Schwann cell-laden scaffolds from low-viscosity hydrogel compositions

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, and then designed/determined the bioprinting process parameters including printing pressure and needle type/size. Bioprinting with a submerged crosslinking method was applied for scaffold fabrication, where the key was to rigorously regulate the bioprinting speed and the crosslinking conditions. Optical imaging techniques and advanced synchrotron imaging-based techniques were utilized to characterize the printed scaffolds; specifically factors including strand diameter, scaffold stability and scaffold pore size were measured and used to characterize the hydrogel printability. Schwann cells laden in the scaffolds were assessed in vitro, with results revealing that the elongation of Schwann cells and thus the aligned DRG neurite outgrowth could be well-regulated through the control of the bioprinting process. Taken together, this study shows that scaffolds can be bioprinted from low-viscosity hydrogel compositions for potential use in tissue regeneration