Printability and Cell Viability in Bioprinting Alginate\nDialdehyde-Gelatin Scaffolds

Abstract

Three-dimensional\n(3D) bioprinting is a promising technique used\nto fabricate scaffolds from hydrogels with living cells. However,\nthe printability of hydrogels in bioprinting has not been adequately\nstudied. The aim of this study was to quantitatively characterize\nthe printability and cell viability of alginate dialdehyde (ADA)-gelatin\n(Gel) hydrogels for bioprinting. ADA-Gel hydrogels of various concentrations\nwere synthesized and characterized using Fourier transform infrared\nspectroscopy, along with rheological tests for measuring storage and\nloss moduli. Scaffolds (with an area of 11 × 11 mm) of 1, 2,\nand 13 layers were fabricated from ADA-Gel hydrogels using a 3D-bioplotter\nunder printing conditions with and without the use of cross-linker,\nrespectively, at room temperature and at 4 °C. Scaffolds were\nthen quantitatively assessed in terms of the minimum printing pressure,\nquality of strands and pores, and structural integrity, which were\ncombined together for the characterization of ADA-Gel printability.\nFor the assessment of cell viability, scaffolds were bioprinted from\nADA-Gel hydrogels with human umbilical vein endothelial cells (HUVECs)\nand rat Schwann cells and were then examined at day 7 with live/dead\nassay. HUVECs and Schwann cells were used as models to demonstrate\nbiocompatibility for potential angiogenesis and nerve repair applications,\nrespectively. Our results illustrated that ADA-Gel hydrogels with\na loss tangent (ratio of loss modulus over storage modulus) between\n0.24 and 0.28 could be printed in cross-linker with the best printability\nfeatured by uniform strands, square pores, and good structural integrity.\nAdditionally, our results revealed that ADA-Gel hydrogels with an\nappropriate printability could maintain cell viability over 7 days.\nCombined together, this study presents a novel method to characterize\nthe printability of hydrogels in bioprinting and illustrates that\nADA-Gel hydrogels can be synthesized and bioprinted with good printability\nand cell viability, thus demonstrating their suitability for bioprinting\nscaffolds in tissue engineering applications.