Low-Temperature Three-Dimensional Printing of Tissue Cartilage Engineered with Gelatin Methacrylamide

Low-concentration gelatin methacryloyl (GelMA) hydrogels have been found to be promising cell-laden bioinks with excellent cell viability. Herein, we report a strategy that accurately deposits cell-containing bioinks at 5% (w/v) GelMA using extrusion three-dimensional (3D) bioprinting technology by utilizing its photo-crosslinkable and thermosensitive properties without the need for any sacrificial materials. During the 3D printing process, regular, smooth microfibers were formed without any discontinuity of extrusion or clogging, and photo-crosslinking was then used to stabilize the printed GelMA structure. After printing, the scaffolds were cultured in a chondrogenic medium to evaluate their significant roles in directing the behaviors of bone mesenchymal stem cells (BMSCs). Evidence of chondrogenic differentiation was demonstrated by Alcian blue staining and immunofluorescence (Col2a1) as well as the expression of chondrogenic genes. Finally, after platelet-rich plasma treatment, the in vivo effects of the BMSCs on cartilage regeneration on the thigh muscles of female nude mice were measured by using immunohistochemical techniques. The results showed that with this strategy, GelMA bioink displays excellent printability and a high cell survival rate. In vitro and in vivo, the cell-laden scaffold successfully regenerated mature cartilage via a cartilage-specific extracellular matrix, which seems to be suitable for cartilage regeneration and repair. Gelatin methacryloyl is a promising material in tissue engineering and has been widely studied in three-dimensional bioprinting. In this study, we report a strategy for precise deposition of a cell-laden gelatin methacrylamide bioink at low concentration by using three-dimensional bioprinting. Cell-laden 5% (w/v) gelatin methacrylamide was successfully printed without any construct deformation or collapse and was permanently crosslinked by blue light. The results indicate that with this strategy, 5% (w/v) gelatin methacrylamide bioink exhibited excellent printability and printing resolution with high cell viability. Bone mesenchymal stem cells could be differentiated into chondrocytes when they were cultured with 5% GelMA in vitro and formed cartilage-like tissues after intramuscular implantation when the constructs were treated with platelet-rich plasma.