Concentrated gelatin/alginate composites for fabrication of predesigned scaffolds with a favorable cell response by 3D plotting

In the present work, gelatin/alginate and gelatin/alginate/hydroxyapatite (HAP) composite scaffolds were fabricated by 3D plotting based on high concentration gelatin/alginate pastes. At temperatures of 37 degrees C or above, the developed pastes could be easily processed into designed 3D structures; sequential crosslinking with Ca2+ ions (effective for alginate) and the carbodiimide EDC (effective for gelatin) resulted in stable scaffolds. Mechanical testing demonstrated that the plotted composite scaffolds had a significantly higher strength and modulus compared to most reported gelatin scaffolds prepared by conventional methods. Cell experiments with human bone marrow-derived mesenchymal stem cells (hBMSC) revealed that the gelatin/alginate composite scaffolds favor cell adhesion and support proliferation. Furthermore, the cells showed a homogeneous distribution and excellent migration in the inner regions of the plotted composite scaffolds over 21 days. In conclusion, gelatin/alginate scaffolds, with or without HAP, fabricated by 3D plotting according to a predesigned CAD-model might be potential candidates for the repair of bony and chondral defects, especially in complex defect situations affecting the osteochondral tissue interface since biphasic scaffolds with a stable connection of the two parts can be easily fabricated by multi-channel 3D plotting.