Osteosarcoma progression in biomimetic matrix with different stiffness: Insights from a three-dimensional printed gelatin methacrylamide hydrogel

Recent studies on osteosarcoma and matrix stiffness are still mostly performed in a 2D setting, which is distinct from in vivo conditions. Therefore, the results from the 2D models may not reflect the real effect of matrix stiffness on cell phenotype. Here, we employed a 3D bioprinted osteosarcoma model, to study the effect of matrix stiffness on osteosarcoma cells. Through density adjustment of GelMA, we constructed three osteosarcoma models with distinct matrix stiffnesses of 50, 80, and 130 kPa. In this study, we found that osteosarcoma cells proliferated faster, migrated more actively, had a more stretched morphology, and a lower drug sensitivity in a softer 3D matrix. When placed in a stiffer matrix, osteosarcoma cells secrete more MMP and VEGF, potentially to fight for survival and attract vascular invasion. Transcriptomic analysis showed that matrix stiffness could impact the signaling pathway of integrin α5-MAPK. The transplantation of 3D printed models in nude mice showed that cells encapsulated in the softer hydrogel were more likely to form subcutaneous tumors. These results suggest that matrix stiffness plays an important role in the development of osteosarcoma in a 3D environment and that inhibition of integrin α5 could block the signal transduction of matrix stiffness.