Tailoring material properties of cardiac matrix hydrogels to induce endothelial differentiation of human mesenchymal stem cells.

Cardiac matrix hydrogel has shown great promise as an injectable biomaterial due to the possession of cardiac-specific extracellular matrix composition. A cardiac matrix hydrogel facilitating neovascularization will further improve its therapeutic outcomes in cardiac repair. In this study, we explored the feasibility of tailoring material properties of cardiac matrix hydrogels using a natural compound, genipin, to promote endothelial differentiation of stem cells. Our results demonstrated that the genipin cross-linking could increase the mechanical properties of the cardiac matrix hydrogel to a stiffness range promoting endothelial differentiation of human mesenchymal stem cells (hMSCs). It also decreased the swelling ratio and prolonged degradation without altering gelation time. Human mesenchymal stem cells cultured on the genipin cross-linked cardiac matrix hydrogels showed great viability. After 1 day culture, hMSCs demonstrated down-regulation of early endothelial marker expression and up-regulation of mature endothelial marker expression. Especially for 1 mM genipin cross-linked cardiac matrix hydrogels, hMSCs showed particularly significant expression of mature endothelial cell marker vWF. These attractive results indicate the potential of using genipin cross-linked cardiac matrix hydrogels to promote rapid vascularization for cardiac infarction treatment through minimally invasive therapy.