Microsphere-Composite\nHydrogel for Recruiting Stem\nCells and Promoting Osteogenic Differentiation

By recruiting stem cells into scaffolds and differentiating\nthem\ninto osteoblasts, stem cells can be mobilized to directly repair bone\ndefects, which avoids a series of disadvantages of exogenous stem\ncell implantation. In this study, a microsphere-composite hydrogel\nfor the recruitment and osteogenic differentiation of stem cells was\nconstructed. Methacrylic anhydride modified gelatin (GelMA) and heparin\n(HepMA), as well as nanohydroxyapatite (nHAP), were used to prepare\nmicrospheres followed by adsorbing platelet-derived growth factor\nBB (PDGF-BB) whose loading efficiency was 53.7 ± 2.2%. Then the\nmicrospheres were compounded to the GelMA hydrogel encapsulated with\nsimvastatin (SIM) to obtain microsphere-composite hydrogel GHnH-P@GS.\nGHnH-P@GS hydrogel could slowly release SIM and PDGF-BB, and the extents\nof release within 7 days were 44.1 ± 2.0% and 32.8 ± 1.1%.\nThe synergistic effect of small molecule drugs and growth factors\nnot only induced the recruitment of rabbit bone marrow-derived mesenchymal\nstem cells, but also promoted the osteogenic differentiation of stem\ncells, which was confirmed by experiments of cell migration, alkaline\nphosphatase, and alizarin red staining. Collectively, the microsphere-composite\nhydrogel GHnH-P@GS has a certain reference significance for the design\nof scaffolds for alveolar bone repair and regeneration.