P24 Loaded Gelatin-Hydroxyapatite-Tricalcium Phosphate Scaffold Induces Bone Regeneration by Activating the ERK/ELK1/PLA2G3 Pathway

The study examined the induction and mechanism of bone regeneration facilitated by the P24-loaded Gelatin-Hydroxyapatite-Tricalcium Phosphate (Gelatin-HA-TCP (P24)) scaffold. The prepared Gelatin-HA-TCP (P24) scaffold was employed to treat human bone marrow mesenchymal stem cells (hBMSCs) and human umbilical vein endothelial cells (HUVECs). Various assays were conducted to assess the impact of the Gelatin-HA-TCP (P24) scaffold on the osteogenic differentiation of hBMSCs and angiogenesis in HUVECs. For mechanistic investigations, hBMSCs were exposed to both the Gelatin-HA-TCP (P24) scaffold and the ERK inhibitor SCH772984. A rat cranial bone defect model was treated through the implantation of the Gelatin-HA-TCP (P24) scaffold. Micro-computed tomography, histological staining, and immunofluorescence techniques were utilized to evaluate the effect of the Gelatin-HA-TCP (P24) scaffold on cranial bone regeneration. Osteogenic differentiation of hBMSCs was facilitated by the Gelatin-HA-TCP (P24) scaffold, as evidenced by increased ALP activity, enhanced Alizarin Red S staining, and upregulated RUNX2, OSX, OCN, and BMP2. Angiogenesis in HUVECs was induced, as demonstrated by improved migration, tube formation, and upregulated CD31. However, the ability of the Gelatin-HA-TCP (P24) scaffold to promote osteogenic differentiation in hBMSCs was counteracted by SCH772984. In the rat cranial bone defect model, implantation of the Gelatin-HA-TCP (P24) scaffold reduced the bone defect area, increased the bone volume/tissue volume ratio, enhanced bone regeneration, decreased bone fibrosis, and upregulated CD31, RUNX2, and BMP2 in bone tissues. Therefore, the Gelatin-HA-TCP (P24) scaffold enhances the osteogenic differentiation of hBMSCs and promotes bone regeneration in cranial bone defects by activating the ERK/ELK1/PLA2G3 pathway. It has potential for bone regeneration therapies.