Co-delivery of NGF and BMP-2 via thermosensitive pluronic F127 hydrogel enhances chondrogenesis and cartilage repair

Cartilage defects are difficult to repair due to the tissue's avascular nature, low cell density, and limited regenerative capacity. Growth factor-based tissue engineering offers a promising strategy for enhancing cartilage regeneration. This study aimed to develop a synergistic and sustained dual-growth factor delivery system by co-loading nerve growth factor (NGF) and bone morphogenetic protein-2 (BMP-2) into a Pluronic-F127 hydrogel, and to investigate its effects and underlying mechanisms in promoting chondrocyte regeneration and mesenchymal stem cell chondrogenesis. A thermosensitive Pluronic-F127 hydrogel was prepared to encapsulate NGF and BMP-2. The loading efficiency and release kinetics of both growth factors were quantified. In vitro experiments were conducted to assess cell proliferation, migration, and differentiation using CCK-8 assays, scratch tests, RT-qPCR, Western blotting, and matrix synthesis assays in human chondrocytes and bone marrow-derived mesenchymal stem cells (hBMSCs). The NGF/BMP-2@Pluronic-F127 hydrogel demonstrated high loading efficiency and sustained release of both factors. Co-delivery significantly enhanced proliferation and migration of chondrocytes and hBMSCs compared to single-factor or control treatments. Expression of chondrogenic markers (COL2A1, AGG, SOX9) was markedly upregulated at both mRNA and protein levels. Additionally, the hydrogel promoted glycosaminoglycan and DNA synthesis, indicating enhanced matrix production and cellular activity. These findings support a synergistic mechanism in which NGF improves cell viability and modulates the microenvironment, while BMP-2 activates chondrogenic signaling pathways to induce differentiation. The NGF/BMP-2@Pluronic-F127 co-delivery system offers a promising strategy for cartilage regeneration by integrating proliferative, migratory, and chondrogenic cues within a single hydrogel platform. This approach may help overcome the limitations of current treatments and improve outcomes in condylar cartilage defect repair.