PF127 Hydrogel-Based Delivery of Exosomal CTNNB1 from Mesenchymal Stem Cells Induces Osteogenic Differentiation during the Repair of Alveolar Bone Defects
Longlong He, Qin Zhou, Hengwei Zhang, Ningbo Zhao, Lifan Liao
Abstract
Pluronic F127 (PF127) hydrogel has been highlighted as a promising biomaterial for bone regeneration, but the specific molecular mechanism remains largely unknown. Herein, we addressed this issue in a temperature-responsive PF127 hydrogel loaded with bone marrow mesenchymal stem cells (BMSCs)-derived exosomes (Exos) (PF127 hydrogel@BMSC-Exos) during alveolar bone regeneration. Genes enriched in BMSC-Exos and upregulated during the osteogenic differentiation of BMSCs and their downstream regulators were predicted by bioinformatics analyses. CTNNB1 was predicted to be the key gene of BMSC-Exos in the osteogenic differentiation of BMSCs, during which miR-146a-5p, IRAK1, and TRAF6 might be the downstream factors. Osteogenic differentiation was induced in BMSCs, in which ectopic expression of CTNNB1 was introduced and from which Exos were isolated. The CTNNB1-enriched PF127 hydrogel@BMSC-Exos were constructed and implanted into in vivo rat models of alveolar bone defects. In vitro experiment data showed that PF127 hydrogel@BMSC-Exos efficiently delivered CTNNB1 to BMSCs, which subsequently promoted the osteogenic differentiation of BMSCs, as evidenced by enhanced ALP staining intensity and activity, extracellular matrix mineralization (p < 0.05), and upregulated RUNX2 and OCN expression (p < 0.05). Functional experiments were conducted to examine the relationships among CTNNB1, microRNA (miR)-146a-5p, and IRAK1 and TRAF6. Mechanistically, CTNNB1 activated miR-146a-5p transcription to downregulate IRAK1 and TRAF6 (p < 0.05), which induced the osteogenic differentiation of BMSCs and facilitated alveolar bone regeneration in rats (increased new bone formation and elevated BV/TV ratio and BMD, all with p < 0.05). Collectively, CTNNB1-containing PF127 hydrogel@BMSC-Exos promote the osteogenic differentiation of BMSCs by regulating the miR-146a-5p/IRAK1/TRAF6 axis, thus inducing the repair of alveolar bone defects in rats.