文摘
In this study, thermosensitive poly(N-isopropylacrylamide) (PNIPAAm) was grafted onto gelatin via atom transfer radical polymerization (ATRP). The chemical structure of PNIPAAm-grafted gelatin (Gel鈥揚NIPAAm) was confirmed by XPS, ATR-IR, and 1H NMR characterizations. Gel鈥揚NIPAAm aqueous solution exhibited sol-to-gel transformation at physiological temperature, and was studied as injectable hydrogel for bone defect regeneration in a cranial model. The hydrogel was biocompatible and demonstrated the ability to enhance bone regeneration in comparison with the untreated group (control). With the incorporation of rat bone mesenchymal stem cells (BMSCs) into the hydrogel, the bone regeneration rate was further significantly enhanced. As indicated by micro-CT, histological (H&E and Masson) and immunohistochemical (osteocalcin and osteopontin) staining, newly formed woven bone tissue was clearly detected at 12 weeks postimplantation in the hydrogel/BMSCs treated group, showing indistinguishable boundary with surrounding host bone tissues. The results suggested that the thermosensitive Gel鈥揚NIPAAm hydrogel was an excellent injectable delivery vehicle of BMSCs for in vivo bone defect regeneration.