Abstract

Injectable biomaterials obtain increasing attention for the repair of bone defect due to the advantage of defect margin adaptability and easy handling. Our previous studies found that RADA16 peptide hydrogel could significantly promote bone formation. In order to improve the mechanical force, RADA16 peptide hydrogel was used to fill the porous calcium   sulfate/nano-hydroxyapatite   (CaSO 4 /HA)   cement biomaterial for the fabrication of RADA16/CaSO 4 /HA composite biomaterial. Especially, RADA16 peptide hydrogel had the ability to slowly release growth factors for bone regeneration. Here, RADA16/CaSO 4 /HA composite biomaterials afforded the controlled and sustainable release of basic fibroblast growth factor   (bFGF) for more than 32 days. Compared to RADA16/CaSO 4 /HA biomaterial, RADA16 + bFGF/CaSO 4 /HA composite biomaterial could further improve in vitro osteogenic differentiation of MC3T3 cells as evidenced by the increased expression of osteogenic markers (i.e. runt-related transcription factor 2 [Runx2], osteocalcin [OCN] and   alkaline phosphatase [ALP]) and in vivo bone formation of femoral condyle defects which were confirmed by histological staining and micro-CT analyses. These indicate that bFGF-incorporated RADA16/CaSO 4 /HA can further improve bone formation through the controlled release of bFGF, which provides a novel injectable biomaterial design to specifically release growth factors for bone defects.