In vitro evaluation of an injectable chitosan gel for sustained local delivery of BMP-2 for osteoblastic differentiation

We investigated the effect of sustained release of bone morphogenetic protein‐2 (BMP‐2) from an injectable chitosan gel on osteoblastic differentiation in vitro. We first characterized the release profile of BMP‐2 from the gels, and then examined the cellular responses of preosteoblast mouse stromal cells (W‐20‐17) and human embryonic palatal mesenchymal (HEPM) cells to BMP‐2. The release profiles of different concentrations of BMP‐2 exhibited sustained releases (41% for 2 ng/mL and 48% for 20 ng/mL, respectively) from the chitosan gels over a three‐week period. Both cell types cultured in the chitosan gels were viable and significantly proliferated for 3 days (p < 0.05). Chitosan gels loaded with BMP‐2 enhanced ALP activity of W‐20‐17 by 3.6‐fold, and increased calcium mineral deposition of HEPM by 2.8‐fold at 14 days of incubation, compared to control groups initially containing the same amount of BMP‐2. In addition, schitosan gels loaded with BMP‐2 exhibited significantly greater osteocalcin synthesis of W‐20‐17 at seven days, and of HEPM at both 7 and 14 days compared with the control groups (p