Osteogenic differentiation of pre-osteoblasts on biomimetic tyrosine-derived polycarbonate scaffolds

The osteogenic potential of biomimetic tyrosine-derived polycarbonate (TyrPC) scaffolds containing either an ethyl ester or a methyl ester group combined with recombinant human bone morphogenetic protein-2 (rhBMP-2) was assessed using the preosteoblast cell line MC3T3-E1. Each composition of TyrPC was fabricated into 3D porous scaffolds with a bimodal pore distribution of micropores <20 μm and macropores between 200 and 400 μm. Scanning electron microscopy (SEM) characterization suggested MC3T3-E1 cell attachment on the TyrPC scaffold surface. Moreover, the 3D TyrPC-containing ethyl ester side chains supported osteogenic lineage progression, alkaline phosphatase (ALP), and osteocalcin (OCN) expression as well as an increase in calcium content compared with the scaffolds containing the methyl ester group. The release profiles of rhBMP-2 from the 3D TyrPC scaffolds by 15 days suggested a biphasic rhBMP-2 release. There was no significant difference in bioactivity between rhBMP-2 releasate from the scaffolds and exogenous rhBMP-2. Lastly, the TyrPC containing rhBMP-2 promoted more ALP activity and mineralization of MC3T3-E1 cells compared with TyrPC without rhBMP-2. Consequently, the data strongly suggest that TyrPC scaffolds will provide a highly useful platform for bone tissue engineering.