DegraPol-foam: a degradable and highly porous polyesterurethane foam as a new substrate for bone formation

Bone morphogenetic protein (BMP) is known to require a suitable carrier to induce ectopic bone formation in vivo. To evaluate the suitability of DegraPol-foam, a degradable, elastic, and highly porous polyesterurethane foam as carrier for BMP-induced bone formation, a fraction containing all the active BMPs (BMP cocktail) was combined with DegraPol-foam and implanted subcutaneously into rats. DegraPol-BMP scaffolds were found to induce osteogenesis 2 weeks after implantation as evidenced by morphological and biochemical observations. In addition, the osteoblast-compatibility of DegraPol-foam was examined here. In vitro, primary rat osteoblasts and osteoblasts from the human cell line (HFO1) attached and proliferated preferentially on the surface of the DegraPol-foam. Both cell types exhibited relatively high attachment and low doubling time that resulted in a confluent cell multilayer with spindle-shaped morphology on the surface of the foam. Osteoblasts produced high concentrations of collagen type I and osteocalcin, and expressed increasing levels of alkaline phosphatase (ALP) activity. Taken collectively, both osteoblasts from rat tibia and from the human cell line HFO1 showed high cell attachment and growth, and preserved their phenotype. The geometrical structure of DegraPol is a suitable carrier for BMP for the induction of bone formation.