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 Degra Pol-foam, a degradable, elastic, and highly porous polyesterurethane foam a s carrier for BMP-induced bone formation, a fraction containing all the act ive BMPs (BMP cocktail) was combined with DegraPol-foam and implanted subcu taneously into rats. DegraPol-BMP scaffolds were found to induce osteogenes is 2 weeks after implantation as evidenced by morphological and biochemical observations. In addition, the osteoblast-compatibility of DegraPol-foam w as examined here. In vitro, primary rat osteoblasts and osteoblasts from th e human cell line (HFO1) attached and proliferated preferentially on the su rface of the DegraPol-foam. Both cell types exhibited relatively high attac hment and low doubling time that resulted in a confluent cell multilayer wi th spindle-shaped morphology on the surface of the foam. Osteoblasts produc ed high concentrations of collagen type I and osteocalcin, and expressed in creasing levels of alkaline phosphatase (ALP) activity. Taken collectively, both osteoblasts from rat tibia and from the human cell line HFO1 showed h igh cell attachment and growth, and preserved their phenotype. The geometri cal structure of DegraPol is a suitable carrier for BMP for the induction o f bone formation.