In vitro investigation of poly(propylene fumarate) cured with phosphonic acid based monomers as scaffolds for bone tissue engineering

Poly(propylene fumarate) (PPF) synthesized via polycondensation of fumaric acid and propylene glycol was thermally cured with changing weight ratios of vinylphosphonic acid (VPA) and diethyl vinylphosphonate (VPES), and the in vitro biocompatibility and bone formation capacity of the PPF copolymers were evaluated for their suitability as bone tissue scaffolds. MTS studies showed that while approximately 1,000 cells attached to VPES containing samples, almost 10,000 cells attached to VPA containing ones. PPF/VPA copolymers supported initial human osteoblast cell (HOb) attachment better than the PPF/VPES copolymers; however, cell numbers increased during the 21- day analysis period for both -VPA and -VPES copolymers, demonstrating that the PPF copolymers were all biocompatible. ALP and OCN assays performed to elucidate the osteoconductivity potential of the copolymers showed higher ALP activity for the PPF/VPA copolymers (ranging between 25-128 & mu;g/ml) compared to the PPF-VPES copolymers (ranging between 14-27 & mu;g/ml) for 20, 30, and 40 wt% co-monomer contents at days 7, 14, 21, and 28. PPF-VPA samples cured with 3% BP expressed significantly higher ALP activity than the samples cured with 2% BP whereas initiator amount did not significantly affect the ALP activity in PPF-VPES samples. The OCN activities of the two copolymers were at similar levels (ranging between 0.05-5.7 ng/ml) throughout the 28-days study period, suggesting that both PPF copolymers supported osteogenesis. In addition, SEM analysis showed that the seeded (HOb) cells extensively proliferated and spread for both of the PPF copolymers, and von Kossa staining experiments demonstrated that both PPF/VPA and PPF/VPES scaffolds supported extracellular matrix formation and mineralization well.

Automated summary

Poly(propylene fumarate) (PPF) was synthesized and thermally cured with different weight ratios of vinylphosphonic acid (VPA) and diethyl vinylphosphonate (VPES). The biocompatibility and bone formation capacity of the PPF copolymers were evaluated for their potential as bone tissue scaffolds. The results showed that PPF/VPA copolymers had better cell attachment and higher ALP activity compared to PPF/VPES copolymers, indicating their suitability for bone regeneration.