Methods: Cell viability and proliferation were measured by MTT assay after 1 and 21 days of culture onto HA microparticles with conventional culture media supplemented with ascorbic acid. Rat dermal fibroblasts were used as control. Protein assay and scanning electron microscopy were used to assess ECM deposition onto HA microparticles. After 21 days in culture the cells were removed, and the resulted HA-ECM constructs were implanted into 8-mm calvaria circular defects in rats. The animals were euthanized at 12 weeks after surgery.
Results: In vitro results showed that the HA microparticles supported rat primary osteoblasts adhesion, growth and ECM production. In vivo evaluation revealed a significant increase of the new bone formation in the rat calvaria defects treated with the HA-ECM constructs compare to the HA alone.
Conclusion: Our results highlight the potential of in vitro generated ECM as a viable scaffold for bone tissue engineering applications. The ECM deposited onto HA microparticles enhances the HA osteogenic capacity. Additional studies are necessary to determine the optimal culture conditions for the osteoinductive cell-secreted ECM production.