Osteoblast proliferation behavior and bone formation on and in CO3apatite-collagen sponges with a porous hydroxyapatite frame

To develop a new biodegradable scaffold biomaterial reinforced with a frame, synthesized CO3apatite (CO3Ap) was mixed with a neutralized collagen gel. Then, 0 and 70% (w/w) CO3Ap-collagen mixtures (70% CO3Ap weight/mixture weight) were lyophilized into sponges in a HAp frame ring with 0.5-mm pores. SEM observation of CO3Ap-collagen sponges showed favorable pores for cells invasion. Mouse osteoblast MC3T3-E1 cells were cultured in alphaMEM with 10% FCS for 1, 10 and 20 days. Matrix substances on the pure collagen sponge samples increased with the culture period such that the sponge surface was almost covered. A sectional view of hematoxylin-eosin staining confirmed that osteoblast cells had well invaded the CO3Ap-collagen sponge. When these sponge-frame complexes were implanted beneath the periosteum cranii of rats, newly created bone was observed to grow toward the inner core of the complex from the surface of the periosteum cranii. Based on these results, reinforced CO3Ap-collagen sponges are expected to be used as hard tissue scaffold biomaterials for therapeutic purposes.