The in vivo
reaction against nano-apatite is still not well understood. We self-prepared four samples using medical-grade collagen and commercial (40 nm) nano-apatite particles (n-HAp), namely (i) collagen sponge (sample C), (ii) n-HAp collagen composite sponge (sample AC), (iii) collagen sponge with basic fibroblast growth factor (b-FGF) (sample CF) and (iv) n-HAp collagen composite sponge with b-FGF (sample ACF); and implanted them in subcutaneous tissues of the back of mice for 1 and 2 weeks. Visual inspections and histological observations revealed that sample ACF caused most intensified angiogenesis with time, followed by sample CF and sample AC, while sample C caused little angiogenesis. More the angiogenetic, more the foreign body reactions. It was confirmed that n-HAp bound in collagen sponge was safe and bio-absorbable; and n-HAp had mi-nor capability of angiogenesis, and if coupled with b-FGF, strong capability of angiogenesis at the implanted site in soft tissues. This biological property could be useful for regeneration of hard tissues as well as soft tissues in the future clinical applications.
Key words: nano-apatite, collagen composite, subcutaneous tissues, angiogenesis, organization