A bone replaceable artificial bone substitute: Cytotoxicity, cell adhesion, proliferation, and alkaline phosphatase activity

Cellular toxicity, cell adhesion and proliferation, and alkaline phosphatase (ALP) activity were investigated for an artificial bone substitute composed of heated carbonate apatite (CAp) and Type I atelocollagen (AtCol) extracted from bovine tail skins (88/12 in %wt/ wt). To enhance the intramolecular crosslinking between collagen molecules, the CAp-AtCol substitutes were irradiated by ultraviolet rays (wave length 254 nm) at 4°C for 4 h or vacuum dried at 150°C for 2 h. Cytotoxicity tests by a direct contact method and an extract dilution method revealed that the CAp-AtCol substitutes were cytocompatible for balb 3T3 fibroblasts. Osteoblast adhesion studies demonstrated that the substitute disks composed of 980°C-heated CAp and AtCol were significantly more adhesive for osteoblasts than those of 1,200°C-sintered CAp and AtCol (p < 0.05). Proliferation studies showed that the number of osteoblasts grown in the media containing substitutes of 980°C-heated CAp and AtCol was statistically higher than grown in those of 1,200°C-sintered CAp and AtCol after 5 days (p < 0.05). It was found that osteoblasts grown in the substitutes of 980°C-heated CAp and AtCol only expressed similar ALP activity to the controls. These results suggested that the substitutes consisting of 980°C-heated CAp and AtCol show more favorable interactions with osteoblasts than those of 1,200°C-sintered CAp and AtCol.