title: Enhancement of the ALP activity of C3H10T1/2 cells by the combination of an oxysterol and apatite.
abstract: Biomimetic apatite coating has been used to load osteogenic biomolecules onto the surface of titanium implants. Apatite on the surface of biomaterials is thought to function as a reservoir of biomolecules as well as enhancing osteoconductivity. In this study, 20alpha-hydroxycholesterol (20alpha-HC), an osteogenic oxysterol, was used to induce differentiation of a mouse embryo fibroblast cell line (C3H10T1/2) by loading the oxysterol on biomimetically coated apatite of titanium discs. We found that the phosphatase (alkaline phosphatase (ALP)) activity of 20alpha-HC was significantly higher with ascorbic acid than alone, suggesting a need for ascorbic acid as a co-factor. When 20alpha-HC was added into the apatite coating solution, the ALP activity of the C3H10T1/2 cells did not increase on the apatite surface, even in the presence of ascorbic acid. However, ALP activity increased dramatically when 20alpha-HC was loaded by volatilization of EtOH from the apatite coat after dipping discs in 20alpha-HC-dissolved EtOH. Interestingly, ascorbic acid was not needed for this increase in ALP activity, suggesting a synergistic effect of 20alpha-HC and apatite. The concentration of calcium ions, a major component of apatite, affected the osteogenic effect of 20alpha-HC, and the increase in ALP activity was attenuated by L-type calcium channel inhibitors, verapamil and nifedipine. These results demonstrate that calcium ions released from apatite are important in the synergistic effect of 20alpha-HC and apatite.
authors.affiliation: Department of Dental Biomaterials Science, Dental Research Institute, School of Dentistry, Seoul National University, Yeonkun-dong, Chongro-ku, Seoul 110-749, Korea.
authors.forename: Kyung Mi
authors.initials: KM
authors.lastname: Son
authors.forename: Hee Chul
authors.initials: HC
authors.lastname: Park
authors.forename: Na Ryoung
authors.initials: NR
authors.lastname: Kim
authors.forename: In-Seop
authors.initials: IS
authors.lastname: Lee
authors.forename: Hyeong-Cheol
authors.initials: HC
authors.lastname: Yang
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism*; D000818:Animals; D001031:Apatites / Q000737:chemistry*; D018929:Cell Culture Techniques / Q000379:methods; D002460:Cell Line; D049109:Cell Proliferation; D002470:Cell Survival; D020099:Coated Materials, Biocompatible / Q000737:chemistry / Q000494:pharmacology*; D004789:Enzyme Activation / Q000187:drug effects; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D006888:Hydroxycholesterols / Q000737:chemistry / Q000494:pharmacology*; D008422:Materials Testing; D051379:Mice; D023822:Tissue Engineering / Q000379:methods*; D014025:Titanium / Q000737:chemistry*
chemical_list: D001031:Apatites; D020099:Coated Materials, Biocompatible; D006888:Hydroxycholesterols; C025813:20-hydroxycholesterol; D014025:Titanium; D000469:Alkaline Phosphatase