Immobilizing hydroxycholesterol with apatite on titanium surfaces to induce ossification.
BACKGROUND
Immobilizing bioactive molecules and osteoconductive apatite on titanium implants have investigated direct ossification. In this study, hydroxycholesterol (HC) was immobilized with apatite on titanium through simply adsorption or sandwich-like coating. Three kinds of hydroxycholesterol were chosen to induce ossification: 20α-hydroxycholesterol (20α- HC), 22(S)-hydroxycholesterol (22(S)-HC) and 25-hydroxycholesterol (25-HC).The effects of HC/apatite coating on ossification abilities were evaluated in vitro and in vivo.


RESULTS
At 6 d, adsorbed apatite/25-HC and apatite/22(S)-HC coating exhibited some cytotoxicity, while the cell viability of apatite/20α-HC coating was similar as apatite coating. Immobilizing HC with apatite significantly enhanced the ALP activities compared with apatite coating. There was no significant difference in ALP value between adsorbed apatite/HC coating and sandwich-like apatite/HC/apatite coating. When compared with apatite coating, the mineral deposition improved by adsorbed HC with apatite at higher concentration in vivo.


CONCLUSIONS
When compared with apatite coating, immobilizing HC with apatite coating induced the ossification in vitro and in vivo.
Bio-X Center, College of Life Sciences, Zhejiang Sci-Tech University, Hangzhou, 310018 China.
Cen
C
Chen
Department of Dental Biomaterials Science, Seoul National University, Seoul, 110-749 Korea.
Hyeong Cheol
HC
Yang
Bio-X Center, College of Life Sciences, Zhejiang Sci-Tech University, Hangzhou, 310018 China ; Institute of Natural Sciences, Yonsei University, Seoul, 120-749 Korea.
In-Seop
IS
Lee
Apatite; Hydroxycholesterol; Ossification; Titanium