The effect of strontium incoporated with hydroxyapatite on osteoblastic differentiation of bone masenchymal stromal cells

Abstract

Objective To determine if strontium-containing hydroxyapatite (Sr-HA) will favor osteoblastic differentiation of bone masenchymal stromal cells (BMSCs). Methods Rat BMSCs were cultured with culture media containing ions released from the strontium-substituted HA ceramics as they dissolved. We had 3 experimental groups and one blank control group. In group A, leaching liquor containing 10 mol% of Sr-HA was used;in group B, leaching liquor containing 5 mol% of Sr-HA was used;in group C,leaching liquor containing 1 mol% of Sr-HA was used;in group D, leaching liquor containing no Sr-HA was used. MTT test, alkaline phosphatase (ALP) activity and osteoblast transcription factor gene (Cbfα1) expression examinations were conducted at different time-points. Results MTT test showed that there were no significant differences in absorbance between the 4 groups after cell culture for 1, 3, 5, 7, 10 days( P ＞ 0. 05),but there were significant differences in absorbance between different time-points within the same group ( P ＜0.05). The ALP activity in groups A and B was significantly greater than in groups C and D ( P ＜ 0. 05) at 6, 9,12, 15 days. At 9 and 12 days, there were significant differences in Cbfα1 mRNA expression between the 4 groups ( P ＜ 0. 05). Compared with the blank control group, Sr-HA groups presented a significant enhancement with regard to ALP activity and Cbfα1 mRNA expression in a concentration-dependent manner. Conclusion Incorportion of strontium in HA ceramics may not promote proliferation of BMSCs, but may stimulate osteoblastic differentiation of BMSCs. Key words: Strontium; Hydroxyapatites; Bone marrow cells; Cell differentiation