Strontium Fortified Calcium Compound Stimulates Osteogenic Factors Expression and New Bone Formation in Large Animal Model

Abstract

INTRODUCTION: Strontium is one of the most exciting concepts in the field of osteoporosis by concomitantly inhibiting bone resorption and enhancing bone formation. We hypothesized that, with the supplementation of a novel strontium fortified calcium compound, calcium will supply nutrition for bone while strontium will display synergistic effects for enhancing bone formation activity. METHODS: 18 ovariectomized goats were divided into four groups: group 1 (3 goats) control; group 2, 3 and 4 (5 per group) were treated daily with 100Ca, 100Ca+24Sr, 100Ca+40Sr mg/kg orally for 16 weeks, respectively. Strontium and calcium contents in serum and bone were determined. BMD of the lumbar vertebrae was measured by DXA. MRNA was isolated from bone matrix and evaluated by RT-PCR to determine the transcription activities of key osteogenic factors. RESULTS: Combination of Sr and Ca treatment significantly increased Sr concentration without changing in Ca concentration. BMD of group 2 and 3 slightly increased from 0.160±0.005 to 0.163±0.013 and determine the transcription activities of key osteogenic factors. RESULTS: Combination of Sr and Ca treatment significantly increased Sr concentration without changing in Ca concentration. BMD of group 2 and 3 slightly increased from 0.160±0.005 to 0.163±0.013 and 0.170±0.015gms/cm², respectively. BMD of group 4 was significantly increased by 9.4% (p<0.05). Calcium significantly depressed TNF- a expression (p<0.05). IGF-I and Runx-2 expression increased, while TNF-a expression decreased in group 3 and 4. However, a considerable increase of Runx-2 and decrease of TNF-a were only found in group 4. CONCLUSION: An increased BMD indicates that strontium combined with calcium stimulated bone formation. Increased IGF-I, Runx-2 and decreased TNF-a expression confirm the anabolic and antiresorptive activity of strontium on bone.