title: Direct effects of caffeine on osteoblastic cells metabolism: the possible causal effect of caffeine on the formation of osteoporosis.
abstract: BACKGROUND
  Caffeine consumption has been reported to decrease bone mineral density (BMD), increase the risk of hip fracture, and negatively influence calcium retention. In this study, we investigated the influence of caffeine on the osteoblasts behaviour.
  
  
  METHODS
  Osteoblasts derived from newborn Wistar-rat calvaria was used in this study. The effects of various concentrations of caffeine on bone cell activities were evaluated by using MTT assay. Alkaline phosphatase (ALP) staining, von Kossa staining and biochemical parameters including ALP, lactate dehydrogenase (LDH), prostaglandin E2 (PGE2) and total protein were performed at day 1, 3, and 7. DNA degradation analysis under the caffeine influence was also performed.
  
  
  CONCLUSIONS
  The results showed that the viability of the osteoblasts, the formation of ALP positive staining colonies and mineralization nodules formation in the osteoblasts cultures decreased significantly in the presence of 10 mM caffeine. The intracellular LDH, ALP and PGE2 content decreased significantly, the LDH and PGE2 secreted into the medium increased significantly. The activation of an irreversible commitment to cell death by caffeine was clearly demonstrated by DNA ladder staining.
  
  
  CONCLUSIONS
  In summary, our results suggest that caffeine has potential deleterious effect on the osteoblasts viability, which may enhance the rate of osteoblasts apoptosis.
authors.affiliation: Department of Orthopedic Surgery, Taipei City Hospital, Taipei, Taiwan, ROC. tsuang66@ms71.hinet.net
authors.forename: Yang-Hwei
authors.initials: YH
authors.lastname: Tsuang
authors.forename: Jui-Sheng
authors.initials: JS
authors.lastname: Sun
authors.forename: Li-Ting
authors.initials: LT
authors.lastname: Chen
authors.forename: Samuel Chung-Kai
authors.initials: SC
authors.lastname: Sun
authors.forename: San-Chi
authors.initials: SC
authors.lastname: Chen