Studies of human osteoblasts in vitro: Estrogen actions and interactions with other hormones at different stages of differentiation
✍ Scribed by Leticia G. Rao; Timothy M. Murray
- Publisher
- John Wiley and Sons
- Year
- 2000
- Tongue
- English
- Weight
- 154 KB
- Volume
- 49
- Category
- Article
- ISSN
- 0272-4391
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✦ Synopsis
The role of estrogen deficiency in the pathogenesis of postmenopausal osteoporosis is well established. Despite this, the cellular mechanisms of action of estrogen in bone are complex and far from clear. In vitro studies of cellular and molecular biology have concentrated on rodent cells. However, species differences have been noted, and an analysis of the skeletal actions of estrogen in human systems is needed. The major effect of estrogen appears to be in inhibiting bone resorption, but effects on osteoblasts have also been reported. This review deals with the studies of estrogen action in cells of the human osteoblast cell lineage. We have discussed and evaluated the different human osteoblast cell models currently available, and those currently being used to study estrogen action. Estrogen has a number of effects on osteoblastic cells, in terms of regulation of cell proliferation, differentiation, regulation of a number of genes, and the synthesis of growth factors and cytokines. However, in most cases the direct effects of estrogen are small. Larger effects are noted when cells are exposed to estrogen in combination with other hormones. A survey of the many studies reported reveals that the major action of estrogen in human osteoblasts in vitro is exerted through interactions with other hormones, cytokines, and growth factors. Furthermore, these effects are highly dependent on the stage of differentiation of the cells, and on estrogen receptor expression in the different cell models.