Estrogen loss may be involved in onset or progression of osteoarthritis. Estrogen receptors are present in chondrocytes, thus estrogen may exert effects directly on cartilage. However, studies on direct estrogen effects on cartilage are limited. We investigated, in an in vitro cartilage explant model, whether estrogen prevents damage or stimulates repair after damage induced by addition of iodoacetate (IA), as an experimental model for osteoarthritis. We used healthy bovine cartilage explants. Prevention experiment: Explants precultured with/without estradiol (E) for 3 days were cultured with IA for 4 h on day 0, and subsequently cultured as in preculture: with/without E. Explants were harvested at day 2 for gene expression analysis. Repair experiment: At day 0, explants were cultured with IA for 4 h on day 0, and subsequently cultured without E or with E. Explants were harvested at days 2, 10, and 14 for gene expression analysis. IA transiently downregulated most genes tested, whereas vascular endothelial growth factor (VEGF) was upregulated on day 2. On day 14, transforming growth factor beta (TGFB)1 and TGFB3 were upregulated, and matrix metalloproteinase (MMP)13 and VEGF downregulated. Estradiol affected gene expression of aggrecan (AGC)1, MMP2, MMP14, tissue inhibitor of metalloproteinase (TIMP)2, TGFB2, and TGFB3. Prevention experiment: Estradiol did not significantly affect IA-induced changes in gene expression (no significant interaction). Repair experiment: Estradiol affected IA-induced changes in expression of collagen (COL)2, MMP2, MMP3, MMP13, MMP14, TIMP2, TGFB2, TGFB3, and VEGF. Estradiol affects expression of anabolic and catabolic genes in bovine cartilage explants and modulates the effects of IA. These effects of estradiol may be beneficial for cartilage maintenance and repair.
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