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Summary: Differential osteogenic potential and responsiveness to 17β-estradiol (E2) of mesenchymal stem cells (MSCs) were found between postmenopausal women with osteoporosis (OP) and osteoarthritis (OA). These results suggest differential biological mechanisms of estrogen deficiency in regulation of bone remodeling between OP and OA. Introduction: OP and OA are two common disorders in postmenopausal women. The inverse relationship has been suggested between OP and OA, but their mechanisms that relate to estrogen deficiency are not fully understood. The aim of this study was to compare the differential responsiveness to E2 of MSCs from osteoporotic versus osteoarthritic donors. Methods: Twenty postmenopausal patients, ten with osteoporotic hip fractures and ten with hip osteoarthritis, were included into this study. MSCs were derived from cancellous bones of femoral heads from OA and OP donors and cultured in osteogenic and adipogenic medium with or without E2 added. The alkaline phosphatase (ALP) activity, calcium content, calcified nodules, lipid droplets, messenger RNA (mRNA) expression of ALP, osteocalcin (OC), collagen 1α (COL1α), peroxisome proliferators-activated receptor γ2 (PPARγ2) and lipoprotein lipase (LPL) were measured and compared between two groups with OP and OA. Results: In osteogenic medium, ALP activity, calcium content and mRNA expression of OC and COL1α in MSCs from OA were significantly higher than those from OP group. In adipogenic condition, there was no significant difference in lipid droplets formation and mRNA expression of PPARγ2 and LPL between OP and OA groups. With E2 added in osteogenic medium, ALP activity, calcium content and OC mRNA were significantly higher in OP group than in OA group, whereas E2 had no significant effect on lipid droplet formation and mRNA expression of PPARγ2 and LPL. Conclusion: Differential osteogenic potential and responsiveness to E2 of MSCs were found between postmenopausal women with OP and OA. These results may provide information for clinical application of MSCs in the differential setting of estrogen deficiency. [ABSTRACT FROM AUTHOR]

Summary: This study examines the association between sex steroids, bone mineral density (BMD), and incident fractures in 1,489 community-living Chinese men aged 65 and over. Chinese men with low serum estradiol levels display elevated bone loss and increased risk of fractures similar to findings in Caucasians. Introduction: This study examines the association between serum total testosterone (TT), free testosterone (free T), estradiol (E), bioavailable estradiol (bioE), sex hormone binding globulin (SHBG), BMD, and incident fractures. Methods: This is a cohort study with 4-year follow-up in the community in Hong Kong SAR, China. One thousand four hundred eighty-nine community-living Chinese men aged 65 and over participated. Sex steroid levels and BMD were measured at baseline; BMD was repeated after 4 years of follow-up, and fracture incidence from ascertainment from hospital databases was determined over 4 years of follow-up. Results: The strongest age-adjusted positive association with total hip and femoral neck BMD was with bioE, followed by E. Greater bone loss occurred in the lowest quartile of E and bioE. The lowest quartile of free T and bioE and the two highest quartile of SHBG were associated with the highest percentage of participants with incident fractures. Those in the lowest quartile of E and bioE had approximately a 50% increased risk of incident fractures compared with the other three quartiles. This relationship remains significant for nonvertebral incident fractures (hip, radius, pelvis, and humerus) for E only, but not bioE. Compared with the group with the three highest quartiles of TT and E, the group with the lowest quartile of both had approximately twice the risk of nonvertebral osteoporosis-related incident fractures. Conclusion: Chinese men with low serum estradiol levels display elevated bone loss and increased risk of fractures similar to findings in Caucasians. [ABSTRACT FROM AUTHOR]