Prevention of osteoporosis in mice after ovariectomy via allograft of microencapsulated ovarian cells.

It is believed that estrogen deficiency is one of the major risk factors associated with osteoporosis. To investigate the effects of the transplantation of microencapsulated ovarian cells in estrogen-deficient mice, ovarian cells from female Kunming (KM) mice (6-weeks old) were separated, cultured, and microencapsulated with alginic acid-polylysine-alginic acid. Female KM mice (8-weeks old) were randomly separated into three groups: intact (normal), ovariectomized (OVX), and treatment (OVX+ implantation). Microencapsulated ovarian cells were found to secrete estrogen at normal levels in vitro. Ninety days after transplantation, serum estradiol levels in the OVX group were significantly lower, and the trabecular bone amount and volume were decreased when compared with the normal group. The expression of alkaline phosphatase in chondrocytes appeared lower, while the expression of matrix metalloproteinase 9 (MMP-9) in the bone matrix was higher. The ratio of MMP-9-positive chondrocytes and osteoblasts to osteoclasts was significantly lower than that of the normal group. The concentrations of hydroxyproline (Hyp), Ca, and P in the left femurs of the OVX group were lower than those of the normal group. However, the aforementioned changes were not seen in the treatment group. In conclusion, microencapsulated ovarian cells survive well after transplantation and secrete estrogen in vivo, and they can prevent in some degree osteoporosis caused by ovariectomy.