engleski

Recombinant human growth hormone stimulates proliferation and differentiation of bone cells in vitro

Growth hormone is one of the major regilators of the bone metabolism since it has essential impact on bone formation and development, although its activity pattern(s)are not yet completely understood. Hence, the purpose of this study was to investigate the effect of human recombinant growth hormone -somatropin on the proliferation and +differentiation of osteoblasts in vitro in respect to the hormone concentration and the serum presence. Human osteoblasts were isolated from the head of the femur and established a primary culture. Murine osteoblasts were isolated from calvaria of one day old C57BL/6 mice. The treatment with somatropin was performed in serum free or low FCS supplementation on semi confluent cultures of osteoblasts and effects were monitored by 3H-thymidine and 3H-aminoacids uptake and by the determination of alkaline phosphatase activity by cytochemcal staining. Very similar were the results obtained with human as well as murine osteoblasts. In short- term experiment /72h) in the presence of 1% FCS, the highest concentration of somatropin (0.1 I.E./ml) showed no influence on 3h-thymidine incorporation, but increase in 3H-aminoacids incorporation, followed by increase in ALP expression in long term cultures (7 days). In concentration of 10-1 I.E./ml somatropin increased 3H-thymidine incorporation into osteoblasts, but did not change 3H-amino acids uptake . However, both for human and for murine osteoblasts, reaction to somatropin presence was influenced by FCS. Thus, under serum free conditions there was alnmost opposite pattern of somatropin activities as to thos seen with 1% serum conditions. Results showed that somatropin can in vitro stimulate proliferation and differentiation of human as well murine osteoblasts depending on concentration used: in high concentrations it primarily stimulates differentiation and in lower, proliferation of the cells. Interference of serum and somatropin activities indicates that humoral growth factors and/or binding proteins play an additional regulatory rolew in determination of the cellular response to the growth hormone.

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nije evidentirano