Potential Role of rhIGF-I/IGFBP-3 in Maintaining Skeletal Mass in Space

Bone loss during space flight may be induced by decreased activity of bone formation. To explore a new method for the bone loss in microgravity, the effects of insulin-like growth factor I (IGF-I), a potent stimulator for osteoblast activities, were studied in in vitro and in vivo system. The complex of IGF-I and its specific binding protein, IGFBP-3, may stimulate the osteoblastic activities via prolonged serum half life and increased cellular association of IGF-I. In an ovariectomy combined with neurectomy model, this complex stimulated bone turnover. IGF-I/IGFBP-3 may be a candidate for the treatment of bone loss induced by the microgravity.