Abnormal osteogenesis in osteoporotic patients is reflected by altered mesenchymal stem cells dynamics

Bone marrow contains a population of mesenchymal stem cells with the abilit y to differentiate into cells that form bone, cartilage, adipose, and other connective tissues. Stem cells can be isolated from bone marrow aspirates and expanded in vitro. Presently, most stem cells studies have been perform ed in cells obtained from "healthy" control subjects. The goal of this stud y was to compare the functional characteristics of mesenchymal stem cells d erived from "healthy" control and osteoporotic postmenopausal women to bett er understand the mechanisms involved in the pathogenesis of this disease. Osteoporotic and control stem cells have similar morphology and size and ex press similar cell surface antigens as evidenced by their reactivity with c ell specific monoclonal antibodies. Mesenchymal stem cells from osteoporoti c women differ from controls in having a lower growth rate than control cel ls, being refractory to the mitogenic effect of IGF-1, and exhibiting a def icient ability to differentiate into the osteogenic linage as evidenced by the alkaline phosphatase activity and calcium phosphate deposition. We conc lude that in osteoporosis stem cell growth, proliferative response and oste ogenic differentiation are significantly affected. Also, the study of mesen chymal stem cells from osteoporotic postmenopausal women may provide a bett er understanding of the mechanisms involved in the pathogenesis of the oste oporosis. It may also serve to test in vitro in rapid manner novel new ther apeutic strategies. J. Cell. Biochem. 75:414-423, 1999. (C) 1999 Wiley-Liss . Inc.