Mesenchymal precursor cells in the blood of normal individuals

Mesenchymal precursor cells found in the blood (BMPCs) of normal persons ad here to plastic and glass and proliferate logarithmically in DMEM-20% fetal calf serum (FCS) without growth factors. They form cells with fibroblast-l ike and stromal morphology, which is not affected by eliminating CD34, CD3, or CD14 cells. Osteogenic supplements (dexamethasone, ascorbic acid, and b eta -glycerophosphate) added to the culture inhibited fibroblast formation, and BMPCs assumed the cuboidal shape of osteoblasts. After 5 days in suppl emented medium, the elutriated cells displayed alkaline phosphatase (AP), a nd the addition of bone morphogenetic protein (BMP)2 (1 ng) doubled AP prod uction (P<0.04). Two weeks later, 30% of the cells were very large and reac ted with anti-osteocalcin antibody. The same cultures also contained sudano phlic adipocytes and multinucleated giant cells that stained for tartrate-r esistant acid phosphatase (TRAP) and vitronectin receptors. Cultured BMPCs immunostain with antibodies to vimentin, type I collagen, and BMP receptors , heterodimeric structures expressed on mesenchymal lineage cells. In addit ion, BMPCs stain with anti-CD105 (endoglin), a putative marker for bone-mar row mesenchymal stem cells (MSCs).