Characterization of nonexpanded mesenchymal progenitor cells from normal adult human bone marrow

Objective Adult bone marrow (BM) mesenchymal stem/progenitor cells (MS/PC) are a potentially useful tool for cell therapy and tissue repair. However, the identification of cell subsets rich in MS/PC from fresh BM has not been described. We have developed a means of identifying such subsets from untouched bone marrow. Material and methods First, MS/PC were enriched by short-time adherence (D1–3) before any cell division to evaluate the efficiency of CD73, CD105, CDw90, and CD49a antigens to select highly purified CD45−CD14− fluorescence-activated sorted subsets enriched in clonogenic mesenchymal cells. Then, we adapted this method to unmanipulated BM mononuclear cells (MNC). Results Short-time (D1–3) adherent CD45−CD14− cells expressing CD73 or CD49a antigens contained all the CFU-F, even though the CD105+ and CDw90+ subsets comprised less than half the total. In fresh unmanipulated BM MNC, CD73 and CD49a were also highly discriminative and allowed up to a 3 log enrichment of CFU-F when compared to BM MNC. Normal culture conditions upregulated most of the tested antigens. Conclusion The CD45−CD14−/CD73+ and CD45−CD14−/CD49a+ phenotypes identified subsets containing all the CFU-F and sufficiently enriched to detect them in fresh BM, enabling evaluation of mesenchymal content of BM collections for cell therapy.