Simultaneous isolation of human BM hematopoietic, endothelial and mesenchymal progenitor cells by flow sorting based on aldehyde dehydrogenase activity: implications for cell therapy

Backgroud ALDH br cells express high aldehyde dehydrogenase (ALDH) activity and have progenitor cell activity in several contexts. We characterized human BM ALDH br cells to determine whether cell sorting based on ALDH activity isolates potentially useful populations for cell therapy. Method We measured the expression of ALDH and cell-surface Ag by flow cytometry and compared the ability of sorted ALDH br, and BM populations remaining after ALDH br cells were removed (ALDH dim populations), to develop into several cell lineages in culture. Results The ALDH br population comprised 1.2 +/- 0.8% (mean +/- SD, n = 30) nucleated cells and was enriched in cells expressing CD34, CD117, CD105, CD127, CD133 and CD166, and in primitive CD34(+) CD38(-) and CD34(+) CD133(+) progenitors. Most of the CD34(+) and CD133(+) cells were ALDH dim. ALDH br populations had 144-fold more hematopoietic colony-forming activity than ALDH dim cells and included all megakaryocyte progenitors. ALDH br populations readily established endothelial cell monolayers in cultures. Cells generating endothelial colonies in 7 days were 435-fold more frequent in ALDH br than ALDH dim populations. CFU-F were 9.5-fold more frequent in ALDH br than ALDH dim cells, and ALDH br cells gave rise to multipotential mesenchymal cell cultures that could be driven to develop into adipocytes, osteoblasts and chondrocytes. Discussion Hematopoietic, endothelial and mesenchymal progenitor cells can be isolated simultaneously from human BM by cell sorting based on ALDH activity. BM ALDH br populations may be useful in several cell therapy applications.