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

BackgroudALDHbr cells express high aldehyde dehydrogenase (ALDH) activity and have progenitor cell activity in several contexts. We characterized human BM ALDHbr cells to determine whether cell sorting based on ALDH activity isolates potentially useful populations for cell therapy.MethodWe measured the expression of ALDH and cell-surface Ag by flow cytometry and compared the ability of sorted ALDHbr, and BM populations remaining after ALDHbr cells were removed (ALDHdim populations), to develop into several cell lineages in culture.ResultsThe ALDHbr 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 ALDHdim. ALDHbr populations had 144-fold more hematopoietic colony-forming activity than ALDHdim cells and included all megakaryocyte progenitors. ALDHbr populations readily established endothelial cell monolayers in cultures. Cells generating endothelial colonies in 7 days were 435-fold more frequent in ALDHbr than ALDHdim populations. CFU-F were 9.5-fold more frequent in ALDHbr than ALDHdim cells, and ALDHbr cells gave rise to multipotential mesenchymal cell cultures that could be driven to develop into adipocytes, osteoblasts and chondrocytes.DiscussionHematopoietic, endothelial and mesenchymal progenitor cells can be isolated simultaneously from human BM by cell sorting based on ALDH activity. BM ALDHbr populations may be useful in several cell therapy applications.