Characterization and Isolation of Very Small Embryonic-like (VSEL) Stem Cells Obtained from Various Human Hematopoietic Cell Sources.

Stem cell transplantation is one of the available treatments for leukemia, lymphoma, hereditary blood diseases and bone marrow failure. Bone marrow (BM), peripheral blood progenitor cells (PBPC), and cord blood (CB) are the predominant sources of stem cells. Recently a new type of stem cell with a pluripotent potential has been identified. These cells were named "very small embryonic like stem cells (VSELs)". It is claimed that VSEL stem cells can be found in adult BM, peripheral blood (PB), CB and other body tissues. This study is designed to characterize and isolate VSEL stem cells from different human hematopoietic sources; CB, PB and apheresis material (PBPC). VSEL stem cells were isolated from MNC and erythrocyte layers for all materials by using centrifugation and ficoll gradient method. We determined embryonic markers by flow cytometry, immunofluorescence and western blotting methods. Results from western blotting and immunofluorescence show high level of NANOG and OCT4 protein expression in PB, apheresis material and CB. Immunofluorescence images showed cytoplasmic and nuclear presence of these proteins. Flow cytometry results exhibited a higher expression of VSELs markers on debris area than CD45- population and higher expression on CB than PB. As a result, these findings have shown that it is necessary to investigate the function of pluripotent stem cell markers in differentiated adult cells. We further conclude that erythrocyte lysis method had the highest cell recovery amount among erythrocyte lysis and ficoll gradient methods. Consequently, this study gives us new information and viewpoints about expression of pluripotent stem cell (PSC) markers in adult tissues.