Phenotypic differences in early outgrowth angiogenic cells based on in vitro cultivation

Bone marrow-derived early outgrowth cells play an important role in endothelial repair. In vitro isolation techniques have identified two distinct morphological early outgrowth cell populations, but it is still unknown whether they present some functional phenotypic differences. Accordingly, the aim of the present study was to determine whether there are phenotypic differences in cellular function between two putative early outgrowth cells in culture. Peripheral blood samples were collected from 18 healthy adults. Thereafter, mononuclear cells were isolated by Ficoll density-gradient centrifugation and plated on 6-well plates coated with human fibronectin. After 2 and 7 days, respectively, non-adherent cells (NAC) and adherent cells (AC) underwent functional assays in order to measure the migratory capacity (Boyden chamber), angiogenic growth factor release (ELISA) and apoptosis (TUNEL). Migration to both VEGF (517 ± 74 vs. 273 ± 74 AU) and SDF-1 (517 ± 68 vs. 232 ± 68 AU) were approximately twofold higher (P < 0.05) in the NAC when compared to AC. Release of angiogenic factors, granulocyte colony-stimulating and hepatocyte growth factor, were not different between cell types. Apoptotic response to staurosporine was significantly lower in NAC (20 ± 32 vs. 125 ± 32%). In summary, NAC and AC demonstrated functional phenotypic differences in migratory capacity and apoptotic susceptibility, which makes it difficult to compare these two early outgrowth cell populations in literature.