Molecular analysis and comparison of CD34+ and CD133+ very small embryonic-like stem cells purified from umbilical cord blood

Abstract

Very small embryonic like stem cells (VSELs) are a dormant population of stem cells that, as proposed, are deposited during embryogenesis in various tissues, including bone marrow (BM). These cells are released under steady state conditions from their tissue locations and circulate at a low level in peripheral blood (PB). Their number increases in response to stressors as well as tissue/organ damage. This increase is evident during neonatal delivery, as delivery stress prompts enrichment of umbilical cord blood (UCB) with VSELs. These cells could be purified from BM, PB, and UCB by multiparameter sorting as a population of very small CXCR4⁺ Lin^- CD45^- cells that express the CD34 or CD133 antigen. In this report, we evaluated a number of CD34⁺ Lin^- CD45^- and CD133⁺ Lin^- CD45^- UCB-derived VSELs. We also performed initial molecular characterization of both cell populations for expression of selected pluripotency markers and compared these cells at the proteomic level. We noticed that CD133⁺ Lin^- CD45^- population is more rare and express, at a higher level, mRNA for pluripotency markers Oct-4 and Nanog as well as the stromal-derived factor-1 (SDF-1) CXCR4 receptor that regulates trafficking of these cells, however both cells population did not significantly differ in the expression of proteins assigned to main biological processes.

Keywords: FACS sorting; Nanog; Oct-4; VSELs; proteomics.