Anaerobic Glycolysis and HIF1α Expression in Haematopoietic Stem Cells Explains Its Quiescence Nature

Metabolic alteration that a stem cell undergoes during proliferation and quiescence are decisive. These cells survive in extreme hypoxic environment that prevails in bone marrow. The present study is aimed to understand this nature in hematopoietic stem cells. These stem cells were mobilized from bone marrow into peripheral blood by giving G-CSF at a concentration of 5 μg/Kg/d and the cells were isolated by apheresis technique. The morphological analysis of these cells using Giemsa stain and SEM showed presence of only single type of cells with conspicuous nuclei, the hematopoietic nature was assessed by the presence of CD34, a glycoprotein using anti-CD34 monoclonal antibodies. The ICC results revealed presence of CD34 marker further; pure population of CD34+ stem cells was described by FACS. These cells were cultured separately in DMEM having 5.5mM, 11.1mM and 25mM glucose respectively. In these cells GK, PK and L-LDH enzyme activities were estimated which showed increased activities at 5.5mM glucose concentration and further elevation of glucose concentration the activities were fallen considerably. Similarly, qPCR analysis of HIF1α and GAPDH genes showed very high expression of HIF1α at 5.5mM glucose concentration which reduced with increased glucose concentration. While GAPDH gene expression enhanced on elevation of glucose concentration. Thus, these results indicate high HIF1α expression in low glucose condition with improved anaerobic glycolysis seems to be one of the key factors in maintaining the quiescent state of CD34+ stem cells.