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Abstract
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 5µg/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 HIF1a and GAPDH genes showed very high expression of HIF1a 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 HIF1a 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.
Keywords: CD34+ cells, Anaerobic glycolysis, Glutaminolysis, HIF1a, Hypoxic niche, enzyme activities
Introduction
Hematopoietic stem cells (HSCs) present in the bone marrow attached to the matrix and can be easily mobilized into peripheral blood using cytokines like Granulocyte colony stimulating factor. HSCs are once thought to be the cells involved in the generation of blood cells however, with the differentiation of these cells into other cell types of the body has prompted researcher's to use these cells in the regeneration and repair of non-blood tissues [1, 2]. This stem cell plasticity tissue-derived regenerative signal is termed as a transdifferentiation phenomenon [3]. Stem cells adopt such changes by varying the metabolic status as such these cells exhibit quiescent nature which is also driven by hypoxic environment that is present in the bone marrow. The HSCs are characterized primarily presence of CD34 or...