Effect And Primary Mechanisms Of Late Endothelial Progenitor Cells On The Response To Acidic Environment

Background Endothelial progenitor cells(EPCs)are a type of naive progenitor cells,divided into two types: early EPCs and late EPCs,of which the late EPCs have a stronger proliferative ability.It can further proliferate and differentiate into vascular endothelial cells.EPCs can promote the repair of injured blood vessels and participate in angiogenesis,and play an important role in wound healing,peripheral vascular diseases,cardiovascular and cerebrovascular diseases and tumor angiogenesis,which has a very broad application prospect.Examples include coronary atherosclerotic heart disease,acute respiratory distress syndrome(ARDS),pulmonary hypertension,limb ischemia,cerebral infarction,and other vascular diseases.However,the number,proliferation,and migration capacity of EPCs in the human body are limited,and mobilizing EPCs to migrate to ischemic sites is difficult to treat serious diseases such as major trauma,vascular embolism,stroke,etc.However,EPCs transplantation can make up for this deficiency.The fluctuation of physiological conditions has little effect on EPCs,while the number and activity of EPCs will change under the stimulation of some pathological conditions or external factors.Confirmed in past research,for example,organization,statins,tissue ischemia,erythropoietin,physical exercise and EPC mobilization factor(such as vascular endothelial growth factor,basic fibroblast growth factor,stromal cell derived factor and granulocyte colony stimulating factor,etc.),such as factors affect the number and activity of EPCs.Therefore,it is very important to find a simple and effective new method for EPCs transplantation.Previous studies have shown that the survival of tumor cells depends on the acidic tumor microenvironment and can enhance the dryness of tumor cells.The acidic substances outside the cell can transform the normal cells near the cancer cells into cancer cells,indicating that the acidic environment gives it a strong growth advantage and migration ability.In addition,there was a certain relationship between the lifespan of yeast and the p H value of vacuoles.The low p H value of vacuoles promoted the function and longevity of mitochondria.However,the effect of the acidic environment on the function of the late EPCs is unknown.Longevity protein 1(Sirtuin 1)is one of the most widely studied genes in recent years,and is the largest member of the nicotinamide adenine dinucleotide(NAD)-dependent deacetylase family.SIRT 1 not only regulates expression genetics through the deacetylation of lysine residues of histones,but also regulates the activities of other key proteins to regulate cell proliferation,differentiation,apoptosis and other physiological functions.Studies conducted in yeast have shown that an increase in vacuolar p H limits mitochondrial function and longevity,possibly related to changes in SIRT 1 expression.Therefore,it is still unclear whether acidic environment will affect the expression of SIRT 1 in EPCs.Objective1.To investigate the effects of acidic environment on the functional activity of late EPCs(including proliferation,migration,adhesion and in vitro angiogenesis);2.To study the effect of acidic environment on the expression of SIRT 1 in late endothelial progenitor cells.Methods1.Umbilical cord blood was collected from healthy puerpera,and mononuclear cells were isolated by density gradient centrifugation method.Late EPCs were further cultured in vitro and identified by cellular immunofluorescence.2.After the application of p H 5.7 PBS for different time,the functional activity(including proliferation,migration,adhesion and in vitro angiogenesis)of the late EPCs and the effect on the expression of SIRT 1 in the late EPC were determined.Result1.Compared with the Control group,the proliferation activity,adhesion ability,migration ability and in vitro angiogenesis of the late EPCs were increased after the intervention of p H 5.7 PBS for 10 min,20min and 30 min,and the proliferation activity and adhesion ability reached the maximum at 20 min,which was statistically significant;At 10 min,the migration capacity reached the maximum,which was statistically significant.At 20 min,the adhesion ability reached the maximum value,which was statistically significant.2.Compared with the Control group,the expression of SIRT1 was up-regulated in both m RNA and protein levels of the late EPC after the intervention of 10 min,20min and 30 min with p H 5.7 PBS,and reached the maximum at 20 min.3.The improved dual fluorescence staining method of DII-AC-LDL and FITC-UEA-I can more easily obtain high quality fluorescence photomicrograph.Conclusion1.The acidic environment enhances the functional activity of late EPCs(including proliferation,migration,adhesion,and in vitro angiogenesis);2.Acid environment may enhance cell function by up-regulating the expression of SIRT1 in the late EPCs.