Vasoreparative dysfunction of CD34+ cells in diabetic individuals involves hypoxic desensitization and impaired autocrine/paracrine mechanisms.
We hypothesized that endothelial progenitor cells derived from individuals with diabetes would exhibit functional defects including inability to respond to hypoxia and altered paracrine/autocrine function that would impair the angiogenic potential of these cells. Circulating mononuclear cells isolated from diabetic (n = 69) and nondiabetic (n = 46) individuals were used to grow endothelial colony forming cells (ECFC), early endothelial progenitor cells (eEPCs) and isolate CD34+ cells. ECFCs and eEPCs were established from only 15% of the diabetic individuals tested thus directing our main effort toward examination of CD34+ cells. CD34+ cells were plated in basal medium to obtain cell-free conditioned medium (CM). In CM derived from CD34+ cells of diabetic individuals (diabetic-CM), the levels of stem cell factor, hepatocyte growth factor, and thrombopoietin were lower, and IL-1β and tumor necrosis factor (TNFα) levels were higher than CM derived from nondiabetic individuals (nondiabetic-CM). Hypoxia did not upregulate HIF1α in CD34+ cells of diabetic origin. Migration and proliferation of nondiabetic CD34+ cells toward diabetic-CM were lower compared to nondiabetic-CM. Attenuation of pressure-induced constriction, potentiation of bradykinin relaxation, and generation of cGMP and cAMP in arterioles were observed with nondiabetic-CM, but not with diabetic-CM. Diabetic-CM failed to induce endothelial tube formation from vascular tissue. These results suggest that diabetic subjects with microvascular complications exhibit severely limited capacity to generate ex-vivo expanded endothelial progenitor populations and that the vasoreparative dysfunction observed in diabetic CD34+ cells is due to impaired autocrine/paracrine function and reduced sensitivity to hypoxia.
Department of Pharmaceutical Sciences, College of Pharmacy, Nursing, and Allied Sciences, North Dakota State University, Fargo, North Dakota, United States of America; Departments of Pharmacology and Therapeutics, College of Medicine, University of Florida, Gainesville, Florida, United States of America.
Yagna P R
YP
Jarajapu
Departments of Pharmacology and Therapeutics, College of Medicine, University of Florida, Gainesville, Florida, United States of America.
Sugata
S
Hazra
Department of Nephrology, College of Medicine, University of Florida, Gainesville, Florida, United States of America.
Mark
M
Segal
Sergio
S
Li Calzi
Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America.
Sergio
S
LiCalzi
Chandra
C
Jadhao
Departments of Pharmacology and Therapeutics, College of Medicine, University of Florida, Gainesville, Florida, United States of America.
Chandra
C
Jhadao
Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America.
Kevin
K
Qian
Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America.
Sayak K
SK
Mitter
Department of Physiology and Functional Genomics College of Medicine, University of Florida, Gainesville, Florida, United States of America.
Mohan K
MK
Raizada
Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America.
Michael E
ME
Boulton
Departments of Pharmacology and Therapeutics, College of Medicine, University of Florida, Gainesville, Florida, United States of America; Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America.
Maria B
MB
Grant
D000328:Adult; D000368:Aged; D018952:Antigens, CD34 / Q000378:metabolism*; D002478:Cells, Cultured; D003924:Diabetes Mellitus, Type 2 / Q000378:metabolism*; D042783:Endothelial Cells / Q000378:metabolism*; D017228:Hepatocyte Growth Factor / Q000378:metabolism; D006801:Humans; D000860:Hypoxia / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D018919:Neovascularization, Physiologic / Q000502:physiology*; D019089:Stem Cell Factor / Q000378:metabolism; D013234:Stem Cells / Q000378:metabolism*; D013926:Thrombopoietin / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
D018952:Antigens, CD34; D019089:Stem Cell Factor; D014409:Tumor Necrosis Factor-alpha; D017228:Hepatocyte Growth Factor; D013926:Thrombopoietin