Recovery from hind limb ischemia is less effective in type 2 than in type 1 diabetic mice: roles of endothelial nitric oxide synthase and endothelial progenitor cells.
OBJECTIVE
We sought to directly compare the effects of type 1 and type 2 diabetes on postischemic neovascularization and evaluate the mechanisms underlying differences between these groups. We tested the hypothesis that type 2 diabetic mice have a greater reduction in endothelial nitric oxide synthase (eNOS) expression, a greater increase in oxidative stress, and reduced arteriogenesis and angiogenesis, resulting in less complete blood flow recovery than type 1 diabetic mice after induction of hind limb ischemia.


METHODS
Hind limb ischemia was generated by femoral artery excision in streptozotocin-treated mice (model of type 1 diabetes), in Lepr(db/db) mice (model of type 2 diabetes), and in control (C57BL/6) mice. Dependent variables included eNOS expression and markers of arteriogenesis, angiogenesis, and oxidative stress.


RESULTS
Postischemia recovery of hind limb perfusion was significantly less in type 2 than in type 1 diabetic mice; however, neither group demonstrated a significant increase in collateral artery diameter or collateral artery angioscore in the ischemic hind limb. The capillary/myofiber ratio in the gastrocnemius muscle decreased in response to ischemia in control or type 1 diabetic mice but remained the same in type 2 diabetic mice. Gastrocnemius muscle eNOS expression was lower in type 1 and 2 diabetic mice than in control mice. This expression decreased after induction of ischemia in type 2 but not in type 1 diabetic mice. The percentage of endothelial progenitor cells (EPC) in the peripheral blood failed to increase in either diabetic group after induction of ischemia, whereas this variable significantly increased in the control group in response to ischemia. EPC eNOS expression decreased after induction of ischemia in type 1 but not in type 2 diabetic mice. EPC nitrotyrosine accumulation increased after induction of ischemia in type 2 but not in type 1 diabetic mice. EPC migration in response to vascular endothelial growth factor was reduced in type 1 and type 2 diabetic mice vs control mice. EPC incorporation into tubular structures was less effective in type 2 diabetic mice. Extensive fatty infiltration was present in ischemic muscle of type 2 but not in type 1 diabetic mice.


CONCLUSIONS
Type 2 diabetic mice displayed a significantly less effective response to hind limb ischemia than type 1 diabetic mice.
Yan
Jinglian
J
Department of Surgery, University of Massachusetts Medical School, Worcester, Mass 01655, USA.
Tie
Guodong
G
Park
Brian
B
Yan
Yagai
Y
Nowicki
Philip T
PT
Messina
Louis M
LM
D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D001835:Body Weight; D002633:Chemotaxis; D003097:Collateral Circulation; D003921:Diabetes Mellitus, Experimental / Q000150:complications / Q000201:enzymology / Q000503:physiopathology*; D003922:Diabetes Mellitus, Type 1 / Q000150:complications / Q000201:enzymology / Q000503:physiopathology*; D003924:Diabetes Mellitus, Type 2 / Q000150:complications / Q000201:enzymology / Q000235:genetics / Q000503:physiopathology*; D042783:Endothelial Cells / Q000201:enzymology*; D006614:Hindlimb; D007511:Ischemia / Q000150:complications / Q000201:enzymology / Q000503:physiopathology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D018482:Muscle, Skeletal / Q000098:blood supply*; D018919:Neovascularization, Physiologic; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism*; D018384:Oxidative Stress; D054411:Receptors, Leptin / Q000235:genetics; D020127:Recovery of Function; D012039:Regional Blood Flow; D013234:Stem Cells / Q000201:enzymology*; D013997:Time Factors; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism
D001786:Blood Glucose; D054411:Receptors, Leptin; D042461:Vascular Endothelial Growth Factor A; C515447:leptin receptor, mouse; C002744:3-nitrotyrosine; D014443:Tyrosine; D052250:Nitric Oxide Synthase Type III; C496315:Nos3 protein, mouse