title: Limb ischemia after iliac ligation in aged mice stimulates angiogenesis without arteriogenesis.
abstract: OBJECTIVE
  Older patients are thought to tolerate acute ischemia more poorly than younger patients. Since aging may depress both angiogenesis and arteriogenesis, we determined the effects of age on both angiogenesis and arteriogenesis in a model of severe acute limb ischemia.
  
  
  METHODS
  Young adult (3-months-old) and aged (18-months-old) C57BL/6 mice underwent right common iliac artery and vein ligation and transection. Data were collected on days 0, 7, and 14. Perfusion was measured with a laser Doppler scan and compared to the contralateral limb. Functional deficits were evaluated with the Tarlov scale. Capillary density and endothelial progenitor cell (EPC) number were determined by direct counting lectin-positive/alpha-actin-negative cells and VEGFR2/CXCR4 dually-positive cells, respectively; angiography was performed to directly assess arteriogenesis.
  
  
  RESULTS
  Young adult and aged mice had a similar degree of decreased perfusion after iliac ligation (young, n = 15: 20.4 +/- 1.9%, vs aged, n = 20: 19.6 +/- 1.3%; P = .72, analysis of variance [ANOVA]); however, young mice recovered faster and to a greater degree than aged mice (day 7, 35 +/- 6% vs 17 +/- 4%, P = .046; day 14, 60 +/- 5% vs 27 +/- 7%, P = .0014). Aged mice had worse functional recovery by day 14 compared to young mice (2.3 +/- 0.3 vs 4.3 +/- 0.4; P = .0021). Aged mice had increased capillary density (day 7, 12.9 +/- 4.4 vs 2.8 +/- 0.3 capillaries/hpf; P = .02) and increased number of EPC incorporated into the ischemic muscle (day 7, 8.1 +/- 0.9 vs 2.5 +/- 1.9 cells; P = .007) compared to young mice, but diminished numbers of collateral vessels to the ischemic limb (1 vs 9; P = .01), as seen on angiography.
  
  
  CONCLUSIONS
  After severe hind limb ischemia, aged animals become ischemic to a similar degree as young animals, but aged animals have significantly impaired arteriogenesis and functional recovery compared to younger animals. These results suggest that strategies to stimulate arteriogenesis may complement those that increase angiogenesis, and may result in improved relief of ischemia.
authors.affiliation: Departments of Surgery, Yale University School of Medicine, New Haven, Connecticut 06520-8089, USA.
authors.forename: Tormod S
authors.initials: TS
authors.lastname: Westvik
authors.forename: Tamara N
authors.initials: TN
authors.lastname: Fitzgerald
authors.forename: Akihito
authors.initials: A
authors.lastname: Muto
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Maloney
authors.forename: Jose M
authors.initials: JM
authors.lastname: Pimiento
authors.forename: Tiffany T
authors.initials: TT
authors.lastname: Fancher
authors.forename: Dania
authors.initials: D
authors.lastname: Magri
authors.forename: Hilde H
authors.initials: HH
authors.lastname: Westvik
authors.forename: Toshiya
authors.initials: T
authors.lastname: Nishibe
authors.forename: Omaida C
authors.initials: OC
authors.lastname: Velazquez
authors.forename: Alan
authors.initials: A
authors.lastname: Dardik
mesh_terms: D000208:Acute Disease; D000367:Age Factors; D000818:Animals; D001158:Arteries / Q000503:physiopathology; D001783:Blood Flow Velocity; D002196:Capillaries / Q000503:physiopathology; D003097:Collateral Circulation; D004195:Disease Models, Animal; D042783:Endothelial Cells / Q000473:pathology; D006614:Hindlimb; D007083:Iliac Artery / Q000601:surgery; D007084:Iliac Vein / Q000601:surgery; D007511:Ischemia / Q000473:pathology / Q000503:physiopathology*; D017078:Laser-Doppler Flowmetry; D008026:Ligation; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008833:Microcirculation; D018482:Muscle, Skeletal / Q000098:blood supply*; D018919:Neovascularization, Physiologic; D020127:Recovery of Function; D012039:Regional Blood Flow; D012720:Severity of Illness Index; D013234:Stem Cells / Q000473:pathology; D013997:Time Factors; D014057:Tomography, X-Ray Computed