Type-2 diabetic Lepr(db/db) mice show a defective microvascular phenotype under basal conditions and an impaired response to angiogenesis gene therapy in the setting of limb ischemia

Costanza Emanueli, Andrea Caporali, Nicolle Krankel, Brunella Cristofaro, Sophie Van Linthout, Paolo Madeddu

Research output: Contribution to journalArticle (Academic Journal)peer-review

Abstract

Diabetes mellitus is associated with macro- and micro-angiopathy, leading to increased risk of peripheral ischemia. In the present study, we have characterized the microvascular phenotype at the level of limb muscles and the spontaneous angiogenesis response to surgically-induced unilateral limb ischemia in a murine model of type-2 diabetes, the obese C57BL/KsOlaHsd-Lepr(db/db) mice (Lepr(db/db)), and in non-diabetic heterozygous Lepr(db/+). Wild type C57BL mice (WT) were used as controls. The basal microvascular phenotype was determined in mice aged 3 or 5 months, while the response to limb ischemia was studied only in 5-month old mice. Moreover, in 5-month old ischemic Lepr(db/db) and Lepr(db/+), we have tested the therapeutic potential of local angiogenesis gene therapy with human tissue kallikrein (hTK) or constitutively-activated Akt kinase (Myr-Akt). We found that in the muscles of 3- or 5-month old Lepr(db/db), apoptosis of endothelial cells was enhanced and the densities of capillary and arteriole were reduced. Arterioles of Lepr(db/db) showed hypertrophic remodelling and, occasionally, lumen occlusion. Following ischemia, Lepr(db/db) showed a defective reparative angiogenesis in ischemic muscle, delayed blood flow recovery, and worsened clinical outcome as compared with controls. Five-month old Lepr(db/+) displayed an increase in endothelial cell apoptosis under basal conditions, while capillary and arteriole densities were normal. Lepr(db/+) mounted a proper reparative angiogenesis response to limb ischemia and regained blood flow to the ischemic limb, regularly. Local gene therapy with hTK or Myr-Akt induced angiogenesis in ischemic muscles of Lepr(db/+) and Lepr(db/db). However, in the Lepr(db/db) neither gene therapy approach improved the blood flow recovery and the clinical outcome from ischemia. In contrast, either hTK or Myr-Akt gene transfer improved the post-ischemic recovery of Lepr(db/+). Type-2 diabetes has a negative impact on the basal microvascular phenotype and severely impairs post-ischemic recovery of limb muscles. Gene therapy-induced stimulation of neovascularization might not suffice as a sole therapeutic strategy to combat type-2 diabetes-related vascular complications. In type-2 diabetic patients, therapeutic angiogenesis may need to be further optimized before being recommended for clinical applications.

Original languageEnglish
Pages (from-to)2003-12
Number of pages10
JournalFrontiers in Bioscience
Volume12
Publication statusPublished - 2007

Keywords

  • Animals
  • Capillaries
  • Diabetes Mellitus, Type 2
  • Diabetic Angiopathies
  • Genetic Therapy
  • Humans
  • Ischemia
  • Lower Extremity
  • Mice
  • Mice, Inbred C57BL
  • Mice, Obese
  • Muscle, Skeletal
  • Neovascularization, Physiologic
  • Nitric Oxide Synthase Type III
  • Phenotype
  • Proto-Oncogene Proteins c-akt
  • Receptors, Cell Surface
  • Receptors, Leptin
  • Tissue Kallikreins
  • Vascular Endothelial Growth Factor A

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