Vascular Endothelial Growth Factor Overexpression Does Not Enhance Adipose Stromal Cell–Induced Protection on Muscle Damage in Critical Limb Ischemia

Abstract

Objectives— Critical limb ischemia complicates peripheral artery disease leading to tissue damage and amputation. We hypothesized that modifying adipose stromal cells (ASCs) to overexpress human vascular endothelial growth factor 165 (VEGF) would limit ischemic muscle damage to a larger extent than nonmodified ASCs. Approach and Results— Rabbits with critical hindlimb ischemia were injected with allogeneic abdominal fat-derived ASCs transfected with plasmid-VEGF 165 (ASCs-VEGF; n=10). Additional rabbits received nontransfected ASCs (ASCs; n=10) or vehicle (placebo; n=10). One month later, ASCs-VEGF rabbits exhibited significantly higher density of angiographically visible collaterals and capillaries versus placebo (both P <0.05) but not versus ASCs (both P =NS). Arteriolar density, however, was increased in both ASCs and ASCs-VEGF groups (both P <0.05 versus placebo). ASCs-VEGF and ASCs showed comparable post-treatment improvements in Doppler-assessed peak systolic velocity, blood pressure ratio, and resistance index. Ischemic lesions were found in 40% of the muscle samples in the placebo group, 19% in the ASCs-VEGF group, and 17% in the ASCs groups (both P <0.05 versus placebo, Fisher test). Conclusions— In a rabbit model of critical limb ischemia, intramuscular injection of ASCs genetically modified to overexpress VEGF increase angiographically visible collaterals and capillary density. However, both modified and nonmodified ASCs increase arteriolar density to a similar extent and afford equal protection against ischemia-induced muscle lesions. These results indicate that modifying ASCs to overexpress VEGF does not enhance the protective effect of ASCs, and that arteriolar proliferation plays a pivotal role in limiting the irreversible tissue damage of critical limb ischemia.

Role of Resident Stem Cells in Vessel Formation and Arteriosclerosis

“…They increased arteriolar density and protected against ischemia-induced muscle lesions. 133 Furthermore, Joe et al 134 purified Lin − /Sca-1 + /CD34 + cells from the stromal vascular fraction of white adipose tissue of GFP (green fluorescence protein) mice by fluorescence-activated cell sorter and transplanted them in matrigel into wild-type mice. Adipocyte progenitor cells were able to form mature unilocular and multilocular adipocytes with GFP expression.…”

Critical Limb Ischemia Induces Remodeling of Skeletal Muscle Motor Unit, Myonuclear-, and Mitochondrial-Domains

“…In its most severe form, referred to as critical limb ischemia (CLI), where blood flow is insufficient to maintain tissue viability, amputation rates can reach up to 50% 1 . While recent regenerative medicine approaches on collateral vessel formation have made some progress, the dysregulation of the skeletal muscle in CLI and the subsequent tissue remodeling have not been thoroughly investigated 2–4 . Recent evidence suggests that the ischemia-induced loss of viable muscle tissue, which acts as an indispensable matrix of growth factors and biomechanical support for new vessel formation, may be the cause of failure for current revascularization therapies 5,6 .…”

Muscle Derived Stem Cells Stimulate Muscle Myofiber Repair and Counteract Fat Infiltration in a Diabetic Mouse Model of Critical Limb Ischemia

“…Therefore, CLI is an important subject for the search for novel vascular regeneration and muscle repair therapies. Stem cell implantation has been tried in animal models of ischemia using various kinds of cells, the most promising in terms of revascularization being Bone Marrow Mesenchymal Stem Cells (BMMSC), Adipose Tissue Derived Stem Cells (ATDSC), and Endometrial Regenerative Cells (ERC) [ 9 – 11 ]. However, few studies have been carried out in true T2D-CLI models, and none involving pharmacological modulation of stem cell stemness and differentiation.…”