Abstract 14227: Glyoxalase-1 Overexpression in Bone Marrow Cells Restores Defective Neovascularization in Type I Diabetes
Background: Methylglyoxal, commonly accumulated in diabetics, disrupts bone marrow (BM) cell function, contributing to the defective neovascularization observed in diabetes. This study assessed whether overexpression of glyoxalase-1 (GLO1), a methylglyoxal-metabolizing enzyme, could reverse BM defects and restore neovascularization in ischemic tissue of diabetics.
Methods: C57BL/6J mice were irradiated and transplanted with BM from: 1) enhanced green fluorescent protein (GFP) mice; or 2) GFP mice that overexpress human GLO1, and subsequently rendered diabetic by streptozotocin. Non-diabetic (ND) mice receiving a GFP BM transplant served as controls. Following 6 wks for marrow reconstitution, hindlimb ischemia was induced. GFP+ circulating cells were analyzed by flow cytometry and perfusion was assessed by laser Doppler over time. At 2 wks, immunohistochemistry and cytokine arrays of tissues were performed.
Results: Compared to baseline, the fold-change in circulating angiogenic GFP+CXCR4+ cells (1.7±0.2) in diabetic mice receiving GLO1 BM transplant (GLO1 BM mice) was greater than in diabetic mice with wild-type GFP BM (GFP BM mice; 1.0±0.1; p=0.02), but not different from ND controls (1.8±0.3; p=0.7) over 2 wks. At 4 to 14 days, circulating GFP+VEGFR2+ cells increased 6.3±1.8-fold in GLO1 BM mice, which was greater than GFP BM mice (2.8±1.1; p=0.02), and similar to ND controls (8.3±2.7;p=0.4). Perfusion (ischemic/non-ischemic ratio) was greater in GLO1 BM mice (1.1±0.1) and ND controls (1.1±0.2) after 2 wks, compared to GFP BM mice (0.4±0.1; p≤0.01). Detection of human GLO1 protein in the hindlimb of GLO1 BM mice demonstrated successful recruitment and engraftment of GLO1 BM cells. Although not different from ND mice, increased localization of GFP+ cells in blood vessels (by 346%), greater numbers of GFP+cells expressing von Willebrand factor (endothelial cell marker; by 526%), and greater arteriole density (by 163%) were observed in hindlimbs of GLO BM mice, compared to GFP BM mice (p≤0.04). The tissue level of VEGF was 1.3-fold greater in GLO BM mice than in GFP BM mice (p=0.05).
Conclusions: This study suggests that GLO1 is a potential target to restore BM function and reverse the defective neovascularization associated with diabetes.
- © 2011 by American Heart Association, Inc.