Abstract 14769: Specific Epigenetic Changes Associated With the Dysfunctional Profile in CD34+ Cells Exposed to High Glucose Concentration
Introduction: CD34+ cells dysfunction in diabetic patients contributes to the pathogenesis of diabetic vascular complications that persist and progress even in patients with good long-term glycemic control. We hypothesized that hyperglycemia jeopardizes CD34+ cell function through epigenetic changes that might contribute to the establishment of “metabolic memory” in these cells.
Methods & Results: Cord blood-derived CD34+ cells exposed for 20 days to high-glucose (HG; 30 mM) in StemSpan™ medium exhibited reduced proliferation, impaired migration and inability to form colony forming units-endothelial cell (CFU-EC) if compared to normoglycemic control (NG; 30 mM mannitol). Here we show that migration defect toward SDF-1 and the down-regulation of CXCR4 receptor in HG-CD34+ cells, both in terms of mRNA and protein expression, were related to a significant increase of methylation status of CXCR4 promoter, determined by qPCR method, when compared to NG-CD34+ cells (n=14; Fold Change 1±0.13 vs 2,1±0.5; p≤0.05). This epigenetic modification was still present 72 hours after glucose normalization. The analysis by qPCR of the mechanisms regulating cell proliferation revealed a significant telomere shortening (n=4; FC 1±0.1 vs 0.6±0.2; p≤0.05) and up-regulation of cyclin-dependent kinase inhibitors p27 and p21 in HG-CD34+ cells (n=13; FC 1±0.3 vs 1.4±0.4; 1±0.3 vs 1.4±0.5; p≤0.05). Consistent with lower ability to form CFU-EC, we found reduced eNOS mRNA expression (n=3; FC 1±0.2 vs 0.5±0.1; p≤0.05) and NO production (n=3; 69%±10 vs 28%±5 p≤0.05) in HG-CD34+-derived EPCs. The defect persisted despite regaining normal glucose levels. Finally, HG-CD34+ cells exhibited a significant overexpression of the p66shc gene (n=10; FC 1±0.5 vs 1.7±0.7; p≤0.05), down-regulation of the antioxidant genes MnSOD and CAT (n=9; FC 1±0,09 vs 0.7±0,06; 1±0.2 vs 0.7±0.2; p≤0.05) and increased ROS production (n=6; FC 1±0.1 vs 1.3±0.1; p≤0.05), as assessed by qPCR and flow cytometry respectively.
Conclusions: Exposure to elevated glucose levels induce CD34+ cell dysfunction that persists after glucose normalization. Increased methylation of CXCR4 promoter suggests that hyperglycemic oxidative stress can be “memorized” by cells in form of altered epigenetic changes.
- Diabetes Mellitus
- Endothelial progenitor cell
- Regenerative medicine stem cells
- Cardiovascular disease
Author Disclosures: V. Bianchessi: None. V. Vigorelli: None. G. Pompilio: None. M. Vinci: None.
- © 2016 by American Heart Association, Inc.