Endothelial colony forming cells (ECFCs) are a defined progenitor subtype with established roles in vascular homeostasis and angiogenesis. Whilst ECFCs hold clear therapeutic potential for improved ischaemic cardiovascular disease (CVD) management, reduced pro-angiogenic capacity associated with diabetes and attenuated efficacy within the CVD microenvironment limit their translational potential. Given association between diabetes and ischaemic CVD pathogenesis, targeting of critical angiogenic-linked pathways remains a focus for both protecting and enhancing intrinsic diabetic ECFC vasoreparative function. Whilst DNA methylation (5 mC) regulates endothelial cell (EC) homeostasis and stress-induced dysfunction, understanding of its role in ECFC angiogenic response is limited. Alteration of maintenance regulators (DNMT1/UHRF1) with aberrant 5 mC is linked with numerous diseases including CVD. The aim of this study was therefore to define the specific influence of 5 mC on ECFC angiogenic dysfunction in both experimental and clinical diabetes. Treatment of healthy cord blood-derived ECFCs with 5'Aza-2-deoxycytidine (DNMT inhibitor; 1uM,72hrs) attenuated tube-forming capacity (Matrigel) in parallel with dysregulation of key pro-angiogenic proteins (Proteome Profiler®), confirming a specific role for ECFC 5 mC. Exposure of ECFCs to experimental diabetes (25 mmol/L D-glucose for 28 days) attenuated angiogenic capacity and increased DNMT1/UHRF1 expression versus L-glucose controls, whilst DNMT1 plasmid overexpression (OE) in healthy ECFCs led to reduced tube formation, specifically linking DNMT1 elevation with pathogenicity. In direct support of clinical relevance, ECFCs isolated from donors with gestational diabetes showed reduced angiogenic potential and increased DNMT1/UHRF1 expression, with TWIST meC screening highlighting intriguing gene-specific differential methylation, including hypermethylation with corresponding transcription changes linked to disrupted angiogenic function. Taken together, these data indicate a pivotal role for 5 mC in maintaining ECFC pro-angiogenic capacity in both health and disease, whilst highlighting exciting potential of selective epigenetic targeting (e.g. methylome editing via CRISPR/Cas9) to harness their intrinsic vasoreparative capacity for as an innovative approach ischaemic CVD management. Conflict of Interest
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