Defining the miRnome of Saphenous Vein Smooth Muscle Cells from Patients with Type 2 Diabetes Mellitus

Type 2 diabetes mellitus (T2DM) patients suffer premature development of cardiovascular disease and commonly require cardiac revascularization using the autologous saphenous vein (SV). Smooth muscle cells (SMCs) are the principal cell type within the vascular wall and are dysfunctional in T2DM SV-SMCs, yet the mechanisms underpinning this are incompletely understood. The purpose of this study was to interrogate differential microRNA (miRNA) expression in SV-SMCs to enhance our understanding of T2DM SV-SMC phenotypic change. miRNA expression in primary human SV-SMCs from T2DM and non-diabetic (ND) donors was determined using an array (n = 6 each of ND and T2DM SV-SMCs). Differentially expressed miRNAs were ranked, and functional annotation of the 30 most differentially expressed miRNAs using DAVID and KEGG analysis revealed pathways related to SMC phenotype, including proliferation, migration, cytokine production and cell signaling. After selecting miRNAs known to be involved in SMC phenotypic regulation, miR-17, miR-29b-2, miR-31, miR-130b and miR-491 were further validated using qRT-PCR (n = 5 each of ND and T2DM SV-SMC), with miR-29b-2 subsequently being removed from further investigation. Potential mRNA targets were identified using mirDIP. Predicted target analysis highlighted likely dysregulation in transcription, epigenetic regulation, cell survival, intracellular signaling and cytoskeletal regulation, all of which are known to be dysfunctional in T2DM SV-SMCs. In conclusion, this paper identified four miRNAs that are dysregulated in T2DM SV-SMCs and are implicated in functional changes in the behavior of these cells. This provides a step forward in our understanding of the molecular and epigenetic regulation of vascular dysfunction in T2DM.