Hyperglycemia Is a Potent Stimulus for Phenotypic Switch of Cultured Arterial and Venous Smooth Muscle Cells

Background: Our previous studies have revealed differences in vascular smooth muscle cell (VSMC) phenotypic switch including cellular dedifferentiation, proliferation and migration in response to hyperglycemia. However, despite the AVFs being commonly created in diabetic patients with ESKD, the impact of hyperglycemia on AVF outcomes are unclear, especially in the context of the differential impact of hyperglycemia on arterial vs venous VSMCs. Methods: Porcine arterial VSMCs (ApSMCs) and venous VSMCs (VpSMCs) were isolated from pig carotid artery and jugular vein. A hyperglycemic milieu was created via addition of 20 mM glucose 24-48 hr before harvesting. PDGF-BB was also applied to create a dedifferentiation setting. MTT assay was utilized to determine cell proliferation ability and cell scratch assay was applied to assess cell migration ability. Cellular expressions of proteins of interest were assessed using Western blots. Results: Hyperglycemia significantly enhanced growth medium (GM)-stimulated cell proliferation in both subtypes of cells. PDGF-BB-stimulated cell proliferation was similar in ApSMCs and VpSMCs under both conditions while the enhancement of hyperglycemia only was detected in ApSMCs. In addition, hyperglycemia stimulated cell migration in ApSMCs and VpSMCs in response to GM. However, no difference was detected between these two subtypes of cells. Importantly, hyperglycemia was able to induce cells dedifferentiation in both subtypes of VSMCs, indicated by suppressing the expression of myocardin and calponin, which was more potent in ApSMCs. Finally, PDGF-BB was able to induce dedifferentiation under either normoglycemic or hyperglycemic conditions in both subtypes of cells, which were more potent in VpSMCs. Conclusion: Hyperglycemia is a potent stimulus for VSMCs dedifferentiation particularly in ApSMCs. PDGF-BB is also able to stimulate VSMCs dedifferentiation in both subtypes of cells under normoglycemic and hyperglycemic conditions. A better understanding of the biology of both arterial and venous VSMCs in response to hyperglycemia is essential for the development of novel therapies to prevent neointimal hyperplasia and enhance outward arterial in the setting of AVF dysfunction in ESKD patients. Funding: NIDDK Support