Type 2 Diabetic Human Coronary Vascular Smooth Muscle Cells Are Less stiff and Less Adhesive to Fibronectin

Abstract

Previous data from our laboratory has demonstrated that type 2 diabetic (T2DM) coronary resistance microvessels (CRMs) undergo inward hypertrophic remodeling associated with reduced stiffness and reduced coronary blood flow in both mice and pig models. Further analysis revealed that the reduced stiffness was in part due to increased tissue elastin expression and decreased vascular smooth muscle cell (VSMC) stiffness in mice. The goal of the present study was to test the hypothesis that T2DM coronary VSMCs from humans are less stiff than normal. De‐identified, low‐passage normal and T2DM human coronary VSMCs were purchased from Lonza and ATCC for all experiments (n=4–5 per group). Using an atomic force microscope with probes coated with fibronectin (FN), a nano‐indentation protocol was used to measure cellular stiffness and adhesion to FN. Elastic modulus, a measurement of cellular stiffness, was reduced in T2DM human coronary VSMCs compared to normal (Normal: 3.60 ± 0.32 kPa vs. T2DM: 2.75 ± 0.22 kPa, p<0.05). Additionally, T2DM human coronary VSMCs were less adhesive to fibronectin compared to normal human coronary VSMCs (Normal: 58.3 ± 7.7 vs. T2DM: 43.5 ± 4.9 pN, p=0.17). Immunoblot analysis showed that T2DM human coronary VSMC expressed reduced vinculin (Normal: 1.0 ± 0.17 vs. T2DM: 0.31 ± 0.11, p<0.05) and increased cofilin (Normal: 1.0 ± 0.16 vs. T2DM: 1.8 ± 0.35, p=0.052) compared to normal human coronary VSMCs; this expression profile favors a less stiff cell phenotype given that vinculin deficient mice exhibit reduced cytoskeletal stiffness and that increased cofilin binding to F‐actin reduces stiffness. These data show that reductions in stiffness and adhesion to the ECM of diabetic CRM VSMCs may be due to underlying alterations in the cytoskeletal arrangement. Collectively, reduced stiffness in T2DM human coronary VSMCs may drive whole tissue microvascular mechanical properties to account for reduced CRM stiffness. These findings will inform future studies on the mechanisms of stiffness in the diabetic coronary circulation.Support or Funding InformationNIH R00 HL116769, NIH R21 EB026518, and Nationwide Children's Hospital to AJTThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.