title: Type 2 diabetes impairs venous, but not arterial smooth muscle cell function: possible role of differential RhoA activity.
abstract: OBJECTIVE
  Coronary heart disease is the leading cause of morbidity in patients with type 2 diabetes mellitus (T2DM), frequently resulting in a requirement for coronary revascularization using the internal mammary artery (IMA) or saphenous vein (SV). Patency rates of SV grafts are inferior to IMA and further impaired by T2DM whilst IMA patencies appear similar in both populations. Smooth muscle cells (SMC) play a pivotal role in graft integration; we therefore examined the phenotype and proliferative function of IMA- and SV-SMC isolated from non-diabetic (ND) patients or those diagnosed with T2DM.
  
  
  METHODS
  SMC were cultured from fragments of SV or IMA. Morphology was analyzed under light microscopy (spread cell area measurements) and confocal microscopy (F-actin staining). Proliferation was analyzed by cell counting. Levels of RhoA mRNA, protein and activity were measured by real-time RT-PCR, western blotting and G-LISA respectively.
  
  
  RESULTS
  IMA-SMC from T2DM and ND patients were indistinguishable in both morphology and function. By comparison, SV-SMC from T2DM patients exhibited significantly larger spread cell areas (1.5-fold increase, P<0.05), truncated F-actin fibers and reduced proliferation (33% reduction, P<0.05). Furthermore, lower expression and activity of RhoA were observed in SV-SMC of T2DM patients (37% reduction in expression, P<0.05 and 43% reduction in activity, P<0.01).
  
  
  CONCLUSIONS
  IMA-SMC appear impervious to phenotypic modulation by T2DM. In contrast, SV-SMC from T2DM patients exhibit phenotypic and functional changes accompanied by reduced RhoA activity. These aberrancies may be epigenetic in nature, compromising SMC plasticity and SV graft adaptation in T2DM patients.
  
  
  CONCLUSIONS
  The internal mammary artery (IMA) is the conduit of choice for bypass grafting and is generally successful in all patients, including those with type 2 diabetes (T2DM). By contrast, saphenous vein (SV) is inferior to IMA and furthermore patients with T2DM suffer strikingly poorer outcomes than their non-diabetic (ND) counterparts. We discovered that SV-SMC from T2DM patients exhibit altered persistent morphology and function compared to ND SV-SMC, with differential expression and activity of the small GTPase RhoA, yet ND and T2DM IMA-SMC were indistinguishable. These data offer an explanation for the superior patency of IMA grafting independent of the presence of diabetes.
authors.affiliation: Division of Cardiovascular and Diabetes Research, Leeds Institute of Genetics, Health and Therapeutics (LIGHT), University of Leeds, Leeds, UK; Multidisciplinary Cardiovascular Research Centre (MCRC), University of Leeds, Leeds, UK.
authors.forename: Kirsten
authors.initials: K
authors.lastname: Riches
authors.affiliation: Division of Cardiovascular and Diabetes Research, Leeds Institute of Genetics, Health and Therapeutics (LIGHT), University of Leeds, Leeds, UK.
authors.forename: Philip
authors.initials: P
authors.lastname: Warburton
authors.affiliation: Multidisciplinary Cardiovascular Research Centre (MCRC), University of Leeds, Leeds, UK; Department of Cardiac Surgery, The Yorkshire Heart Centre, Leeds General Infirmary, Leeds, UK.
authors.forename: David J
authors.initials: DJ
authors.lastname: O'Regan
authors.affiliation: Division of Cardiovascular and Diabetes Research, Leeds Institute of Genetics, Health and Therapeutics (LIGHT), University of Leeds, Leeds, UK; Multidisciplinary Cardiovascular Research Centre (MCRC), University of Leeds, Leeds, UK.
authors.forename: Neil A
authors.initials: NA
authors.lastname: Turner
authors.affiliation: Division of Cardiovascular and Diabetes Research, Leeds Institute of Genetics, Health and Therapeutics (LIGHT), University of Leeds, Leeds, UK; Multidisciplinary Cardiovascular Research Centre (MCRC), University of Leeds, Leeds, UK. Electronic address: medkep@leeds.ac.uk.
authors.forename: Karen E
authors.initials: KE
authors.lastname: Porter
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D049109:Cell Proliferation; D048430:Cell Shape; D002478:Cells, Cultured; D003924:Diabetes Mellitus, Type 2 / Q000150:complications* / Q000201:enzymology / Q000473:pathology; D003925:Diabetic Angiopathies / Q000201:enzymology / Q000209:etiology* / Q000473:pathology; D015536:Down-Regulation; D005260:Female; D006801:Humans; D008297:Male; D008323:Mammary Arteries / Q000201:enzymology / Q000473:pathology; D008875:Middle Aged; D009131:Muscle, Smooth, Vascular / Q000201:enzymology* / Q000473:pathology; D032389:Myocytes, Smooth Muscle / Q000201:enzymology*; D010641:Phenotype; D012501:Saphenous Vein / Q000201:enzymology / Q000473:pathology; D013997:Time Factors; D020742:rhoA GTP-Binding Protein / Q000378:metabolism*
chemical_list: C066737:RHOA protein, human; D020742:rhoA GTP-Binding Protein
keywords: Cell phenotype; Internal mammary artery; RhoA; Saphenous vein; Smooth muscle cell; Type 2 diabetes