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Updated: May 2, 2026
Isolation of Murine Coronary Vascular Smooth Muscle Cells
Published on: May 30, 2016
Type 2 diabetes impairs venous, but not arterial smooth muscle cell function: possible role of differential RhoA
Kirsten Riches1, Philip Warburton2, David J O'Regan3
1Division 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.
Insights
Internal mammary artery smooth muscle cells (SMC) are unaffected by type 2 diabetes (T2DM), unlike saphenous vein SMC. T2DM alters saphenous vein SMC function and morphology, potentially explaining poorer graft outcomes in diabetic patients.
Area of Science:
- Vascular Biology
- Diabetic Complications
- Surgical Outcomes
Background:
- Coronary heart disease is a leading cause of morbidity in type 2 diabetes mellitus (T2DM) patients.
- Coronary revascularization often uses internal mammary artery (IMA) or saphenous vein (SV) grafts.
- SV graft patency is inferior to IMA and further compromised by T2DM.
Purpose of the Study:
- To investigate the phenotype and proliferative function of IMA and SV smooth muscle cells (SMC) from non-diabetic (ND) and T2DM patients.
- To elucidate the cellular mechanisms underlying differential graft patency in T2DM patients.
Main Methods:
- SMC were isolated and cultured from human IMA and SV.
- Morphological analysis included spread cell area and F-actin staining.
- Proliferation was assessed by cell counting.
- RhoA (small GTPase) expression, protein levels, and activity were quantified.
Main Results:
- IMA-SMC from T2DM and ND patients were phenotypically and functionally indistinguishable.
- SV-SMC from T2DM patients showed increased cell area, altered F-actin, and reduced proliferation compared to ND SV-SMC.
- T2DM SV-SMC exhibited significantly lower RhoA expression and activity.
Conclusions:
- T2DM does not alter IMA-SMC phenotype or function.
- T2DM induces phenotypic and functional changes in SV-SMC, associated with reduced RhoA activity.
- These SV-SMC alterations may be epigenetic, impacting graft adaptation and patency in T2DM patients.
Background/Purpose:
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/Materials:
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.
Summary:
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.
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