Molecular differences between arterial and venous grafts in the first year after coronary artery bypass grafting
Christina Maria Steger1, Arndt Hartmann2, Ralf Joachim Rieker2
1Department of Pathology, Academic Teaching Hospital Feldkirch, Affiliation of the Innsbruck Medical University, Carinagasse 47, 6800, Feldkirch, Austria. christina.steger@lkhf.at.
Insights
Internal thoracic artery grafts show better patency than saphenous vein grafts due to distinct molecular signaling. This study reveals differences in growth factors and cytokines influencing graft performance after bypass surgery.
Area of Science:
- Vascular Biology
- Surgical Research
- Biomedical Engineering
Background:
- Saphenous vein (SV) grafts have lower patency rates than internal thoracic artery (ITA) grafts in coronary artery bypass surgery.
- Differences in vessel wall structure, oxidative stress, and molecular signaling may explain graft performance disparities.
Purpose of the Study:
- To investigate the molecular and cellular differences between SV and ITA grafts post-implantation.
- To compare neointima formation, media preservation, and expression of key signaling molecules over time.
Main Methods:
- Human post-mortem study of 150 bypass grafts (75 SV, 75 ITA) from 60 patients.
- Grafts analyzed at various time points post-implantation (baseline to 1 year).
- Histological and immunohistochemical examination of graft tissues.
Main Results:
- ITA grafts exhibited less neointima formation and better media preservation compared to SV grafts.
- Distinct patterns of TNF-α, PDGFR-α, VEGF-A, MMP-7, MMP-9, EGFR, and bFGF expression were observed in both graft types.
- Expression levels peaked at different times within various vessel wall layers of SV and ITA grafts.
Conclusions:
- The observed differences in growth factors, receptors, and cytokines suggest distinct MAPK pathway activation in SV and ITA grafts post-bypass surgery.
- These molecular differences likely contribute to the differential patency rates of SV and ITA grafts.
Abstract:
Despite commonly used for coronary artery bypass surgery, saphenous vein (SV) grafts have significantly lower patency rates in comparison to internal thoracic artery (ITA) grafts, which might be due to the structural characteristics of the vessel wall but also due to differences in oxidative stress adaptation and molecular signaling and regulation. This human post mortem study included a total of 150 human bypass grafts (75 SV grafts and 75 ITA grafts) obtained from 60 patients divided into five groups due to the time period of implantation: group 1: baseline group without grafting; group 2: 1 day; group 3: > 1 day-1 week; group 4: > 1 week-1 month; group 5: > 1 month-1 year. Pieces of 3 mm length were fixed with formaldehyde, dehydrated, wax embedded, cut into sections of 3 µm thickness, and histologically and immunohistochemically examined. Over the whole time period, we observed a lower neointima formation and a better preserved media in ITA grafts with a higher percentage of TNF-α, PDGFR-α, and VEGF-A in nearly all vessel wall layers, a higher amount of MMP-7, MMP-9, EGFR, and bFGF positive cells in SV grafts and a timely different peak not only between ITA and SV grafts but also within the various vessel wall layers of both graft types. Since most of the examined growth factors, growth factor receptors and cytokines are regulated by MAPKs, our results suggest an activation of different pathways in both vessel graft types immediately after bypass grafting.
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