Temporal Network Based Analysis of Cell Specific Vein Graft Transcriptome Defines Key Pathways and Hub Genes in Implantation Injury

Vein graft failure occurs between 1 and 6 months after implantation due to obstructive intimal hyperplasia, related in part to implantation injury. The cell-specific and temporal response of the transcriptome to vein graft implantation injury was determined by transcriptional profiling of laser capture microdissected endothelial cells (EC) and medial smooth muscle cells (SMC) from canine vein grafts, 2 hours (H) to 30 days (D) following surgery. Our results demonstrate a robust genomic response beginning at 2 H, peaking at 12–24 H, declining by 7 D, and resolving by 30 D. Gene ontology and pathway analyses of differentially expressed genes indicated that implantation injury affects inflammatory and immune responses, apoptosis, mitosis, and extracellular matrix reorganization in both cell types. Through backpropagation an integrated network was built, starting with genes differentially expressed at 30 D, followed by adding upstream interactive genes from each prior time-point. This identified significant enrichment of IL-6, IL-8, NF-κB, dendritic cell maturation, glucocorticoid receptor, and Triggering Receptor Expressed on Myeloid Cells (TREM-1) signaling, as well as PPARα activation pathways in graft EC and SMC. Interactive network-based analyses identified IL-6, IL-8, IL-1α, and Insulin Receptor (INSR) as focus hub genes within these pathways. Real-time PCR was used for the validation of two of these genes: IL-6 and IL-8, in addition to Collagen 11A1 (COL11A1), a cornerstone of the backpropagation. In conclusion, these results establish causality relationships clarifying the pathogenesis of vein graft implantation injury, and identifying novel targets for its prevention

High-flow gas insufflation to facilitate MIDCAB [4]

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Injury of the coronary endothelium at implantation increases endothelial dysfunction and intimal hyperplasia after heart transplantation

Background: Coronary endothelial dysfunction occurs early after heart transplantation and predicts the development of intimal thickening characteristic of cardiac allograft vasculopathy. Objectives: To assess the effects of removal of the endothelium by balloon injury of coronary arteries of allografts without rupture of the internal elastic lamina at the time of implantation and on coronary endothelial dysfunction, and to assess the development of accelerated atherosclerosis after heart transplantation. Methods: A porcine model of heterotopic heart transplantation with preoperative immunologic typing, enabling progressive rejection without immunosuppression, was used to study the effect of endothelial removal on these 2 end points. Endothelium-dependent relaxations of epicardial coronary arteries from allografts submitted to endothelial denudation after harvest, arteries from allografts not undergoing denudation, and native coronary arteries were compared 30 days after graft implantation by using standard organ chamber experiments. Intimal thickening was measured by light microscopy with a semiquantitative scale (0 to 4+ grading). Results: Relaxations to serotonin and to bradykinin were significantly decreased in denuded arteries compared with nondenuded allograft arteries. There was a significant increase in the incidence of severe intimal hyperplasia in denuded arteries compared with nondenuded arteries, which were both significantly increased compared to native coronary arteries. Conclusions: Endothelial injury at implantation worsens the endothelial dysfunction as a result of rejection after heart transplantation and compounds the intimal thickening leading to cardic allograft vasculopathy. All efforts should be deployed to maintain a morphologically intact and functional endothelium at the time of graft implantation. Copyright © 2005 by the International Society for Heart and Lung Transplantation.link_to_subscribed_fulltex

Comparative study of coronary endothelial dysfunction after heart transplantation in domestic versus microswines

The present study was designed to compare the coronary endothelial dysfunction due to rejection and the development of accelerated atherosclerosis after heart transplantation in domestic (Large-White) versus microswines (Yucatan). A porcine model of heterotopic heart transplantation with preoperative immunologic typing of class I and II antigen of the major histocompatibility complex, permitting slow rejection without immunosuppression, was used to study these two end-points. The endothelium-dependent relaxations of allografted epicardial coronary arteries and native coronary arteries from domestic and microswines were compared 60 days after graft implantation using standard organ chamber experiments. There was a significant decrease of relaxations to serotonin and UK 14,304 (agonists coupled to Gi-proteins) and to sodium fluoride, a direct G-protein activator in both allografted coronary arteries from domestic and microswines. There was a significant increase in the prevalence of intimal thickening of allografted coronary arteries in both domestic and microswines. Domestic and microswines are useful animals for the study of coronary endothelial dysfunction and accelerated atherosclerosis after heart transplantation. Potential advantages of the microswines include ease of management for long-term use and chronic studies.link_to_subscribed_fulltex

Effect of intracoronary L-NAME infusion on endothelial dysfunction and intimal hyperplasia after heart transplantation

The present study was designed to examine the effect of nitric oxide synthase inhibition on coronary endothelial dysfunction and the development of accelerated atherosclerosis after heart transplantation. A porcine model was used to study the effect of inhibition of endothelial nitric oxide synthase by intracoronary L-Nitro Arginine Methyl Ester (L-NAME; 1 mg/kg/day) infusion by an osmotic pump on these two end-points. The endothelium-dependent relaxations of allografted epicardial coronary arteries, allografted arteries infused with L-NAME, allografted arteries mounted with the pump and vehicle and native coronary arteries were compared 30 days after graft implantation using standard organ chamber experiments. Intimai thickening was measured by light microscopy examination using a semiquantitative scale (0 to 4+ grading). There was a significant decrease of relaxations to serotonin in allografted arteries infused directly with L-NAME compared with allografted arteries from swines receiving the drug. There was a significant increase in the prevalence and severity of intimai thickening in allografted coronary arteries infused with L-NAME compared to allografts without infusion (prevalence: 100%, grade 3-4+ lesions 37.5%, and prevalence: 46.6%, grade 3-4 lesions: 0% respectively). Inhibition of the nitric oxide pathway accelerates the intimai thickening process leading to graft coronary vasculopathy.link_to_subscribed_fulltex

Endothelial effects of hemostatic devices for continuous cardioplegia or minimally invasive operations

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