In a rat model of bypass DuraGraft ameliorates endothelial dysfunction of arterial grafts

Coronary artery bypass surgery can result in endothelial dysfunction due to ischemia/reperfusion (IR) injury. Previous studies have demonstrated that DuraGraft helps maintain endothelial integrity of saphenous vein grafts during ischemic conditions. In this study, we investigated the potential of DuraGraft to mitigate endothelial dysfunction in arterial grafts after IR injury using an aortic transplantation model. Lewis rats (n = 7-9/group) were divided in three groups. Aortic arches from the control group were prepared and rings were immediately placed in organ baths, while the aortic arches of IR and IR + DuraGraft rats were preserved in saline or DuraGraft, respectively, for 1 h before being transplanted heterotopically. After 1 h after reperfusion, the grafts were explanted, rings were prepared, and mounted in organ baths. Our results demonstrated that the maximum endothelium-dependent vasorelaxation to acetylcholine was significantly impaired in the IR group compared to the control group, but DuraGraft improved it (control: 89 ± 2%; IR: 24 ± 1%; IR + DuraGraft: 48 ± 1%, p < 0.05). Immunohistochemical analysis revealed decreased intercellular adhesion molecule-1, 4-hydroxy-2-nonenal, caspase-3 and caspase-8 expression, while endothelial cell adhesion molecule-1 immunoreactivity was increased in the IR + DuraGraft grafts compared to the IR-group. DuraGraft mitigates endothelial dysfunction following IR injury in a rat bypass model. Its protective effect may be attributed, at least in part, to its ability to reduce the inflammatory response, oxidative stress, and apoptosis.

Zinc-aspirin preconditioning reduces endothelial damage of arterial grafts in a rodent model of revascularization

Introduction

Coronary artery bypass grafting (CABG) is the most common cardiac surgical procedure. The prognosis of revascularization via CABG is determined by the patency of the used grafts, for which an intact endothelium is essential. The degree of ischemia-reperfusion injury (IRI), which occurs during the harvest and implantation of the grafts, is an important determinant of graft patency. Preconditioning with aspirin, a nonsteroidal anti-inflammatory drug has been shown to reduce the functional and molecular damage of arterial grafts in a rodent model. Studies have found that the zinc-aspirin complex may be able to exert an even better protective effect in pathological cardiovascular conditions. Thus, our aim was to characterize the protective effect of zinc-aspirin complex on free arterial grafts in a rodent model of revascularization.

Methods

Donor Lewis rats were treated with either zinc-aspirin, aspirin, or placebo (n = 8) for 5 days, then the aortic arches were harvested and stored in cold preservation solution and implanted heterotopically in the abdominal cavity of the recipient rats, followed by 2 h of reperfusion. There was also a non-ischemia-reperfusion control group (n = 8). Functional measurements using organ bath and histomorphological changes using immunohistochemistry were analyzed.

Results

The endothelium dependent maximal vasorelaxation was improved (non-transplanted control group: 82% ± 3%, transplanted control group: 14% ± 2%, aspirin group: 31% ± 4%, zinc-aspirin group: 52% ± 4%), the nitro-oxidative stress and cell apoptosis decreased, and significant endothelial protection was shown in the groups preconditioned with aspirin or zinc-aspirin. However, zinc-aspirin proved to be more effective in the reduction of IRI, than aspirin alone.

Discussion

Preconditioning with zinc-aspirin could be a promising way to protect the function and structural integrity of free arterial grafts, thus improving the outcomes of CABG.

Effect of Prostaglandin E1 Injected Into Donors in a Heterotopic Heart Transplant Model of Sprague Dawley Rats

INTRODUCTION

Prostaglandin E₁ (PGE₁) administered to patients in the immediate post-transplant period has been known to reduce ischemic reperfusion injuries (IRIs), but the effect on IRI of PGE₁ administered to the donor is unknown. The purpose of this study was to determine the effect on IRI of PGE₁ injected into donor rats during heterotopic heart transplantation.

METHODS

Genetically identical male Sprague Dawley rats with a body weight of 300-320 g at 8-9 weeks of age were used for the study. Experimental methods were the same in the control (G₀, n = 6) and experimental groups (G₁, n = 6), but only the donor rats in the experimental group received an intramuscular injection of PGE₁ (5 μg/kg) prior to the donor surgery. On day 1 the animals were sacrificed with the removal of the transplanted heart. Histologic analysis was performed in the hematoxylin-eosin-stained slides to assess interstitial edema and neutrophil infiltration by a pathologist.

RESULTS

Median times of the donor organ procurement, cold ischemia, and warm ischemia were 37, 69, and 35 minutes, respectively, in the G₀ group and 38, 76.5, and 33 minutes respectively in G₁ group; there were no statistical differences. Heartbeats were observed in the transplanted graft in 2 of the G₀ group and 2 of G₁ group immediately after heart transplantation, but in all transplanted grafts on day 1 after surgery. Histologic scores for neutrophil infiltration showed significantly lower in the G₁ group than in the G₀ group.

CONCLUSION

PGE₁ administration to donors in a rat heart transplantation model may significantly reduce IRI.

TiProtec preserves endothelial function in a rat model

BACKGROUND

Coronary artery bypass surgery provides excellent patency rates; however, the early and/or late graft failure reduces the long-term benefit of myocardial revascularization. We investigated the effectiveness of generally used saline, Custodiol solutions and a new solution (TiProtec) at preserving endothelium after cold ischemia and warm reperfusion injury.

MATERIALS AND METHODS

Aortic transplantations were performed in Lewis rats. Aortic arches were stored in saline, Custodiol, and TiProtec solutions for 2 h then were transplanted into the abdominal aorta. Two, 24 hours and 1 week after transplantation, the implanted grafts were harvested. Endothelium-dependent and -independent vasorelaxations were investigated in organ bath. DNA strand breaks were assessed by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling-method, messenger RNA expressions by quantitative real-time polymerase chain reaction, and the expression of CD-31 and alpha smooth muscle actin by immunochemistry.

RESULTS

Severely impaired endothelial function and integrity of implanted aortic grafts were shown after 2 h in the saline, Custodiol group (maximal vasorelaxation to acetylcholine: control: 91 ± 2%, saline: 26 ± 5%, Custodiol: 24 ± 5%, CD-31-positive area control: 96 ± 2%, saline: 35 ± 13% Custodiol: 54 ± 5%, P < 0.05, respectively); however, a preserved endothelial function was observed in the TiProtec group when compared with the saline and Custodiol group (maximal vasorelaxation: 46 ± 7%, CD-31-positive area: 54 ± 10%, P < 0.05). After 1 wk, endothelial function was partially recovered in all groups; however, it was significantly better in the TiProtec group (maximal vasorelaxation to acetylcholine: saline: 42 ± 3%, Custodiol: 48 ± 3%, TiProtec: 56 ± 3%, CD-31-positive area: saline: 56 ± 5%, Custodiol: 54 ± 4%; TiProtec: 83 ± 6%, P < 0.05, respectively). In addition, messenger RNA levels of Bax, B-cell lymphoma-2, endothelial NOS, vascular endothelial growth factor 2, and caspase-3 were significantly altered in both groups.

CONCLUSIONS

TiProtec appears to be superior for the preservation of endothelial- and smooth muscle cells of bypass graft after cold storage and warm reperfusion in our murine model.