Nutritional Extracts Protect Rats’ Vascular Grafts from In Vitro Ischemia/Reperfusion Injury

Background: Ischemia/reperfusion (IR) injury affects harvested vascular grafts during coronary artery bypass surgery, influencing clinical outcomes. Previous studies have shown that bread crust extract (BCE), which contains a significant amount of advanced glycation end products, has beneficial effects against IR injury. We hypothesized that BCE protects rats’ vascular grafts from IR injury.

Method: Thoracic aortic rings from male Wistar rats were harvested and immediately mounted on organ bath chambers (control group, n = 49 rings from 13 rats) or were subjected to ischemia for 24 hours in 4°C saline solution (IR group, n = 36 rings from 10 rats) or saline supplemented with 7% BCE (IR + BCE group, n = 43 rings from 11 rats). During organ bath experiment, rings from both IR groups were exposed to 200 µM hypochlorite for 30 minutes to simulate warm reperfusion injury. Vascular function was measured ex vivo, and immunohistochemical analysis for nitrotyrosine (a marker of nitro-oxidative stress) and poly(ADP-ribose)-polymerase (PARP)-1 (as an apoptotic marker) was performed. The expression level of 88 genes involved in oxidative stress, apoptosis, and inflammation was surveyed using polymerase chain reaction (PCR) array.

Results: Impaired maximum endothelium-dependent vasorelaxation to acetylcholine (control 73 ± 2% vs. IR 40 ± 2% vs. IR + BCE 63 ± 3%, p < 0.05) increased maximal phenylephrine-induced contractile responses (control 2.7 ± 0.1 g vs. IR 3.6 ± 0.3 g vs. IR + BCE 4.4 ± 0.2 g, p < 0.05), and decreased high K+-induced depolarization (control 4.7 ± 0.1 g vs. IR 2.4 ± 0.2 g vs. IR + BCE 4.2 ± 0.1 g, p < 0.05) in the IR group compared with controls were significantly improved by BCE. PCR analysis showed that compared with controls IR altered the mRNA expression of 36 genes, including upregulation of l1a, l1b, Il6, Ccl2, Ccl12, Cd40, Tnf, and downregulation of Tnfsf10. These alterations were maintained in the IR + BCE rings compared with controls, whereas they were prevented in the IR + BCE rings compared with the IR group. Furthermore, BCE significantly lowered nitrotyrosine and PARP-1 immunoreactivity compared with the IR rings.

Conclusion: Preservation of vascular grafts with BCE alleviates vascular dysfunction following IR injury. Its protective effect may be linked to the reduction of nitro-oxidative stress and appears to be independent of lowering inflammatory responses.

Publikationsverlauf

Artikel online veröffentlicht:
03. Februar 2022