ALPHA-1-Antitrypsin Protects Vascular Grafts of Brain-Dead Rats against In Vitro Ischemia/Reperfusion Injury

Objectives: Coronary endothelial dysfunction has been described as a potential side effect of brain death. Ischemia/reperfusion (IR) injury during heart transplantation may lead to further endothelial damage. Protective effects of α-1-antitrypsin (AAT), a human neutrophil serine protease inhibitor, against IR injury have been demonstrated. We hypothesized that physiological saline-supplemented AAT would protect brain-dead (BD) rats' vascular grafts from IR injury.

Methods: Male Lewis donor rats were subjected to brain death by inflation of a subdural balloon. After 5.5 hours, thoracic aortic rings were harvested, prepared and immediately mounted in organ bath chambers for isometric tension recordings (BD group, n = 7) or preserved for 24 hours in 4°C physiological saline, supplemented either with a vehicle (BD-IR group, n = 8) or AAT (BD-IR + AAT group, n = 14) prior to mounting. Exposure of aortic rings to hypochlorite simulated reperfusion-associated endothelial injury. Vascular endothelial function was measured in vitro. Immunohistochemical detection of apoptosis-related caspase proteins was performed.

Result: The preservation of BD-IR aortic rings with AAT significantly improved IR-induced decreased maximum endothelium-dependent vasorelaxation (Rmax) to acetylcholine compared with the vehicle-treated BD-IR group (Rmax to acetylcholine: BD 81 ± 3% vs. BD-IR 50 ± 3% vs. BD-IR + AAT 65 ± 2%, p < 0.05), indicating an improvement in endothelial function. Additionally, an increase in the aortic ring smooth musculatures' sensitivity (pD2-value: -log 50% maximum response) to acetylcholine was noted after AAT treatment (pD2 to acetylcholine: BD-IR + AAT 7.3 ± 0.1 vs BD-IR 6.7 ± 0.2, p < 0.05). Furthermore, aortic caspase-3, -8, -9, and -12 immunoreactivity was significantly lower in BD-IR + AAT rings compared with the BD-IR group (histological score for caspase-3 4.0 ± 0.5 vs 6.9 ± 0.8; caspase-8: 4.1 ± 0.6 vs. 7.4 ± 0.6; caspase-9: 3.1 ± 0.6 vs. 7.3 ± 0.8; caspase-12: 5.0 ± 0.5 vs. 7.9 ± 0.4; BD-IR + AAT vs. BD-IR, p < 0.05).

Conclusion: Endothelial dysfunction induced by brain death and IR injury is improved by preservation of vascular grafts with a neutrophil serine protease inhibitor. This protective effect may partly be associated with the inhibition of caspase-3, -8, -9, and -12 mediated apoptosis.

Publication History

Article published online:
19 February 2021