Cardioprotective Effect of a Hemoglobin-Based Oxygen Carrier on Cold Ischemia/Reperfusion Injury

Objectives: The etiology of myocardial ischemia/reperfusion (I/R) injury is multifactorial, but activation of the innate immune system and the resulting inflammatory response are important components of I/R injury. The aim of this study was to investigate the protective effect of a hemoglobin-based oxygen carrier (HBOC) on cold I/R heart and to explore the underlying mechanisms. Methods: Isolated Sprague-Dawley rat hearts were perfused in the Langendorff mode. After 30 min of basal perfusion, rat hearts were arrested with histidine-tryptophan-ketoglutarate solution (HTKs) with or without an HBOC and hypothermically stored (4°C) for 9 or 14 h, followed by 2 h of reperfusion. Results: Compared with HTKs alone, the HBOC in HTKs greatly improved heart contraction and decreased infarct size, necrosis and apoptosis, which was related to the reduced expression of Toll-like receptor 2 (TLR 2), TLR 4, TNF-α, IL-1β and nuclear factor-ĸB (NF-ĸB) activation. Conclusions: Our results demonstrated that the HBOC protected isolated rat heart from cold I/R injury and this protection was associated with attenuation of the expression of the TLR 2 and TLR 4/NF-ĸB signaling pathway, which may down-regulate the inflammatory response.