Background

Warm ischemia followed by blood reperfusion is associated with reduced myocardial contractility. Circulatory death (CD) hearts are maintained by machine perfusion (MP) with blood. However, the impact of MP with histidine-tryptophane-ketoglutarate (HTK) or novel HTK-N solution on reconditioning of CD-heart contractility is unknown.

Methods

In a porcine model, native hearts were directly harvested (control), or CD was induced before harvesting, followed by left ventricular (LV) contractile assessment. In MP-groups, CD-hearts were maintained for 4 h by MP with blood (CD-B), cold oxygenated HTK (CD-HTK) or HTK-N (CD-HTK-N) before contractile evaluation (all groups n = 8). We performed immunohistochemistry of LV myocardial samples. We profiled myocardial expression of 84 oxidative stress-related genes and correlated the findings with myocardial contractility via a machine learning algorithm.

Results

HTK-N improved end-systolic pressure (ESP=172±10 vs 132±5 mmHg, p = 0.02) and maximal slope of pressure increment (dp/dt_max=2161±214 vs 1240±167 mmHg/s, p = 0.005) compared to CD, whereas CD-B failed to improve contractility. Dp/dt_max (2161±214 vs 1177±156, p = 0.08) and maximal rate of pressure decrement (dp/dt_min=-1501±228 vs -637±79, p = 0.005) were also superior in CD-HTK-N compared to CD-B. In CD-HTK-N, myocardial 4-hydroxynonenal (marker for oxidative stress; p<0.001), nitrotyrosine (marker for nitrosative stress; p = 0.004), poly(adenosine diphosphate–ribose)polymerase (marker for necrosis; p = 0.028) immunoreactivity and cell swelling (p = 0.008) were decreased compared to CD-B. Strong correlation of gene expression with ESP was identified for oxidative stress defense genes in CD-HTK-N.

Conclusion

During harvesting procedure, MP with HTK-N reconditions CD-heart systolic and diastolic function by reducing oxidative and nitrosative stress and preventing cardiomyocytes from cell swelling and necrosis.

中文翻译：

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用新型 HTK-N 保存液体外机器灌注修复循环死亡心脏

背景

热缺血继之以血液再灌注与心肌收缩力降低有关。循环死亡 (CD) 心脏通过机器灌注 (MP) 与血液维持。然而，MP 与组氨酸-色氨酸-酮戊二酸 (HTK) 或新型 HTK-N 溶液对 CD 心脏收缩性再调节的影响尚不清楚。

方法

在猪模型中，直接采集天然心脏（对照），或在采集前诱导 CD，然后进行左心室 (LV) 收缩评估。在 MP 组中，CD 心脏在收缩评估前通过 MP 与血液 (CD-B)、冷氧 HTK (CD-HTK) 或 HTK-N (CD-HTK-N) 维持 4 小时（所有组n  = 8）。我们对 LV 心肌样本进行了免疫组化。我们分析了 84 个氧化应激相关基因的心肌表达，并通过机器学习算法将这些发现与心肌收缩力相关联。

结果

HTK-N 改善了收缩末期压力 (ESP=172±10 vs 132±5 mmHg, p  = 0.02) 和最大压力增量斜率 (dp/dt _max =2161±214 vs 1240±167 mmHg/s, p  = 0.005 ) 与 CD 相比，而 CD-B 未能提高收缩力。Dp/dt _max (2161±214 vs 1177±156, p  = 0.08) 和最大压力下降率 (dp/dt _min =-1501±228 vs -637±79, p  = 0.005) 在 CD-HTK 中也有优势-N 与 CD-B 相比。在 CD-HTK-N 中，心肌 4-羟基壬烯醛（氧化应激标志物；p <0.001）、硝基酪氨酸（亚硝化应激标志物；p = 0.004），聚（二磷酸腺苷-核糖）聚合酶（坏死标志物；p = 0.028） 与 CD-B 相比， 免疫反应性和细胞肿胀（p = 0.008）降低。对于 CD-HTK-N 中的氧化应激防御基因，确定了基因表达与 ESP 的强相关性。

结论

在收获过程中，带有 HTK-N 的 MP 通过减少氧化和亚硝化应激并防止心肌细胞肿胀和坏死来修复 CD 心脏的收缩和舒张功能。