Objective To explore the construction of heart preservation model of empty beating donor based on extracorporeal membrane oxygenation (ECMO). Methods From January 2022 to August 2023, 20 Guangxi Bama miniature pigs weighing 25-30 kg were selected, half male and half female. Under general anesthesia and heparinization, a midline thoracotomy was performed. The pericardium was cut after freeing the anterior and posterior vena cavae, and a perfusion needle was inserted near the brachiocephalic artery in the ascending aorta, connected to a blood collection bag to collect 500-600 mL of blood. The anterior and posterior vena cavae were ligated, the aorta was blocked and perfused with HTK solution to stop the heart beating. The superior and inferior vena cavae were cut off, the right pulmonary vein was decompressed, the aorta and left and right pulmonary arteries and veins were cut off, and the whole heart was removed. An ECMO device was used to continuously perfuse a cardioprotective solution mainly composed of oxygenated warm blood, maintaining the isolated pig heart beating for 8 hours, monitoring (once/hour) ECMO perfusion parameters, blood gas indicators, perfusate electrolytes, inflammatory factors, myocardial enzymes, myoglobin, and troponin levels. Myocardial tissue was taken for hematoxylin-eosin (HE) staining to observe myocardial cell damage and evaluate the quality of heart preservation. Results Among the 20 isolated beating pig hearts, 17 successfully resumed beating, 3 experienced ventricular fibrillation, resuscitated after intracardiac electrical defibrillation, and all 20 pig hearts successfully beat for 8 hours. There was no statistical difference in ECMO perfusion parameters, blood gas indicators, perfusate electrolytes, and inflammatory factors at each time point (P>0.05). There were statistical increases in myocardial enzymes, myoglobin, and troponin levels (P<0.05). HE staining results suggested that there was no severe myocardial damage. Conclusion ECMO technology can be used for pig heart preservation with good results, and this study provides experimental evidence for improving heart preservation research in clinical heart transplantation.

Objective To investigate the regulatory effect of Xuebijing injection on inflammatory reaction during the preservation of isolated empty beating pig hearts with extracorporeal membrane oxygenation.Methods Twelve healthy Guangxi Bama miniature pigs were randomly divided into the Xuebijing group(n=6)and normal saline group(n=6).After the models were established in the Xuebijing group,Xuebijing injection was given at a dose of 5 mL/h through micropump in membrane oxygenator.In the normal saline group,an equivalent amount of 0.9％sodium chloride injection was pumped.Continuous pumping was performed for 8 h in both groups.The time of cardiac resuscitation and perfusion pressure,heart rate,perfusion flow rate after 8 h preservation were recorded in two groups.Pathological and ultrastructural changes of myocardial tissues in the left ventricular wall of hearts with cardiac arrest were observed after 8 h preservation.Serum levels of myocardial injury markers and inflammatory cytokines were detected in two groups at the beginning(T0),2 h(T2),4 h(T4),6 h(T6)and 8 h(T8)after model establishment,respectively.The expression levels of NOD-like receptor protein 3(NLRP3),cysteinyl aspartate specific proteinase-1(Caspase-1),apoptosis-associated speck-like protein containing a CARD(ASC)messenger RNA(mRNA)in myocardial tissues were measured at T0,T2,T4,T6 and T8,respectively.Results There were no significant differences in the time of cardiac resuscitation and perfusion pressure,heart rate,perfusion flow rate after 8 h preservation between two groups(all P＞0.05).Compared with the normal saline group,the levels of lactate dehydrogenase(LDH)at T4,creatine kinase(CK),LDH and α-hydroxybutyrate dehydrogenase(α-HBDH)at T6 and T8,tumor necrosis factor(TNF)-α at T4,T6 and T8,and interleukin(IL)-6,IL-18 and IL-1 β at T0,T2,T4,T6 and T8 were lower,and the mRNA relative expression levels of NLRP3 and Caspase-1 at T2,T4 and T6,and Caspase-1 and ASC at T8 were lower in the Xuebijing group,respectively(all P＜0.05).Hematoxylin-eosin staining and transmission electron microscopy showed that the degree of myocardial injury in the Xuebijing group was slighter than that in the normal saline group.Conclusions Xuebijing injection may effectively mitigate inflammatory response and exert certain myocardial protection effect during the ECMO preservation of isolated empty beating pig hearts.

Objective To study the effect of Pioglitazone(PIO) on intimal hyperplasia after vein graft and its potential mechanism.Methods 32 male Sprague-Dawley rats were randomly divieded into two groups,one admisnistrated with PIO(3 mg· kg-1 · d-1) and the other with saline.A week later,the right common carotid arteries were reconstructed using homolateral external jugular veins in rats.The drugs treatment was continued after surgery for 2 or 4 weeks until grafted veins were harvested.The neointima thickness was measured by Computer image analysis software.To observe the activation of ERK1/2 pathway,the western blot were performed.In vitro,human great saphenous vein smooth muscle cells were co-cultured with PIO,and cells proliferation was detected by the CCK-8 assay.The TUNEL staining was performed to determine apoptosis.Results PIO treatment significantly attenuated intimal thickening compared with the the control group both at second [(8.56 ± 1.64) μm vs (25.44 ± 0.89) μm,P ＜ 0.01] and fourth week [(10.51 ± 1.47) μm vs (35.69 ± 1.07) μm,P ＜ 0.01)] after veins graft.Also PIO inhibited the ERK1/2 activation in grafted veins.In vitro,PIO significantly reduced PDGF-induced cells proliferation and increased cells apoptosis.Conclusion PIO effectively improved intimal hyperplasia in grafted veins perhaps associated with its ability to suppress vascular smooth muscle cells proliferation and enhance cell apoptosis,and might be related to the down regulation of ERK1/2 activity.

Objective To study the effect of Perfadex and Wisconsin Unviersity solution on the function of pulmonary artery endothelium.Methods Small lobe pulmonary arteries were dissected from nine porcine lungs.The artery from each lung was cut into six rings in 2mm.Two of them were randomly incubated in Krebs,Perfadex or Wisconsin Unviersity solution (UW solution) at 4℃ for 4 hours.Endothelium-derived hyperpolarizing factor (EDHF)-mediated relaxation (percentage of-7.5 logM U46619 precontraction) induced by bradykinin or calcium ionophone A23187 in the present of indomethacin,L-NNA and oxyhemoglobin were measured at 37 ℃ in the organ chambers.Results Vasoconstriction induced by U46619 is no significant difference among three groups (P＞ 0.05).Compared with Krebs group,the relaxation induced by bradykinin or A23187 was significantly decreased in Perfadex group (P＜0.01),while there is no significant difference in UW group (P＞0.05).Conclusion Endothelium-derived hyperpolarizing factor (EDHF) plays an important role in endothelium-mediated relaxation of porcine pulmonary artery.EDHF-mediated relaxation is impaired when the lung preserved with Wisconsin Unviersity solution,wheras its function is not affected by Perfadex solution.