"EX VIVO" MACHINE PRESERVATION OF THE ABDOMINAL ORGANS OF A PIG.

The aim of the study is to test the developed perfusion machine for long-term preservation of the liver, to evaluate the perfusion scheme that provides two different (arterial and venous) flows, and to evaluate hemodynamic of parallel perfusion of the liver together with the kidney. We have developed a perfusion machine to enable simultaneous perfusion of the liver and kidney, based on clinically proven constant flow blood pump. In the developed device, constant blood flow is converted into pulsed blood flow using a device of its own design - a pulsator. The device was tested on 6 pigs, whose liver and kidney were explanted for preservation. Organs were explanted along with the aorta and caudal vena cava on a common vascular pedicle and perfused through the aorta and portal vein. With a constant flow pump, part of the blood was directed through a heat exchanger, an oxygenator, and a pulsator and delivered to the organs through the aorta. The other part was sent to the upper reservoir, from which the blood gravitationally entered the portal vein. The organs were irrigated with warm saline. Blood flows were regulated by gas composition, temperature, blood flow volume and pressure. One experiment was put to an end due to technical problems. In 5 experiments, during the 6-hour perfusion, all physiological parameters remained within the normal range. During the conservation process, slight, correctable changes in gas exchange parameters affecting pH stability were noted. The production of bile and urine was noted. Results of the experiments with the achievement of a stable 6-hour perfusion preservation with confirmed physiological activity of the liver and kidney, make it possible to consider the design capabilities of the applied device with pulsating blood flow. It is possible to assess the original perfusion scheme, which provides two different flows, by one blood pump. The possibility of increasing the duration of liver preservation with further improvement of the perfusion machine and methodological support was noted.

[PRESERVATION OF ORGANS VIABILITY BY THE HEART-LUNG BYPASS MACHINE IN THE NON-HEART-BEATING DONORS (REVIEW)].

In a wide range of acute, debatable problems of transplantology, the problem of donation should be highlighted. It includes the selection and management of the donors, ethical and religious aspects and issues on the prevention, treatment and rehabilitation of the organ before its transplantation. Among the many methods of organ preservation, in the last decade, machine perfusion methods are on the forefront. They are designed to minimize or repair the ischemic-reperfusion damages in tissues and cells. This became possible in conditions of technical progress and the introduction of artificial circulation systems that provide adequate tissue microcirculation in non-heart-beating donors. However, this approach should take into account the complexity of the perfusion machines design, its various connection schemes and the nature of the perfusion parameters - the composition and temperature of the perfusion liquor. Experimental studies confirm that the use of machine perfusion is a technology whose possibilities will radically change the approaches to organ transplantation.

[THEORETICAL BACKGROUND OF FINDING ORGANS FOR TRANSPLANTATION AMONG NON-HEART BEATING DONORS UNDER UNSUCCESSFUL EXTRACORPOREAL RESUSCITATION (LITERATURE REVIEW)].

The number of patients who are in the "Transplant Waiting List" is increasing each year. At the same time, as a result of the significant shortage of donor organs, part of the patients dies without waiting till surgery. According to the Maastricht classification for non-heart beating donors, the patients, who had cardiac arrest outside the hospital (in the uncontrolled by medical staff conditions) should be considered as a potential donors of category II. For these patients, the most effective resuscitation is recommended. The extracorporeal life support (ECLS) considers the connection to a special artificial perfusion system for the restoration of blood circulation out-of-hospital with further transportation to the hospital. If restoration of independent cardiac activity does not occur, in spite of the full range of resuscitative measures, these patients may be regarded as potential donors. The final decision should be received in the hospital, by the council of physicians, lawyers and patient's family members. Until the final decision, the prolongation of ECLS and maintaining adequate systemic and organic circulation is recommended.

Ductular reaction at the early terms of common bile duct ligation in the rats.

Ductular reaction (DR) in bile duct ligated rats generally appears from 2nd day after biliary obstruction (BO). However, we show that increased amount of ductular profiles is evident already in 6 hours after BDL. The study aims to explain the origin of such an early DR in response to BO. Male Lewis rats were subjected to common bile duct ligation (CBDL) for 3, 6, 12 and 24 hours and sham operation. Liver samples were studied histologically, immunohistochemically (Ki67, pan-Cytokeratin /AE1 + AE3/ and OV-6) and by immunoblotting analyses. It appeared that number of ductular profiles increase in time-related manner after BO. These ductular profiles are formed by biliary epitheliocyte-like cells; No mitotic activity was revealed. Part of hepatocytes reveals pan-Cytokeratin positivity on 12 and 24 hours after BO. Total cytokeratins content at 24 hours after CBDL was 37% higher in comparison with control data. The significant increase was observed for the cytokeratins with molecular weights: 61, 56 and 40 KDa. Thus, early DR after BDL is mediated by widening of the existed finest biliary ramifications and is not associated with proliferation activities. This DR is accompanied by differentiation of hepatocytes toward bile duct-like cells.

New model of veno-venous bypass for management of anhepatic phase in experimental study on dogs.

Blood is shunted from the inferior vena cava and portal vein to the superior vena caval system to prevent congestion in the lower parts of the body during the anhepatic phase (AP) of liver transplantation. It leads to overload in the superior vena caval system retarding cranial outflow due to a nonphysiological blood redistribution. To overcome this problem, we developed a new bypass in dogs: blood is shunted from the inferior (caudal) vena cava and portal vein to the suprahepatic inferior (caudal) vena cava. This model was compared with traditional one with or without a pump. Blood pressure and flow parameters were estimated during 3 hours of AP in four groups of four dogs each. The current study showed that a nontraditional scheme of venous bypass reduced circulatory complications during AP, especially in the cranial vena caval system, although a low rate of congestion remains in the caudal vena cava and portal vein systems. Whereas the same scheme using a pump effectively prevented congestion in all of the systems: cranial, caudal, and portal. We concluded that application of a nontraditional bypass scheme, providing venous blood return into suprahepatic part of caudal vena cava, can be considered to be a method of choice for experimental liver transplantation.

Experimental liver autotransplantation with novel scheme of veno-venous bypass as a model of liver denervation and delymphatization.

The impact of denervation and delymphatization (DD) on liver tissue remains a topic of major interest in liver transplantation, as the organ or its part continues to function well. Various chemical and/or surgical interventions have been developed to achieve in situ liver denervation and delymphatization, but it is evident that DD can be achieved only through "ectomia", ie, complete isolation of the organ from adjacent and connected structures. This Study describes a liver DD model based on a technique of autotransplantation (replantation), maximally preventing ischemia in the transplanted (replanted) graft and dyscirculatory complications in the recipient. Experiments were performed on eight male mongrel dogs. Venous reservoir and roller pumps were used in a forced nontraditional bypass scheme. Autotransplantation was performed by step-by-step dissection of the suprahepatic, infrahepatic, and portal structures, leading to DD, with subsequent recovery of the blood vessel and bile duct. DD was achieved successfully with stable hemodynamic parameters during all surgery periods. All animals survived. This model of liver autotransplantation lead to DD of the organ. It was characterized by hemodynamic stability of the liver as well as of the whole body at every stage of the surgery, proffering liver DD for experimental studies.