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An experimental study was conducted in the rat to evaluate the sensitivity of the liver to hyperthermia and ischemia. A 15-min asanguineous isolated hyperthermic in vivo perfusion of the liver was done in rats with a normal liver and in rats with an hepatocarcinoma induced by chronic 3'-diethylaminoazobenzene intoxication. The perfusion was made using various ranges of temperature of the perfusate. In normal rats, the in vivo perfusion was well tolerated as long as the mean intrahepatic temperature remained under 38 degrees C. Postoperative evolution of serum transaminase level was similar whatever the temperature of the perfusate. Histological lesions of the hepatic parenchyma were as severe as the temperature of the perfusate was elevated. In rats with tumors, the mortality rate was elevated in the animals with large tumors. A moderate decrease in the serum alpha-fetoprotein level was observed during the first days after liver perfusion. In all cases, death occurred apparently as a direct consequence of liver injury. This study defines the sensitivity of the normal or neoplastic rat liver to hyperthermia and ischemia using a model of isolated in vivo perfusion of the liver. It provides a basis for further investigations on the effect of hyperthermia on experimental liver tumors.

Natural antidonor antibodies are known to play a prominent role in hyperacute xenograft rejection. The aim of this work was to devise an experimental protocol to prolong the survival time of guinea pig heart xenografts transplanted into rats. A technique of continuous plasma exchange adapted to small animals was used to remove the natural cytotoxic antibodies from the recipient prior to the transplantation. In some experiments, cyclosporine (CsA), cyclophosphamide (CY), or splenectomy were associated with the plasma exchange. In this highly discordant xenogenic donor-recipient combination, the mean graft survival time in nontreated rats was 16 min. When an exchange of 1.5 plasma volume was performed 24 hr before the transplantation, no prolongation of the graft survival time was observed. When CsA, CY, or splenectomy were associated with the plasma exchange, the graft survival time was significantly increased by more than 2500% (up to 418 min with CsA). When used isolately, none of these 3 immunosuppressive methods was able to prolong the graft survival time. Natural cytotoxic antibodies were monitored by a complement-mediated cytotoxicity assay. After a plasma exchange, the titers decreased from 1:16–1:32 to 1:1–1:2. When no immunosuppressive method was associated with the plasma exchange, the antibodies returned to their initial level within the 24 hr that preceded the transplantation, and the graft was rejected as in nontreated animals. When an immunosuppressive method was associated with the plasma exchange, and particularly in the case of CsA, the titers remained low, and the hyperacute rejection was delayed. Therefore, it can be concluded that plasma exchanges, associated with CsA, are an efficient experimental protocol in the rat to increase the survival time of guinea pig heart xenografts. The effect of the treatment is correlated with the decrease in natural cytotoxic antidonor antibodies. © 1988 by The Williams & Wilkins Co.

In cirrhosis, the phagocytic function of the reticuloendothelial system (RES) is decreased. In order to investigate the mechanisms of the hepatic reduced phagocytic activity present in cirrhosis, the hepatic and splenic uptake of 51Cr sheep red blood cells (SRBC) and of colloidal carbon was measured in three groups of Sprague-Dawley rats. Group 1 consisted of 42 control rats, group 2 of 36 rats with end-to-side portacaval shunt and group 3 of 24 rats with carbon tetrachloride-induced cirrhosis. The hepatic uptake of 51Cr SRBC and of colloidal carbon was significantly (p less than 0.001) reduced in cirrhotic rats (group 3). Conversely, in rats with a portacaval shunt and a noncirrhotic liver (group 2), the hepatic uptake of 51Cr SRBC was moderately reduced, whereas the colloidal carbon hepatic uptake was not found to be decreased. These results suggest that the decreased RES phagocytic activity observed in cirrhotic rats is only partially due to portacaval shunt and that an intrinsic defective activity of hepatic phagocytic cells is probably present.

The need for liver grafts is critical in countries where brain death is not accepted as a legal criterion for organ retrieval. This experimental study was conducted with nonhuman primates in order to evaluate the feasibility of liver transplantation using a living donor. An original technique was employed to remove the left part of the liver from the donor: transection of the parenchyma was done while the blood flow was kept to the left part of the liver. In the recipients, the graft was placed heterotopically. No blood transfusions were administered to donors or recipients. In spite of a few failures, due to consequences of intraoperative bleeding, several donor operations using this original technique were successful, in the immediate postoperative period as well as several months later. Among the recipients, the large number of early failures suggests that the heterotopic position is probably not the appropriate one and that orthotopic transplantation should be preferred.

Efficacy of transplanted hepatocytes was evaluated in rats with a surgically induced acute hepatic failure. After 75% liver resection and portacaval shunt, the intrasplenic or intraperitoneal injection of 20 million isolated fresh hepatocytes was shown to significantly reduce the mortality rate. These results confirm that the transplantation of isolated hepatocytes may prevent death in rats with acute hepatic failure, and suggest that hepatocyte transplantation acts by a mechanism of hepatic support.

In the present study, subtotal hepatectomy was evaluated as a model of acute liver failure in the rat. Sprague-Dawley rats, weighing 250-300 g, underwent hepatectomy under varying basal conditions of temperature and glucose administration. Rats operated and maintained postoperatively at ambient temperature (25 degrees C external environment) developed hypothermia with a rate of return to normal temperature which was related to the extent of hepatectomy and the availability of glucose postoperatively. However, no significant difference in survival was observed between groups maintained at ambient temperature and those whose core temperature was maintained at 37 degrees C by passive external warming. Severe hypoglycemia was observed in rats undergoing 90 and 95% hepatectomy without glucose postoperatively. With 20% glucose available in drinking water the mortality of 90% hepatectomy was reduced from 95 to 40% (p less than 0.0001). With increase of the hepatectomy to 95%, 90% mortality was observed despite glucose support. Transplantation of 4 x 10(7) isolated syngeneic hepatocytes intraperitoneally at the time of hepatectomy did not increase survival after 90 or 95% hepatectomy; addition of testosterone therapy did not improve survival either alone or with hepatocyte transplantation. In this study, hepatectomy exceeding 90% was lethal and did not respond to the supportive measures provided. Hepatocyte transplantation and testosterone pretreatment, both therapies which are thought to increase regeneration, were ineffective in improving survival in this resection model.

2 observations de cette complication rare (sur une serie de 76 transplantations hepatiques, dont 46 chez des enfants. L'excision de l'anevrysme est conseillee. La ligature de l'artere hepatique semble possible si la transplantation date de plus d'un mois, mais elle risque d'entrainer une ischemie et une dehiscence de l'anastomose

It has been suggested that the liver may have the ability to reduce the strength of the graft versus host (GVH) reaction (Eloy et al. 1976). Other studies have shown that portal venous drainage of various organ allografts resulted in delayed rejection compared with caval drainage (Boeckx et al. 1975; Fukuda et a1. 1969; Sakai 1970) and that liver allografting was liable to induce a state of specific unresponsiveness in several combinations of inbred rats (Gugenheim et al. 1981; Kamada et a1. 1980; Lie et a1. 1980). All these facts favor the hypothesis that the liver may have some immunosuppressive properties. In order to analyze further the protective capacities of the liver against a GVH reaction, we developed a technique of spleen transplantation with portal venous drainage in the rat and compared the strength of the GVH reaction observed when the spleen was drained through the portal vein rather than through the versa cava.

The privileged status of liver allografts compared with other organ allografts is illustrated by the spontaneous tolerance of liver allografts in pigs (Calne 1973) and in several combinations of inbred rats (Houssin et al. 1979; Zimmermann et al. 1979). Another remarkable peculiarity of liver transplantation is the absence of hyperacute rejection of liver allografts in man in case of an ABO-incompatible transplantation or when preformed lymphocytotoxic antibodies directed toward the donor are present in the recipient (Starzl et al. 1982). The reason for the relative resistance of the liver to cytotoxic antibodies is still unclear. In order to study further the effect of cytotoxic antibodies on the liver, the fate of donor-specific liver allografts was compared with that of donor-specific heart allografts in hypersensitized rats.

Systematic screening for hepatocellular carcinoma (HCC) in cirrhotic patients by alpha-fetoprotein and ultrasound permits the detection of small asymptomatic tumors. Owing to the small tumor size, more liver resections can now be performed than in the past. These resections are performed in a more economical way in terms of loss of functional parenchyma and in a more appropriate manner with regard to carcinology: surgical techniques of liver segmentectomy and use of intraoperative echography are mandatory. Favorable long-term results obtained in Eastern countries by resecting such lesions are encouraging but remain to be confirmed in the Western hemisphere.

Spontaneous tolerance of liver allografts can be observed in inbred rats. In order to study the influence of the density of major histocompatibility complex alloantigens on the fate of liver allografts in the rat, liver allografts were performed in a semi-allogeneic and a fully allogeneic combination. Comparisons of the fate of heart and kidney allografts were made in the same combinations. A similar proportion of spontaneously tolerated liver allografts was observed in the two combinations; after a few months these animals were in a state of donor-specific unresponsiveness. A spontaneous prolongation of kidney allografts was observed only in the semi-allogeneic combination. These animals were not in a state of donor-specific unresponsiveness. These results suggest that induction of liver allograft tolerance in the rat is not decisively influenced by the importance of the density of major histocompatibility complex antigens present on the graft and that its mechanism may be different from that which causes spontaneous prolongation of semi-allogeneic kidney allografts.

This study was conducted to evaluate various methods to reduce the mortality rate following acute portal vein occlusion in rat: systemic heparinization, intravenous saline infusion, enteral antibiotics and simultaneous clamping of the superior mesenteric artery were tested alone or in combination. Each of these treatments improved the survival rate after 45 or 60 min occlusion of the portal vein; combination of all treatments provided better results than each treatment alone. These results indicate that, following acute portal vein occlusion in the rat, several factors cooperate to cause death. The decrease in mean arterial blood pressure during occlusion of the portal vein was correlated with the mortality rate; this correlation was significant in the animals with 45 min occlusion of the portal vein. It appeared in this study that, when used in association, simple therapeutic methods are highly effective in improving the survival rate following acute portal vein occlusion in the rat.

In several combinations of inbred rats, liver allografts are spontaneously tolerated, and after a few weeks liver tolerant rats are in a state of donor-specific transplantation tolerance. In vivo and in vitro experiments were conducted to analyze the immunological status of LEW or BN rats with spontaneously tolerated (LEW X BN) F1 liver allografts several months after transplantation. Acute rejection of secondary donor-specific heart allografts retransplanted from liver-tolerant rats to normal syngeneic hosts suggests that the state of tolerance in liver-tolerant rats is related to an active modification of the immune system of the rat and not to a reduced immunogenicity of the graft. No cytotoxic antibodies or cells were found in liver-tolerant rats. Reactivity in mixed lymphocyte culture was normal or slightly reduced. Arguments for the presence of splenic suppressor cells were found in LEW tolerant rats using a local graft-versus-host assay, but these could not be found in BN rats, or when attempting to transfer or to break the tolerance state. A nonspecific humoral blocking factor was found in vitro in liver-tolerant rats but transfer of serum from liver-tolerant rats to normal syngeneic hosts did not permit a significant prolongation of donor-specific heart allografts. These results suggest that more than one mechanism may be involved at the maintenance phase of liver allograft tolerance.

Orthotopic liver allografts in the nonrejecting DA-to-PVG strain combination and in the DA-to-LEW strain combination were studied at various times after transplantation for donor class I and class II MHC expression using immunohistological techniques and quantitative analyses. DA-to-DA isografts were also studied. In the isografts, weak class I induction on hepatocytes and biliary epithelium was noted from day 5, and this persisted to day 15, the last time point examined. In DA-to-PVG allografts, class I induction also appeared on hepatocytes and biliary epithelium from day 5, but was more intense than in the isografts. Nevertheless, the induction was patchy within most grafts, and in some grafts was not prominent. Quantitative absorption analyses demonstrated that the maximum increase in donor class I expression was only 3-fold over the normal liver. In the strong DA-to-LEW combination, class I induction on hepatocytes seemed to appear earlier, beginning at day 3, and was more uniform and intense than in the DA-to-PVG model from day 5. In the isografts, there was no induction of class II antigens on hepatocytes or biliary epithelium at any stage, but from days 5 to 15 there was a marked increase in the number of isolated, class II-positive cells in the hepatic lobule, probably representing class II induction in the Kupffer cells of the isografts. In DA-to-PVG allografts, biliary epithelium became class II-positive from day 5, and this persisted to day 30, the last time point examined. Weak but definite class II induction was seen on some hepatocytes from day 5 through day 30. However, the majority of hepatocytes remained class II-negative. By day 30, there was virtually no donor class II staining the sinusoids, but isolated class II-positive cells of recipient type were seen, the pattern suggesting a replacement of the graft Kupffer cells by recipient Kupffer cells at this stage. By quantitative absorption analysis, donor class II expression in the grafts increased approximately 5-fold. In DA-to-LEW allografts, class II induction was not noticeably different from that seen in the DA-to-PVG model, except that induction of class II antigens on the Kupffer cells possibly appeared earlier in this strain combination.

Dans deux combinaisons de lignees (DA→LEW et LEW→BN) le rejet suraigu du cœur transplante est retarde significativement par une hemoperfusion extracorporelle sur foie specifique du donneur. L'hemoperfusion sur foie d'une 3eme lignee ne retarde que de peu le rejet

An experimental study was conducted in rats to evaluate the sensitivity of the liver to infrared hyperthermia. A 15-min hyperthermia session treating only the liver was done in rats with a normal hepatic parenchyma and in rats with hepatocarcinoma induced by chronic 3'-diethylaminoazobenzene intoxication, at various ranges of intrahepatic temperature. In normal rats, 40-42 degrees C hyperthermia was well tolerated, but the mortality rate increased when the intrahepatic temperature exceeded 42 degrees C. In rats with tumors, a 40-42 degrees C hyperthermia session was well tolerated in case of small tumors, but resulted in a high mortality rate in case of large tumors. In all cases, death occurred as a consequence of liver injury. This study using a simple method of hyperthermia defines the thermosensitivity of the neoplastic or normal rat liver and provides a basis for further investigations on the effect of hyperthermia on experimental liver tumors.

In this study, the beneficial effect of intrasplenic transplantation of hepatocytes or splenocytes was shown in animals with 75% hepatectomy and portacaval shunt but not in animals with total dehepatization by hepatic vascular exclusion. No enhancement of the phagocytic activity was observed in the animals with 75% hepatectomy and portacaval shunt after injection of hepatocytes or splenocytes. This study confirms the efficacy of hepatocytes for the treatment of experimental liver failure but shows that nonhepatic cells may be equally as effective. Metabolic activity of the transplanted cells and stimulation of the phagocytic activity of the reticuloendothelial system probably do not explain the therapeutic effect of the transplanted cells.

A patient with end-stage cirrhosis complicating HBsAg-positive chronic active hepatitis given a heterotopic liver transplant is alive and well 28 months after transplantation; liver function is normal, and there are no hepatitis-B related lesions on the liver graft despite positivity of HBsAg in the serum. This observation confirms that a heterotopic liver graft can offer long-term survival in man and suggests that this technique may be a more suitable procedure than orthotopic transplantation in end-stage cirrhotics.

Preformed antibodies are involved in xenograft rejection. The purpose of this work was to characterize porcine xenoantigens recognized by human preformed IgG (hpIgG), and to investigate the role of hpIgG in xenogeneic rejection. IgG eluted from porcine livers perfused with human plasma, human sera and total human IgG were immunoblotted on porcine aortic endothelial cell extracts. The amino acid sequence of a 76-kDa antigen constantly revealed was 100% homologous with porcine serotransferrin (psTf). hpIgG from human sera, human IgG1 and IgG2 and F(ab')2gamma specifically bound to psTf. Neutralization by psTf abolished that binding. Although alpha1,3-linked galactose residues (Gal(alpha)1,3Gal) is the dominant epitope recognized by preformed antibodies in the swine-to-human combination, the analysis of carbohydrate composition of psTf showed that the molecule was devoid of Gal(alpha)1,3Gal moieties and that preformed anti-psTf IgG bound to epitopes localized on the peptide core of the molecule. Purified human anti-psTf IgG antibodies were able to bind to psTf linked to its receptor on porcine endothelial cells, and to kill those cells through antibody-dependent cellular cytotoxicity.

Rejection times of heart xenografts in several donor-recipient combinations including the guinea pig, rat, hamster, and mouse are examined in light of the paleontological history of rodents and the resulting phylogenetic distances between taxa. This multidisciplinary review at the molecular, chromosomal and morphological levels suggests that xenograft rejection time is inversely proportional to the time divergence or phylogenetic distance, and that the binomial terminology concordant/discordant does not reflect the amplitude of phylogenetic distances.

Therapeutic gene transfer has progressed quite rapidly in recent years. Noticeably, it has now reached the clinical stage in both fields of inherited and acquired diseases. Numerous studies of liver-targeted gene therapy and cancer gene therapy have supported the hope that such innovative approaches may be of help in the treatment of primary or secondary liver tumors. In this article, the main strategies of experimental, hepatic cancer gene therapy in the prospect of a clinical use are reviewed.