In situ retrovirus-mediated gene transfer into dog liver.

Dogs were used as a large animal model to assess the feasibility and safety of a surgical method for gene transfer into hepatocytes in vivo. This method, which we previously described in rats, consists of a partial hepatectomy aimed at inducing liver regeneration, followed by the selective in situ perfusion of the remnant liver parenchyma with a retrovirus preparation. Isolation of the liver was obtained by clamping the afferent and efferent blood vessels, a procedure that prevented retroviral vector dissemination and genetic modification of nonhepatic organs. A helper-free retrovirus vector encoding beta-galactosidase targeted to the nucleus was perfused in the liver of 5 golden retriever dogs. Volumes up to 1,650 ml of fresh or concentrated vector stocks were perfused and the procedure was well tolerated. Gene transfer, observed in 3 of 5 treated dogs when documented on liver biopsy fragments obtained at day 4, involved 0.15-0.6% hepatocytes and persisted at equivalent levels at the time of sacrifice, 6 weeks later. No propagation of the vector to other tissues was detected. These observations suggest that the selective perfusion of the regenerating liver might be considered an alternative to liver transplantation for the treatment of certain severe genetic liver disorders, or for the delivery of a therapeutic protein into the serum.

In vivo hepatocyte retrovirus-mediated gene transfer through the rat biliary tract.

Delivering retroviruses targeted to hepatocytes in vivo involves the injection of retroviruses directly into the blood stream of the portal vein. The aim of this work was to delineate the conditions for delivering retroviruses in vivo by perfusing in situ the bile duct of the regenerating rat liver, and to study the hepatocyte transgene expression. At 24 hr after partial hepatectomy, during the S phase of the cell cycle, regenerating livers were perfused for 2.8+/-0.5 hr through the bile duct with 36.2+/-6.8 ml (0.3+/-01 ml/min) of fresh culture supernatant containing amphotropic recombinant retroviruses encoding the beta-galactosidase gene. The virus total titer was 1.5 x 10(8) ffu (group I) or 6.5 x 10(8) ffu (groups II and III). The hepatic artery blood flow was either maintained (groups I and II) or interrupted (group III) during bile duct perfusion. Liver biopsies taken 7 days later showed that 31.4+/-24.2% (group I), 58.7+/-23.6% (group II), and 45.1+/-21.4% (group III) of hepatocytes expressed beta-galactosidase activity, predominantly in the periportal and mediolobular zones. This study demonstrates that hepatocytes of regenerating rat livers that have entered the S phase of the cell cycle as a result of partial hepatectomy can be transduced in vivo by retroviral vectors delivered in situ by bile duct perfusion. Furthermore, the number of transduced hepatocytes closely correlated with the viral total titer and was diminished by hepatic artery blood flow occlusion during perfusion.

A "distant" bystander effect of suicide gene therapy: regression of nontransduced tumors together with a distant transduced tumor.

Antitumor gene therapy using herpes simplex type 1 thymidine kinase (TKh) and ganciclovir (GCV) treatment has revealed an important intratumoral bystander effect. A whole tumor can be eliminated when only a fraction of its tumor cells express TKh. We now report that the bystander effect not only acts within a tumor, but also between distant tumors. One TKh+ tumor was generated simultaneously with one or multiple TKh- tumors in different rat liver lobes such that there was no contact between the resulting tumors. Both the TKh+ and the TKh- tumors regressed after GCV treatment and showed infiltration with macrophages and T lymphocytes. This distant bystander effect, which is likely immune mediated, should be of major importance for gene therapy of disseminated tumors.

Efficient retroviral-mediated gene transfer into primary culture of murine and human hepatocytes: expression of the LDL receptor.

The ex vivo approach to hepatic gene therapy involves several steps, which include the isolation and culture of hepatocytes, followed by their transduction with a retrovirus. Subsequently, autologous hepatocytes are transplanted. The number of hepatocytes that can be transduced by retroviruses bearing the therapeutic gene is one of the limiting steps that can impair the success of this strategy. We presently describe an experimental approach that leads to improved transduction efficiency in mouse and human hepatocytes in vitro. By using a recombinant retrovirus bearing the Escherichia coli beta-galactosidase gene, we show that addition of growth factors to the cells, namely human hepatocyte growth factor (HGF), allows marked increase in the transduction efficiency in mouse (up to 80%) and human (40%) hepatocytes. Familial hypercholesterolemia (FH) is due to mutation in the low-density lipoprotein (LDL) receptor gene and results in a deficiency in LDL receptors. Transduction of the human LDL receptor cDNA under the transcriptional control of the L-type pyruvate kinase promoter-activator into mouse hepatocytes led to an elevated tissue-specific expression of the human protein. These results suggest that the ex vivo approach remains a promising alternative for hepatic gene therapy.

Liposomal encapsulation of ganciclovir enhances the efficacy of herpes simplex virus type 1 thymidine kinase suicide gene therapy against hepatic tumors in rats.

Suicide gene therapy based on ganciclovir (GCV) metabolism by transgene herpes simplex thymidine kinase (HSV-1 TK) has been used to selectively kill proliferating cells in clinical settings such as cancer, vascular restenosis, and immunological disorders. We investigated whether encapsulation of ganciclovir (GCV) into liposomes would improve its efficacy, especially against hepatic tumors. Large unilamellar liposomes containing GCV were prepared by reversed-phase evaporation. Pharmacokinetic studies in rats showed that, compared with free GCV, the intravenous injection of liposome-encapsulated GCV (lip-GCV) led to a faster decrease in GCV plasma concentrations, but higher liver-blood ratios. After treatment of syngeneic HSV-1 TK+ liver metastases in rats, histologically active tumors were found in 95% of the transplanted lesions when physiological saline had been given and in 50% when free GCV had been given at 90.2 microM/kg twice daily. This dose is known to be insufficient for the eradication of HSV-1 TK+ tumors. In contrast, only 5% viable tumors were found in rats receiving lip-GCV at this same concentration. Average tumor volumes were 19 +/- 15, 7 +/- 9, and <1 mm3 for the control, free GCV, and lip-GCV groups, respectively. GCV-related toxicity was no longer observed. The results demonstrate that liposomal encapsulation of GCV is feasible and significantly enhances its efficacy against HSV-1 TK+ hepatic tumors.

Liver transplantation in Langerhans' cell histiocytosis (histiocytosis X).

Two children with biopsy-proven LCH underwent successful hepatic transplantation for end-stage liver disease. These patients were thought not to have active LCH disease at the time of transplantation, although one had developed a new osteolytic lesion a few months before the operation and the other had suspicious osteolytic lesions at the time of transplantation. The histologic examination of the excised liver showed features consistent with primary sclerosing cholangitis. The two patients had an excellent recovery with no evidence of progression of LCH or recurrence of the underlying disease in the hepatic allograft at 1 and 3 years after organ transplantation.

Morphological changes in rat pancreatic acinar cells induced by long-term treatment with cyclosporine and their reversal after withdrawal.

Cyclosporine (CsA), administered to rats at daily doses of 10 and 50 mg/kg body weight, for 21 days, influenced negatively the structures involved in the synthesis, storage and secretion of digestive enzymes in pancreatic acinar cells. A dose-related, significant reduction in basophilic cell regions, secretion granule content, and overall size of acinar cells was appreciable by light microscopy and morphometry. By electron microscopy, the acinar cells of the rats given 10 mg/kg/day CsA were similar to the controls, whereas with the higher dose most cells showed reduction in the size of nucleoli, increase in the number of lysosomes, and evidence of autophagy. In only a few cells was autophagy particularly severe and involved almost the entire cytoplasm. Nine weeks after withdrawal from CsA treatment, the structural recovery of acinal cells was complete, and features indicating enhanced protein synthesis and mitochondrial multiplication were observed by electron microscopy. In conclusion, prolonged administration of CsA to rats induces changes in the acinar cells indicating a depression of their activity, without substantial impairment in the viability of the most of them, even at high doses. This accounts for complete restoration of the acinar tissue upon withdrawal.

Immunocytochemical and ultrastructural changes of islet cells in rats treated long-term with cyclosporine at immunotherapeutic doses.

Daily cyclosporine doses of 10 mg/kg body weight for 21 days in Wistar rats cause impairment in glucose homeostasis and changes in the amount of immunostainable hormones and in the ultrastructure of the cells of the pancreatic islets. CsA induces hyperglycemia and reduced glucose tolerance, and causes a decrease in immunoreactive insulin and an increase of somatostatin and pancreatic polypeptide (PP) immunoreactivities, leaving glucagon immunoreactivity unaffected. Ultrastructurally, different degrees of dilation of rough endoplasmic reticulum cisternae and enlargement of Golgi apparatus can be observed in B cells, together with a pronounced reduction in the number of secretory granules. Nevertheless, there were no apparent morphological changes of the other cytoplasmic organelles, suggesting that the drug, besides a depression of protein synthesis, as previously stated, also induces a substantial defect in granulogenesis, probably due to impairment in the intracellular transport of the hormone from the sites of synthesis to the secretory granules. The B cell alterations are not accompanied by any sign of B cell degeneration or death. Non-B cells did not show any of the ultrastructural changes found in B cells and were similar to those of the control rats. The above findings indicate that CsA at immunotherapeutic doses causes impairment in the secretory processes of B cells specifically. An hypothesis on the mode of action of CsA on B cells is drawn.

Cholestatic effect of cyclosporine in the rat. An inhibition of bile acid secretion.

Cyclosporine administration in patients with organ transplants may cause cholestasis. In the rat, intraperitoneal administration of cyclosporine, 10 mg/kg, for three weeks did not cause liver function test abnormalities or hepatic histological lesions. However a significant reduction of bile flow and bile acid secretion rates was observed. The fact that reduction of bile flow was related to a decrease of the bile acid-independent flow suggests that cyclosporine-induced cholestasis results from an inhibition of bile acid secretion. Whether this inhibition is caused by the parental molecule or by cyclosporine metabolites needs to be clarified.

Target antigens of hyperacute xenogeneic rejection in the rat to guinea pig to rat discordant combinations.

The increasing shortage in allografts has led to a renewed interest in xenogeneic transplantation. Discordant combinations are characterized by hyperacute rejection partly due to the presence of natural antixenogeneic antibodies in the recipient. The aim of this work was to characterize the target antigens, using 2 discordant models. In the rat into guinea pig model, analysis of organ homogenates by immunoblotting revealed numerous bands. Some of these bands were organ specific, whereas others, namely in the 55-kDa region, were detected in liver, heart, lung, and kidney. Using membrane extracts of liver cells or of aortic endothelial cells, only bands of 55 kDa were revealed. No band could be seen using extracts of isolated hepatocytes. Two bands of 55 kDa disappeared after preabsorption of guinea pig sera on the various rat tissue homogenates, suggesting that they represent xenoantigens common to these tissues. In order to investigate the in vivo relevance of these 55-kDa antigens, isolated rat livers were perfused with decomplemented guinea pig sera. Eluates revealed one single print of 55 kDa on rat tissue homogenates. Finally, preincubation of rat mononuclear cells with various xenogeneic sera did not inhibit the binding of mAb specific for rat class I or class II MHC antigens, suggesting that the latter are not recognized by natural xenoantibodies. In the guinea pig to rat model, the antigens detected had a molecular mass ranging from 95 to 110 kDa. Absorption and perfusion experiments also showed that these antigens were common to various tissues and involved in the binding of rat natural antibodies ex vivo. In conclusion, our results indicate that rat xenoantigens of about 55 kDa are recognized by guinea pig natural antibodies, while guinea pig xenoantigens of 95-110 kDa are bound by rat natural antibodies. These antigens are common to liver, heart, lung, and kidney, are borne by endothelial cells, and cannot be found on hepatocytes.

Enhanced risk of steroid-resistant acute rejection following pretransplant steroid therapy in liver graft recipients.

Most episodes of acute rejection will resolve after steroid therapy without detrimental consequences on the liver allograft. However, steroid-resistant acute rejection may induce irreversible lesions of the graft and is associated with an increased risk of chronic rejection. The aim of this study was to determine whether there were predictive factors for steroid-resistant acute rejection after liver transplantation. A total of 108 adult liver recipients with a follow-up of at least 2 years have been analyzed; sixty-two (57%) patients had at least one episode of acute rejection. The rates of steroid resistance were 35%, 52% and 83% after a first (n = 62), second (n = 25), or third (n = 7) episode of acute rejection, respectively. Steroid resistance of acute rejection was significantly associated with a past history of pretransplant steroid therapy (P = 0.004). High levels of ALT (P = 0.03) and serum bilirubin (P = 0.002) were also predictive of steroid-resistant acute rejection. Eight (7%) patients eventually developed chronic rejection. Predictive factors for chronic rejection included steroid-resistant acute rejection (P = 0.01), recurrent acute rejection (P = 0.03), and CMV infection (P = 0.01). In conclusion, this study suggests that pretransplant steroid administration or high levels of ALT and bilirubin in rejecting patients are risk factors for steroid resistance and should lead to aggressive antirejection therapy without delay.

Orthotopic liver transplantation in children with chronic liver disease and severe hypoxemia.

Liver transplantation has been considered until recently as an absolute contraindication in hypoxemic patients. We report our experience in nine patients who had orthotopic liver transplantation between June 1986 and June 1992. These patients had cirrhosis-related hypoxemia with intrapulmonary shunting (IPS). The arterial oxygen pressure (PaO2) on room air ranged from 47 to 78 mmHg. OLT resulted in resolution of hypoxemia and closure of IPS in five patients whose hypoxemia was higher than 60 mmHg, and in death for the remaining four patients who had severe hypoxemia (PaO2 < 60 mmHg). We conclude that hypoxemia is no longer a contraindication to liver transplantation. Patients having PaO2 levels higher than 60 mmHg should have OLT as soon as possible before reaching lower levels of PaO2, and combined lung-liver transplantation or heart-lung-liver transplantation should be discussed in patients with severe hypoxemia (PaO2 < 60 mmHg).

Liver transplantation in children with Alagille syndrome--a study of twelve cases.

Cholestasis associated with Alagille syndrome may, in a few cases, be extremely severe and result in major impairment in the quality of life during early childhood and end up in cirrhosis eventually. We report the results of liver transplantation in 12 children with a severe hepatic form of Alagille syndrome. All children presented with cholestatic jaundice from birth, peculiar facies, stenosis of the peripheral pulmonary artery, and posterior embryotoxon; butterfly-like vertebrae were present in 9 children. At the time of transplantation (mean age 7 years 10 months) refractory pruritus was present in 9 children, xanthoma in 11, and height and weight retardation in 11. Total serum bilirubin ranged from 116 to 322 mumol/L and total serum cholesterol from 3.5 to 29 mmol/L. Systolic right ventricular pressure was moderately raised (36 to 48 mmHg) in 5 children; mean creatinine clearance was 99 ml/min/1.73 m2. Histologic examination of the removed livers showed cirrhosis, severe annular fibrosis, and moderate portal fibrosis in 4 children each. Follow-up in the 11 survivors has ranged from 14 months to 5 1/2 years. All lead normal lives. Pruritus and xanthomas disappeared. Increase in height was observed in 8 of the 10 survivors who had growth retardation prior to transplantation. School level is normal in 4 (median age at LT: 5 yr 9 mo) and below normal in 6 (median age at OLT: 9 yr 9 mo). Liver function tests are normal in 10 children. Mean creatinine clearance is 101 ml/min/1.73 m2. These results indicate that the quality of life can be considerably improved after liver transplantation in children with a severe hepatic form of Alagille syndrome and suggest that it could be carried out before these children attend elementary school.

Use of intravenous immunoglobulin to delay xenogeneic hyperacute rejection. An in vivo and in vitro evaluation.

The delaying action of intravenous immunoglobulin (IVIG) from human origin on hyperacute xenogeneic rejection was assessed in the guinea pig-to-rat combination. IVIG (1500 mg/kg) injected i.v. into Lewis rats 1 hr before grafting significantly prolonged the mean guinea pig heart survival time (167 min, P < 0.005) compared with control injections using NaCl (12 min) or the IVIG glycine vehicle (11 min). The effect of IVIG was also assessed in vitro in the pig-to-human combination. A dose-dependent inhibition of the complement-mediated direct cytotoxicity of human serum on pig RBC was shown using IVIG. The weak direct cytotoxicity of IVIG to pig RBC, which was abolished after preincubating IVIG with pig RBC, was attributed to the anti-pig xenoreactive natural antibodies (XNA) contained in the IVIG preparation. In vitro, XNA-depleted IVIG exerted a significantly stronger inhibitory effect than non-XNA-depleted IVIG, suggesting the use XNA-depleted IVIG in the pig-to-human combination. Although the mechanism of the inhibitory effect of IVIG remains to be clarified, IVIG may represent a new and simple therapeutic modality against xenogeneic hyperacute rejection.

The role of natural IgM in the hyperacute rejection of discordant heart xenografts.

The mechanism of xenograft hyperacute rejection in discordant species combinations remains controversial. The purpose of this work was to study the role of natural antibodies in the hyperacute rejection of guinea pig hearts transplanted into rats, a highly discordant combination. This study was conducted in vitro, ex vivo, and in vivo. The endothelial cells of the graft being the first targets damaged in the process of hyperacute rejection, the binding of rat natural antibodies to guinea pig endothelial cells was studied by immunofluorescence. The study was carried out in vitro on guinea pig endothelial cells in culture, and ex vivo on isolated guinea pig hearts perfused with either rat serum or immunoglobulins or immunoglobulin fragments bearing the antigen-binding site. In vitro and ex vivo, rat natural IgM were found to bind specifically to guinea pig endothelial cells, since IgM fragments bearing the antigen-binding site (Fab mu and Fab' mu) could be detected on these cells. IgM fragments were able to inhibit the fixation of native IgM molecules. In contrast, rat IgG only bound to endothelial cells through Fc portions. Thus rat natural IgM might play a role in hyperacute rejection by binding to the graft endothelial cells and triggering the complement cascade activation. In order to test the role of natural IgM in vivo, isolated guinea pig hearts were first perfused with rat Fab' mu, which inhibit the binding of IgM and are unable to activate the complement cascade. These hearts were then transplanted into Lewis rats. The rejection time of Fab' mu-perfused guinea pig hearts was prolonged compared with hearts perfused with buffer or IgG F(ab')2. Therefore, in the guinea pig to rat combination, preventing the binding of the recipient's natural IgM to the graft endothelium delays the hyperacute rejection. In addition, natural IgM are likely to play a greater role than natural IgG.

Costs and outcomes of liver transplantation in adults: a prospective, 1-year, follow-up study. GRETHECO study group.

BACKGROUND: Orthotopic liver transplantation (OLT) is widely used to treat patients with end-stage liver disease. However, data on the cost of the procedure are fragmentary. We evaluated the costs, as calculated from resource use, and outcomes of OLT in adults, from registration on the transplant waiting list to the end of the 1st-year of follow-up after the transplant. METHODS: Two parallel cohort studies were conducted from 1994 to 95. All patients ages 18 years and older, on the waiting list (n=33) according to national criteria or having undergone transplants (n=38) were followed for 1 year or until either the transplant (waiting list cohort) or death (waiting list and transplantation cohorts). RESULTS: Eighty percent of the patients undergoing transplants were alive after 1 year, and no patient died while on the waiting list. However, the estimated cost of the procedure was high: more than 55,000 pound silver for the 1st year after OLT, to be added to 5,500 pound silver for evaluation and further costs motivated by the planned transplant during an average 6.5 months on the waiting list. Age over 40 and a baseline Child-Pugh score of 10 and over were predictive of high costs. The proportion of costs associated with immunosuppressive therapy and rejection were very high. CONCLUSIONS: This medical and economic cohort study suggests that OLT is still expensive; the study identifies sources of extra cost that could be limited either by improved selection of patients or, in the future, by technological advances in immunosuppressive therapy that help avoid medical complications. It also suggests the situation is precarious, with outcomes and costs being very sensitive to variation in graft availability.

Spontaneous long-term acceptance of RT-1-incompatible liver allografts in inbred rats. Analysis of the immune status.

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.

Donor class I and class II major histocompatibility complex antigen expression following liver allografting in rejecting and nonrejecting rat strain combinations.

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.