Long-Term Amerlioration of Bilirubin Glucuronidation Defect in Gunn Rats by Transplanting Genetically Modified Immortalized Autologous Hepatocytes

Ex vivo gene therapy, in which hepatocytes are harvested from mutants, retrovirally transduced with a normal gene and transplanted back into the donor, has been used for correction of inherited metabolic defects of liver. Major drawbacks of this method include limited availability of autologous hepatocytes, inefficient retroviral transduction of primary hepatocytes, and the limited number of hepatocytes that can be transplanted safely. To obviate these problems, we transduced primary hepatocytes derived from inbred bilirubin–UDP–glucuronosyl–transferase (BUGT)-deficient Gunn rats by infection with a recombinant retrovirus expressing temperature-sensitive mutant SV40 large T antigen (tsT). The immortalized cells were then transduced with a second recombinant retrovirus expressing human B-UGT, and a clone expressing high levels of the enzyme was expanded by culturing at permissive temperature (33°C). At 37°C, tsT antigen was degraded and the cells expressed UGT activity toward bilirubin at a level approximately twice that present in normal rat liver homogenates. For seeding the cells into the liver bed, 1 × 107 cells were injected into the spleens of syngeneic Gunn rats five times at 10-day intervals. Excretion of bilirubin glucuronides in bile was demonstrated by HPLC analysis and serum bilirubin levels were reduced by 27 to 52% in 40 days after the first transplantation and remained so throughout the duration of the study (120 days). None of the transplanted Gunn rats or SCID mice transplanted with the immortalized cells developed tumors. © 1998 Elsevier Science Inc.

Late graft loss and long-term outcome after isolated intestinal transplantation in children

BACKGROUND/PURPOSE

The aim of this study was to determine causes of late graft loss and long-term outcome after isolated intestinal transplantation in children at a single center.

METHODS

All children who underwent primary isolated intestinal transplantation at our center with a minimum follow-up of 1 year were the subject of this retrospective study.

RESULTS

Twenty-eight children underwent primary isolated intestinal transplantation. Median graft survival was 705 days (range, 0 to 2,630 days) and median patient survival was 1,006 days (range, 0 to 2,630 days). There were 6 deaths and 15 graft losses (including the 6 nonsurvivors). Seven of the losses occurred 6 or more months after transplant. Of these, 2 losses occurred because of death of the recipients of sepsis; both recipients had functioning grafts. The 5 remaining late graft losses occurred because of acute rejection in 2 patients, chronic rejection in 2 (1 with concomitant acute rejection) and a diffuse stricturing process without the histologic hallmarks of chronic rejection in the fifth. All late survivors with intact grafts are off total parenteral nutrition (TPN).

CONCLUSIONS

Late graft loss remains a concern in a small percentage of patients after isolated intestinal transplantation. Nutritional autonomy from TPN is possible in the majority of these children after transplantation.

A new technique for combined liver/small intestinal transplantation

The most common application of small bowel transplantation is for the patient with parenteral nutrition-induced liver failure. In this setting, the small intestine is transplanted simultaneously with the liver. We identified three technical problems that we believe contributed to complications in our first eight patients. First, pancreaticoduodenectomy was challenging in the infant donor. Second, the bowel graft was prone to volvulus around the skeletonized donor portal vein. Third, in the pediatric recipient, use of the donor bowel for Roux-en-Y biliary reconstruction was associated with biliary leaks in the early postoperative period. Our surgical technique of liver/small bowel (L/SB) transplantation has evolved since our early experience in 1990. Modifications in the L/SB operation, reported briefly in 1996 and 1997, have led to easier graft preparation and have reduced the incidence of technical complications.

Extracorporeal support with a cadaver liver as a bridge to transplantation

Extracorporeal liver perfusion (ECLP) has been used for detoxifying blood in patients in class IV hepatic encephalopathy. Palliation of the moribund patient utilizing extracorporeal devices with cross-circulation of a cadaver liver has been documented for over three decades. Common problems associated with this procedure which appear in the literature include cadaver liver distention, increased resistance to blood flow, and limited time of extracorporeal support due to cadaver liver failure. This report summarizes the experiences of the perfusion team in utilizing an extracorporeal circuit with an otherwise nontransplantable cadaveric liver, to support the decompensating hepatic patient as a bridge to transplantation. Between January and July 1992, three patients were supported for hepatic failure with ECLP. Two patients were placed on ECLP with a modified circuit containing two positive displacement pumps and one centrifugal pump. The third patient was placed on ECLP with a circuit that contained two centrifugal pumps and one positive displacement pump. Patient age ranged from 6 to 38 years and length of support ranged from 24 to 72 hours. In all three patients, a centrifugal pump was placed in the suprahepatic inferior vena cava line to facilitate cadaver liver drainage and decompression. Intensive monitoring of both patient and cadaver liver hemodynamics, hepatic function, and hematological status was performed. All three patients were successfully weaned from ECLP. Two patients received successful orthotopic liver transplantation. The third died of complications unrelated to ECLP after support was discontinued.(ABSTRACT TRUNCATED AT 250 WORDS)

Extracorporeal liver perfusion using human and pig livers for acute liver failure

BACKGROUND

Patients with fulminant hepatic failure (FHF) often die awaiting liver transplantation. Extracorporeal liver perfusion (ECLP) has been proposed as a method of "bridging" such patients to transplantation. We report the largest experience to date of ECLP using human and porcine livers in patients with acute liver failure.

METHODS

Patients with FHF unlikely to survive without liver transplantation were identified. ECLP was performed with human or porcine livers. Patients underwent continuous perfusion until liver transplantation or withdrawal of support. Two perfusion circuits were used: direct perfusion of patient blood through the extracorporeal liver and indirect perfusion with a plasma filter between the patient and the liver.

FINDINGS

Fourteen patients were treated with 16 livers in 18 perfusion circuits. Nine patients were successfully "bridged" to transplantation. ECLP stabilized intracranial pressure (ICP) and cerebral perfusion pressure (CPP). Arterial ammonia levels fell from a median of 146 to 83 micromol/liter within 12 hr and this reduction was maintained at least 48 hr. Pig and human ECLP lowered ammonia levels equally. Serum bilirubin levels also fell from a median of 385 to 198 micromol/liter over the first 12 hr but the response was not sustained as well with porcine livers. There was no immunological benefit to using the the filtered perfusion circuit.

INTERPRETATION

These data demonstrate that ECLP is safe and can provide metabolic support for comatose patients with fulminant hepatic failure for up to 5 days. While labor and resource intensive, this technology is available to centers caring for patients with acute liver failure and deserves wider evaluation and application.

Construction of a non-tumorigenic rat hepatocyte cell line for transplantation: reversal of hepatocyte immortalization by site-specific excision of the SV40 T antigen

BACKGROUND/AIMS

Hepatocytes immortalized with a temperature-sensitive SV40 large T antigen (SV40Tag) function as well as primary hepatocytes following transplantation to reverse hepatic encephalopathy and improve survival in rodents with liver failure. The continued presence of SV40Tag in the conditionally immortalized hepatocytes may increase the risk of malignant tumor growth in transplant recipients.

METHODS

We immortalized hepatocytes using a recombinant retrovirus containing the gene encoding SV40Tag flanked by loxP recombination target sites. Excision of SV40Tag from immortalized cells could then be accomplished by site-specific recombination with Cre-recombinase.

RESULTS

Cells immortalized with this recombinant virus expressed SV40Tag and doubled in number every 48 h. After excision of the gene encoding SV40Tag with Cre-recombinase, cells stopped growing, DNA synthesis fell by 90%, and production of liver-specific mRNAs was either increased or became newly detectable. In addition, the morphology and epithelial cell polarity of the cells became more characteristic of differentiated hepatocytes. To determine their malignant potential, immortalized hepatocytes were transfected to express a second oncogene, activated H-ras. SV40Tag+/H-ras+-immortalized cells were capable of anchorage-independent growth and developed into tumors when injected in severe combined immunodeficiency mice. While Cre-recombinase delivery by recombinant adenovirus infection was not 100% efficient, when SV40Tag excision occurred anchorage-independent growth stopped and tumor formation in immunodeficient mice was abolished. Immortalized hepatocytes also contained the gene encoding herpes simplex virus thymidine kinase and treatment with ganciclovir produced complete regression of established tumors in mice.

CONCLUSIONS

These studies extend previous work that indicates that a transplantable hepatocyte cell line could be developed for clinical use.

Treatment of carbon tetrachloride and phenobarbital-induced chronic liver failure with intrasplenic hepatocyte transplantation

Hepatocyte transplantation (HTx) has been shown to improve the survival of laboratory animals with experimentally induced acute liver failure and to ameliorate the physiologic abnormalities associated with liver-based metabolic deficiencies. However, the role of HTx in the treatment of liver cirrhosis (LC) has not been adequately studied. In order to address this issue, HTx was performed in rats following induction of stable LC using phenobarbital (PhB) and carbon tetrachloride (CCl4). Intrasplenic transplantation of 50 x 10(6) primary hepatocytes could significantly improve liver functions and prolong the survival of rats with irreversible, decompensated LC.

Isolated intestinal transplantation for intestinal failure

OBJECTIVE

Parenteral nutrition sustains life in patients with intestinal failure. However, some experience life-threatening complications from parenteral nutrition, and in these individuals intestinal transplantation may be lifesaving.

METHODS

This is a retrospective review of 28 consecutive isolated small bowel transplants performed in eight adults and 20 children between December 1993 and June 1998 at the University of Nebraska Medical Center.

RESULTS

The 1-yr patient and graft survivals were 93% and 71%, respectively. The causes of graft loss were hyperacute rejection (n = 1), acute rejection (n = 5), vascular thrombosis (n = 1), and patient death (n = 1). The median length of time required until full enteral nutrition was 27 days. All 28 patients have experienced acute rejection of their small bowel grafts and rejection led to graft failure in five. Jaundice and/or hepatic fibrosis was present preoperatively in 17 of the 28 recipients and hyperbilirubinemia was completely reversed in all patients with functional grafts within 4 months of transplantation. Three patients developed post-transplant lymphoproliferative disease (11%). Three recipients developed cytomegalovirus enteritis and all were successfully treated.

CONCLUSIONS

Patient survival after intestinal transplantation is comparable to parenteral nutrition for patients with intestinal failure. Better immunosuppressive regimens are needed to decrease the risk of graft loss from acute rejection. The incidence of posttransplant lymphoproliferative disorder is higher after intestinal transplantation than after other solid organ transplants and the risk of cytomegalovirus enteritis is low with the use of cytomegalovirus seronegative donors. Liver dysfunction in the absence of established cirrhosis can be reversed.

Hepatocyte transplantation in rats with decompensated cirrhosis

Hepatocyte transplantation improves the survival of laboratory animals with experimentally induced acute liver failure and the physiological abnormalities associated with liver-based metabolic deficiencies. The role of hepatocyte transplantation in treating decompensated liver cirrhosis, however, has not been studied in depth. To address this issue, cirrhosis was induced using phenobarbital and carbon tetrachloride (CCL(4)) and animals were studied only when evidence of liver failure did not improve when CCL(4) was held for 4 weeks. Animals received intrasplenic transplantation of syngeneic rat hepatocytes (G1); intraperitoneal transplantation of syngeneic rat hepatocytes (G2); intraperitoneal transplantation of a cellular homogenate of syngeneic rat hepatocytes (G3); intraperitoneal transplantation of syngeneic rat bone marrow cells (G4); or intrasplenic injection of Dulbecco's modified Eagle medium (DMEM) (G5). After transplantation, body weight and serum albumin levels deteriorated over time in all control (G2-G5) animals but did not deteriorate in animals receiving intrasplenic hepatocyte transplantation (G1) (P <.01). Prothrombin time (PT), total bilirubin, serum ammonia, and hepatic encephalopathy score were also significantly improved toward normal in animals receiving intrasplenic hepatocyte transplantation (P <. 01). More importantly, survival was prolonged after a single infusion of hepatocytes and a second infusion prolonged survival from 15 to 128 days (P <.01). Thus, hepatocyte transplantation can improve liver function and prolong the survival of rats with irreversible, decompensated cirrhosis and may be useful in the treatment of cirrhosis in humans.

Establishment of a tightly regulated human cell line for the development of hepatocyte transplantation

Hepatocyte transplantation (HTX) could be an attractive treatment for patients with liver failure and liver-based metabolic disease. Human primary hepatocytes are ideal in this modality, but the shortage of human livers available for hepatocyte isolation severely limits the use of this form of therapy. A tightly regulated human hepatocyte cell line that grows economically in culture and exhibits differentiated liver functions would be an attractive alternative to the primary human hepatocytes. To test the feasibility, human hepatocytes were immortalized by a retroviral vector expressing simian virus 40 large T antigen and herpes simplex virus-thymidine kinase. A highly differentiated immortal hepatocyte line NKNT-3 was established. NKNT-3 cells grew in chemically defined serum-free medium, retained highly differentiated liver functions, and were sensitivity to ganciclovir as a prodrug. Essentially unlimited availability of NKNT-3 cells may be clinically useful for HTX and bioartificial liver.

Prevention of acute liver failure in rats with reversibly immortalized human hepatocytes

Because of a critical shortage in suitable organs, many patients with terminal liver disease die each year before liver transplantation can be performed. Transplantation of isolated hepatocytes has been proposed for the temporary metabolic support of patients awaiting liver transplantation or spontaneous reversion of their liver disease. A major limitation of this form of therapy is the present inability to isolate an adequate number of transplantable hepatocytes. A highly differentiated cell line, NKNT-3, was generated by retroviral transfer in normal primary adult human hepatocytes of an immortalizing gene that can be subsequently and completely excised by Cre/Lox site-specific recombination. When transplanted into the spleen of rats under transient immunosuppression, reversibly immortalized NKNT-3 cells provided life-saving metabolic support during acute liver failure induced by 90% hepatectomy.

Disaccharidase activities and fat assimilation in pediatric patients after intestinal transplantation

BACKGROUND

Intestinal transplantation has become an accepted therapy for short bowel syndrome and other types of intestinal failure. In order to assess digestive capabilities and feeding practices in a group of 22 pediatric patients after intestinal transplantation, we assessed mucosal disaccharidase activities and assimilation of total dietary lipid and vitamin E. Twelve of the patients had undergone contemporaneous liver transplantation.

METHODS

Mucosal biopsies were assayed for disaccharidase activities between 15 and 412 days after transplantation in 7 of the 22 when all were receiving some enteral nutrition and were free of rejection. Coefficients of lipid absorption were determined in those patients receiving total enteral feeding (two-thirds polymeric/one-third elemental) between 43 and 1032 days after transplantation; oral vitamin E tolerance tests were done at about the same time.

RESULTS

Activities of lactase, sucrase, maltase, and palatinase consistently exceeded reference ranges (P<0.05). Mean coefficient of lipid absorption equaled 86+/-12% and was not influenced by duration of time after transplantation. No patient required dietary lipid restriction. No significant absorption of vitamin E was demonstrated until 160 days after transplantation. Vitamin E absorption did correlate with length of time elapsed after surgery (r=0.64, P<0.0011).

CONCLUSIONS

The results of this investigation show that, in the absence of histologic or clinical indications of allograft rejection, pediatric intestinal transplant recipients do not have primary disaccharidase deficiencies. Similarly, absorption of usual dietary lipid content is adequate once weaning from parenteral nutrition is complete. In contrast, early assimilation of vitamin E is poor. Vitamin E absorption subsequently improves, but the mechanism is obscure.

Effect of surrogate tolerogenesis on the vascular rejection of pig heart xenografts

BACKGROUND

Organ xenografts are fulminantly rejected by antibody-mediated vascular rejection. Surrogate tolerogenesis (ST), the induction of tolerance within the donor, is effective with aorta xenografts. This preliminary study assesses the effect of ST on preformed antibodies and rejection of porcine heart xenografts.

METHODS

Tolerance to the donor pig was induced by infusing recipient marrow into fetal pigs. Later, pig splenocytes were transfused and heterotopic pig hearts transplanted using chimeric or nonchimeric pigs. Anti-pig antibodies were assessed.

RESULTS

With ST alone, xenografts developed cellular rejection at 4-6 days, whereas control grafts developed vascular rejection at 3-4 days (cellular vs. vascular, P<0.03). There was a reduction in preformed antibodies (P<0.03). ST combined with moderate cyclosporine prevented rejection at 9+ and 25 days in sensitized recipients compared with vascular rejection at 0.5-2 days for controls (P<0.07).

CONCLUSIONS

ST seems to provide protection against vascular rejection. The cellular rejection seems sensitive to cyclosporine.

Hepatocyte transplantation for the treatment of human disease

A great deal of work with animal models indicates that hepatocytes transplanted into the liver or spleen survive, function, and participate in the normal regenerative process. Recent clinical studies suggest that hepatocyte transplantation may be useful for bridging patients to whole organ transplantation and for providing metabolic support during liver failure and for replacing whole organ transplantation in certain metabolic liver diseases. In specific situations where the rate of death of host hepatocytes is high, the transplanted cells can repopulate the native liver. Techniques have been established for the large scale isolation, culture and cryopreservation of human hepatocytes. Shortage of donor organs and the need for immunosuppression are two major hurdles to widespread application of this procedure, and current research in experimental animals is aimed at addressing these problems.

Immunochemical properties of anti-Gal alpha 1-3Gal antibodies after sensitization with xenogeneic tissues

In antigen-driven immune responses to proteins, antibodies of low avidity and limited complement fixing capacity undergo affinity maturation to yield antibodies of higher avidity which fix complement to a greater extent. The products of antigen-driven responses to carbohydrates are less defined. To investigate the evolution of natural antibodies against carbohydrates following sensitization, we studied natural antibodies specific for Gal alpha 1-3Gal in patients sensitized to that antigen as a result of perfusion of their blood through porcine livers for the treatment of hepatic failure. The natural antibodies against Gal alpha 1-3Gal, which occur in all unsensitized individuals, were predominantly IgM and IgG2, with average functional avidities of 5 x 10(-9) and 2 x 10(-8) M, respectively. After sensitization, the classes of anti-Gal alpha 1-3Gal included IgM, IgG2, and IgG1, and the average functional avidities of IgM and IgG were 3 x 10(-9) and 2 x 10(-9) M, respectively. The activation of complement by anti-Gal alpha 1-3Gal per microgram of Ab, measured by the fixation of C3bi on porcine cells, increased after sensitization owing to changes in subclass and avidity. Deposition of C3bi correlated with the concentrations of IgG1 and IgM but not IgG2 against Gal alpha 1-3Gal. Consistent with this finding, purified IgG1, but not IgG2, anti-Gal alpha 1-3Gal fixed complement on porcine cells. These results demonstrate that the properties of anticarbohydrate antibodies evolve after sensitization to increase complement fixation on potential targets. These properties may result from the altered costimulation of the humoral response to Gal alpha 1-3Gal due to sensitization.

Long-term amelioration of bilirubin glucuronidation defect in Gunn rats by transplanting genetically modified immortalized autologous hepatocytes

Ex vivo gene therapy, in which hepatocytes are harvested from mutants, retrovirally transduced with a normal gene and transplanted back into the donor, has been used for correction of inherited metabolic defects of liver. Major drawbacks of this method include limited availability of autologous hepatocytes, inefficient retroviral transduction of primary hepatocytes, and the limited number of hepatocytes that can be transplanted safely. To obviate these problems, we transduced primary hepatocytes derived from inbred bilirubin-UDP-glucuronosyl-transferase (BUGT)-deficient Gunn rats by infection with a recombinant retrovirus expressing temperature-sensitive mutant SV40 large T antigen (tsT). The immortalized cells were then transduced with a second recombinant retrovirus expressing human B-UGT, and a clone expressing high levels of the enzyme was expanded by culturing at permissive temperature (33 degrees C). At 37 degrees C, tsT antigen was degraded and the cells expressed UGT activity toward bilirubin at a level approximately twice that present in normal rat liver homogenates. For seeding the cells into the liver bed, 1 x 10(7) cells were injected into the spleens of syngeneic Gunn rats five times at 10-day intervals. Excretion of bilirubin glucuronides in bile was demonstrated by HPLC analysis and serum bilirubin levels were reduced by 27 to 52% in 40 days after the first transplantation and remained so throughout the duration of the study (120 days). None of the transplanted Gunn rats or SCID mice transplanted with the immortalized cells developed tumors.

Correlation of mucosal disaccharidase activities with histology in evaluation of rejection following intestinal transplantation

Following intestinal transplantation, we have found that recovery from severe rejection may be difficult to identify. In this study we sought to ascertain whether concurrent determination of mucosal disaccharidase activities and histologic assessment improves the accuracy of diagnosis of rejection. Histologic changes were graded blindly using a standard set of diagnostic criteria, and these changes were compared over time to maltase, sucrase, lactase, and palatinase activities in four pediatric patients under treatment for severe rejection. The histologic criteria, which included magnitude of enterocyte loss, degree of granulation tissue, severity of villus atrophy, and frequency of apoptosis and cryptitis, were found to correlate with one another over time irrespective of outcome (r = 0.72 to r = 0.85). Enzyme activities were also correlated with each other over time (r = 0.64 to r = 0.80). However, the correlation between histologic diagnosis and enzyme activity was weaker (r = -0.48 to r = -0.57). Furthermore, neither histologic nor enzyme evaluation early in the course of rejection predicted ultimate clinical outcome. The results of this investigation show that determination of mucosal disaccharidase activity provides no additional useful information concerning efficacy of anti-rejection therapy as compared to histologic analysis alone.

Biliary atresia-polysplenia syndrome: surgical and clinical relevance in liver transplantation

OBJECTIVE

To review a single center's 10-year experience with liver transplantation (LTx) for the biliary atresia-polysplenia syndrome (BA-PS) and to define surgical and clinical guidelines for its management.

SUMMARY BACKGROUND DATA

BA is the most common indication for pediatric liver transplantation (LTx) and is associated with PS in 12% of cases. Only a few studies of LTx for BA-PS have been reported, and the optimal management of BA-PS patients undergoing LTx has yet to be determined.

METHODS

From July 1985 to September 1995, 166 liver transplants were performed in 130 patients with BA and were included in the study. The malformations most commonly associated with BA-PS, surgical techniques used to overcome these anomalies, and surgical pitfalls that could have contributed to the outcome were characterized. Actuarial 10-year patient and graft survival for patients undergoing LTx for BA-PS were calculated and compared to those with isolated BA.

RESULTS

Ten patients (7.8%) with BA had associated PS. An additional patient with PS without BA was included in the study. The diagnosis of PS was unknown before the transplantation in 72% of cases. Thirteen liver transplants were performed in these 11 patients. Modifications of the usual surgical technique were used to overcome the complex anatomy encountered. There was no association between the type of anomaly and the outcome, nor were there any significant differences in patient survival (72% vs. 73.5%, p = 0.79) or graft survival (56.4% vs. 54.6%, p = 0.54).

CONCLUSIONS

The association of BA with various anomalies should be considered a spectrum that may vary widely from patient to patient. The finding of two or more of these malformations in a patient awaiting transplantation should lead the surgeon to look systematically for other associated anomalies. With some special surgical considerations, the outcome in BA-PS patients should not differ from those with isolated BA.

Long-term follow-up of auxiliary orthotopic liver transplantation for the treatment of fulminant hepatic failure

BACKGROUND

Auxiliary orthotopic liver transplantation (AOLT) was investigated as a bridge to native liver recovery in patients with fulminant hepatic failure (FHF).

METHODS

In the last 5 years seven patients with FHF were treated with AOLT at our institution. Five patients underwent resection of the native left lobe and orthotopic replacement with a donor left lobe (n = 3) or left lateral segment (n = 2). Two patients underwent left trisegmentectomy and whole liver auxiliary grafting. Conventional immunosuppression was used in all patients.

RESULTS

One patient had poor initial graft function and required retransplantation. Native liver function returned to normal in the six other patients. Immunosuppression was gradually tapered and completely discontinued in three patients, allowing for atrophy of the allograft. The allograft was removed in the other four patients. Despite evidence of native liver regeneration, two patients with aplastic anemia died after allograft removal. Four patients are alive at a mean follow-up of 3.5 years.

CONCLUSIONS

AOLT is technically feasible, rapidly restores liver function, and should be considered an important alternative to standard orthotopic liver transplantation (OLT) in the treatment of FHF. AOLT has the advantage that patients transplanted for FHF are not committed to lifelong immunosuppression with its attendant risks.

Treatment of surgically induced acute liver failure by transplantation of conditionally immortalized hepatocytes

The shortage of human livers available for hepatocyte isolation limits its clinical application. The availability of cloned, conditionally immortalized hepatocytes that could be grown in culture but would lose their transformed phenotype and provide metabolic support upon transplantation would greatly facilitate the treatment of acute liver failure. Toward this goal, we transduced isolated Lewis rat hepatocytes using a replication-defective recombinant retrovirus capable of transferring a gene encoding a thermolabile mutant simian virus 40 T antigen (SV40ts). The cloned, immortalized hepatocytes proliferate at 33 degrees C. At the nonpermissive temperatures (37-39 degrees C), they stop growing and exhibit characteristics of differentiated hepatocytes. These cells did not produce tumors when transplanted in mice with severe combined immunodeficiency disease or in syngeneic rats. To induce acute liver failure, Lewis rats were subjected to 90% hepatectomy (Hpx) and given 5% oral dextrose. All rats that did not undergo hepatocyte transplantation died within 96 hr. Fifty percent of rats that received intrasplenic injection of 10 x 10(6) primary Lewis rat hepatocytes (G2, n=6) or 10 x 10(6) SV40ts-conditionally immortalized (SV40ts-ci) hepatocytes (G3, n=8) 1 day before 90% hepatectomy survived, whereas 80% of rats that received an intraperitoneal injection of 200 x 10(6) primary Lewis rat hepatocytes (G4, n=10) or 200 x 10(6) SV40ts-ci hepatocytes (G5, n=10) on the day of hepatectomy survived. Survival after intraperitoneal injection of a cellular homogenate of 200 x 10(6) primary Lewis rat (G7, n=9) or SV40ts-ci hepatocytes (G8, n=10) on the day of Hpx was 33% and 40%, respectively, whereas survival after intraperitoneal injection of 200 x 10(6) Lewis rat bone marrow cells (G6, n=7) was 29%. Thus, transplanted, conditionally immortalized hepatocytes can be as effective as primary hepatocytes in supporting life during acute liver insufficiency. This work represents the first step in developing an hepatocyte cell line that would partially alleviate the organ-donor shortage and could be of potential clinical value.

Use of gene therapy to suppress the antigen-specific immune responses in mice to an HLA antigen

Hematopoietic chimerism has been used in the laboratory to induce life-long immunologic tolerance to donor antigens. The present study demonstrates that mice transplanted with autologous bone marrow cells retrovirally transduced to express HLA-A2.1 develop a significantly depressed immune response to this antigen while retaining normal reactivity to HLA-B7. Retrovirus-mediated transduction was performed using whole bone marrow-producer cell coculture. This approach did not result in significant gene transfer into hematopoietic progenitor cells. Despite this, the antibody response to HLA-A2.1 in mice reconstituted with genetically modified BMC was completely suppressed three months following bone marrow transplantation. Cell-mediated immunity to HLA-A2.1 was partially suppressed in three-fourths of animals tested three months later, although one animal had a CTL profile similar to that an of HLA-A2.1 transgenic mouse. Complete suppression of the antibody-mediated immune response occurred when only one-third of mice had evidence of the introduced genes in their spleen and one-tenth had the introduced sequences in their circulating WBCs by PCR. In conclusion, engineering of BMC to express donor MHC genes may be an alternative to xenogeneic BMT to induce chimerism and tolerance. More efficient transduction of bone marrow progenitor cells may result in more persistent gene expression and long-lasting transplantation tolerance in recipients of genetically modified bone marrow. Successful application of this technology may also be useful in altering immune responses to other external and self antigens.

Transplantation of conditionally immortalized hepatocytes to treat hepatic encephalopathy

Transplantation of hepatocytes has been shown to provide metabolic support during liver failure in experimental models. The potential clinical application of hepatocyte transplantation, however, is limited by the need for readily available, well-characterized cells, and a worldwide shortage of donor organs. A clonal hepatocyte cell line that could be grown economically in vitro and would exhibit a differentiated, nontransformed phenotype following transplantation would be an attractive solution to this problem. To test this alternative, primary Lewis rat hepatocytes were conditionally immortalized by retroviral transduction with a thermolabile mutant Simian virus 40 (SV40) large T antigen. The cloned immortalized cells proliferate in culture at 33 degrees C and stop growing at 37 degrees C to 39 degrees C. Transplanted into normal livers, these hepatocytes integrate normally into liver cords. When transplanted into the spleens of portacaval-shunted rats, they protect recipients from hyperammonemia-induced hepatic encephalopathy. The cells engrafted in the spleen exhibit normal morphology, secrete bile, and express albumin messenger RNA. The protection from hyperammonemia is reversed by splenectomy. These studies show that hepatocytes can be conditionally immortalized, expanded in culture, and are capable of providing metabolic support in chronic liver insufficiency. Safeguards that could make these cells clinically useful can be accomplished using currently available technology.

Morbidity in patients with posttransplant diabetes mellitus following orthotopic liver transplantation

It is not well understood whether posttransplant diabetes mellitus (PTDM) following orthotopic liver transplantation (OLTx) alters postoperative morbidity. This study was designed to evaluate this question. All adult patients who received an OLTx between July 1985 and March 1993 (n = 497) were evaluated by retrospective chart review for evidence of PTDM after OLTx. The patients identified with PTDM (n = 26) were case matched with nondiabetic OLTx recipients based on primary liver disease diagnosis, age, gender, date of first OLTx, and survival. Liver synthetic function, number and severity of rejection episodes, graft survival, total number of hospital days within the first year post-OLTx, renal function, and number and type of infection episodes were analyzed to assess differences in morbidity between the PTDM and control patients after OLTx. Of the 497 adult patients who underwent OLTx, 26 (5.2%) were identified as having PTDM within 1 month of discharge. Factors which identified individuals at higher risk for DM after OLTx included higher pre-OLTx fasting blood glucose (P = .04); lower body mass index after OLTx (P = .02); and cyclosporine rather than OKT3 induction (P = .009). Graft survival, synthetic function, and the total number of rejection episodes during the first year were not different between the two groups. The morbidity variables of total number of days in the hospital during the first 12 months, renal function, and type and number of infections were also similar between the two groups. In summary, 5.2% of adult patients developed DM within 1 month of OLTx. Pre-existing insulin resistance, postoperative stress, and immunosuppression medications all likely contribute to the development of overt hyperglycemia after OLTx. Although PTDM can be a consequence of OLTx, it does not have a significant impact on patient outcome in the first year after OLTx.

Combined liver/small bowel transplantation using a blood group compatible but nonidentical donor

A successful liver/small intestinal transplantation with a blood group O donor to a blood type A recipient is described. Mild graft versus host disease developed, manifested by hemolysis, but did not result in graft loss or patient mortality. This suggests that minor ABO incompatibility may be tolerated with intestinal transplantation, despite the transplantation of large amounts of lymphoid tissue.

Preliminary experience with intestinal transplantation in infants and children

OBJECTIVE

This report discusses the preliminary experience with intestinal transplantation in children at the University of Nebraska Medical Center.

PATIENTS

During the past 4 years, 16 intestinal transplants have been performed in infants and children. Thirteen have been combined liver and bowel transplants, and the reminder were isolated intestinal transplants. Nearly half of the patients were younger than 1 year of age at the time of surgery, and the vast majority were younger than 5 years of age. All but one had short bowel syndrome.

RESULTS

The 1-year actuarial patient and graft survival rates for recipients of liver and small bowel transplants were 76% and 61%, respectively. Eight of 13 patients who received liver and small bowel transplants remain alive at the time of this writing, with a mean length of follow-up of 263 (range, 7 to 1223) days. Six patients are currently free of total parenteral nutrition. All three patients receiving isolated intestinal transplants are alive and free of parenteral nutrition. The mean length of follow-up is 384 (range, 330 to 450) days. Major complications have included severe infections and rejection. Lymphoproliferative disease, graft-versus-host disease, and chylous ascites have not been major problems.

CONCLUSIONS

Although intestinal transplantation is in its infancy, these preliminary results suggest combined liver and bowel transplants and isolated intestinal transplantation may be viable options for some patients with intestinal failure caused by short bowel syndrome or other gastrointestinal disease in whom long-term total parenteral nutrition is not an attractive option.

Low incidence of intraspousal transmission of hepatitis C virus after liver transplantation

Although the incidence of spousal transmission of hepatitis C virus (HCV) in chronic carriers is extremely low (1.4% to 8%), hepatitis C recurrence after liver transplantation is common with markedly increased serum HCV RNA levels. Thus, partners of these patients may be at higher risk of acquiring infection. This study evaluates the prevalence of spousal transmission of hepatitis C after liver transplantation. Twenty-two of 25 couples who were eligible agreed to the retrospective study. Twenty-two patients (17 males, 5 females) and spouses (5 males, 17 females) were studied with respective mean ages of 50.2 years (35 to 65 years) and 46.9 years (33 to 66 years). Liver enzymes, second-generation enzyme-linked immunosorbent assay (ELISA) for antibody to HCV (anti-HCV) and HCV RNA by polymerase chain reaction (PCR), and branched DNA assay were performed. HCV-associated antibodies were detected in 1 of 22 (5%) spouses and 21 of 22 (95%) patients (P < .0001). Nineteen of 22 (86%) patients tested positive by PCR with a mean value of 16,218,100 Eq/mL (464,700 to 51,980,000). All spouses including the only ELISA anti-HCV positive spouse tested negative by PCR (P < .0001). Eight of 21 spouses tested negative for anti-HCV pretransplantation, (13 of 21 pretransplantation were not tested). Estimated mean duration of hepatitis C infection in patients was 14 years (3 to 40 years). Mean patient follow-up posttransplantation was 654.5 days (141 to 1,959 days). Mean duration of marriage was 22.6 years (2.5 to 46 years). No risk factors other than exposure to index patients were observed in spouses. The incidence of spousal transmission of HCV in liver transplantation remains low (5%) and similar to chronic carriers of HCV.

Procurement and preparation of human isolated small intestinal grafts for transplantation

We have developed a donor operation that incorporates en bloc removal of the liver and intestine with a limited surgical resection in vivo. Over the past 18 months, we have used the following technique for the retrieval and preparation of seven isolated small intestinal allografts. The donor operation and bench preparation can be divided into three phases. During the first phase, the small intestine is removed with the liver, pancreas, and an aortic segment. In the second phase performed ex vivo, the donor liver can be separated from the specimen. The third phase involves additional bench dissection to yield an isolated intestinal allograft. The principle advantage of this technique is that it reduces potential liver injury by minimizing the surgical dissection required in vivo. Also, dividing the liver from the intestine ex vivo allows the organs to be separated in a bloodless field under controlled conditions that may be especially important when two different surgical teams are involved.

Proton spectroscopy of brain glutamine in acute liver failure

Evidence indicates that the accumulation of glutamine in the brain plays an important role in the pathogenesis and severity of the encephalopathy of acute liver failure (ALF). This study uses in vivo proton magnetic resonance spectroscopy (1H MRS) to assess brain glutamine (GLN) in five cases of acute liver failure. The findings are consistent with prior investigations and suggest that the alpha 1H of the GLN molecule can be used for noninvasive spectroscopic quantitation of brain GLN in patients with ALF.

Conditional immortalization of Gunn rat hepatocytes: an ex vivo model for evaluating methods for bilirubin-UDP-glucuronosyltransferase gene transfer

Viral vectors and protein carriers utilizing asialoglycoprotein receptor (ASGR)-mediated endocytosis are being developed to transfer genes for the correction of bilirubin-UDP-glucuronosyltransferase (bilirubin-UGT) deficiency. Ex vivo evaluation of these gene transfer vectors would be facilitated by a cell system that lacks bilirubin-UGT, but expresses differentiated liver functions, including ASGR. We immortalized primary Gunn rat hepatocytes by transduction with a recombinant Moloney murine leukemia virus expressing a thermolabile mutant SV40 large T antigen (tsA58). At 33 degrees C, the immortalized hepatocyte clones expressed SV40 large T antigen, synthesized DNA, and doubled in number every 2 to 3 days. At this temperature, differentiated hepatocyte markers, e.g., albumin, ASGR, and androsterone-UGT, were expressed at 5% to 10% of the levels found in primary hepatocytes maintained in culture for 24 hours. Glutathione-S-transferase Yp (GST-Yp), an oncofetal protein, was expressed in these cells at 33 degrees C, but was undetectable in primary hepatocytes. In contrast, when the cells were cultured at 39 degrees C or 37 degrees C, the large T antigen was degraded, DNA synthesis and cell growth stopped, and morphologic characteristics of differentiated hepatocytes were observed. The expression of albumin, ASGR, and androsterone-UGT, and their corresponding mRNAs, increased to 25% to 40% of the level in primary hepatocytes, whereas GST-Yp expression decreased. Functionality of ASGR was demonstrated by internalization of Texas red-labeled asialoorosomucoid, and binding and degradation of 125I-asialoorosomucoid. After liposome-mediated transfer of a plasmid containing the coding region of human bilirubin-UGT1, driven by the SV40 large T promoter, active human bilirubin-UGT1 was expressed in these cells. The immortalized cells were not tumorigenic after transplantation into severe combined immunodeficiency mice. These conditionally immortalized cells will be useful for ex vivo evaluation of bilirubin-UGT gene transfer vectors.

Aplastic anemia after liver transplantation for fulminant liver failure

We determined the incidence and outcome of aplastic anemia among 56 patients who underwent liver transplantation for fulminant liver failure at the University of Nebraska Medical Center between July 1985 and December 1993. Aplastic anemia developed in 6 of 18 (33%) children and 1 of 19 (5%) adults who had fulminant non-A, non-B hepatitis; no cases of aplastic anemia occurred among patients with other causes of fulminant liver failure. None of these patients had evidence of a preexisting hematological disorder or infection with hepatitis C virus (as determined with a second-generation ELISA). Aplastic anemia was diagnosed at a median of 4 wk after the onset of hepatitis, with five cases seen before transplantation. Six patients received antithymocyte globulin to promote remission of aplastic anemia. Three children died (fungal infection in two, intracranial hemorrhage in one)--one at 43, one at 108 and one at 119 days after transplantation--without remission of aplastic anemia. Among the four surviving patients, with median follow-up of 25 mo, complete and partial remission of aplastic anemia have occurred in three and one, respectively. Liver allograft function is stable in all surviving patients. The data demonstrate that aplastic anemia is a common complication among children who undergo liver transplantation for fulminant non-A, non-B hepatitis. It is associated with a high rate of mortality, although most survivors appear to have full hematological recovery.

Transfusion-induced graft-versus-host disease after liver transplantation. Documentation using polymerase chain reaction with HLA-DR sequence-specific primers

Graft-versus-host disease (GVHD) occurring after liver transplantation can pose a difficult diagnostic dilemma. Similar clinical and pathologic skin and gastrointestinal manifestations can result from other causes (i.e., drugs, infections). Treatment for each of these entities differs, and the high mortality associated with GVHD makes this distinction critical. GVHD has been assumed to result from the cotransplantation of donor lymphoid tissue along with the allograft. In most instances, the patient also receives blood products during the operation, and occasionally during the postoperative period, and the lymphoid cells in these products are also a potential source of concern. In this report, we describe a patient who developed GVHD after liver transplantation. Using molecular diagnostic techniques, we determined that the source for this GVHD was not the organ donor, but was most likely nonirradiated blood products received during the hospital course. Our results suggest that transplant recipients with concomitant hematopoietic dysfunction would benefit from irradiated blood products to reduce the likelihood of this complication.