Liver transplantation: perspectives after 250 liver transplants at the Ochsner Clinic

At the Ochsner Clinic we recently performed our 250th liver transplant. Reaching this milestone has led us to reflect back on the history of liver transplant, both at our own institution and nationally, noting the many achievements and improvements in liver transplantation during the relatively brief history of this therapeutic modality. Furthermore, there are a number of issues both medical and political which will likely be affecting how liver transplantation is performed in the future.

Two are better than one

On March 29, 1996, Marwan Abouljoud, MD, and Francisco Escobar III, MD, of Henry Ford Hospital, Detroit, performed the first split liver transplant in Michigan on two patients who were both dying from liver disease. At that time, fewer than 20 such procedures had been done nationwide.

Liver splitting and living donor techniques

Split liver transplantation (SLT) and living related transplantation (LRT) have been developed following advancements in liver surgery. In experienced hands they can yield results comparable to full organ liver transplantation. They are today a reality which has to be implemented and used more widely. LRT is the best procedure available and should be the method of choice despite the high success of SLT. Any method safely enlarging the pool of donors has to be utilized, especially in view of the possible future application for adults. The procedures should be initially performed and tested in centres specialized in liver transplantation and liver surgery, with the aim of making the techniques more widely available in the future. High ethical standards are required to perform LRT. In the short term, SLT and LRT are the methods more apt to increase the organ pool and thus decrease pre-transplant mortality both in children and adults.

Clinical trials and projected future of liver xenotransplantation

The trial and error of the pioneering xenotransplant trials over the past three decades has defined the limitation of the species used. Success was tantalizingly close with the chimpanzee, baboon, and other primates. The use of more disparate species has been frustrated by the xenoantibody barrier. Future attempts at clinical xenotransplantation will be hampered by the consideration of the species of animals and the nature of the organs to be transplanted. On one hand, primate donors have the advantage of genetic similarity (and therefore potential compatibility) and less risk of immunologic loss. On the other hand, pig donors are more easily raised, are not sentient animals, and may be less likely to harbor transmissible disease. It is recognized that the success of xenotransplantation may very with different organs. Because it is relatively resistant to antibody-mediated rejection, the liver is the organ for which there is the greatest chance of long-term success. Consideration of using xenotransplants on a temporary basis, or as a "bridge" to permanent human transplantation, may allow clinical trials utilizing hearts or kidney xenografts. Issues on metabolic compatibility and infection risks cannot be accurately determined until routine success in clinical xenotransplantation occurs. Based on a limited experience, the conventional approaches to allotransplantation are unlikely to be successful in xenotransplantation. The avoidance of immediate xenograft destruction by hyperacute rejection, achieved using transgenic animals bearing human complement regulatory proteins or modulating the antigenic target on the donor organ, is the first step to successful xenotransplantation. The ability to achieve tolerance by establishing a state of bone marrow chimerism is the key to overcoming the long-term immunologic insults and avoiding the necessarily high doses of nonspecific immunosuppression that would otherwise be required and associated with a high risk of infections complications. Xenotransplantation faces criticism that is strongly reminiscent of that leveled against human-to-human transplantation during the late 1960s and early 1970s. Yet with persistence, the field of human-to-human transplantation has proved highly successful. This success was the result of a stepwise increase in our understanding of the biology of rejection, improvements in drug management, and experience. It is possible that xenotransplantation may not be universally successful until further technologic advances occur; yet cautions exploration of xenotransplantation appears warranted to identify those areas that require further study.

Organ transplantation in Taiwan

We performed the first successful kidney transplantation in Taiwan on May 27, 1968. Since then, kidney, heart, lung, pancreas, liver, and heart-kidney transplantations have been increasingly successful in restoring lives of otherwise dying patients with organ failure. The first successful kidney, liver, and heart transplantations in Asia were achieved in Taiwan in 1968, 1984, and 1987. respectively. Individual organ transplantation, organ transplant recipient survival, graft survival, and problems and pitfalls encountered in the care of organ transplantation recipients are analyzed. Using polymerase chain reaction amplification with sequence-specific primers, donor-specific DNA was detected in the peripheral blood of the patient who survived the longest (26 years) in this series. Interestingly enough, recently, we had a patient undergoing cadaveric renal transplantation in whom chimerism was detected in her lymph nodes and skin only 3 years after transplantation. Organ procurement in Taiwan is the greatest problem, and we have been exerting our maximal effort to establish a transplantation coordination team to create a central network and to educate, procure, preserve, distribute, and increase the availability of organs and tissues for transplantation.

[Liver transplantation--present status]

Living related liver transplantation (LPLT) as well as reduced sized graft or split liver transplantation has come from the situation with donor shortage for conventional whole liver transplantation from brain dead donors (cadaveric liver transplantation; CLT). To date, about fifty thousands liver transplants have been undergone all over the world. CLT has much diversity of the original diseases, but mainly liver cirrhosis in adults and biliary atresia in children. Original diseases for LRLT have been deviated to cholestatic diseases in childhood, but now LRLT for adults and other diseases in children, i.e. fulminant hepatitis and metabolic disorders, are increasing. The survival rate of LRLT in Kyoto University for first 230 consecutive cases was 79.5%. The main cause of death was infection-related events. There are several problems in LRLT to be resolved; perioperative management of infectious complications, how to deal with the unavoidable ABO incompatible matching transplants, how to expand the national capacity of LRLT to respond the urgent transplantations. Earlier establishment of CLT program in Japan will be necessary to make the liver transplantation the beneficial procedure for more people with end stage liver diseases.

Prospects for xenotransplantation of the liver

Because of the tremendous success of clinical transplantation of the liver and other organs in the last three decades, the demand for organs for transplantation has risen sharply and there is now a substantial shortage. The utilization of organs from other species, xenotransplantation, is increasingly viewed as a potential solution to this problem. The major limitation to xenotransplantation is the formidable immunological barriers that prevent the successful transplantation of non-human organs into human recipients. Here we review current knowledge about the immunology of xenotransplantation and the limited clinical and experimental experience in xenotransplantation of the liver.

Decreased mortality from technical failure improves results in pediatric liver transplantation

BACKGROUND

Until recently, pediatric liver transplantation was associated with a high rate of technical failure, which contributed substantially to the overall prognosis.

OBJECTIVE

To assess the impact of technical failure on outcome in pediatric liver transplantation.

DESIGN AND SETTING

We retrospectively analyzed 90 pediatric transplant procedures in a university medical center.

PATIENTS

Between February 1988 and December 1995, 80 children ( < 15 years old) received 90 transplants. Fifty-three percent (n = 42) were less than 2 years of age, 45% (n = 36) had cholestatic liver disease, 26% (n = 21) had metabolic errors, and 11% (n = 9) had fulminant hepatitis.

INTERVENTION

Patients underwent grafting using previously reported techniques, including cadaveric whole (61% [n = 55]), reduced-size (17% [n = 15]), and living related (22% [n = 20]) liver transplantation.

MAIN OUTCOME MEASURES

Patient and graft survival and selected surgical complications. Outcomes were compared before (group 1) and after (group 2) the introduction of living related transplantation in July 1992.

RESULTS

In group 1, 32 patients received 36 grafts (4 retransplants [13%]), and in group 2, 48 patients received 54 grafts (6 retransplants [13%]). Six- and 12-month patient survival rates were 78% (n = 25) and 75% (n = 24), respectively, for group 1 and 98% (n = 47) and 94% (n = 45) for group 2. Of the 9 deaths in group 1, 6 occurred early as a consequence of surgical complications, while in group 2, all 5 deaths that occurred were caused by the consequences of immunosuppression (lymphoproliferative disease, n = 2; late infections, n = 3).

CONCLUSIONS

These results suggest that mortality caused by surgical complications has been reduced by improvement in management in recent years. Living related grafts have supplemented the graft supply and may be associated with the improved overall results. Despite these advances, children receiving transplants continue to experience the consequences of imperfect immunosuppression.

Liver transplantation in the United States: current problems and future goals

The status of liver transplantation in the United States as of 1994 is presented. The successes, new developments and problems associated with success are identified. Evolving new approaches to these problems are identified.

[Liver transplantation. Current aspects]

The development of liver transplantation has led to technical refinements such as liver graft reduction or splitting for transplantation in two recipients, the use of living related donors, and the temporary orthotopic transplantation of auxiliary liver grafts. Regarding immuno-suppression, new drugs are currently under evaluation, such as tacrolimus (FK 506) which could be effective on some severe rejections. On the other hand, the indications of liver transplantation have been revisited according to clinical results. In France, the increasing development of organ and tissue transplantation has led to the creation of the Etablissement Français des Greffes, which has the following missions: managing the waiting lists, supporting organ donation, ensuring sanitary safety, and evaluating transplantation activities. Future alternatives to allogenic liver transplantation are mainly represented by xenografting with monkey or pig livers, hepatic assistance and bioartificial liver, and gene therapy.

Recent findings concerning liver transplantation in the United States

CENTERS

The growth in liver transplantation activity recorded by the Pitt-UNOS Liver Transplant Registry since October 1987 continued. However, for the first time since the establishment of the LTR, there was no net gain in the number of centers in 1995. The large differences in volume per center also diminished.

PATIENTS

The age of pediatric recipients increased significantly in 1995, due to a decrease in the proportion of recipients under age one. For the first time, in 1995 fewer than half of transplantations in children were for biliary atresia. The addition of bone marrow transplantations, for which collection began in 1994, accounted for half of the multi-organ transplantations in 1995. Many of the characteristics examined for adult recipients changed between 1994 and 1995. The proportion of Hispanic recipients increased. The mean age of adult recipients continued to increase, but there was not a significant change in the prevalence of positive CMV serology. Reversing a trend, the proportion of adult recipients awaiting transplantation outside of the hospital decreased between 1994 and 1995. As with children, the proportion of adult multi-organ transplantations which included bone marrow increased. Hepatitis non-A, non-B, or C and alcoholic liver disease (ALD) were the most common reasons for LTX in 1995. While the proportion of recipients with ALD alone decreased slightly, the proportion with ALD and hepatitis C increased from 1994 to 1995.

OUTCOME

The cumulative probability of surviving (without retransplantation) for 8 years after initial transplantation was .71 (.60) for pediatric recipients. The one-year survival for pediatric recipients changed significantly over time with the increase from 1994 to 1995 being similar to the increase between 1994 and prior years. Independent risk factors for survival among children included age, race, location awaiting transplantation, primary liver disease, and serum creatinine. Year of transplantation and bilirubin were independently associated with retransplantation-free survival, whereas multi-organ transplantation was associated with poorer patient survival. The cumulative probability of adults surviving (without retransplantation) for 7 years following LTX was .58 (.50). Independent risk factors were year of transplantation, age, location awaiting transplantation, primary liver disease, albumin, creatinine, and ABO match. Black recipients had poorer patient survival rates than other recipients whereas increased prothrombin time and CMV-positive donors were risk factors for retransplantation or death.

Artificial liver. Evolution and future perspectives

Whole organ transplantation is the only clinically effective method of treating fulminant hepatic failure and chronic liver failure due to specific genetic, hepatocellular, and anatomic defects of liver function. However, wider application of liver transplantation is limited by shortage of organ donors, high cost, a relatively high morbidity rate, and need for life long immunotherapy. As a result, investigators have attempted to develop alternative methods to treat liver insufficiency. These ranged from use of plasma exchange to use of detoxification columns and extracorporeal devices loaded with various liver tissue preparations. Several liver support systems were developed in the 1950s and 1960s, but it was not until recently that advances in hepatocyte isolation and culture, improved understanding of hepatocyte-matrix interactions, availability of new biomaterials, improved hollow fiber technology, and better understanding of flow and mass transport across semipermeable membranes resulted in the development of a new generation of liver assist devices. Some of these devices are being tested in the clinical setting. In this article, the authors review past experience with liver support systems, critically examine the current status of the field by drawing primarily on their own experience, and attempt to speculate on the future direction of liver assist system development.

Liver transplantation. The last ten years

8960741 10 years have witnessed a number of changes in the liver transplant process. Key among these changes are the longer preservation times allowed with UW solution, the development of the new techniques for the transplantation of pediatric patients, and the reintroduction of xenotransplantation for both permanent and temporary hepatic support. Early referral and prompt transplant of patients are among the most important keys to successful transplantation. However, owing to the present organ allocation system and the lack of suitable organ donors, potential liver transplant recipients will continue to experience a significant mortality rate on the waiting list. In addition, owing to the long waiting times for suitable donor organs, many patients who would have been excellent low-risk candidates will deteriorate as their liver disease progresses and become high-risk patients for liver transplantation. Expanding the donor pool and modifying the present liver allocation system to shift the flow of organs to the better-risk patients will do more to improve the results of liver transplantation than any other change in the management and transplantation of patients with severe liver disease.

Changing indications in liver transplantation

During the last decade orthotopic liver transplantation has become virtually a routine procedure and most centres are reporting, in elective cases, survival rates at 1 year in excess of 90%. As experience with liver transplantation has grown, attention has focused more on refining the indications for transplantation and determining the optimal time for the procedure. In patients with fulminant hepatic failure, it may still be difficult to select those patients who require liver replacement early enough in their illness so that a suitable organ can be found and the procedure carried out before the onset of irreversible complications. Alternatives to orthotopic liver transplantation, including liver support, heterotopic transplantation, partial orthotopic liver transplantation and xenografting, are being assessed. Progress too has been made in improving indications in patients undergoing transplantation for viral hepatitis and alcoholic liver disease. Nonetheless, liver replacement remains a poor substitute for prevention of end-stage liver disease. Even with advances made in immunosuppression, there are long-term sequelae as a consequence of liver transplantation, and now more recently attention is being paid to reducing the toll of immunosuppressive drugs.

[Liver transplantation in children]

Liver transplantation has become the treatment of many chronic liver diseases, acute hepatic failure and several metabolic diseases in children. Early referral to a transplantation center represents the major condition for its favourable outcome, in order to undertake this complex surgical procedure under the best conditions and to allow a rapid and complete recovery. The increasing shortage of organs leading to graft reduction, graft splitting and living related donation, the feasibility of multiple organ transplantation, the progress of gene therapy, the development of new extra-corporeal liver assist devices and the introduction of the auxiliary partial orthotopic liver transplantation have all contributed to significative changes in the perspectives of pediatric liver transplantation. Furthermore, new immunosuppressors as well as encouraging experimental results on graft tolerance may help in the near future to improve the long-term quality of life of pediatric recipients.

[Liver transplantation]

Liver transplantation is performed in all the Nordic countries except Iceland. A Nordic action group with members from every centre draws up guidelines for organ exchange, treatment and research projects. The indications have been established, and results are steadily improving. The demand for organs is a manifest problem, particularly in acute cases where a new liver is required within a few days. After a successful transplantation, quality of life is comparable with that in the general population.