Whole-organ Transplantation Research Articles

Sharing of split livers between centers is easily feasible

HE splitting of donor organs allows increasing overall organ availability in liver transplantation. In our own experience we have systematically applied split-liver transplantation (SLTX) in our program since 1994. More than 100 split organs have been transplanted at our institution thus far, with a patient and graft survival comparable to that of whole-organ transplantation. If no suitable recipients for both grafts were available on our list or when a graft for a high-urgency recipient was procured, we actively sought the sharing of such grafts with other centers. The purpose of the present study was to evaluate the outcome of those grafts transplanted at other centers and to determine the satisfaction of the transplant surgeons who shared these organs with us.

Split liver transplantation.

This study reviews the indications, technical aspects, and experience with ex vivo and in situ split liver transplantation. The shortage of cadaveric donor livers is the most significant factor inhibiting further application of liver transplantation for patients with end-stage liver disease. Pediatric recipients, although they represent only 15% to 20% of the liver transplant registrants, suffer the greatest from the scarcity of size-matched cadaveric organs. Split liver transplantation provides an ideal means to expand the donor pool for both children and adults. This review describes the evolution of split liver transplantation from reduced liver transplantation and living-related liver transplantation. The two types of split liver transplantation, ex vivo and in situ, are compared and contrasted, including the technique, selection of patients for each procedure, and the most current results. Ex vivo splitting of the liver is performed on the bench after removal from the cadaver. It is usually divided into two grafts: segments 2 and 3 for children, and segments 4 to 8 for adults. Since 1990, 349 ex vivo grafts have been reported. Until recently, graft and patient survival rates have been lower and postoperative complication rates higher in ex vivo split grafts than in whole organ cadaveric transplantation. Further, the use of ex vivo split grafts has been relegated to the elective adult patient because of the high incidence of graft dysfunction (right graft) when placed in an emergent patient. Reasons for the poor function of ex vivo splits except in elective patients have focused on graft damage due to prolonged cold ischemia times and rewarming during the long benching procedure. In situ liver splitting is accomplished in a manner identical to the living donor procurement. This technique for liver splitting results in the same graft types as in the ex vivo technique. However, graft and patient survival rates reported for in situ split livers have exceeded 85% and 90%, respectively, with a lower incidence of postoperative complications, including biliary and reoperation for bleeding. These improved results have also been observed in the urgent patient. Splitting of the cadaveric liver expands the donor pool of organs and may eliminate the need for living-related donation for children. Recent experience with the ex vivo technique, if applied to elective patients, results in patient and graft survival rates comparable to whole-organ transplantation, although postoperative complication rates are higher. In situ splitting provides two grafts of optimal quality that can be applied to the entire spectrum of transplant recipients: it is the method of choice for expanding the cadaver liver donor pool.

Infectious pulmonary disease in patients receiving immunosuppressive therapy for organ transplantation

Infectious pulmonary disease in patients receiving immunosuppressive therapy for organ transplantation

Microchimerism and graft tolerance: cause or effect?

Increasing survival of patients after organ transplantation has highlighted the serious side-effects of the life-long immunosuppressive therapy that these patients take to prevent graft rejection. These complications include opportunistic infection and an increased incidence of malignancy as a consequence of immunosuppression as well as direct drug toxicity, particularly nephrotoxicity and hypertension with cyclosporin and tacrolimus. These problems have stimulated a re-evaluation of the ability of transplants to be tolerated in some recipients without the need for long-term immunosuppression. Donor-specific acceptance of transplants can be demonstrated in some animal models, and survival of patients who had stopped immunosuppressive therapy without graft rejection led to the suggestion that tolerance develops in some human graft recipients. 1 Starzl TE Demetris AJ Trucco M et al. Cell migration and chimerism after whole-organ transplantation: the basis of graft acceptance. Hepatology. 1993; 17: 1127-1152 Crossref PubMed Scopus (662) Google Scholar The mechanisms underlying tolerance to the donor organ are obviously of great importance for the development of new therapeutic approaches aimed at establishing stable tolerance in human transplant recipients. The achievement of such a tolerant state would allow patients to be transplanted without the need for long-term immunosuppression. Microchimerism and rejection in clinical transplantationThese data suggest that a significant percentage of the recipients had persistent donor class II DNA in the peripheral circulation for at least 1 year after transplantation. We showed that a pretransplant blood sample is critical to avoid a false-positive result, and suggest that detectable chimerism may vary over time in individual patients. Therefore, analysis of microchimerism with a single, post-transplant analysis may not help in making clinical decisions for individual patients. Full-Text PDF

Techniques for intrasplenic hepatocyte transplantation in the large animal model.

The preferred therapy for acute and chronic liver insufficiency and severe heritable disorders of liver metabolism is whole-organ transplantation. However, due to the shortage of organ donors and high cost, alternative therapeutic approaches have been proposed, including transplantation of normal allogeneic hepatocytes. Recently, it has been reported that many hepatocytes transplanted into the spleen migrated to the liver. We therefore carried out a series of large-animal experiments to reexamine the intrasplenic route and to develop a method for large-scale hepatocellular transplantation in pigs. Allogeneic porcine hepatocytes were transplanted using the following routes: (1) retrograde injection of cells via the splenic vein, (2) intraarterial injection of cells, (3) direct intrasplenic injection of cells after laparotomy, (4) percutaneous intrasplenic injection of cells under laparoscopic control, (5) laparoscopic intrasplenic injection of cells. The number of cells injected varied from 2 x 10(9) to 10 x 10(9) cells. Of all the methods tested, only direct intrasplenic injection of 2 bln of cells was found to be compatible with survival. However, even with this "small" number of cells (2% original liver mass), there was a significant risk of spleen infarction, perisplenic adhesion formation, and portal vein thrombosis. The laparoscopic approach was found to be reliable, simple, and safe. Even though the spleen is considered by many authors the optimal site for hepatocellular transplantation, transplantation of cells in a number needed to support the failing liver may be associated with significant complications, morbidity, and mortality.

The politics of grafting cadaver kidneys

The politics of grafting cadaver kidneys

Variable chimerism, graft-versus-host disease, and tolerance after different kinds of cell and whole organ transplantation from Lewis to brown Norway rats.

The bidirectional paradigm of tolerance involving reciprocal host vs. graft and graft vs. host reactions was examined after Lewis (LEW)-->Brown Norway (BN) transplantation of different whole organs (liver, intestine, heart, and kidney) or of 2.5 x 10(8) LEW leukocytes obtained from bone marrow, spleen, lymph nodes, and thymus. The experiments were performed without immunosuppression or under 14 daily doses of postoperative tacrolimus, which were continued in weekly doses to 100 days in a "continuous treatment" subgroup, and to 27 days in a short treatment group. Without immunosuppression, all organs and cell suspensions failed to engraft or were acutely rejected. GVHD (usually fatal) was always caused when either the long or short treatment was used for recipients of intestinal grafts and cell suspensions of spleen and lymph nodes. In contrast, both immunosuppressive protocols allowed engraftment of bone marrow cells, liver, heart, and kidney without clinical GVHD, whereas thymus cell suspensions and small doses of whole blood neither engrafted nor caused GVHD. At 100 days, now drug-free for 73 days, the liver, bone marrow, and heart recipients were tolerant in that they accepted all challenge LEW heart and/or liver grafts for 100 more days despite in vitro evidence of donor-specific reactivity (split tolerance). At 200 days, histopathologic studies of the challenge livers were normal no matter what the priming graft. However, the still-beating challenge hearts had a spectrum from normal to severe chronic rejection that defined the tolerogenicity of the original primary grafts: liver best-->bone marrow next-->heart least. Both the GVHD propensity and tolerogenicity in these experiments were closely associated with recipient tissue chimerism 30 and 100 days after the experiments began. The tissue chimerism was invariably multilineage, but the GVHD outcome was associated with T cell over-representation. These observations provide guidelines that should be considered in devising leukocyte augmentation protocols for human whole organ recipients. The results are discussed in relation to the historical tolerance studies of Billingham, Brent, and Medawar; Good; Monaco; and Calne.

Islet transplantation

Since the first appreciation of the role of the pancreas in diabetes, investigators have tried to replace the function of the insulin-producing β cells. Because type I diabetes is caused by autoimmune destruction of these β cells, transplanting islets is attractive, although somewhat elusive. Rodent islet transplants were performed in the 1970s, but the application to humans required many advances that spanned a decade. Even after the methods for the automated large-scale isolation of the number and quality of cells required for human investigation were available, it was not until 1990 that the first successful human islet allografts were reported. Human islet autografts were increasingly successful during this period, giving hope for successes with allografts. Long-term results of euglycemia with islet autografts and allografts have now established the feasibility of islet transplantation in humans. Although there are many clear advantages to cellular transplants compared with whole-organ transplants, the success rate is currently unacceptably low because of rejection. Recent developments in the field of organ acceptance and tolerance and the successful use of barrier devices in large animals and recently in humans to protect islet grafts provide real hope that more widespread application of islet transplantation in healthy patients may be possible.

The spectrum of bile duct complications in pediatric liver transplantation

It has been noted that reduced-size liver transplants are associated with increased rates of biliary complications, and it has been suggested that some of these complications can be handled nonoperatively. In a 6-year period, 91 orthotopic liver transplants were performed in 77 children. The medical records were reviewed to analyze the effect of reduced-size grafts on the incidence of bile duct complications and to investigate the utility of interventional radiology techniques for treatment. Forty-two children received 47 whole-organ transplants, and 35 children received 44 reduced-size transplants. The median age and weight were greater for children receiving whole-organ transplants (age, 4.25 years; weight, 16 kg) than for those receiving reduced-size grafts (age, 1.0 year; weight, 8 kg). The overall incidence of bile duct complications was 19.5% (n = 15). The incidence was not different between the whole organ group (17%) and the reduced-size group (16%). Four of the children with bile duct complications had associated hepatic artery thrombosis, two of whom had another transplant. Complications included anastomotic stricture (n = 6), anastomotic leak (n = 5), intraparenchymal biloma (n = 3), and multiple strictures (n = 1). Twelve of 15 children presented within 3 months of transplantation. Six children had initial percutaneous drainage or placement of transanastomotic stents (external). Operative repair was eventually required for all 15 children, three of whom received a second transplant. There was a 40% incidence of cytomegalovirus infection involving the liver or extrahepatic bile ducts near the time of presentation. There were two deaths among the 15 children; only one was a direct result of the bile duct complication. Neither the rate nor type of bile duct complication differs between the whole-organ and the reduced-size group. Nonoperative therapy was uniformly unsuccessful. Percutaneous approaches allowed for clinical improvement before operative intervention.

Cell migration and chimerism after whole-organ transplantation: The basis of graft acceptance

Improvements in the prevention or control of rejection of the kidney and liver have been largely interchangeable (1, 2) and then applicable, with very little modification, to thoracic and other organs. However, the mechanism by which anti rejection treatment permits any of these grafts to be “accepted” has been an immunological enigma (3, 4). We have proposed recently that the exchange of migratory leukocytes between the transplant and the recipient with consequent long-term cellular chimerism in both is the basis for acceptance of all whole-organ allografts and xenografts (5). Although such chimerism was demonstrated only a few months ago, the observations have increased our insight into transplantation immunology and have encouraged the development of alternative therapeutic strategies (6).

Cell migration and chimerism after whole-organ transplantation: The basis of graft acceptance

Cell migration and chimerism after whole-organ transplantation: The basis of graft acceptance

DUODENAL MUCOSAL pH AS A REPERFUSION INDICATOR IN PANCREATIC-DUODENAL TRANSPLANTATION IN THE PIG

We have studied differences in reperfusion between the pancreas and the duodenum after 6 hr of cold storage in a porcine whole-organ pancreaticoduodenal allograft transplantation model. Two different flush-out and storage solutions, Perfadex and EuroCollins, were compared. Graft duodenal mucosal pH (pHi) was measured as an indicator of duodenal mucosal reperfusion. Pancreatic reperfusion was estimated indirectly using a ratio between the release of immunoreactive cationic trypsin (irCT) to serum 10 and 60 min following reperfusion. Twelve pigs (Perfadex n = 6, EuroCollins n = 6) were transplanted and all showed preserved endocrine and exocrine function postoperatively. Our data support the concept that reperfusion of a pancreaticoduodenal graft can be estimated using duodenal pHi and that the ratio of irCT at 10 and 60 min gives an indirect estimate of pancreatic reperfusion. The results also show that grafts stored in EuroCollins reperfuse more slowly than grafts stored in Perfadex.

Fetal pancreatic transplantation

S ince the first pancreas transplantation was performed in 1966 it has been repeatedly demonstrated that by transplanting most or all of the pancreas as a vascularized organ to patients with insulin-dependent diabetes mellitus (IDD~l), norrnoglycemia is achieved without the need for insulin injections. The procedure has become more frequent in recent years and success rates have been markedly improved," However, there arc three major problems that remain: (1) results with a pancreas transplantation that has not been combined with previous or simultaneous kidney transplantation have, in most studies, been discouraging and therefore the treatment can not be offered until late complications (ie, renal failure) have already occurred; (2) it is difficult to foresee that recipients ofvascularized organ grafts will not have to commit to a life-long regimen of immunosupprcssives; (3) because the primary objective of transplanting endocrine pancreatic tissue is to achieve insulin independency sufficiently carl}' in the course of the disease for prevention oflate complications, most patients with IDD~1should be candidates for this kind of therapy and, taking this into account, there \\;11 be a considerable donor organ shortage. It should also be kept in mind that, because the whole-organ procedure per se is not lifesaving, it has become a much debated procedure and is questioned by many diabctologists.' Concurrent with the development of the wholeorgan transplantation technique as an alternative approach, islet cell transplantation has been pursued. The idea of replacing only the desired endo-

Initiation of Rejection of Established Islet Allografts by Third-Party Thyroid Allografts and Splenic Dendritic Cells

Due to concerns of cross-reactivity between renal and islet allografts in initiation of rejection, we determined the ability of donor-specific and third-party splenic dendritic cells (DCs) and thyroids (whole-organ transplant) to initiate rejection of established islet allografts. Purified islets from neonatal F-344 (RT1Lv1) rats were transplanted bilaterally under the kidney capsule of Wistar-Furth (W/F, RT1u) rats without immunosuppression. The islet allografts were not rejected by 21 days posttransplantation. On day 22, freshly isolated or cultured DCs were injected intraperitoneally into the host. Both freshly isolated and cultured donor-specific (F-344) and some third-party (Buffalo, RT1b; ACI, RT1a) DCs initiated rejection of the islets as indicated by lymphocyte infiltration and destruction of the allograft. DCs, whether freshly isolated or cultured for 8 days from the recipient strain (W/F) and one third-party rat (Brown Norway, RT1n), did not initiate rejection. Splenic DCs from the Lewis (RT1l) rat, which has the same class I and II antigen haplotype as F-344 islet donor rats, also initiated rejection. Only 10(3)-10(4) DCs isolated from the spleen of donor rats were required to initiate rejection of the allograft. In a parallel series of W/F rats with islet allografts, a thyroid (half lobe) from the islet donor strain (F-344), recipient strain (W/F), or third-party rat (Buffalo, Brown Norway, or ACI) was inserted under the kidney capsule at 22 days post-islet transplantation. At 35 days, all thyroids and most islet allografts exhibited active or complete rejection after thyroid transplant from Buffalo, F-344, or ACI rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Transplantation of fetal cells

Cellular transplantation is an attractive alternative to whole-organ transplantation when only a discrete function of the organ is deficient. Early fetal donor cells have an advantage because they engraft readily and do not cause graft-versus-host disease. Similarly, the fetus is an ideal recipient of allogeneic fetal cells as it is incapable of rejecting them early in gestation. This review presents the theoretical rationale, recent research advances, and clinical implications for adults with diabetes mellitus and Parkinson's disease; we also describe in utero transplantation of fetal hematopoietic stem cells and hepatocytes for the treatment of inherited hematologic and hepatic deficiencies, as well as the use of fetal islet cells and dopamine-producing cells to treat postnatal conditions.

Early experience with reduced-size liver transplants

Scarcity of small donors results in a high mortality rate for children on liver transplant waiting lists. To alleviate this problem, we have recently started to reduce the size of livers from older donors to use in children. In the last year, a total of 20 liver transplants were performed in 17 patients, including seven reduced-size liver transplants (RSLT) in six children. Mortality on the waiting list has been reduced to negligible amounts compared with a mortality rate of 25% before starting RSLT in patients with acute liver failure or those whose weght was less than 10 kg. Children undergoing RSLT weighed 10.8 ± 8.5 kg compared with 20.9 ± 20.3 for all others (NS). Cold ischemia time was significantly longer in the RSLT group (9.5 ± 3.0 v 6.0 ± 2.8 hours, P < .05) as was intraoperative blood loss (9.4 ± 9.4 v 3.0 ± 3.5 blood volumes). There was no significant difference in postoperative aspartate aminotransferase and prothrombin time between the two groups. Four children received a RSLT as a primary procedure and three have survived with good liver function. Two patients were retransplanted with RSLT after a failed first transplant and both died of nonhepatic complications. This compares with 11 of 13 survivors in the whole liver transplant group. Causes of death in children who died after RSLT include cytomegalovirus sepsis (2) and myocardial infarction (1). We conclude that RSLT significantly decreases mortality on the waiting list of children with biliary atresia and fulminant hepatic failure and that the results when RSLT is used as a primary procedure are comparable to those obtained after whole-organ transplantation. Liver function after RSLT was satisfactory in all cases and no deaths were due to complications of the procedure itself. The results suggest that RSLT should be used not only as a salvage procedure for patients in critical care settings, but that the indications for this procedure should be expanded to include all children waiting for transplantation at home or in hospital.

Pancreas and islet-cell transplantation

In the past two decades, results of whole-organ pancreas transplantation have improved considerably. Patient survival rates of 95% to 100% and graft success rates of more than 70% at 1 year have been reported. After successful transplantation, exogenous insulin can be discontinued and the patient's quality of life improved. In the field of islet-cell transplantation, remarkable progress has been made in isolation techniques. However, the problem of rejection without serious sequelae remains. Immunoisolation of islet cells in microcapsules offers an exciting solution, but research is still in preliminary stages. Early results in large animal models are extremely encouraging.

PROLONGED SURVIVAL OF MURINE THYROID ALLOGRAFTS AFTER 7 DAYS OF HYPERBARIC ORGAN CULTURE IN THE UW PRESERVATION SOLUTION AT HYPOTHERMIA

Organ culture of murine thyroid allografts in hyperbaric oxygen (95% O2 at 25 psi, 37 degrees C) for 48 hr, results in prolonged allograft survival. Endocrine tissues can be cultured at 37 degrees C--however, this method may not be applicable to vascularized organs at normothermia. The aim of this study was to apply hyperbaric oxygen culture (HOC) under organ preservation conditions (hypothermia, UW solution) that have been shown to be successful in clinical organ transplantation. B10BR/SGSNJ murine thyroid lobes were transplanted beneath the kidney capsule of C57BL/10J recipients. Thyroids were cultured in Eagle's MEM at 37 degrees C (controls) and at 5 degrees C, under hyperbaric conditions (95% O2:5% CO2, 25 psi). Alternatively, thyroids were cultured in UW solution (+/- allopurinol/GSH) at 5 degrees C, for up to 7 days. Graft survival was determined 21 days posttransplant by 125I uptake and by histology. In Eagle's MEM, HOC at 37 degrees C/48 hr and 5 degrees C/7 days, resulted in 93% and 20% allograft survivals, respectively. In UW solution (- allopurinol/glutathione [GSH]), HOC at 5 degrees C/7 days resulted in 83% allograft survival: immunoperoxidase staining showed a decrease of MHC class I alloantigen expression. Oxygen free radical scavenger (allopurinol/GSH) addition to the UW solution diminished this effect and suggested an oxygen free radical-mediated mechanism in immunoalteration. These results demonstrate that HOC for 7 days reduced the antigenicity and immunogenicity of murine thyroid grafts under conditions that simulate organ preservation. Hypothermic hyperbaric oxygen culture conditions require testing in a higher animal species and in vascularized grafts to determine if this method can be applied to whole-organ transplantation.

PANCREATIC ENZYMES IN SERUM AND URINE AS INDICATORS OF PANCREATIC ALLOGRAFT REJECTION IN THE PIG

We have studied the reliability of serum and urinary immunoreactive anionic trypsin (irAT), immunoreactive cationic trypsin (irCT), and amylase activity as rejection indicators in a porcine whole-organ pancreaticoduodenal transplantation model with exocrine drainage to the urinary bladder. No immunosuppressive therapy was administered. Exocrine tissue integrity and function were studied by measuring these enzymes in serum and urine. Urine analyses were performed before and after an intravenous secretin-cholecystokinin stimulation. Of 16 transplanted pigs, 10 became diabetic during a 2-week observation period while six remained normoglycemic. Serum irAT was found to predict rejection while serum amylase and serum irCT did not. An increase in irAT was seen in rejecting pigs preceding the onset of hyperglycemia by a median of 2 days (range 1-9). Secretion of irAT into the urine remained high during the observation period in nondiabetic pigs while the output declined in diabetic pigs. This decline was seen after the increase in serum irAT. When urine was sampled after a secretin-CCK stimulation, these findings were clearly evident, but less unequivocal results were obtained without stimulation. IrAT measurements were superior to measurements of amylase, irCT, or bicarbonate. Thus rejection of a pancreatic allograft was first indicated by a temporary rise in serum immunoreactive anionic trypsin, probably due to the onset of tissue damage. Thereafter, stimulated urinary enzyme output levels gradually declined and finally, hyperglycemia developed.

Canine pancreaticoduodenal autotransplantation: a preparation for human pancreatic transplantation.

This canine pancreaticodunodenal autotransplantation model includes virtually the entire pancreas attached to a duodenal cuff (second portion). The blood supply is based on the superior pancreaticoduodenal artery and the venous outflow on the gastroduodenal vein. The vascular anastomoses are end-to-side to the external iliac artery and vein. Exocrine drainage is channeled through the bladder from the transplanted duodenum. This technique closely resembles whole-organ pancreas transplant in humans with a cystoduodenostomy. The bowel reconstruction consists of a Billroth I gastroduodenostomy and a cholecystoduodenostomy. The entire procedure is relatively free of major complications and may be performed in less than 4 hours.