Intestinal transplantation in composite visceral grafts or alone

Study of morbidity in orthotopic small intestine transplantation with Wistar rats. Experimental study

BACKGROUND

Transplantation of the small intestine is a surgical procedure currently under investigation for its possible application in the treatment of patients with short bowel syndrome, aiming at the reintroduction of an oral diet.

AIM

To define the morbidity and mortality of intestinal transplantation in small animals using microsurgery. Intra and postoperative morbidity and mortality were studied in Wistar rats submitted to orthotopic intestinal allotransplantation.

MATERIAL AND METHOD

The animals were divided into three groups: group A (37 donor animals), group B (37 recipient animals), and group C (10 control animals). Group B was divided into three subgroups according to survival time. Subgroup TI consisted of animals that died during surgery or due to causes directly related to surgical intervention, subgroup T2 consisted of animals that died between the 4th and 29th postoperative day, and subgroup T3 consisted of animals that survived after 30 days. Transplanted animals were evaluated in terms of surgical technique used (vascular and intestinal anastomosis), graft quality, surgical time, and clinical parameters. The animals that died by the 29th postoperative day were submitted to autopsy and the remaining ones were sacrificed after 30 days.

RESULT

There was a high rate of complication of a surgical nature. Early mortality rate, i.e., mortality up to the third postoperative day, was 54% with vascular anastomosis being the major cause of death. Surgical time was evaluated in a restricted and homogeneous group and showed a strong prognostic value in terms of successful transplantation. Clinical parameters such as weight loss, reduction of ingestion, reduction of motor activity and diarrhea were directly correlated with acute rejection.

CONCLUSION

The experimented intestinal transplant is a procedure companied by considerable morbidity and mortality due to surgical complications in postoperative period, vascular anastomosis and total surgical time.

Serum citrulline and rejection in small bowel transplantation: a preliminary report

BACKGROUND

There is no known serum marker for intestinal rejection. Serum concentrations of the amino acid citrulline arise almost exclusively from the intestinal mucosa. We examined the impact of acute cellular rejection (ACR) of intestinal allografts on serum citrulline levels.

METHODS

Citrulline concentrations were assayed in serum samples of healthy volunteers (n=6) and seven patients who underwent small bowel transplants (SBTx). Trends in mean citrulline concentrations versus degree of ACR were assessed by matching posttransplantation citrulline concentrations with patients' grade of ACR at time of serum collection. Rejection was confirmed by biopsy and graded by following standardized criteria. An additional patient had citrulline concentrations determined for 31 sequential specimens 3-60 days posttransplant.

RESULTS

Mean citrulline concentrations in controls were significantly higher than posttransplantation samples at any rejection grade. Mean concentrations declined significantly as rejection severity increased. The overall downward trend was statistically significant (P<0.05). In sequential measurements, citrulline levels increased significantly over time with declining severity of rejection. The increase in mean citrulline concentration between posttransplant days 3-16 and 52-60 was significant (P<0.01).

CONCLUSIONS

Serum citrulline levels decline with increasing grade of ACR and may be a useful serum marker for intestinal rejection.

Clinical intestinal transplantation: a decade of experience at a single center

OBJECTIVE

To assess the long-term efficacy of intestinal transplantation under tacrolimus-based immunosuppression and the therapeutic benefit of newly developed adjunct immunosuppressants and management strategies.

SUMMARY BACKGROUND DATA

With the advent of tacrolimus in 1990, transplantation of the intestine began to emerge as therapy for intestinal failure. However, a high risk of rejection, with the consequent need for acute and chronic high-dose immunosuppression, has inhibited its widespread application.

METHODS

During an 11-year period, divided into two segments by a 1-year moratorium in 1994, 155 patients received 165 intestinal allografts under immunosuppression based on tacrolimus and prednisone: 65 intestine alone, 75 liver and intestine, and 25 multivisceral. For the transplantations since the moratorium (n = 99), an adjunct immunosuppressant (cyclophosphamide or daclizumab) was used for 74 transplantations, adjunct donor bone marrow was given in 39, and the intestine of 11 allografts was irradiated with a single dose of 750 cGy.

RESULTS

The actuarial survival rate for the total population was 75% at 1 year, 54% at 5 years, and 42% at 10 years. Recipients of liver plus intestine had the best long-term prognosis and the lowest risk of graft loss from rejection (P =.001). Since 1994, survival rates have improved. Techniques for early detection of Epstein-Barr and cytomegaloviral infections, bone marrow augmentation, the adjunct use of the interleukin-2 antagonist daclizumab, and most recently allograft irradiation may have contributed to the better results.

CONCLUSION

The survival rates after intestinal transplantation have cumulatively improved during the past decade. With the management strategies currently under evaluation, intestinal transplant procedures have the potential to become the standard of care for patients with end-stage intestinal failure.

Bacterial translocation in clinical intestinal transplantation

BACKGROUND

Bacterial translocation (BT) has been suggested to be responsible for the high incidence of infections occurring after small bowel transplantation (SBTx). Bacterial overgrowth, alteration of the mucosal barrier function as a consequence of preservation injury or acute rejection (AR), and potent immunosuppression are all associated with BT. The aim of this study was to evaluate and quantify the correlation of BT with these events.

METHODS

Fifty pediatric SBTx recipients on tacrolimus and prednisone immunosuppression were analyzed. Blood, stool, and liver biopsies and peritoneal fluid were cultured (circa 4000 total specimens) when infection was clinically suspected or as part of follow-up. BT episodes were considered when microorganisms were found simultaneously in blood or liver biopsy and stool.

RESULTS

BT (average of 2.0 episodes/patient) was evident in 44% of patients and was most frequently caused by Enterococcus, Staphylococcus, Enterobacter, and Klebsiella. The presence of a colon allograft was associated with a higher rate of BT (75% vs. 33.3%). Furthermore, the transplantation procedure (colon vs. no colon) affected the rate of BT: SBTx=40% vs. 25%, combined liver and SBTx=100% vs. 30%, multivisceral transplantation=25% vs. 50%. AR was associated with 39% of BT episodes. BT followed AR in 9.6% of the cases. In 5.2% of the cases, positive blood cultures without stool confirmation of the bacteria were seen. Prolonged cold ischemia time (CIT) affected BT rate significantly (CIT>9 hr 76% vs. CIT<9 hr 20.8%).

CONCLUSIONS

This study shows that 1) a substantial percentage of, but not all, BT is associated with AR, 2) the presence of a colon allograft increases the risk for BT, and 3) a long CIT is associated with a high incidence of BT after SBTx.

Intestinal transplantation for the treatment of desmoid tumors associated with familial adenomatous polyposis

BACKGROUND

Desmoid tumors associated with familial adenomatous polyposis (FAP) are locally invasive. Often occurring in the mesentery of the intestine, they sometimes recur after resection. Complications can include intestinal failure and dependence on parenteral nutrition. We describe 9 patients who underwent intestinal transplantation for the treatment of desmoid tumors associated with FAP.

METHODS

Records of patients undergoing intestinal transplantation for desmoid tumors at 2 transplant centers were reviewed for patient age, sex, type of graft, procedure date, tumor site, desmoid complications, medications, extracolonic manifestations, status at follow-up, and length of survival.

RESULTS

Nine patients with FAP and intestinal failure caused by desmoid tumors were treated with isolated intestinal (n = 6), multivisceral (n = 2), or combined liver-intestinal transplantation (n = 1). Desmoid tumors recurred in the abdominal walls of 2 patients. Two patients died: one as a result of sepsis, the other because of a rupture of a mycotic aneurysm of the aortic anastomosis. One graft lost to severe rejection was replaced with a second intestinal graft. Eleven to 53 months after transplantation, 7 patients were alive, well, independent of parenteral treatment, and leading apparently normal lifestyles.

CONCLUSIONS

Transplantation of the intestine alone or as part of a multivisceral transplantation may help rescue otherwise untreatable patients with complicated desmoid tumors.

Immunomodulation for intestinal transplantation by allograft irradiation, adjunct donor bone marrow infusion, or both

BACKGROUND

The passenger leukocytes in the intestine have a lineage profile that predisposes to graft-versus-host disease (GVHD) in some animal models and have inferior tolerogenic qualities compared with the leukocytes in the liver, other solid organs, and bone marrow. Elimination by ex vivo irradiation of mature lymphoid elements from the bowel allografts is known to eliminate the GVHD risk. We hypothesized that infusion of donor bone marrow cells (BMC) in recipients of irradiated intestine would improve tolerogenesis without increasing the risk of GVHD.

METHODS

Orthotopic small intestine transplantation was performed with the GVHD-prone Lewis (LEW)-to-Brown Norway (BN) combination and the reverse GVHD-resistant BN-to-LEW model under a short course of tacrolimus treatment (1 mg/kg/day, days 0-13, 20, 27). Grafts were irradiated ex vivo, using a 137Cs source. In selected experimental groups, donor BMC (2.5 x 10(8)) were infused on the day of small intestine transplantation.

RESULTS

The unmodified LEW intestine remained intact, whether transplanted alone or with adjunct donor BMC infusion, but all of the BN recipients died of GVHD after approximately 2 months. Intestinal graft irradiation (10 Gy) effectively prevented the GVHD and prolonged survival to 92.5 days, but all of the BN recipients died with chronic rejection of the LEW grafts, which was prevented by infusion of adjunct donor BMC without causing GVHD. In the GVHD-resistant reverse strain direction (BN-->LEW), all intestinal recipients treated for 27 days with tacrolimus survived > or =150 days without regard for graft irradiation or adjunct BMC, but chronic rejection was severe in the irradiated intestine, moderate in the unaltered graft, and least in the irradiated intestine transplanted with adjunct BMC. Mild arteritis in the 150 day allografts of both strain combinations (i.e., LEW--> BN and BN-->LEW) may have been irradiation associated, but this was prevented when weekly doses of tacrolimus were continued for the duration of the experiment rather than being stopped at 27 days.

CONCLUSIONS

Recipients are protected from GVHD by irradiating intestinal allografts, but the resulting leukocyte depletion leads to chronic rejection of the transplanted bowel. The chronic rejection is prevented with adjunct donor BMC without causing GVHD. Although application of the strategy may be limited by the possibility of radiation injury, the results are consistent with the paradigm that we have proposed to explain organ-induced graft acceptance, tolerance, and chronic rejection.

Advances in pediatric liver and intestinal transplantation

BACKGROUND

Significant progress has been made with liver and intestinal transplantation in pediatric patients. Shortage of whole-organ cadaveric grafts has resulted in a high mortality rate for children awaiting transplantation. New surgical procedures such as split-liver transplantation and living-related liver transplantation have evolved over the last decade to maximize donor utilization in pediatric patients.

METHODS

In this article we review the current indications and contraindications for liver and intestinal transplantation in children, the surgical innovations to expand an exceedingly small cadaveric liver pool, postoperative management, and the impact on patient and graft survival.

RESULTS

Reduced-size liver transplantation provides children with much needed small grafts; however, split-liver transplantation may eliminate the need for reduced-size and living-related liver transplantation except in urgent situations.

CONCLUSION

Liver transplantation is a durable procedure that provides excellent long-term survival. The use of living-related and split-liver transplantation has dramatically reduced the waiting periods for children and improved survival. In the past decade significant progress has been made with intestinal transplantation owing to improvements in surgical technique, immunosuppressive agents, and early identification and treatment of postoperative complications.

History of clinical transplantation

The emergence of transplantation has seen the development of increasingly potent immunosuppressive agents, progressively better methods of tissue and organ preservation, refinements in histocompatibility matching, and numerous innovations in surgical techniques. Such efforts in combination ultimately made it possible to successfully engraft all of the organs and bone marrow cells in humans. At a more fundamental level, however, the transplantation enterprise hinged on two seminal turning points. The first was the recognition by Billingham, Brent, and Medawar in 1953 that it was possible to induce chimerism-associated neonatal tolerance deliberately. This discovery escalated over the next 15 years to the first successful bone marrow transplantations in humans in 1968. The second turning point was the demonstration during the early 1960s that canine and human organ allografts could self-induce tolerance with the aid of immunosuppression. By the end of 1962, however, it had been incorrectly concluded that turning points one and two involved different immune mechanisms. The error was not corrected until well into the 1990s. In this historical account, the vast literature that sprang up during the intervening 30 years has been summarized. Although admirably documenting empiric progress in clinical transplantation, its failure to explain organ allograft acceptance predestined organ recipients to lifetime immunosuppression and precluded fundamental changes in the treatment policies. After it was discovered in 1992 that long-surviving organ transplant recipients had persistent microchimerism, it was possible to see the mechanistic commonality of organ and bone marrow transplantation. A clarifying central principle of immunology could then be synthesized with which to guide efforts to induce tolerance systematically to human tissues and perhaps ultimately to xenografts.

Small bowel transplantation

The development of small bowel transplantation has long been hindered by the immunological and infectious barriers peculiar to the small bowel. Gradual progress has been achieved during the past decade with the use of tacrolimus and the availability of better anti-infection prophylaxis. The current status of small bowel transplantation as a life-saving option for patients failing on total parenteral nutrition and those who have developed irreversible liver failure is undisputed. Small bowel transplantation can be performed as either an intestine-only graft or as part of a composite graft with the liver and, on occasion, other organs. The various techniques of donor and recipient operations are relatively standardized. Despite the progress made, the most common causes of death and graft loss continue to be sepsis, rejection, and lymphomas. Further progress can be achieved by development of more effective immunosuppressive and immunomodulatory strategies. The role of inducing chimerism by adjuvant donor-specific bone marrow transfusions to promote graft tolerance is uncertain. Until the mortality and graft losses are further reduced, the role of small bowel transplantation will be limited to a salvage procedure for failure of total parenteral nutrition rather than a primary treatment of intestinal failure.

Multivisceral transplantation for megacystis microcolon intestinal hypoperistalsis syndrome

BACKGROUND

Megacystis microcolon intestinal hypoperistalsis syndrome (MMIHS) is a rare autosomal recessive disorder causing a functional neonatal bowel obstruction. Its etiopathogenesis is not fully understood. The prognosis is poor in the majority of cases; most patients die before the age of 6 months. In this report, we describe our experience with three patients with MMIHS in whom multivisceral transplantation was performed.

METHODS

Three patients with MMIHS underwent multivisceral transplantation. All patients were females with a history of long-term total parenteral nutrition (TPN) with TPN-related cholestatic liver disease.

RESULTS

Patient 1 died 17 months after transplantation because of aspiration after revision of her feeding gastrostomy. At the time of death, the graft was functioning and the patient was completely off TPN. Patient 2 is alive 17 months after transplant. She is a fully functional, active 2-year-old and has also recently begun oral feeding after intensive rehabilitation. Patient 3 died on day 44 of multisystem failure.

CONCLUSIONS

This is the first report in the literature of multivisceral transplantation for MMIHS. Although one of the three patients died 44 days after surgery from multiorgan system failure, the other two patients had long-term survival after transplant and both grew well on enteral feeding alone. One patient died 17 months from a non-transplant-related complication, while the other is living at home off of TPN, with almost complete dietary rehabilitation 17 months after transplant. Our case reports suggest that multivisceral transplantation is a valuable therapeutic option for patients affected by MMIHS with TPN-induced liver failure.

Pediatric transplantation

Advances in organ preservation, surgical technique, and postoperative care have permitted the rapid development of liver transplantation in children. Consequently, the applicability of this procedure has gone beyond the treatment of life-threatening complications of chronic liver disease and now includes disabling morbidities and quality-of-life issues. The use of hepatic segments for transplantation with reduced or split cadaveric grafts and living-related donors has decreased the mortality of children awaiting liver transplantation. We are presently armed with a new potent immunosuppressive drug, tacrolimus, and an understanding that the migration and grafting of passenger leukocytes of bone marrow origin is the seminal explanation for allograft acceptance. The next forefront will involve manipulation of the process not only for the transplantation of already successful whole organs--such as the liver, kidney, pancreas, and heart--but also in the development of the intestinal transplantation program. Thus, augmentation of leukocyte traffic in unconditioned recipients of cadaver allografts with concomitant intravenous infusion of donor bone marrow cells under the same immunosuppressive management of tacrolimus-prednisone treatment will be the path into the future.

Quality of life after small intestinal transplantation and among home parenteral nutrition patients

BACKGROUND

The purpose of the study was to quantify changes in the quality of life of small bowel recipients before and after transplantation and of home parenteral nutrition (HPN)-dependent patients before and after therapy. We examined quality of life across multiple areas of function including physical, social, and emotional indices.

METHODS

The Quality of Life Instrument in the form of a self-administered questionnaire was completed voluntarily by the recipients of small intestinal transplants and by a cohort of HPN-dependent patients.

RESULTS

Small intestinal transplant recipients reported significant improvement in the quality of their life and function. They also rated their quality of life and function during the pretransplant, TPN-dependent period to be worse than before the development of chronic intestinal failure. Similarly, HPN recipients reported significant worsening across most areas of quality of life when they compared their premorbid period to the HPN-dependent state.

CONCLUSIONS

TPN dependence causes significant impairment in the quality of life in most areas of functioning. In contrast, small intestinal transplantation restores the quality of life among recipients with functioning grafts.

Absorptive function following small intestinal transplantation

All studies involving small intestinal transplantation and absorptive function are reviewed. The effects ischemia-reperfusion, lymphatic disruption, denervation, rejection, immunosuppressive medication, and infection are elucidated as far as the studies allow. Species differences are discussed. Conclusions regarding the major absorptive defects are drawn.

Allogeneic fetal intestinal transplantation with FK506 immunosuppression

PURPOSE

Small intestinal transplantation remains a significant clinical problem. Allogeneic fetal intestinal (AFI) transplantation shows promise, particularly regarding procurement; however, no studiesto date have evaluated the potential success of true allogeneic loci implantation. The authors hypothesized that isolated segments of AFI could be heterotopically transplanted but would require immunosuppression to survive.

METHODS

Donor tissue was obtained from late-gestation Brown Norway rat fetuses with a histo-locus RTN and Fischer fetuses with a histo-locus RT1L. The recipients were adolescent male Fischer rats with a histo-locus RT1L. A 1.2-cm segment of fetal small bowel was implanted in the omentum of the recipient rat and allowed to mature for 5 weeks. Animals were then separated into five groups. Group A served as controls with syngeneic fetal intestinal (SFI) transplant. Group B received AFI with no immunosuppression; group C, AFI transplant with five days of FK506; group D, AFI with 10 days of FK506; and Group E, AFI with daily FK506 for the entire 5-week maturation period. Animals were killed on day 35.

RESULTS

All animals gained weight over the maturation period. Groups B, C, and D had no viable transplant segments at day 35. Groups A and E both had well-developed viable segments confirmed by gross and histological evaluation.

CONCLUSIONS

FK506 allows for normal intestinal development for use in allogeneic fetal bowel transplantation. With this observation, the use of fetal intestine transplanted into the portal circulation emerges as a potentially viable alternative to present intestinal transplant models.

Clinical intestinal transplantation: new perspectives and immunologic considerations

BACKGROUND

Although tacrolimus-based immunosuppression has made intestinal transplantation feasible, the risk of the requisite chronic high-dose treatment has inhibited the widespread use of these procedures. We have examined our 1990-1997 experience to determine whether immunomodulatory strategies to improve outlook could be added to drug treatment.

STUDY DESIGN

Ninety-eight consecutive patients (59 children, 39 adults) with a panoply of indications received 104 allografts under tacrolimus-based immunosuppression: intestine only (n = 37); liver and intestine (n = 50); or multivisceral (n = 17). Of the last 42 patients, 20 received unmodified adjunct donor bone marrow cells; the other 22 were contemporaneous control patients.

RESULTS

With a mean followup of 32 +/- 26 months (range, 1-86 months), 12 recipients (3 intestine only, 9 composite grafts) are alive with good nutrition beyond the 5-year milestone. Forty-seven (48%) of the total group survive bearing grafts that provide full (91%) or partial (9%) nutrition. Actuarial patient survival at 1 and 5 years (72% and 48%, respectively) was similar with isolated intestinal and composite graft recipients, but the loss rate of grafts from rejection was highest with intestine alone. The best results were in patients between 2 and 18 years of age (68% at 5 years). Adjunct bone marrow did not significantly affect the incidence of graft rejection, B-cell lymphoma, or the rate or severity of graft-versus-host disease.

CONCLUSIONS

These results demonstrate that longterm rehabilitation similar to that with the other kinds of organ allografts is achievable with all three kinds of intestinal transplant procedures, that the morbidity and mortality is still too high for their widespread application, and that the liver is significantly but marginally protective of concomitantly engrafted intestine. Although none of the endpoints were markedly altered by donor leukocyte augmentation (and chimerism) with bone marrow, establishment of the safety of this adjunct procedure opens the way to further immune modulation strategies that can be added to the augmentation protocol.

The extracellular matrix: an early target of preservation/reperfusion injury and acute rejection after small bowel transplantation

BACKGROUND

Endothelial cells are known to be an early target of preservation/reperfusion injury and acute rejection, whereas the extracellular matrix (ECM) may also play an equally important role in the sequelae of both events.

METHODS

Syngeneic and allogeneic rat small bowel transplantations (SBTX) were performed after 6 hr of preservation. Animals were subsequently killed at defined time points for determination of ECM parameters within the graft and in plasma.

RESULTS

Laminin levels were significantly increased 20 min after reperfusion (syngeneic SBTX: 357+/-65.9 ng/ml; allogeneic SBTX: 361+/-79.6 ng/ml; P< or =0.01). After syngeneic transplantation, laminin levels normalized by postoperative day (POD) 7, whereas there was a rejection-induced increase after allogeneic SBTX (POD 7: 179+/-60.1 ng/ml; POD 9: 333+/-13.6 ng/ml; P< or =0.01 vs. syngeneic SBTX). This increase was accompanied by an increase in tumor necrosis factor-alpha levels at POD 9. Hyaluronic acid levels were significantly elevated after 24 hr (syngeneic SBTX: 1086+/-176 microg/L; allogeneic SBTX: 918+/-108 microg/L; P< or =0.01). After syngeneic SBTX, hyaluronic acid levels normalized by POD 7, whereas persistently higher levels were observed after allogeneic SBTX. Immunohistochemistry confirmed early changes (20 min after reperfusion) at the ECM. Anti-laminin and anti-CD44 staining normalized at POD 5 after syngeneic SBTX. After allogeneic SBTX, rejection-specific changes were evident with anti-laminin staining commencing on POD 5 and progressing until POD 9. At similar time points, increased expression of fibronectin- and interferon-gamma-positive material was evident.

CONCLUSIONS

The ECM can be considered to be an early target of preservation/reperfusion injury and acute rejection. Plasma parameters reliably reflected the changes observed within the graft. Laminin and hyaluronic acid levels may be used as indicators of initial graft function. Furthermore, the increase in laminin levels was an early indicator of acute rejection. Determination of these parameters may significantly improve monitoring after SBTX.

Heterotopic intestinal transplantation aggravates the insult of chronic rejection

BACKGROUND

Intestinal grafts are placed either heterotopically (out of continuity) or orthotopically (in continuity); the latter is believed to be advantageous, as intraluminal nutrients and intestinal secretions might modulate the intestinal immune status and possibly delay rejection.

METHODS

This study was designed to delineate the effects of heterotopic versus orthotopic allograft position on the morphology and function of intestinal smooth muscle in our rat model of chronic rejection. Syngeneic orthotopic grafts were evaluated to control for changes due to the transplantation process.

RESULTS

Histochemistry of the graft's muscularis externa showed a significant thickening due to hyperplasia and hypertrophy, which was most pronounced in heterotopic grafts (control = 92+/-2.4 microm, syngeneic grafts = 140+/-6.7 microm, orthotopic allografts = 278+/-26.6 microm, heterotopic allografts = 456+/-50 microm). In terms of function, muscle strips from allografts only generated 23% of the total bethanechol-induced contractile force in vitro compared to unoperated controls and syngeneic grafts. The mean resting membrane potential of control and isograft muscle cells was -69 +/- 0.9 mV with a slow-wave amplitude of 20+/-0.5 mV. Chronic rejection hyperpolarized the resting membrane potential of orthotopic allografts (-66 +/- 0.5 mV) and even more so of heterotopic allografts (-58 +/- 3.4 mV). Slow-wave amplitudes were decreased in orthotopic (14+/-0.9 mV) and nearly abolished in heterotopic allografts (2+/-1.2 mV).

CONCLUSIONS

Our data indicate that allografts in heterotopic position are most susceptible to the insult of chronic rejection exemplified by increased proliferative and hypertrophic transformation of intestinal smooth muscle and a marked decrease in mechanical and electrical activity.

Effect of donor-specific splenocytes via portal vein and FK506 in rat small bowel transplantation

BACKGROUND

To investigate the role of the liver in immune responses after small bowel transplantation, donor-specific splenocytes were infused perioperatively, via the portal vein, in a rat heterotopic small bowel transplant model.

METHODS

Heterotopic small bowel transplantation between the fully allogenic Brown Norway (BN) (RT1n) and Lewis (RT1[1]) strain rats were performed. We prepared donor splenocytes from BN or third-party WKA (RT1k) rat spleens for Lewis hosts and injected the splenocytes perioperatively via the host portal vein or the systemic vein. The hosts were treated with a short course of the immunosuppressive agent, FK506 (0.5 mg/kg, 0-3 days postoperatively), following the experimental protocols.

RESULTS

Untreated Lewis hosts rejected BN small bowel grafts at 5.4+/-0.9 days (n=8). BN splenocytes given alone caused fatal graft-versus-host disease in six of eight animals, and two others died from graft rejection. FK506 alone did not significantly prolong graft survival (6.3+/-1.0 days, n=10). However, BN splenocytes injected via the portal vein, combined with FK506, prolonged graft survival to 12.7+/-2.1 days (n=12, P < 0.01) and 10 of 12 rats survived more than 70 days. This was donor antigen specific. BN splenocytes administered systemically caused fatal graft-versus-host disease in all recipients, and FK506 did not ameliorate this. Histologic findings of graft rejection were remarkably mild in the recipients of the combined therapy, compared with the recipients that were given FK506 alone. Down-regulation of one-way mixed lymphocyte reaction to BN splenocytes was observed in the splenocytes of the tolerant hosts.

CONCLUSIONS

Combined administration of donor splenocytes and FK506 reduced allograft rejection and prolonged survival in this rat model of small bowel transplantation.

Graft-versus-host disease after liver and small bowel transplantation in a child

An 8-month-old child with an immunodeficiency disorder characterized by abnormal lymphocyte function and by low IgG and IgA levels had combined liver and small bowel transplantation under tacrolimus and steroid immunosuppression for the treatment of short gut syndrome and hepatic cirrhosis. The patient developed an early postoperative episode of Pneumocystis carinii pneumonia, and a subsequent surgical complication, prompting discontinuance of tacrolimus. A skin rash eventually shown to be graft-versus-host disease (GVHD) developed in the flank on the 12th post-transplant day and gradually became generalized. Peritonitis, sepsis, multisystem organ failure including the liver allograft led to death on the 23rd post-operative day. The mechanisms leading to post-transplant GVHD under the specific circumstances in this case are discussed.

Small-intestinal transplantation

The management of patients with intestinal failure has benefited from progress in parenteral nutrition (PN), especially home-based PN. Intestinal transplantation is therefore possible and is now, in some conditions, the logical therapeutic option. Since 1985, more than 180 small-bowel grafts have been done, involving the isolated small bowel with or without the colon (38%), the liver-small bowel (46%) or several organs (16%). Two-thirds of recipients were under 20 years of age, and indications were short-bowel syndrome (64%), severe intractable diarrhoea (13%), abdominal cancer (13%) or chronic intestinal pseudo-obstruction syndrome (8%). Of the patients, 51% survived > 2 years after the graft. Patient and graft survival depends on the type of immunosuppression, i.e. cyclosporine or FK506. The results must be interpreted carefully as they represent the first experience in numerous centres using different immunosuppressive protocols, without any randomization. The results from the largest of these centres reflect the current situation more closely. Functional grafts lead to gastrointestinal autonomy (weaning of PN) while maintaining satisfactory nutritional status and normal growth in childhood. Intestinal transplantation is theoretically indicated for all patients permanently or dependent for a long time on PN. However, as PN is generally well tolerated, even for long periods, each indication for transplantation must be carefully weighed up in terms of the iatrogenic risk and quality of life. When PN has reached its limits, especially in those associated with vascular, infectious, hepatic or metabolic complications, intestinal transplantation must be undertaken. Transplantation of the small bowel alone remains the first option, as combined liver-small bowel grafting is only indicated in the case of life-threatening progressive cirrhogenic liver disease.

Effect of a glutamine-enriched diet on small bowel allograft during immunosuppressive therapy

The effect of an orally administered glutamine-enriched elemental diet was examined following orthotopic small bowel allotransplantation using Brown Norway rats as donors and Lewis rats as recipients. The recipients was treated with FK 506 and randomized to receive glutamine-free elemental enteral diet solution (glutamine-free group), glutamine-enriched elemental diet solution containing 7500 mg of glutamine per 100 g diet (glutamine-enriched group) or standard chow (chow group) ad libitum for 7 d. There were no histological changes due to resection. Weight loss in the glutamine-enriched group was significantly less than that of the chow group. Both plasma glutamine levels and the ratio of glutamine to total amino acids in the homogenate of the graft mucosa of the glutamine-enriched group were significantly higher than those of the glutamine-fee group. Villous height and crypt depth were significantly decreased in the glutamine-free group. The BrdU labeling index in the graft epithelium and alkaline phosphatase activity in the homogenate of the graft mucosa of the glutamine-enriched group were significantly higher than those of the glutamine-free group. Therefore, orally administered glutamine-enriched elemental diet appears to promote the regeneration and differentiation of the graft mucosa following small bowel allotransplantation.

Increased expression of tissue cytokines in graft-versus-host disease after small bowel transplantation in the rat

BACKGROUND

Graft-versus-host disease (GVHD) occurs in the recipient after small bowel transplantation (SBT). Proinflammatory cytokines, such as tumor necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma), and interleukin 6 (IL-6), may be important mediators of GVHD. Increased expression of these cytokines might precede the clinical manifestations of GVHD induced by SBT.

METHODS

Heterotopic SBT was performed using Lewis donors into Lewis x Brown Norway F1 (LBN-F1) recipients. The isograft control was performed from LBN-F1 into LBN-F1. Animals were killed on the 5th and 11th postoperative day (POD). mRNA was isolated from recipient native small bowel, colon, spleen, liver, and mesenteric lymph nodes and from nonsurgical controls as baseline. Semiquantitative reverse transcriptase polymerase chain reaction was performed to amplify mRNA transcripts for TNF-alpha, IFN-gamma, and IL-6 using alpha32P-dATP incorporation. Clinical signs, histologic assessment, and cytokine expression were correlated.

RESULTS

On POD 5, there were neither clinical signs nor histologic features of GVHD, but mRNA expression of TNF-alpha and IL-6 in small bowel, IL-6 in spleen, and IFN-gamma in mesenteric lymph nodes were significantly increased in allograft animals when compared with normal and isograft tissues. On POD 11, both the clinical signs and histologic features of GVHD were seen, and TNF-alpha and IL-6 in native small bowel, TNF-alpha in colon, IFN-gamma in spleen, and IL-6 in mesenteric lymph nodes were significantly increased in allograft animals when compared with that in normal and isograft tissues.

CONCLUSIONS

In conclusion, TNF-alpha, IFN-gamma, and IL-6 expression precede clinical onset and histologic evidence of GVHD in specific tissues. Therefore, increased expression of these cytokines is correlated with the development of GVHD in this model of SBT.

Blockage of mesenteric lymphatic flow in rats

An experimental model of blockage of the mesenteric lymphatic flow (MLF) in rats was designed, and morphologic changes of mesenteric lymphatic vessels (MLV) and lymph nodes were investigated by mesenteric lymphangiography and histopathologic examination. Body weight in rats with blockage of MLF did not increase normally. Mesenteric lymphangiography revealed dilation of the MLV, reverse flow into the peripheral MLV, and leakage of contrast medium, resulting in chylous ascites. Remarkable dilation of the lymphatic sinuses and dilated and increased rough endoplasmic reticulum in lymphocytes in the mesenteric lymph nodes due to lymph stagnation were observed by light and electron microscopic examination, respectively.

Acetaminophen absorption test as a marker of small bowel transplant rejection

We recently evaluated the acetaminophen absorption test as a marker of graft rejection for small bowel transplantation(SBTX). Randomly bred male Wistar rats were used as recipients and donors. Rats (n=45) received heterotopic small intestinal transplants and were divided into three groups (n=15 for each group). In group A, a 10-cm segment of jejunum of was exteriorized as a Thiry-Vella loop. In group B, immunosuppression was not given after SBTX. In group C, rats were treated with FK506 after SBTX (0.3 mg/kg body weight, 0-6 postoperative days). Serum acetaminophen concentrations were measured 15 min after instillation of 0.15 g/kg acetaminophen into the intestinal loop on postoperative days 1, 3, and 7 (n=5 for each group). Blood flow and histology of the graft were also evaluated. In the SBTX group only, the grafts showed the histological change after acute rejection. On day 3, plasma acetaminophen concentrations in this group showed a significant decrease, which correlated with the mild histological changes of graft rejection. Graft blood flow of the SBTX group decreased significantly on day 7, following the severe graft destruction of advanced rejection. No remarkable changes were observed in the other two groups. The acetaminophen absorption test appears to be useful for the early detection of SBTX graft rejection.

Treatment with an HLA-peptide and cyclosporine A prolongs rat small bowel allograft survival

BACKGROUND

The ultimate treatment for severe short bowel syndrome is small bowel transplantation (SBT). Current immunosuppression for SBT is relatively ineffective and toxic. Peptides derived from residues 75-84 of the HLA-B7 molecule are immunomodulatory in vitro, and in rodents, when combined with subtherapeutic doses of cyclosporine (CsA), prolong cardiac and skin allograft survival without altering the recipient's rejection kinetics to third party allografts. We investigated the effects of HLA-B7 peptide fragment in a rat model of SBT.

METHODS

Heterotopic allogeneic SBT was performed in Dagouti (RT1a) to Lewis (RT1l) high-responder rat strain combination. B7.75-84 (40 mg/kg/d) and subtherapeutic CsA (10 mg/kg/d) were administered alone, or in combination, by gavage to allograft recipients on days 0 to 4 after SBT. Recipient pretreatment with B7.75-84 on days -14, -12, -10, and -7 followed by subtherapeutic CsA on days 0 to 4 after SBT was also carried out. Graft rejection was determined by the presence of a palpable abdominal mass on daily examination or by loss of more than 10% initial body weight.

RESULTS

Without immunosuppression allografts rejected at a median time of 6 days (range, 5 to 7; n = 7). This was not significantly altered with either CsA therapy alone (median 6 days; range, 6 to 7; n = 6) or B7.75-84 alone (median, 5 days; range, 5 to 6; n = 6). Recipient combination therapy with B7.75-84 and CsA after allografting significantly prolonged allograft survival (median, 11 days; range, 9 to 13; n = 9), as did recipient B7.75-84 pretransplant therapy (median, 10 days; range, 9 to 12; n = 6), when administered over a 2-week period before allografting.

CONCLUSION

Post-SBT recipient treatment with B7.75-84 produced statistically significant improvement in allograft survival only after combination with subtherapeutic CsA. Recipient pre-SBT treatment with B7.75-84 alone however, resulted in statistically significant improvement in allograft survival in combination with post-SBT subtherapeutic CsA. These synergistic effects may be valuable in achieving improved SBT survival clinically and warrant further exploration.

In situ neural isolation of the entire canine upper gut: effects on fasting and fed motility patterns

BACKGROUND

Multiorgan upper gut transplantation is becoming clinically feasible; however, the effects of multivisceral transplantations on gastrointestinal motility are unknown. Our aim was to determine the neural and hormonal mechanisms controlling motility patterns after complete extrinsic denervation of the upper gut as a model of multivisceral upper gut autotransplantation.

METHODS

Seven dogs successfully underwent in situ neural isolation of the stomach, entire small intestine, proximal colon, liver, and pancreas by transecting all connections (distal esophagus, midcolon, all nerves, lymphatics) to this multivisceral complex except the celiac artery, superior mesenteric artery, and the suprahepatic and infrahepatic vena cava; these vessels were meticulously stripped of adventitia under optical magnification. Blood flow was not disrupted to prevent confounding effects of ischemia-reperfusion injury. After 1- to 2-week recovery, myoelectric and manometric recordings of stomach and myoelectric recordings of small bowel were obtained from conscious animals.

RESULTS

During fasting the characteristic cycling migrating motor complex (MMC) was observed in the stomach and small intestine. The gastric component of the MMC was absent in one of the seven dogs. Regular cycling of the MMC during fasting, however, was intermittently disrupted and replaced by a noncyclic pattern of intermittent contractions in two of seven dogs 43% of the recording time. A small meal (50 gm liver) did not abolish the MMC as occurs in normal dogs; in contrast, a large meal (500 gm liver) did abolish the MMC.

CONCLUSIONS

Extrinsic innervation to the upper gut modulates but is not requisite for interdigestive and postprandial motility of the stomach. Because relatively normal global motility patterns are preserved, multivisceral upper gut transplantation should be a viable option in selected patients.

Current status of small bowel transplantation in children

Small bowel transplantation is gradually changing from an experimental procedure to a very desirable and viable treatment option in children with irreversible intestinal failure due to either short bowel syndrome or functional impairment. Long term total parenteral nutrition and home parenteral nutrition would be necessary to manage these children in the absence of a small bowel transplant programme. Parenteral nutrition is also associated with complications which can result in chronic liver disease. In India, there is no infrastructure for this treatment option and even if it was there the cost of this method of treatment is likely to be more than the cost of post-operative immunosuppression. Small bowel can be transplanted as an isolated graft, in combination with the liver or as part of a multivisceral transplant. The operative techniques have been standardised. Major post-operative complications result from sepsis and lymphoproliferative diseases. The best results have been obtained with a combined liver and small bowel transplant.