Selective Bcl-2 inhibition promotes hematopoietic chimerism and allograft tolerance without myelosuppression in nonhuman primates

Hematopoietic stem cell transplantation (HSCT) has many potential applications beyond current standard indications, including treatment of autoimmune disease, gene therapy, and transplant tolerance induction. However, severe myelosuppression and other toxicities after myeloablative conditioning regimens have hampered wider clinical use. To achieve donor hematopoietic stem cell (HSC) engraftment, it appears essential to establish niches for the donor HSCs by depleting the host HSCs. To date, this has been achievable only by nonselective treatments such as irradiation or chemotherapeutic drugs. An approach that is capable of more selectively depleting host HSCs is needed to widen the clinical application of HSCT. Here, we show in a clinically relevant nonhuman primate model that selective inhibition of B cell lymphoma 2 (Bcl-2) promoted hematopoietic chimerism and renal allograft tolerance after partial deletion of HSCs and effective peripheral lymphocyte deletion while preserving myeloid cells and regulatory T cells. Although Bcl-2 inhibition alone was insufficient to induce hematopoietic chimerism, the addition of a Bcl-2 inhibitor resulted in promotion of hematopoietic chimerism and renal allograft tolerance despite using only half of the dose of total body irradiation previously required. Selective inhibition of Bcl-2 is therefore a promising approach to induce hematopoietic chimerism without myelosuppression and has the potential to render HSCT more feasible for a variety of clinical indications.

Bcl-2 Inhibition with Venetoclax Promotes Induction of Mixed Chimerism and Renal Allograft Tolerance Without Severe Myelosuppression in Non-human Primates

Background

Specific Bcl-2 inhibition has been shown to promote mixed chimerism and allograft tolerance without myelosuppressive conditioning in murine models. We extended this approach to nonhuman primates in combined kidney and bone marrow transplantation (CKBMT).

Methods

In Group A, recipients received CKBMT with the regimen including total body irradiation (TBI,3 Gy) thymic irradiation (TI, 7Gy) and ATG, followed by a short course of anti-CD154 antibody and cyclosporine. In Group B, TBI was reduced to 1.5Gy. In Group C, peri-transplant Bcl-2 inhibitor (Venetoclax) was added to Group B regimen. In Group D, Group C regimen without TBI. In Group E, Group C regimen without TI.

Results

7/8 recipients in Group A developed transient chimerism and achieved long-term renal allograft survival without immunosuppression. However, these recipients developed transient but severe pancytopenia between days 10–17 post CKBMT. Both recipients in Group B failed to develop chimerism. By adding Venetoclax to Group B regimen, 3/3 Group C recipients developed significantly higher and longer mixed chimerism without severe myelosuppression. These three recipients also achieved long-term immunosuppression free renal allograft survival without rejection (>316, >575, >239 days). In Group D, both recipients failed to develop chimerism and rejected their allografts on days 140 and 120. Although three Group E recipients successfully developed chimerism, all rejected their renal allografts on days 100, 97, 163 with early recovery of CD31+ naive T cells.

Conclusion

Enhancement of intrinsic apoptosis with Bcl-2 inhibition is a promising strategy to achieve robust mixed chimerism and allograft tolerance with reduced myelosuppressive conditioning.

Preclinical and clinical studies for transplant tolerance via the mixed chimerism approach

Based upon observations in murine models, we have developed protocols to induce renal allograft tolerance by combined kidney and bone marrow transplantation (CKBMT) in non-human primates (NHP) and in humans. Induction of persistent mixed chimerism has proved to be extremely difficult in major histocompatibility complex (MHC)-mismatched primates, with detectable chimerism typically disappearing within 30-60 days. Nevertheless, in MHC mismatched NHP, long-term immunosuppression-free renal allograft survival has been achieved reproducibly, using a non-myeloablative conditioning approach that has also been successfully extended to human kidney transplant recipients. CKBMT has also been applied to the patients with end stage renal disease with hematologic malignancies. Renal allograft tolerance and long-term remission of myeloma have been achieved by transient mixed or persistent full chimerism. This review summarizes the current status of preclinical and clinical studies for renal and non-renal allograft tolerance induction by CKBMT. Improving the consistency of tolerance induction with less morbidity, extending this approach to deceased donor transplantation and inducing tolerance of non-renal transplants, are critical next steps for bringing this strategy to a wider range of clinical applications.

Prolonged Survival Following Pig-to-Primate Liver Xenotransplantation Utilizing Exogenous Coagulation Factors and Costimulation Blockade

Since the first attempt of pig-to-primate liver xenotransplantation (LXT) in 1968, survival has been limited. We evaluated a model utilizing α-1,3-galactosyltransferase knockout donors, continuous posttransplant infusion of human prothrombin concentrate complex, and immunosuppression including anti-thymocyte globulin, FK-506, methylprednisone, and costimulation blockade (belatacept, n = 3 or anti-CD40 mAb, n = 1) to extend survival. Baboon 1 remained well until postoperative day (POD) 25, when euthanasia was required because of cholestasis and plantar ulcers. Baboon 2 was euthanized following a seizure on POD 5, despite normal liver function tests (LFTs) and no apparent pathology. Baboon 3 demonstrated initial stable liver function but was euthanized on POD 8 because of worsening LFTs. Pathology revealed C4d positivity, extensive hemorrhagic necrosis, and a focal cytomegalovirus inclusion. Baboon 4 was clinically well with stable LFTs until POD29, when euthanasia was again necessitated by plantar ulcerations and rising LFTs. Final pathology was C4d negative and without evidence of rejection, inflammation, or thrombotic microangiopathy. Thus, nearly 1-mo rejection-free survival has been achieved following LXT in two of four consecutive recipients, demonstrating that the porcine liver can support life in primates for several weeks and has encouraging potential for clinical application as a bridge to allotransplantation for patients with acute-on-chronic or fulminant hepatic failure.

Chimerism-based tolerance in organ transplantation: preclinical and clinical studies

Induction of allograft tolerance has been considered the ultimate goal in organ transplantation. Although numerous protocols to induce allograft tolerance have been reported in mice, a chimerism-based approach through donor haematopoietic stem cell transplantation has been the only approach to date that induced allograft tolerance reproducibly following kidney transplantation in man. Renal allograft tolerance has been achieved by induction of either transient mixed chimerism or persistent full donor chimerism. Although the risk of rejection may be low in tolerance achieved via durable full donor chimerism, the development of graft-versus-host disease (GVHD) has limited the wider clinical application of this approach. In contrast, tolerance induced by transient mixed chimerism has not been associated with GVHD, but the risk of allograft rejection is more difficult to predict after the disappearance of haematopoietic chimerism. Current efforts are directed towards the development of more clinically feasible and reliable approaches to induce more durable mixed chimerism in order to widen the clinical applicability of these treatment regimens.

Immunosuppression With CD40 Costimulatory Blockade Plus Rapamycin for Simultaneous Islet-Kidney Transplantation in Nonhuman Primates

The lack of a reliable immunosuppressive regimen that effectively suppresses both renal and islet allograft rejection without islet toxicity hampers a wider clinical application of simultaneous islet-kidney transplantation (SIK). Seven MHC-mismatched SIKs were performed in diabetic cynomolgus monkeys. Two recipients received rabbit antithymocyte globulin (ATG) induction followed by daily tacrolimus and rapamycin (ATG/Tac/Rapa), and five recipients were treated with anti-CD40 monoclonal antibody (mAb) and rapamycin (aCD40/Rapa). Anti-inflammatory therapy, including anti-interleukin-6 receptor mAb and anti-tumor necrosis factor-α mAb, was given in both groups. The ATG/Tac/Rapa recipients failed to achieve long-term islet allograft survival (19 and 26 days) due to poor islet engraftment and cytomegalovirus pneumonia. In contrast, the aCD40/Rapa regimen provided long-term islet and kidney allograft survival (90, 94, >120, >120, and >120 days), with only one recipient developing evidence of allograft rejection. The aCD40/Rapa regimen was also tested in four kidney-alone transplant recipients. All four recipients achieved long-term renal allograft survival (100% at day 120), which was superior to renal allograft survival (62.9% at day 120) with triple immunosuppressive regimen (tacrolimus, mycophenolate mofetil, and steroids). The combination of anti-CD40 mAb and rapamycin is an effective and nontoxic immunosuppressive regimen that uses only clinically available agents for kidney and islet recipients.

Prophylactic orthosteric inhibition of leukocyte integrin CD11b/CD18 prevents long-term fibrotic kidney failure in cynomolgus monkeys

Ischaemic acute kidney injury (AKI), an inflammatory disease process, often progresses to chronic kidney disease (CKD), with no available effective prophylaxis. This is in part due to lack of clinically relevant CKD models in non-human primates. Here we demonstrate that inhibition of the archetypal innate immune receptor CD11b/CD18 prevents progression of AKI to CKD in cynomolgus monkeys. Severe ischaemia-reperfusion injury of the right kidney, with subsequent periods of the left ureter ligation, causes irreversible right kidney failure 3, 6 or 9 months after AKI. Moreover, prophylactic inactivation of CD11b/CD18, using the orthosteric CD11b/CD18 inhibitor mAb107, improves microvascular perfusion and histopathology, reduces intrarenal pro-inflammatory mediators and salvages kidney function long term. These studies reveal an important early role of CD11b⁺ leukocytes in post-ischaemic kidney fibrosis and failure, and suggest a potential early therapeutic intervention to mitigate progression of ischaemic AKI to CKD in humans.

Laparoscopic vs open donor nephrectomy: Lessons learnt from single academic center experience

AIM

To compare laparoscopic and open living donor nephrectomy, based on the results from a single center during a decade.

METHODS

This is a retrospective review of all living donor nephrectomies performed at the Massachusetts General Hospital, Harvard Medical School, Boston, between 1/1998 - 12/2009. Overall there were 490 living donors, with 279 undergoing laparoscopic living donor nephrectomy (LLDN) and 211 undergoing open donor nephrectomy (OLDN). Demographic data, operating room time, the effect of the learning curve, the number of conversions from laparoscopic to open surgery, donor preoperative glomerular filtration rate and creatinine (Cr), donor and recipient postoperative Cr, delayed graft function and donor complications were analyzed. Statistical analysis was performed.

RESULTS

Overall there was no statistically significant difference between the LLDN and the OLDN groups regarding operating time, donor preoperative renal function, donor and recipient postoperative kidney function, delayed graft function or the incidence of major complications. When the last 100 laparoscopic cases were analyzed, there was a statistically significant difference regarding operating time in favor of the LLDN, pointing out the importance of the learning curve. Furthermore, another significant difference between the two groups was the decreased length of stay for the LLDN (2.87 d for LLDN vs 3.6 d for OLDN).

CONCLUSION

Recognizing the importance of the learning curve, this paper provides evidence that LLDN has a safety profile comparable to OLDN and decreased length of stay for the donor.

Reproductive and Contraceptive Characteristics of Premenopausal Kidney Transplant Recipients

Objective

To obtain information on menstrual patterns before and after transplantation, desire for future pregnancy, and use of contraception among premenopausal kidney transplant recipients.

Study Design

This observational study collected information using self-administered anonymous questionnaires during a routine outpatient clinic visit.

Results

Of the 107 women who completed the questionnaire, 41 identified themselves as being premenopausal. Among the 41 premenopausal women, approximately half of the women reported their current menstrual patterns as normal and 26% were not using any form of contraception. Overall, 10 women (24%) reported a desire to become pregnant and 4 women (10%) had a successful pregnancy after transplantation. Most of the women who desired a future pregnancy (8/10) were receiving an immunosuppressive regimen that included mycophenolate mofetil.

Conclusion

Kidney transplantation in the current era is associated with a return of normal menstrual function in the majority of female transplant recipients. A substantial fraction of women desire pregnancy after transplantation and many are using an immunosuppressive drug with limited safety data on use during pregnancy. More caution should be used with the use of newer immunosuppressive agents in sexually active premenopausal transplant recipients until more safety data are available.

Induced regulatory T cells in allograft tolerance via transient mixed chimerism

Successful induction of allograft tolerance has been achieved in nonhuman primates (NHPs) and humans via induction of transient hematopoietic chimerism. Since allograft tolerance was achieved in these recipients without durable chimerism, peripheral mechanisms are postulated to play a major role. Here, we report our studies of T cell immunity in NHP recipients that achieved long-term tolerance versus those that rejected the allograft (AR). All kidney, heart, and lung transplant recipients underwent simultaneous or delayed donor bone marrow transplantation (DBMT) following conditioning with a nonmyeloablative regimen. After DBMT, mixed lymphocyte culture with CFSE consistently revealed donor-specific loss of CD8⁺ T cell responses in tolerant (TOL) recipients, while marked CD4⁺ T cell proliferation in response to donor antigens was found to persist. Interestingly, a significant proportion of the proliferated CD4⁺ cells were FOXP3⁺ in TOL recipients, but not in AR or naive NHPs. In TOL recipients, CD4⁺FOXP3⁺ cell proliferation against donor antigens was greater than that observed against third-party antigens. Finally, the expanded Tregs appeared to be induced Tregs (iTregs) that were converted from non-Tregs. These data provide support for the hypothesis that specific induction of iTregs by donor antigens is key to long-term allograft tolerance induced by transient mixed chimerism.

Effect of tolerance versus chronic immunosuppression protocols on the quality of life of kidney transplant recipients

BACKGROUND

Kidney transplant patients on tolerance protocols avoid the morbidity associated with the use of conventional chronic immunosuppressive regimens. However, the impact of tolerance versus conventional regimens on the quality of life (QOL) of kidney transplant patients is unknown.

METHODS

Five patients who achieved long-term immunosuppression-free renal allograft survival after combined kidney and bone marrow transplantation (tolerant group) were compared with thirty-two comparable kidney transplant recipients on conventional immunosuppression (conventional group). QOL was compared with 16 conventional recipients using the Kidney Disease Quality of Life Short Form 36 (KDQOL SF-36) and the Modified Transplant Symptom Occurrence and Symptom Distress Scale (MTSOSD-59R).

RESULTS

Patients in the tolerant group required significantly less treatment after transplant for hypertension and no medications for diabetes (P < 0.01). There was no incidence of diabetes, dyslipidemia, or malignancies in the tolerant group, while these were observed in 12.5%, 40.6%, and 11.8% of the conventional group, respectively. Tolerant patients experienced better overall health (P < 0.01) and scored higher on kidney transplant-targeted scales and healthy survey scales than patients in the conventional group according to the KDQOL SF-36 (P < 0.05). Tolerant patients were less likely to experience depression, dyspnea, excessive appetite/thirst, flatulence, hearing loss, itching, joint pain, lack of energy, muscle cramps, and lack of libido than conventional patients according to the MTSOSD-59R (P < 0.05).

CONCLUSION

Kidney transplant recipients who achieved tolerance experience significantly fewer incidences of complications, improved QOL, and fewer comorbid symptoms compared with patients on conventional immunosuppression. These results support the expanded use of tolerance protocols in kidney transplantation.

The Effects of Exogenous Administration of Human Coagulation Factors Following Pig-to-Baboon Liver Xenotransplantation

We sought to determine the effects of exogenous administration of human coagulation factors following pig-to-baboon liver xenotransplantation (LXT) using GalT-KO swine donors. After LXT, baboons received no coagulation factors (historical control, n = 1), bolus administration of a human prothrombin concentrate complex (hPCC; 2.5 mL/kg, n = 2), continuous infusion of hPCC (1.0 mL/h, n = 1) or continuous infusion of human recombinant factor VIIa (1 µg/kg per hour, n = 3). The historical control recipient demonstrated persistent thrombocytopenia despite platelet administration after transplant, along with widespread thrombotic microangiopathy (TMA). In contrast, platelet levels were maintained in bolus hPCC recipients; however, these animals quickly developed large-vessel thrombosis and TMA, leading to graft failure with shortened survival. Recipients of continuous coagulation factor administration experienced either stabilization or an increase in their circulating platelets with escalating doses. Furthermore, transfusion requirements were decreased, and hepatic TMA was noticeably absent in recipients of continuous coagulation factor infusions compared with the historical control and bolus hPCC recipients. This effect was most profound with a continuous, escalating dose of factor VIIa. Further studies are warranted because this regimen may allow for prolonged survival following LXT.

Longitudinal studies of a B cell-derived signature of tolerance in renal transplant recipients

Biomarkers of transplant tolerance would enhance the safety and feasibility of clinical tolerance trials and potentially facilitate management of patients receiving immunosuppression. To this end, we examined blood from spontaneously tolerant renal transplant recipients and patients enrolled in two interventional tolerance trials using flow cytometry and gene expression profiling. Using a previously reported tolerant cohort as well as newly identified tolerant patients, we confirmed our previous finding that tolerance was associated with increased expression of B cell-associated genes relative to immunosuppressed patients. This was not accounted for merely by an increase in total B cell numbers, but was associated with the increased frequencies of transitional and naïve B cells. Moreover, serial measurements of gene expression demonstrated that this pattern persisted over several years, although patients receiving immunosuppression also displayed an increase in the two most dominant tolerance-related B cell genes, IGKV1D-13 and IGLL-1, over time. Importantly, patients rendered tolerant via induction of transient mixed chimerism, and those weaned to minimal immunosuppression, showed similar increases in IGKV1D-13 as did spontaneously tolerant individuals. Collectively, these findings support the notion that alterations in B cells may be a common theme for tolerant kidney transplant recipients, and that it is a useful monitoring tool in prospective trials.

Transient mixed chimerism for allograft tolerance

Mixed chimerism discovered in Freemartin cattle by Ray Owen 70 years ago paved the way for research on immune tolerance. Since his discovery, significant progress has been made in the effort to induce allograft tolerance via mixed chimerism in various murine models. However, induction of persistent mixed chimerism has proved to be extremely difficult in major histocompatibility complex mismatched humans. Chimerism induced in humans tends to either disappear or convert to full donor chimerism, depending on the intensity of the conditioning regimen. Nevertheless, our studies in both NHPs and humans have clearly demonstrated that renal allograft tolerance can be induced by transient mixed chimerism. Our studies have shown that solid organ allograft tolerance via transient mixed chimerism 1) requires induction of multilineage hematologic chimerism, 2) depends on peripheral regulatory mechanisms, rather than thymic deletion, for long-term maintenance, 3) is organ specific (kidney and lung but not heart allograft tolerance are feasible). A major advantage of tolerance induction via transient mixed chimerism is exclusion of the risk of graft-versus-host disease. Our ongoing studies are directed toward improving the consistency of tolerance induction, reducing the morbidity of the conditioning regimen, substituting clinically available agents, such as Belatacept for the now unavailable anti-CD2 monoclonal antibody, and extending the protocol to recipients of deceased donor allografts.

Kidney Versus Islet Allograft Survival After Induction of Mixed Chimerism With Combined Donor Bone Marrow Transplantation

We have previously reported successful induction of transient mixed chimerism and long-term acceptance of renal allografts in MHC mismatched nonhuman primates. In this study, we attempted to extend this tolerance induction approach to islet allografts. A total of eight recipients underwent MHC mismatched combined islet and bone marrow (BM) transplantation after induction of diabetes by streptozotocin. Three recipients were treated after a nonmyeloablative conditioning regimen that included low-dose total body and thymic irradiation, horse Atgam (ATG), six doses of anti-CD154 monoclonal antibody (mAb), and a 1-month course of cyclosporine (CyA) (Islet A). In Islet B, anti-CD8 mAb was administered in place of CyA. In Islet C, two recipients were treated with Islet B, but without ATG. The results were compared with previously reported results of eight cynomolgus monkeys that received combined kidney and BM transplantation (Kidney A) following the same conditioning regimen used in Islet A. The majority of kidney/BM recipients achieved long-term renal allograft survival after induction of transient chimerism. However, prolonged islet survival was not achieved in similarly conditioned islet/BM recipients (Islet A), despite induction of comparable levels of chimerism. In order to rule out islet allograft loss due to CyA toxicity, three recipients were treated with anti-CD8 mAb in place of CyA. Although these recipients developed significantly superior mixed chimerism and more prolonged islet allograft survival (61, 103, and 113 days), islet function was lost soon after the disappearance of chimerism. In Islet C recipients, neither prolonged chimerism nor islet survival was observed (30 and 40 days). Significant improvement of mixed chimerism induction and islet allograft survival were achieved with a CyA-free regimen that included anti-CD8 mAb. However, unlike the kidney allograft, islet allograft tolerance was not induced with transient chimerism. Induction of more durable mixed chimerism may be necessary for induction of islet allograft tolerance.

Clinical significance of microscopic melanoma metastases in the nonhottest sentinel lymph nodes

IMPORTANCE

A practice gap exists in the surgical removal of sentinel lymph nodes, from removal of only the most radioactive (hottest) lymph node to removal of all lymph nodes with radioactivity greater than 10% of the hottest lymph node.

OBJECTIVE

To determine the clinical significance of melanoma in sentinel lymph nodes that are not the hottest sentinel node and to determine the risk for disease progression based on sentinel lymph node status and primary tumor characteristics.

DESIGN, SETTING, AND PARTICIPANTS

Consecutive patients with cutaneous melanoma with sentinel lymph nodes resected from January 5, 2004, to June 30, 2008, with a mean follow-up of 59 months, at Massachusetts General Hospital were included in this retrospective review. The last year of follow-up was 2012. The operative protocol led to resection of all sentinel lymph nodes with radioactivity greater than 10% of the hottest lymph node. The number of lymph nodes removed, technetium-99m counts for each sentinel lymph node, presence or absence of sentinel lymph node metastases, primary tumor characteristics, disease progression, and melanoma-specific survival were recorded.

MAIN OUTCOMES AND MEASURES

Microscopic melanoma metastases in the hottest and nonhottest sentinel lymph nodes and factors that correlate with disease progression and mortality.

RESULTS

A total of 1575 sentinel lymph nodes were analyzed in 475 patients. Ninety-one patients (19%) had positive sentinel lymph nodes. Of these, 72 (79%) had metastases in the hottest sentinel lymph node. Of 19 cases with tumor present, but not in the hottest sentinel lymph node, counts ranged from 26% to 97% of the hottest node. Progression occurred in 43% of patients with sentinel node metastasis, regardless of whether the hottest lymph node was positive. In patients with negative sentinel lymph nodes, 11% developed metastases beyond the sentinel lymph node basin and 3.4% recurred in the basin. Mitogenicity of the primary tumor was associated with mortality (odds ratio, 2.435; 95% CI, 1.351-4.391; P < .001). Removing only the hottest sentinel lymph node would have led to false-negative results in 19 of 475 (4%) of all patients and 19 of 91 patients (21%) with positive sentinel lymph nodes. The 8-year survival in patients with at least 1 positive sentinel lymph node was less than 55%. The presence of more than 1 mitosis per square millimeter in the primary cutaneous melanoma was associated with decreased survival.

CONCLUSIONS AND RELEVANCE

Microscopic melanoma metastases was associated with disease progression and mortality, whether present in the hottest sentinel lymph node or not. These observations emphasize the importance of removing the less hot nodes, addressing a practice gap in the surgical approach to patients with melanoma.

Competition in liver transplantation: helpful or harmful?

Improved outcomes of liver transplantation have led to increases in the numbers of US transplant centers and candidates on the list. The resultant and ever-expanding organ shortage has created competition among centers, especially in regions with multiple liver transplant programs. Multiple reports now document that competition among the country's transplant centers has led to the listing of increasingly high-risk patients and the utilization of more marginal liver allografts. The transplant and medical communities at large should carefully re-evaluate these practices and promote innovative approaches to restoring trust in the allocation of donor organs and confirming that there is nationwide conformity in the guidelines used for evaluating and listing potential candidates for this scarce resource.

Use of CTLA4Ig for induction of mixed chimerism and renal allograft tolerance in nonhuman primates

We have previously reported successful induction of renal allograft tolerance via a mixed chimerism approach in nonhuman primates. In those studies, we found that costimulatory blockade with anti-CD154 mAb was an effective adjunctive therapy for induction of renal allograft tolerance. However, since anti-CD154 mAb is not clinically available, we have evaluated CTLA4Ig as an alternative agent for effecting costimulation blockade in this treatment protocol. Two CTLA4Igs, abatacept and belatacept, were substituted for anti-CD154 mAb in the conditioning regimen (low dose total body irradiation, thymic irradiation, anti-thymocyte globulin and a 1-month posttransplant course of cyclosporine [CyA]). Three recipients treated with the abatacept regimen failed to develop comparable lymphoid chimerism to that achieved with anti-CD154 mAb treatment and these recipients rejected their kidney allografts early. With the belatacept regimen, four of five recipients developed chimerism and three of these achieved long-term renal allograft survival (>861, >796 and >378 days) without maintenance immunosuppression. Neither chimerism nor long-term allograft survival were achieved in two recipients treated with the belatacept regimen but with a lower, subtherapeutic dose of CyA. This study indicates that CD28/B7 blockade with belatacept can provide a clinically applicable alternative to anti-CD154 mAb for promoting chimerism and renal allograft tolerance.

Alefacept promotes immunosuppression-free renal allograft survival in nonhuman primates via depletion of recipient memory T cells

Renal allograft tolerance has been achieved in MHC-mismatched primates via nonmyeloablative conditioning beginning 6 days prior to planned kidney and donor bone marrow transplantation (DBMT). To extend the applicability of this approach to deceased donor transplantation, we recently developed a novel-conditioning regimen, the "delayed protocol" in which donor bone marrow (DBM) is transplanted several months after kidney transplantation. However, activation/expansion of donor-reactive CD8(+) memory T cells (TMEM) occurring during the interval between kidney and DBM transplantation impaired tolerance induction using this strategy. In the current study, we tested whether, Alefacept, a fusion protein which targets LFA-3/CD2 interactions and selectively depletes CD2(high) CD8(+) effector memory T cells (TEM) could similarly induce long-term immunosuppression-free renal allograft survival but avoid the deleterious effects of anti-CD8 mAb treatment. We found that Alefacept significantly delayed the expansion of CD2(high) cells including CD8(+) TEM while sparing naïve CD8(+) T and NK cells and achieved mixed chimerism and long-term immunosuppression-free renal allograft survival. In conclusion, elimination of CD2(high) T cells represents a promising approach to prevent electively the expansion/activation of donor-reactive TEM and promotes tolerance induction via the delayed protocol mixed chimerism approach.

Native portal vein embolization for persistent hyperoxaluria following kidney and auxiliary partial liver transplantation

Type 1 primary hyperoxaluria (PH1) causes renal failure, for which isolated kidney transplantation (KT) is usually unsuccessful treatment due to early oxalate stone recurrence. Although hepatectomy and liver transplantation (LT) corrects PH1 enzymatic defect, simultaneous auxiliary partial liver transplantation (APLT) and KT have been suggested as an alternative approach. APLT advantages include preservation of the donor pool and retention of native liver function in the event of liver graft loss. However, APLT relative mass may be inadequate to correct the defect. We here report the first case of native portal vein embolization (PVE) to increase APLT to native liver mass ratio (APLT/NLM-R). Following initial combined APLT-KT, both allografts functioned well, but oxalate plasma levels did not normalize. We postulated the inadequate APLT/NLM-R could be corrected by trans-hepatic native PVE. The resulting increased APLT/NLM-R decreased serum oxalate to normal levels within 1 month following PVE. We conclude that persistently elevated oxalate levels after combined APLT-KT for PH1 treatment, results from inadequate relative functional capacity. This can be reversed by partial native PVE to decrease portal flow to the native liver. This approach might be applicable to other scenarios where partial grafts have been transplanted to replace native liver function.

Prophylaxis of hepatitis B infection in solid organ transplant recipients

Rates of transmission of hepatitis B virus (HBV) infection from organ donors with HBV markers to recipients along with reactivation of HBV during immunosuppression following transplantation have fallen significantly with the advent of hepatitis B immune globulin (HBIg) and effective antiviral therapy. Although the availability of potent antiviral agents and HBIg has highly impacted the survival rate of HBV-infected patients after transplantation, the high cost associated with this practice represents a major financial burden. The availability of potent antivirals with high genetic barrier to resistance and minimal side effects have made it possible to recommend an HBIg-free prophylactic regimen in selected patients with low viral burden prior to transplant. Significant developments over the last two decades in the understanding and treatment of HBV infection necessitate a re-appraisal of the guidelines for prophylaxis of HBV infection in solid organ transplant recipients.

Laparoscopic living donor nephrectomy: is there a difference between using a left or a right kidney?

BACKGROUND

The goal of this study was to review the results of 279 laparoscopic living donor nephrectomies (LLDN) regarding outcomes of using the left or the right kidney.

METHODS

Among 279 patients who underwent LLDN between August 1998 and April 2009, 260 underwent a left (group L) and 19, a right (group R) nephrectomy. The two groups were compared regarding intra- and postoperative parameters, including pre- and postoperative renal function, length of surgery, conversion to an open approach, delayed graft function, and complications.

RESULTS

There were no significant differences between the two groups regarding preoperative glomerular filtration rate (L = 129.5 ± 32 mL/min versus group R = 127.3 ± 26 mL/min), length of surgery (group L = 228 ± 58 minutes versus group R = 226 ± 62 minutes group), postoperative donor creatinine (group L = 1.36 ± 0.9 mg/dL versus group R = 1.48 ± 0.8 mg/dL), conversion to open (group L = 6.6% versus group R = 5.3%), delayed graft function (group L = 7.2% versus group R = 6.3%) and recipient postoperative creatinine at 1 month (group L = 1.54 ± 1.4 mg/dL versus group R = 1.32 ± 1.1 mg/dL). There were three intraoperative donor complications in group L (bleeding in one donor required transfusion), and none in group R. Similarly, there was a great albeit not a significant difference in the number of major postoperative donor complications among group L (n = 16) versus group R (n = 2). The right kidney was chosen because of the number of vessels (n = 5), presence of cysts (n = 5), size and renal function (n = 6), presence of renal stones (n = 2), and tortuous ureter (n = 1). The reasons for conversion to open included bleeding, anatomic issues, and presence of adhesions. It should be noted that during the last 3 years there were no conversions to open, whereas the only conversion among group R was the first case.

CONCLUSIONS

Intra- and postoperative parameters were comparable between the groups. Considering the limitations of the small sample size of right LLDNs in this study, it appears that it is as safe and effective as a left procedure. The learning curve is extremely important, as can be seen by the lack of conversion in the last 3 years.

Up to 9-day survival and control of thrombocytopenia following alpha1,3-galactosyl transferase knockout swine liver xenotransplantation in baboons

BACKGROUND

With standard miniature swine donors, survivals of only 3 days have been achieved in primate liver-transplant recipients. The recent production of alpha1,3-galactosyl transferase knockout (GalT-KO) miniature swine has made it possible to evaluate xenotransplantation of pig organs in clinically relevant pig-to-non-human primate models in the absence of the effects of natural anti-Gal antibodies. We are reporting our results using GalT-KO liver grafts.

METHODS

We performed GalT-KO liver transplants in baboons using an immunosuppressive regimen previously used by our group in xeno heart and kidney transplantation. Post-operative liver function was assessed by laboratory function tests, coagulation parameters and histology.

RESULTS

In two hepatectomized recipients of GalT-KO grafts, post-transplant liver function returned rapidly to normal. Over the first few days, the synthetic products of the donor swine graft appeared to replace those of the baboon. The first recipient survived for 6 days and showed no histopathological evidence of rejection at the time of death from uncontrolled bleeding, probably caused by transfusion-refractory thrombocytopenia. Amicar treatment of the second and third recipients led to maintenance of platelet counts of over 40 000 per μl throughout their 9- and 8-day survivals, which represents the longest reported survival of pig-to-primate liver transplants to date. Both of the last two animals nevertheless succumbed to bleeding and enterococcal infection, without evidence of rejection.

CONCLUSIONS

These observations suggest that thrombocytopenia after liver xenotransplantation may be overcome by Amicar therapy. The coagulopathy and sepsis that nevertheless occurred suggest that additional causes of coagulation disturbance must be addressed, along with better prevention of infection, to achieve long-term survival.

Clinical strategy for induction of transplantation tolerance through mixed chimerism

Following the demonstration that transplant tolerance could be induced in non-human primate recipients treated with non-myeloablative conditioning that resulted in only transient chimerism, we began in 1998 to evaluate this approach first in patients with end stage renal disease (ESRD), secondary to multiple myeloma (MM). A total of 10 patients with ESRD and MM have been treated with this initial protocol. Only 2 recipients developed evidence of reversible renal allograft rejection after stopping immunosuppression. Long-term (up to 14 years) operational renal allograft tolerance has been observed in all 10 patients, even in those with transient hematopoietic chimerism. Control of the MM has been less complete, as recurrent disease developed in five of these patients, three of whom expired. Nevertheless, in view of the essentially 100% 3-5 year mortality typically expected with alternative treatments for this challenging population, it has been suggested that combined kidney and donor bone marrow transplantation (CKBMT) following non-myeloablative conditioning should become the standard therapy for patients with ESRD secondary to MM (27). These encouraging results, as well as the acceptable morbidity observed in cancer patients receiving non-myeloablative human leukocyte antigen (HLA)-mismatched bone marrow transplantation in our center, led us to next evaluate CKBMT in 10 patients of HLA-mismatched transplants. All 10 subjects developed transient chimerism and in seven of these, immunosuppression was successfully discontinued. Four subjects continue to be immunosuppression free for periods of 4.5-11 years, while in three, reinstitution of immunosuppression was advised or accomplished after 5-8 years due to recurrence of original disease or chronic antibody mediated rejection. Donor-specific antibodies were frequently detectable in the earlier recipients. In contrast, no donor-specific antibodies were detected after immunosuppression was discontinued in the last four subjects, who showed more consistent and durable B-cell depletion. In conclusion, our studies have shown that immunosuppression-free renal allograft survival can be achieved in both HLAmatched and mismatched donor-recipient pairs, with follow up times now of greater than 14 years after induction of transient chimerism through CKBMT.

Liver transplantation results in complete neurologic recovery from malignant hypertension secondary to fulminant hepatic failure: a case report

BACKGROUND

Uncontrolled intracranial hypertension can lead to cerebral herniation and death in patients with acute liver failure.

CASE REPORT

A 26-year-old female was admitted for acute liver failure following inadvertent acetaminophen overdose. The pH on admission was 6.9. Her neurologic status precipitously deteriorated and she was listed for liver transplantation. An intracranial pressure (ICP) monitoring catheter was inserted, which revealed a pressure >60 mmHg. After neurointensive care treatment, ICP was lowered and an emergency left lobe living donor liver transplant was performed. Intraoperative management of the ICP, which rose to 80 mmHg during the explant phase, was achieved by therapy with barbiturates and hypothermia. After surgery, hepatic function improved initially, but 7 days post transplantation the graft showed signs of acute failure. The pathology report of a liver biopsy suggested acute rejection and liver retransplantation using a deceased donor liver was then carried out. The postoperative course was uneventful and the patient recovered completely without any residual neurologic deficits.

CONCLUSIONS

This case states that favourable outcomes can result from sub-optimal starting points, and that the human brain has the ability to overcome extremely adverse conditions. Critical in this effort is the role of proper neuromonitoring which helps implement the appropriate treatment measures.

Differential effects of denileukin diftitox IL-2 immunotoxin on NK and regulatory T cells in nonhuman primates

Denileukin diftitox (DD), a fusion protein comprising IL-2 and diphtheria toxin, was initially expected to enhance antitumor immunity by selectively eliminating regulatory T cells (Tregs) displaying the high-affinity IL-2R (α-β-γ trimers). Although DD was shown to deplete some Tregs in primates, its effects on NK cells (CD16(+)CD8(+)NKG2A(+)CD3(-)), which constitutively express the intermediate-affinity IL-2R (β-γ dimers) and play a critical role in antitumor immunity, are still unknown. To address this question, cynomolgus monkeys were injected i.v. with two doses of DD (8 or 18 μg/kg). This treatment resulted in a rapid, but short-term, reduction in detectable peripheral blood resting Tregs (CD4(+)CD45RA(+)Foxp3(+)) and a transient increase in the number of activated Tregs (CD4(+)CD45RA(-)Foxp3(high)), followed by their partial depletion (50-60%). In contrast, all NK cells were deleted immediately and durably after DD administration. This difference was not due to a higher binding or internalization of DD by NK cells compared with Tregs. Coadministration of DD with IL-15, which binds to IL-2Rβ-γ, abrogated DD-induced NK cell deletion in vitro and in vivo, whereas it did not affect Treg elimination. Taken together, these results show that DD exerts a potent cytotoxic effect on NK cells, a phenomenon that might impair its antitumoral properties. However, coadministration of IL-15 with DD could alleviate this problem by selectively protecting potentially oncolytic NK cells, while allowing the depletion of immunosuppressive Tregs in cancer patients.

Contributions of direct and indirect alloresponses to chronic rejection of kidney allografts in nonhuman primates

The relative contribution of direct and indirect allorecognition pathways to chronic rejection of allogeneic organ transplants in primates remains unclear. In this study, we evaluated T and B cell alloresponses in cynomolgus monkeys that had received combined kidney/bone marrow allografts and myeloablative immunosuppressive treatments. We measured donor-specific direct and indirect T cell responses and alloantibody production in monkeys (n = 5) that did not reject their transplant acutely but developed chronic humoral rejection (CHR) and in tolerant recipients (n = 4) that never displayed signs of CHR. All CHR recipients exhibited high levels of anti-donor Abs and mounted potent direct T cell alloresponses in vitro. Such direct alloreactivity could be detected for more than 1 y after transplantation. In contrast, only two of five monkeys with CHR had a detectable indirect alloresponse. No indirect alloresponse by T cells and no alloantibody responses were found in any of the tolerant monkeys. Only one of four tolerant monkeys displayed a direct T cell alloresponse. These observations indicate that direct T cell alloresponses can be sustained for prolonged periods posttransplantation and result in alloantibody production and chronic rejection of kidney transplants, even in the absence of detectable indirect alloreactivity.

Acute renal endothelial injury during marrow recovery in a cohort of combined kidney and bone marrow allografts

An idiopathic capillary leak syndrome ('engraftment syndrome') often occurs in recipients of hematopoietic cells, manifested clinically by transient azotemia and sometimes fever and fluid retention. Here, we report the renal pathology in 10 recipients of combined bone marrow and kidney allografts. Nine developed graft dysfunction on day 10-16 and renal biopsies showed marked acute tubular injury, with interstitial edema, hemorrhage and capillary congestion, with little or no interstitial infiltrate (≤10%) and marked glomerular and peritubular capillary (PTC) endothelial injury and loss by electron microscopy. Two had transient arterial endothelial inflammation; and 2 had C4d deposition. The cells in capillaries were primarily CD68(+) MPO(+) mononuclear cells and CD3(+) CD8(+) T cells, the latter with a high proliferative index (Ki67(+) ). B cells (CD20(+) ) and CD4(+) T cells were not detectable, and NK cells were rare. XY FISH showed that CD45(+) cells in PTCs were of recipient origin. Optimal treatment remains to be defined; two recovered without additional therapy, six were treated with anti-rejection regimens. Except for one patient, who later developed thrombotic microangiopathy and one with acute humoral rejection, all fully recovered within 2-4 weeks. Graft endothelium is the primary target of this process, attributable to as yet obscure mechanisms, arising during leukocyte recovery.

Host alloreactive memory T cells influence tolerance to kidney allografts in nonhuman primates

Transplant tolerance, defined as indefinite allograft survival without immunosuppression, has been regularly achieved in laboratory mice but not in nonhuman primates or humans. In contrast to laboratory mice, primates regularly have high frequencies of alloreactive memory T cells (TMEMs) before transplantation. These TMEMs are poorly sensitive to conventional immunosuppression and costimulation blockade, and the presence of donor-reactive TMEMs in primates may account for their resistance to transplant tolerance protocols that have proven consistently effective in mice. We measured the frequencies of anti-donor TMEMs before and after transplantation in a series of rejecting and tolerant monkeys that underwent nonmyeloablative conditioning, short-term immunosuppression, and combined allogeneic kidney/cell transplantation. Transplants were acutely rejected in all the monkeys with high numbers of donor-specific TMEMs before transplantation. In contrast, long-term survival was observed in the recipients harboring lower frequencies of anti-donor TMEMs before transplantation. Similar amounts of TMEM homeostatic expansion were recorded in all transplanted monkeys upon hematopoietic reconstitution; however, only the tolerant monkeys had no expansion or activation of donor-reactive TMEMs after transplantation. These results indicate that the presence of high frequencies of host donor-reactive TMEMs before transplantation impairs tolerance induction to kidney allografts in this nonhuman primate model. Indeed, recipients harboring a low anamnestic reactivity to their donor before transplantation were successfully rendered tolerant via infusion of donor cells and short-term immunosuppression. This suggests that selection of allogeneic donors with low memory responses in recipients may be essential to successful transplant tolerance induction in patients.

Immuno-intervention for the induction of transplantation tolerance through mixed chimerism

The induction of transplantation tolerance could liberate organ transplant recipients from the complications of life-long chronic immunosuppression. The original description of tolerance induction through mixed hematopoietic chimerism in mice utilized lethal whole body irradiation as the preparative regimen for achieving mixed chimerism. While such a regimen might be acceptable for treatment of patients with malignancies, which might also respond to the therapeutic effects of radiation, its toxicity would be unacceptable for patients in need only of an organ transplant. Graft-vs.-host disease, which is frequently a complication of mismatched bone marrow transplantation, would likewise be unacceptable for ordinary clinical transplantation. Therefore, as we have extended the use of this modality for tolerance induction from mice to large animal models, we have attempted to design preparative regimens that avoid both of these complications. In this article, we review our studies of mixed chimerism in mice, miniature swine and monkeys, as well as the results of our recent clinical studies that have extended this treatment modality to a series of kidney transplant patients who have been successfully weaned from all immunosuppression while maintaining stable renal function for up to 8 years.

Dendritic cell maturation occurs through the inhibition of GSK-3β

Dendritic cell (DC) maturation results in changes in antigen processing and presentation, governing the fate of adaptive immunity. Understanding the intracellular signaling pathways governing DC maturation is therefore critical. In this study, we observed that the kinase, GSK-3β, is present in its active form in resting immature DCs isolated from the spleen and bone marrow of mice. Induction of DC maturation using GM-CSF, IL-4 and TNF-α resulted in GSK-3β inhibition, as reflected by increased phosphorylation of Serine 9 on the kinase, and concomitant stabilization of its substrate, β-catenin. Treatment of immature DCs with a GSK-3β inhibitor increased cell surface expression of CD80, CD86 and CD40 on DCs, enhancing their ability to present antigen and activating IL-2 secretion by T cells. GSK-3β inhibition also parallels dendritic cell maturation in vivo. Our results show that GSK-3β signaling controls DC maturation and suggest that this kinase could be manipulated to modulate adaptive immunity.

Partial abdominal evisceration and intestinal autotransplantation to resect a mesenteric carcinoid tumor

Background

Midgut carcinoids are neuroendocrine tumors that commonly metastasize to the intestinal mesentery, where they predispose to intestinal obstruction, ischemia and/or congestion. Because of their location, many mesenteric carcinoid tumors are deemed unresectable due to the risk of uncontrollable bleeding and prolonged intestinal ischemia.

Case Presentation

We report the case of a 60-year-old male with a mesenteric carcinoid tumor obstructing his superior mesenteric vein, resulting in intestinal varices and severe recurrent GI bleeds. While his tumor was thought to be unresectable by conventional techniques, it was successfully resected using intestinal autotransplantation to safely gain access to the tumor. This case is the first described application of this technique to carcinoid tumors.

Conclusions

Intestinal autotransplantation can be utilized to safely resect mesenteric carcinoid tumors from patients who were not previously thought to be surgical candidates. We review the literature concerning both carcinoid metastases to the intestinal mesentery and the use of intestinal autotransplantation to treat lesions involving the mesenteric root.

Changing pattern of organ donation at a single center: are potential brain dead donors being lost to donation after cardiac death?

Donation after cardiac death (DCD) has proven effective at increasing the availability of organs for transplantation.We performed a retrospective examination of Massachusetts General Hospital (MGH) records of all 201 donors from 1/1/98 to the 11/2008, including 54 DCD, 115 DBD and 32 DCD candidates that did not progress to donation (DCD-dnp). Comparing three time periods, era 1 (01/98-12/02), era 2 (01/03-12/05) and era 3 (01/06-11/08), DCD’s comprised 14.8,48.4% and 60% of donors, respectively (p = 0.002). A significant increase in the incidence of cardiovascular/cerebrovascular as cause of death was evident in era 3 versus eras 1 and 2; 74% versus 57.1% (p<0.001),as was a corresponding decrease in the incidence of traumatic death. Interestingly, we noted an increase in utilization of aggressive neurological management over time, especially in the DCD group.We detected significant changes in the make-up of the donor pool over the past decade. That the changes in diagnosis over time did not differ between DCD and DBD groups suggests this difference is not responsible for the increase in DCD rates. Instead, we suggest that changes in clinical practice, especially in management of patients with severe brain injury may account for the increased proportion of DCD.

Induction of tolerance in clinical kidney transplantation

Induction of donor-specific tolerance has been an ultimate goal in organ transplantation. Although numerous regimens for the induction of allograft tolerance have been developed in rodents, their application to primates has been limited. The approaches that have been successfully applied in primates can be divided into (i) use of total lymphoid irradiation, (ii) costimulatory blockade, (iii) profound depletion of recipient T cells, (iv) infusion of regulatory cells and (v) donor bone marrow (DBM) infusion/transplantation. Among these approaches, successful allograft tolerance has been achieved in clinical kidney transplantation using DBM transplantation.

Suppressive regulatory T cell activity is potentiated by glycogen synthase kinase 3{beta} inhibition

The mechanism by which regulatory T (Treg) cells suppress the immune response is not well defined. A recent study has shown that β-catenin prolongs Treg cell survival. Because β-catenin is regulated by glycogen synthase kinase 3β (GSK-3β)-directed phosphorylation, we focused on GSK-3β and the role it plays in Treg cell function. Inhibition of GSK-3β led to increased suppression activity by Treg cells. Inhibitor-treated Treg cells exhibited prolonged FoxP3 expression and increased levels of β-catenin and of the antiapoptotic protein Bcl-xL. Systemic administration of GSK-3β inhibitor resulted in prolonged islet survival in an allotransplant mouse model. Our data suggest that GSK-3β could be a useful target in developing strategies designed to increase the stability and function of Treg cells for inducing allotransplant tolerance or treating autoimmune conditions.

Stem cell mobilization and collection for induction of mixed chimerism and renal allograft tolerance in cynomolgus monkeys

BACKGROUND

We have previously observed that donor bone marrow hematopoietic stem cells successfully induce transient mixed chimerism and renal allograft tolerance following non-myeloablative conditioning of the recipient. Stem cells isolated from the peripheral blood (PBSC) may provide similar benefits. We sought to determine the most effective method of mobilizing PBSC for this approach and the effects of differing conditioning regimens on their engraftment.

METHODS

A standard dose (10 μg/kg) or high dose (100 μg/kg) of granulocyte colony-stimulating factor (GCSF) with or without stem cell factor (SCF) was administered to the donor, and PBSC were collected by leukapheresis. Cynomolgus monkey recipients underwent a nonmyeloablative conditioning regimen (total body irradiation, thymic irradiation, and ATG) with splenectomy (splenectomy group) or a short course of anti-CD154 antibody (aCD154) (aCD154 group). Recipients then received combined kidney and PBSC transplantation and a 1-mo post-transplant course of cyclosporine.

RESULTS

Treatments with either two cytokines (GCSF+SCF) or high dose GCSF provided significantly more hematopoietic progenitor cells than standard dose GCSF alone. Recipients in the aCD154 group developed significantly higher myeloid and lymphoid chimerism (P < 0.0001 and P = 0.0002, respectively) than those in the splenectomy group. Longer term renal allograft survival without immunosuppression was also observed in the aCD154 group, while two of three recipients in the splenectomy group rejected their allografts soon after discontinuation of immunosuppression.

CONCLUSIONS

Protocols including administration of two cytokines (GCSF + SCF) or high dose GCSF alone significantly mobilized more PBSC than standard dose GCSF alone. The recipients of PBSC consistently developed excellent chimerism and survived long-term without immunosuppression, when treated with CD154 blockade.

Biliary reconstruction and complications after living-donor liver transplantation

BACKGROUND

The technique of biliary reconstruction remains controversial in living-donor liver transplantation (LDLT). The objective of this study was to assess the incidence of biliary complications after LDLT based on the reconstruction technique.

METHODS

Between 1997 and 2007, 30 patients underwent LDLT. The type of allograft was the right lobe in 15, left lobe in 4 and left lateral sector in 11 patients. There were 18 adult and 12 paediatric recipients. The mean follow-up was 48 months (range 18-120 months). Biliary complications were defined as leak or stricture requiring intervention.

RESULTS

Biliary reconstruction was achieved with Roux-en-Y choledochojejunostomy (RYCJ) in 17 patients and duct-to-duct (DD) anastomosis in 13 patients. An external biliary stent was placed in all patients (except one) in the RYCJ group and reconstruction over a T-tube was done in 6 out of 13 patients in the DD Group. Twenty-five (83.3%) patients had one biliary anastomosis and the remaining five (16.7%) had multiple anastomoses (one in the RYCJ group and four in the DD group). The overall incidence of biliary complications was 30%.; 29.4% in the RYCJ group and 38.4% in the DD group (P = 0.6). Biliary complications occurred equally in patients with and without an external stent or T-tube stenting (12.5% vs. 18.8%). The incidence of biliary leakage was 23.5% for RYCJ and 15.3% for DD (P = 0.4). Although the incidence of biliary stricture was significantly higher in the DD (23.1%) compared with the RYCY group (5.9 %) (P < 0.01), all DDCC strictures were successfully managed endoscopically. Need for operative revision of biliary anastomoses was significantly higher in patients with RYCY compared with DD reconstruction; 17.7% vs. 7.7% (P < 0.01).

CONCLUSIONS

Although there was a higher rate of biliary stricture formation in the DDCC group, we feel that because of physiological bilioenteric continuity, comparable incidence of leakage and easy endoscopic access, DD reconstruction is the preferred approach for biliary drainage in LDLT. After LDLT, the endoscopic approach has been shown to provide effective treatment of most biliary complications.

Transplant center regulations--a mixed blessing? An ASTS Council viewpoint

The Centers for Medicare and Medicaid Services (CMS) has developed a set of regulations that spell out the Conditions of Participation (CoPs) for provider hospitals that wish to be certified (and thus eligible for reimbursement) by Medicare for transplant services. The American Society of Transplant Surgeons (ASTS) Council has played a major role in providing CMS with advice and guidance in the development and ongoing implementation of these conditions through a process of fruitful dialogue. In this report, we highlight the events that led to the development of the regulations and describe the process to date in implementing the CoPs. We have raised some important questions regarding the effectiveness of the regulations for improving safety, and we have highlighted the cost associated with their implementation. This report has been vetted by and represents the opinions of the Council of the ASTS.

Impact of donor kidney recovery method on lymphatic complications in kidney transplantation

INTRODUCTION

Prolonged lymphatic drainage and lymphocele are undesirable complications following kidney transplantation. We evaluated the impact of kidney recovery methods (deceased donor vs laparoscopic nephrectomy) on the lymphatic complications of the kidney transplant recipients.

METHOD

The incidence of lymphatic complications was retrospectively analyzed in recipients of deceased donor kidneys (DD, n = 62) versus laparoscopically procured kidneys from living donors (LP, n = 61). A drain was placed in the retroperitoneal space in all recipients. The drain was maintained until the output became less than 30 mL/d with no evidence of fluid collection by ultrasound examination.

RESULTS

There was no statistically significant difference in the patient demographics (age, gender, and original disease and procedure time) between two groups. The incidence of lymphocele that required therapeutic intervention was comparable in both groups (3.2%). However, the duration of drain placement was significantly longer in the LP group than in the DD group, 8.6 +/- 2.5 days versus 5.4 +/- 2.5 day, respectively (P < .05).

CONCLUSION

The recipients of laparoscopically removed kidneys had a higher incidence of prolonged lymphatic leakage. More meticulous back table preparation may be required in LP kidneys to prevent prolonged lymphatic drainage after kidney transplantation. These observations may indicate that the major source of persistent lymphatic leakage is lymphatics of the allograft rather than severed recipient lymphatics.

Prospective study of liver transplant recipients with HCV infection: evidence for a causal relationship between HCV and insulin resistance

An association between hepatitis C virus (HCV) infection and insulin resistance (IR) has been recently reported. However, causality has not been established. The cross-sectional nature of most reported studies and varying degrees of fibrosis have limited definitive conclusions about the independent role of HCV in development of IR. We sought to evaluate whether HCV induces IR by prospectively analyzing a cohort of adult liver transplant (LT) recipients. A total of 34 adults (14 HCV(+) and 20 HCV(-)) who underwent consecutive LT were followed during the first year posttransplantation. IR was estimated using the homeostasis model assessment (HOMA). Univariate and multivariate repeated measures analyses and Cox regression models were used. There were no significant differences between the groups with respect to age, body mass index (BMI), family history of diabetes, alcohol consumption, or laboratory indices. The cohort had no or minimal fibrosis. There was lower prednisone use in the HCV(+) group, and no difference in the use of tacrolimus between the two groups was found. IR was 77% higher in HCV(+) subjects during the first year post-LT when controlling for BMI (P = 0.035). Subjects with high HCV ribonucleic acid (RNA) levels reached high HOMA-IR significantly earlier than those with lower HCV RNA (P = 0.03). Following the first month post-LT, HCV(+) subjects were 4 times more likely to become diabetic than HCV(-) controls (P < 0.01). In conclusion, there is significantly higher IR in the HCV(+) group during the first year post-LT. This cannot be explained by differences in BMI, medications used, alcohol consumption, or degree of fibrosis. Higher HCV RNA levels were associated with earlier elevations in HOMA-IR. Collectively, these results provide strong evidence that HCV induces the development of IR.

HLA-mismatched renal transplantation without maintenance immunosuppression

Five patients with end-stage renal disease received combined bone marrow and kidney transplants from HLA single-haplotype mismatched living related donors, with the use of a nonmyeloablative preparative regimen. Transient chimerism and reversible capillary leak syndrome developed in all recipients. Irreversible humoral rejection occurred in one patient. In the other four recipients, it was possible to discontinue all immunosuppressive therapy 9 to 14 months after the transplantation, and renal function has remained stable for 2.0 to 5.3 years since transplantation. The T cells from these four recipients, tested in vitro, showed donor-specific unresponsiveness and in specimens from allograft biopsies, obtained after withdrawal of immunosuppressive therapy, there were high levels of P3 (FOXP3) messenger RNA (mRNA) but not granzyme B mRNA.