Splenic Vein Thrombosis Following Pancreas Transplantation: Identification of Factors That Support Conservative Management.

Prophylaxis for graft portal/splenic venous thrombosis following pancreas transplant varies between institutions. Similarly, treatment of venous thrombosis ranges from early re-exploration to conservative management with anticoagulation. We wished to determine the prevalence of graft splenic vein (SV) thrombosis, as well as the clinical significance of non-occlusive thrombus observed on routine imaging. Records of 112 pancreas transplant recipients over a 5-year period at a single center were reviewed. Venous thrombosis was defined as absence of flow or presence of thrombus identified in any part of the graft SV on ultrasound. Thirty patients (27%) had some degree of thrombus or absence of flow in the SV on postoperative ultrasound. There were 5 graft losses in this group. Four were due to venous thrombosis, and occurred within 20 days of transplant. All patients with non-occlusive partial SV thrombus but normal arterial signal on Doppler ultrasound were successfully treated with IV heparin followed by warfarin for 3-6 months, and remained insulin independent. Findings of arterial signal abnormalities, such as absence or reversal of diastolic flow within the graft, require urgent operative intervention since this finding can be associated with more extensive thrombus that may lead to graft loss.

Pancreas-After-Islet Transplantation in Nonuremic Type 1 Diabetes: A Strategy for Restoring Durable Insulin Independence.

Islet transplantation offers a minimally invasive approach for ß cell replacement in diabetic patients with hypoglycemic unawareness. Attempts at insulin independence may require multiple islet reinfusions from distinct donors, increasing the risk of allogeneic sensitization. Currently, solid organ pancreas transplant is the only remaining surgical option following failed islet transplantation in the United States; however, the immunologic impact of repeated exposure to donor antigens on subsequent pancreas transplantation is unclear. We describe a case series of seven patients undergoing solid organ pancreas transplant following islet graft failure with long-term follow-up of pancreatic graft survival and renal function. Despite highly variable panel reactive antibody levels prior to pancreas transplant (mean 27 ± 35%), all seven patients achieved stable and durable insulin independence with a mean follow-up of 6.7 years. Mean hemoglobin A1c values improved significantly from postislet, prepancreas levels (mean 8.1 ± 1.5%) to postpancreas levels (mean 5.3 ± 0.1%; p = 0.0022). Three patients experienced acute rejection episodes that were successfully managed with thymoglobulin and methylprednisolone, and none of these preuremic type 1 diabetic recipients developed stage 4 or 5 chronic kidney disease postoperatively. These results support pancreas-after-islet transplantation with aggressive immunosuppression and protocol biopsies as a viable strategy to restore insulin independence after islet graft failure.

Under Utilization of Pancreas Transplants in Cystic Fibrosis Recipients in the United Network Organ Sharing (UNOS) Data 1987-2014.

Despite a high prevalence of pancreatic endocrine and exocrine insufficiency in cystic fibrosis (CF), pancreas transplantation is rarely reported. United Network for Organ Sharing (UNOS) data were used to examine utilization of pancreas transplant and posttransplant outcomes in CF patients. Between 1987-2014, CF patients (N = 4600) underwent 17 liver-pancreas, three lung-pancreas, one liver-lung pancreas, four kidney-pancreas, and three pancreas-only transplants. Of the 303 CF patients who received liver transplantation, 20% had CF-related diabetes (CFRD) before transplantation, and nine of those received a liver-pancreas transplant. Of 4241 CF patients who underwent lung transplantation, 33% had CFRD before transplantation, and three of those received a pancreas transplant. Of 49 CF patients who received a liver-lung transplant, 57% had CFRD before transplantation and one received a pancreas transplant. Posttransplantation diabetes developed in 7% of CF pancreas transplant recipients versus 24% of CF liver and 29% of CF lung recipients. UNOS has no data on pancreas exocrine insufficiency. Two-year posttransplantation survival was 88% after liver-pancreas transplant, 33% after lung-pancreas transplant, and 100% after pancreas-kidney and pancreas-only transplants. Diabetes is common pretransplantation and posttransplantation in CF solid organ transplant recipients, but pancreas transplantation remains rare. Further consideration of pancreas transplant in CF patients undergoing other solid organ transplant may be warranted.

A Comparative Analysis of the Safety, Efficacy, and Cost of Islet Versus Pancreas Transplantation in Nonuremic Patients With Type 1 Diabetes.

Few current studies compare the outcomes of islet transplantation alone (ITA) and pancreas transplantation alone (PTA) for type 1 diabetes (T1D). We examined these two beta cell replacement therapies in nonuremic patients with T1D with respect to safety, graft function and cost. Sequential patients received PTA (n = 15) or ITA (n = 10) at our institution. Assessments of graft function included duration of insulin independence; glycemic control, as measured by hemoglobin A1c; and elimination of severe hypoglycemia. Cost analysis included all normalized costs associated with transplantation and inpatient management. ITA patients received one (n = 6) or two (n = 4) islet transplants. Mean duration of insulin independence in this group was 35 mo; 90% were independent at 1 year, and 70% were independent at 3 years. Mean duration of insulin independence in PTA was 55 mo; 93% were insulin independent at 1 year, and 64% were independent at 3 years. Glycemic control was comparable in all patients with functioning grafts, as were overall costs ($138 872 for ITA, $134 748 for PTA). We conclude that with advances in islet isolation and posttransplant management, ITA can produce outcomes similar to PTA and represents a clinically viable option to achieve long-term insulin independence in selected patients with T1D.

Effect of Immigration Status on Outcomes in Pediatric Kidney Transplant Recipients.

Kidney transplantation is the optimal treatment for children with end-stage renal disease. For children with undocumented immigration status, access to kidney transplantation is limited, and data on transplant outcomes in this population are scarce. The goal of the present retrospective single-center study was to compare outcomes after kidney transplantation in undocumented children with those of US citizen children. Undocumented residency status was identified in 48 (17%) of 289 children who received a kidney transplant between 1998 and 2010. In undocumented recipients, graft survival at 1 and 5 years posttransplantation was similar, and mean estimated glomerular filtration rate at 1 year was higher than that in recipients who were citizens. The risk of allograft failure was lower in undocumented recipients relative to that in citizens at 5 years posttransplantation, after adjustment for patient age, donor age, donor type, and HLA mismatch (p < 0.04). In contrast, nearly one in five undocumented recipients who reached 21 years of age lost their graft, primarily because they were unable to pay for immunosuppressive medications once their state-funded insurance had ended. These findings support the ongoing need for immigration policies for the undocumented that facilitate access to work-permits and employment-related insurance for this disadvantaged group.

Islet product characteristics and factors related to successful human islet transplantation from the Collaborative Islet Transplant Registry (CITR) 1999-2010.

The Collaborative Islet Transplant Registry (CITR) collects data on clinical islet isolations and transplants. This retrospective report analyzed 1017 islet isolation procedures performed for 537 recipients of allogeneic clinical islet transplantation in 1999-2010. This study describes changes in donor and islet isolation variables by era and factors associated with quantity and quality of final islet products. Donor body weight and BMI increased significantly over the period (p<0.001). Islet yield measures have improved with time including islet equivalent (IEQ)/particle ratio and IEQs infused. The average dose of islets infused significantly increased in the era of 2007-2010 when compared to 1999-2002 (445.4±156.8 vs. 421.3±155.4×0(3) IEQ; p<0.05). Islet purity and total number of ß cells significantly improved over the study period (p<0.01 and <0.05, respectively). Otherwise, the quality of clinical islets has remained consistently very high through this period, and differs substantially from nonclinical islets. In multivariate analysis of all recipient, donor and islet factors, and medical management factors, the only islet product characteristic that correlated with clinical outcomes was total IEQs infused. This analysis shows improvements in both quantity and some quality criteria of clinical islets produced over 1999-2010, and these parallel improvements in clinical outcomes over the same period.

Combined pancreatic islet and kidney transplantation in a child with unstable type 1 diabetes and end-stage renal disease.

Islet transplantation after successful kidney transplantation is a recognized treatment for adults with diabetes and end-stage renal disease (ESRD), but has not been considered an option in the pediatric population. To our knowledge, we report the first combined islet and kidney transplant in a child. The patient was born with bilateral renal hypoplasia and was diagnosed with type 1 diabetes mellitus at age 13 months. He had erratic glycemic control and hypoglycemia unawareness. At 6 years of age, the child safely underwent simultaneous islet and live donor kidney transplantation. Although function of the islet graft was transient, the combined transplant provided significant benefits in terms of glucose control and overall growth and development. Such an approach represents a viable treatment option for pediatric patients with ESRD and unstable diabetes.

Islet transplantation in type 1 diabetics using an immunosuppressive protocol based on the anti-LFA-1 antibody efalizumab.

The applicability of islet transplantation as treatment for type 1 diabetes is limited by renal and islet toxicities of currently available immunosuppressants. We describe a novel immunosuppressive regimen using the antileukocyte functional antigen-1 antibody efalizumab which permits long-term islet allograft survival while reducing the need for corticosteroids and calcineurin inhibitors (CNI). Eight patients with type 1 diabetes and hypoglycemic unawareness received intraportal allogeneic islet transplants. Immunosuppression consisted of antithymocyte globulin induction followed by maintenance with efalizumab and sirolimus or mycophenolate. When efalizumab was withdrawn from the market in mid 2009, all patients were transitioned to regimens consisting of mycophenolate and sirolimus or mycophenolate and tacrolimus. All patients achieved insulin independence and four out of eight patients became independent after single-islet transplants. Insulin independent patients had no further hypoglycemic events, hemoglobin A1c levels decreased and renal function remained stable. Efalizumab was well tolerated and no serious adverse events were encountered. Although long-term follow-up is limited by discontinuation of efalizumab and transition to conventional imunnosuppression (including CNI in four cases), these results demonstrate that insulin independence after islet transplantation can be achieved with a CNI and steroid-free regimen. Such an approach may minimize renal and islet toxicity and thus further improve long-term islet allograft survival.

Prevention of autoimmune diabetes in the BB rat by intrathymic islet transplantation at birth.

Spontaneous diabetes in the BioBreeding (BB) rat, like human type I diabetes, results from the destruction of pancreatic islets by autoreactive T lymphocytes recognizing beta cell-specific antigens. T cell tolerance is in part mediated by interactions of maturing thymocytes with antigens expressed in the thymic microenvironment; islets were therefore implanted into the thymus of neonatal diabetes-prone BB rats to determine whether exposure of T cell precursors to beta cell antigens could influence the development of diabetes. This treatment completely prevented diabetes and insulitis in the native pancreas. The effect may be the result of specific modulation of diabetogenic T cells maturing in an islet-bearing thymus.

Induction of donor-specific unresponsiveness by intrathymic islet transplantation.

The application of isolated pancreatic islet transplantation for treatment of diabetes mellitus has been hampered by the vulnerability of islet allografts to immunologic rejection. Rat islet allografts that were transplanted into the thymus of recipients treated with a single injection of anti-lymphocyte serum survived indefinitely. A state of donor-specific unresponsiveness was achieved that permitted survival of a second donor strain islet allograft transplanted to an extrathymic site. Maturation of T cell precursors in a thymic microenvironment that is harboring foreign alloantigen may induce the selective unresponsiveness. This model provides an approach for pancreatic islet transplantation and a potential strategy for specific modification of the peripheral immune repertoire.

Human albumin preserves islet mass and function better than whole serum during pretransplantation islet culture.

OBJECTIVE: Human islet transplant protocols frequently include a brief period of islet culture before transplantation. Some investigators have suggested that medium supplementation with human serum might quench collagenase activity and provide better culture conditions when compared with human albumin. We studied the effect of whole serum on islet count, islet equivalence, insulin secretion, and DNA content in human islets. METHODS: Adult human islets isolated from a single pancreas with purity >50% were cultured in identical 150 islet equivalent samples at 37 degrees C using CMRL 1066-based islet medium (Mediatech) supplemented with either 0.5% human albumin or 10% human AB serum. Prior to culture and after 3 days, islets were assessed in vitro using dithizone staining (n = 4), insulin release after static glucose stimulation (n = 8), and DNA content (n = 8). RESULTS: After 3 days, islet mass (defined by the number of islets and islet equivalents counted after dithizone staining) was better preserved in islets cultured in 0.5% human albumin. Although the stimulation index and total DNA content were similar between groups, islets cultured in human albumin demonstrated greater absolute insulin secretion (p = .02) and insulin secretion per cell (p = .02). CONCLUSIONS: When used to supplement CMRL 1066-based islet culture medium, human albumin preserves islet mass and secretory capacity better than whole human serum. Human serum offers no advantage in islet preservation or function.

Routine upper GI series after gastric bypass does not reliably identify anastomotic leaks or predict stricture formation.

BACKGROUND: Many surgeons who perform Roux-en-Y gastric bypass (RYGB) for morbid obesity routinely obtain an upper gastrointestinal (GI) series in the early postoperative period to search for anastomotic leaks and signs of stricture formation at the gastrojejunostomy. We hypothesized that this practice is unreliable. METHODS: We analyzed 654 consecutive RYGBs, of which 63% were completed laparoscopically. An upper GI series was obtained in 634 (97%) patients. The radiographic findings (leak or delayed emptying) were compared with clinical outcomes (leak or stricture formation) to calculate the sensitivity and specificity. Univariate analysis identified risk factors for leaks or stricture formation; events were too few for multivariate analysis. RESULTS: Of 634 routine upper GI series, anastomotic leaks at the gastrojejunostomy were diagnosed in 5 (0.8%); 2 of these 5 were later reinterpreted as artifacts. Four leaks were not seen on the initial upper GI series, yielding an overall sensitivity of 43% and a positive predictive value (PPV) of 60%. Univariate analysis showed that cases done early (odds ratio [OR] 5.4 for the first 100 cases, p = 0.02) and prolonged operating time (OR 7.8 for cases >or= 300 min, p = 0.01) were associated with leaks. Emptying into the Roux-en-Y limb was delayed in 127 (20%) of the upper GI series. Strictures requiring dilatation developed in 16 (2.4%) patients. The PPV of delayed emptying for stricture formation was 6%. Risk factors for stricture formation included stapled anastomosis (OR 7.8, p = 0.002), surgeon inexperience (OR 2.9 for first 50 cases, p = 0.04), and delayed emptying (OR 3.3; p = 0.02). CONCLUSIONS: Because the incidence of anastomotic complications and the sensitivity of upper GI series were both low, routine upper GI series did not reliably identify leaks or predict stricture formation. A selective approach, whereby imaging is reserved for patients with clinical evidence of a leak or stricture, may be more appropriate.

Promotion of pancreatic islet allograft survival by intrathymic transplantation of bone marrow.

An important goal in the treatment of insulin-dependent diabetes by pancreatic islet transplantation is the development of strategies that allow permanent survival of islet allografts without continuous host immunosuppression. In this study, we demonstrate that inoculation of allogeneic bone marrow into the thymus of adult rats treated with a single dose of anti-lymphocyte serum induces an unresponsive state that permits survival of subsequent pancreatic islet allografts transplanted to an extrathymic site. This effect is donor specific, cannot be reproduced by systemic administration of bone marrow, and is associated with persistence of chimeric cells in the thymus of the recipient. In addition, lymph node cells from long-term recipients of intrathymic bone marrow display markedly reduced proliferative responses to donor alloantigens in mixed lymphocyte culture. Interaction of maturing thymocytes with foreign alloantigens may produce the unresponsiveness. This model offers a potential approach for establishing donor-specific allograft acceptance in adult recipients.

Pretransplant islet culture: a comparison of four serum-free media using a murine model of islet transplantation.

INTRODUCTION: Human islet transplant protocols frequently incorporate a brief period of islet culture before transplantation. The optimal medium for pretransplant islet culture is unknown. METHODS: We compared four serum-free media formulated for human islets: Miami (MM1), Memphis (M-SFM), Edmonton (EDM), and hCell OCZEM-SF/AF (hCell). Islets isolated from a single human pancreas with purity >80% were cultured in 2500-islet-equivalent (IE) fractions using the media listed. After 7 days, each 2500-IE fraction was grafted under the kidney capsule of a streptozocin-diabetic rag1 mouse (n = 4 per group). Mice were evaluated with serum glucose monitoring, stimulated C-peptide release, and glucose tolerance tests. Islet fractions transplanted immediately after isolation (n = 4 mice) served as controls. In vitro islet function was assessed on days 0 and 3 and included insulin release (after static glucose stimulation), total cellular C-peptide content, cell count, and viability. RESULTS: Glucose control was improved in all cohorts of mice after transplant, but only islet grafts cultured in MM1 were statistically indistinguishable from fresh islets. MM1- and hCell-cultured islet grafts showed improved glucose tolerance compared with fresh islets; C-peptide release was similar among the four cohorts. In vitro, only islets cultured in MM1 had similar stimulation index to fresh islets, whereas only hCell- and MM1-cultured islets demonstrated recovery of C-peptide content and insulin release. CONCLUSIONS: Media choice before transplant can influence islet quality, even when culture periods are short. Miami MM1 and hCell media may provide better islet protection than alternative media.

Changes in vertebral bone marrow fat and bone mass after gastric bypass surgery: A pilot study.

Bone marrow fat may serve a metabolic role distinct from other fat depots, and it may be altered by metabolic conditions including diabetes. Caloric restriction paradoxically increases marrow fat in mice, and women with anorexia nervosa have high marrow fat. The longitudinal effect of weight loss on marrow fat in humans is unknown. We hypothesized that marrow fat increases after Roux-en-Y gastric bypass (RYGB) surgery, as total body fat decreases. In a pilot study of 11 morbidly obese women (6 diabetic, 5 nondiabetic), we measured vertebral marrow fat content (percentage fat fraction) before and 6 months after RYGB using magnetic resonance spectroscopy. Total body fat mass declined in all participants (mean ± SD decline 19.1 ± 6.1 kg or 36.5% ± 10.9%, p<0.001). Areal bone mineral density (BMD) decreased by 5.2% ± 3.5% and 4.1% ± 2.6% at the femoral neck and total hip, respectively, and volumetric BMD decreased at the spine by 7.4% ± 2.8% (p<0.001 for all). Effects of RYGB on marrow fat differed by diabetes status (adjusted p=0.04). There was little mean change in marrow fat in nondiabetic women (mean +0.9%, 95% CI -10.0 to +11.7%, p=0.84). In contrast, marrow fat decreased in diabetic women (-7.5%, 95% CI -15.2 to +0.1%, p=0.05). Changes in total body fat mass and marrow fat were inversely correlated among nondiabetic (r=-0.96, p=0.01) but not diabetic (r=0.52, p=0.29) participants. In conclusion, among those without diabetes, marrow fat is maintained on average after RYGB, despite dramatic declines in overall fat mass. Among those with diabetes, RYGB may reduce marrow fat. Thus, future studies of marrow fat should take diabetes status into account. Marrow fat may have unique metabolic behavior compared with other fat depots.

Promotion of rat cardiac allograft survival by intrathymic inoculation of donor splenocytes.

Donor-specific unresponsiveness to LEW heterotopic cardiac allografts was induced in WF rats following intrathymic inoculation of LEW splenocytes in conjunction with a single intraperitoneal dose of antilymphocyte serum. In contrast, LEW cardiac allografts were promptly rejected in WF recipients pretreated with an intravenous inoculation of donor splenocytes. Without transient immunosuppression with antilymphocyte serum neither intrathymic nor intravenous inoculation of splenocytes led to allograft survival. Substitution of antilymphocyte serum by a short course of cyclosporine did not permit allograft survival, suggesting that a T-cell-depleting regimen is crucial to tolerance induction by this protocol. The unresponsive state could be transferred to secondary syngeneic hosts by spleen cells from long-term recipients of intrathymic splenocytes and cardiac allografts but not by spleen cells from recipients of intrathymic splenocytes alone. This suggests that persistence of donor alloantigen from the graft is necessary for maintenance of the tolerant state. The unresponsive state after intrathymic inoculation of allogeneic splenocytes may be mediated through interaction of maturing host thymocytes with donor alloantigen.

Prolonged survival of rat orthotopic liver allografts after intrathymic inoculation of donor-strain cells.

Permanent donor-specific tolerance to tissue or organ allografts can be readily achieved without immunosuppression by administration of donor lymphohematopoietic cells to neonatal rodents. In adult recipients, however, induction of transplantation tolerance by this strategy generally requires intensive cytoablative conditioning of the recipient. We have now demonstrated that intrathymic inoculation of donor bone marrow or hepatic cells in conjunction with a single dose of antilymphocyte serum is effective in prolonging survival of DA rat orthotopic liver allografts in LEW strain recipients, which ordinarily rapidly reject such transplants. The unresponsive state achieved is donor-specific, as evidenced by the failure of intrathymic inocula of third-party WF cells to promote survival of LEW recipients of orthotopic DA liver allografts. Moreover, intravenous administration of the donor cells fails to extend liver allograft survival, demonstrating that the inoculum must be present in the thymus to promote unresponsiveness. Established DA liver allografts induced a state of systemic tolerance in LEW hosts, allowing their subsequent acceptance of donor-strain skin allografts. We hypothesize that the unresponsive state achieved by intrathymic inoculation of donor cells may result from the deletion or functional inactivation of alloreactive clones in a thymus bearing donor alloantigens. In this regard, cells of the macrophage/dendritic lineage (descendants of the bone marrow inoculum or hepatic Kupffer cells) may play a critical role by promoting thymic microchimerism and exerting modulatory effect on T cell development.

Major-histocompatibility-complex restricted and nonrestricted autoimmune effector mechanisms in BB rats.

To investigate whether the immunologic mechanisms of autoimmune pancreatic beta-cell destruction are MHC restricted, we examined the relative vulnerability of islet allografts from a panel of MHC-compatible and -incompatible donors to autoimmune damage after transplantation to spontaneously diabetic BB recipients. To circumvent a potentially confounding allograft response to the foreign islet graft, we utilized two strategies: (1) pretransplant in vitro culture of islets to delete intraislet APCs; and (2) induction of islet donor-specific immunologic tolerance in diabetes-prone BB rats. Experiments employing organ culture to prevent rejection demonstrated that MHC-incompatible grafts were significantly less vulnerable to autoimmunity than MHC-compatible grafts. In contrast, when we used the model of immunologic tolerance to exclude rejection, both MHC-compatible and -incompatible islet grafts were equally susceptible to autoimmune damage. The reason for this discrepancy has not been defined fully but may be related to our observation that tolerant BB animals exhibit increased peripheral blood NK-cell activity. NK cells are known to be cytotoxic to islets in vitro and could play a role in a non-MHC-restricted diabetogenic response in vivo. We conclude that both MHC-restricted and nonrestricted mechanisms are capable of contributing to anti-beta-cell autoimmunity in BB rats.

The effect of islet cell culture in vitro at 24 degrees C on graft survival and MHC antigen expression.

A period of in vitro culture prior to transplantation has been shown to prolong the survival of many types of MHC-incompatible endocrine grafts. The effectiveness of this strategy has been attributed to a selective depletion of intragraft antigen-presenting cells. We report that in vitro culture at 24 degrees C results in a significantly better survival of rat isolated islet allografts than does culture at 37 degrees C. Using in vitro assays of APC activity, we were unable to detect differences in the quantity of residual intraislet APCs between 24 degrees C and 37 degrees C culture preparations. In contrast, islet endocrine cells cultured at 24 degrees C evidenced a reduced level of cell surface class I MHC antigen expression and were significantly less vulnerable to lysis in vitro by CTL. These findings suggest that culture at 24 degrees C produces islet alterations other than APC depletion, and that its beneficial effect on graft survival correlates with a reduction in endocrine cell class I MHC antigen expression.

The failure of intrathymic transplantation of nonimmunogenic islet allografts to promote induction of donor-specific unresponsiveness.

Freshly isolated allogenic pancreatic islets transplanted into the thymus of transiently immunosuppressed rats are not rejected but survive indefinitely while also inducing a state of specific unresponsiveness that permits survival of secondary donor-strain islets transplanted extrathymically. Since freshly isolated pancreatic islets contain intraislet antigen-presenting cells as well as endocrine cells it is unclear which cellular component is primarily responsible for mediating unresponsiveness. We therefore examined the impact of pretransplant in vitro culture (a maneuver which selectively depletes intraislet APCs) on the capacity of islet allografts to induce unresponsiveness after intrathymic implantation. APC-depleted pancreatic islets, which are known to have reduced immunogenicity, survived indefinitely in the thymus of allogeneic hosts whether or not brief immunosuppression was employed, but failed to promote survival of subsequent donor-strain islets transplanted to an extrathymic site. These findings emphasize the central role of APCs in the induction of transplantation tolerance in this model, and are consistent with the established role of this population in the development of T cell tolerance in the thymus.