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Background: Pancreatogenic diabetes, a consequence of pancreatic tissue loss following pancreatectomy, poses a significant challenge for patients undergoing pancreatic surgery. Islet autotransplantation (IAT) offers a promising approach to prevent or alleviate pancreatogenic diabetes, but its application has been limited to individuals with painful chronic pancreatitis., Methods: This study presents a 15-y clinical experience with the Milan Protocol, which expands IAT after pancreatectomy to a broader spectrum of patients with malignant and nonmalignant pancreatic diseases. The analysis evaluates feasibility, efficacy, and safety of IAT. Modified Igls criteria validated through the arginine test and mixed meal tolerance tests were used to assess long-term metabolic outcomes., Results: Between November 2008 and June 2023, IAT procedures were performed on 114 of 147 candidates. IAT-related complications occurred in 19 of 114 patients (16.7%), with 5 being potentially serious. Patients exhibited sustained C-peptide secretion over the 10-y follow-up period, demonstrating a prevalence of optimal and good beta-cell function. Individuals who underwent partial pancreatectomy demonstrated superior metabolic outcomes, including sustained C-peptide secretion and a reduced risk of developing diabetes or insulin dependence compared with those who underwent total pancreatectomy. For patients who had total pancreatectomy, the quantity of infused islets and tissue volume were identified as critical factors influencing metabolic outcomes. An increased risk of recurrence or progression of baseline diseases was not observed in subjects with neoplasms., Conclusions: These findings provide valuable insights into the benefits and applications of IAT as a therapeutic option for pancreatogenic diabetes after pancreatic surgery, expanding its potential beyond painful chronic pancreatitis., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2024 The Author(s). Published by Wolters Kluwer Health, Inc.)

Objective: To compare pancreaticoduodenectomy (PD) and total pancreatectomy (TP) with islet autotransplantation (IAT) in patients at high risk of postoperative pancreatic fistula (POPF)., Background: Criteria to predict the risk of POPF occurrence after PD are available. However, even when a high risk of POPF is predicted, TP is not currently accepted as an alternative to PD, because of its severe consequences on glycaemic control. Combining IAT with TP may mitigate such consequences., Methods: Randomized, open-label, controlled, bicentric trial (NCT01346098). Candidates for PD at high-risk pancreatic anastomosis (ie, soft pancreas and duct diameter ≤3 mm) were randomly assigned (1:1) to undergo either PD or TP-IAT. The primary endpoint was the incidence of complications within 90 days after surgery., Results: Between 2010 and 2019, 61 patients were assigned to PD (n=31) or TP-IAT (n=30). In the intention-to-treat analysis, morbidity rate was 90·3% after PD and 60% after TP-IAT ( P =0.008). According to complications' severity, PD was associated with an increased risk of grade ≥2 [odds ratio (OR)=7.64 (95% CI: 1.35-43.3), P =0.022], while the OR for grade ≥3 complications was 2.82 (95% CI: 0.86-9.24, P =0.086). After TP-IAT, the postoperative stay was shorter [median: 10.5 vs 16.0 days; P <0.001). No differences were observed in disease-free survival, site of recurrence, disease-specific survival, and overall survival. TP-IAT was associated with a higher risk of diabetes [hazard ratio=9.1 (95% CI: 3.76-21.9), P <0.0001], but most patients maintained good metabolic control and showed sustained C-peptide production over time., Conclusions: TP-IAT may become the standard treatment in candidates for PD, when a high risk of POPF is predicted., Competing Interests: The authors report no conflicts of interest., (Copyright © 2022 The Author(s). Published by Wolters Kluwer Health, Inc.)

Background: Europe is currently the most active region in the field of pancreatic islet transplantation, and many of the leading groups are actually achieving similar good outcomes. Further collaborative advances in the field require the standardization of islet cell product isolation processes, and this work aimed to identify differences in the human pancreatic islet isolation processes within European countries., Methods: A web-based questionnaire about critical steps, including donor selection, pancreas processing, pancreas perfusion and digestion, islet counting and culture, islet quality evaluation, microbiological evaluation, and release criteria of the product, was completed by isolation facilities participating at the Ninth International European Pancreas and Islet Transplant Association (EPITA) Workshop on Islet-Beta Cell Replacement in Milan., Results: Eleven islet isolation facilities completed the questionnaire. The facilities reported 445 and 53 islet isolations per year over the last 3 years from deceased organ donors and pancreatectomized patients, respectively. This activity resulted in 120 and 40 infusions per year in allograft and autograft recipients, respectively. Differences among facilities emerged in donor selection (age, cold ischemia time, intensive care unit length, amylase concentration), pancreas procurement, isolation procedures (brand and concentration of collagenase, additive, maximum acceptable digestion time), quality evaluation, and release criteria for transplantation (glucose-stimulated insulin secretion tests, islet numbers, and purity). Moreover, even when a high concordance about the relevance of one parameter was evident, thresholds for the acceptance were different among facilities., Conclusions: The result highlighted the presence of a heterogeneity in the islet cell product process and product release criteria.

Background: Results in murine and nonhuman primate suggested that the bone marrow (BM) might be an alternative site for pancreatic islet transplantation., Methods: We report the results of 2 clinical studies in patients with type 1 diabetes receiving an intra-BM allogeneic islet transplantation: a feasibility study in patients with hepatic contraindications for liver islet allotransplantation receiving a single intra-BM islet infusion (n = 4) and a pilot randomized trial (1:1 allocation using blocks of size 6) in which patients were randomized to receive islets into either the liver (n = 6) or BM (n = 3) to evaluate islet transplant function and survival., Results: We observed no adverse events related to the intrabone injection procedure or the presence of islets in the BM. None of the recipient of an intra-BM allogeneic islet transplantation had a primary nonfunction, as shown by measurable posttransplantation C-peptide levels and histopathological evidence of insulin-producing cells or molecular markers of endocrine tissue in BM biopsy samples collected during follow-up. All patients receiving islets in the BM except 1 lost islet function during the first 4 months after infusion (2 with an early graft loss). Based on biopsies and immunomonitoring, we concluded that the islet loss was primarily caused by the recurrence of autoimmunity., Conclusions: Bone marrow is not a suitable alternative site for pancreatic islet allotransplantation in patients with type 1 diabetes.

β-cell replacement therapy, available currently as pancreas or islet transplantation, has developed without a clear definition of graft functional and clinical outcomes. The International Pancreas and Islet Transplant Association and European Pancreas and Islet Transplantation Association held a workshop to develop consensus for an International Pancreas and Islet Transplant Association and European Pancreas and Islet Transplant Association Statement on the definition of function and failure of current and future forms of β-cell replacement therapy. There was consensus that β-cell replacement therapy could be considered as a treatment for β-cell failure, regardless of etiology and without requiring undetectable C-peptide, accompanied by glycemic instability with either problematic hypoglycemia or hyperglycemia. Glycemic control should be assessed at a minimum by glycated hemoglobin (HbA1c) and the occurrence of severe hypoglycemia. Optimal β-cell graft function is defined by near-normal glycemic control (HbA1c ≤6.5% [48 mmol/mol]) without severe hypoglycemia or requirement for insulin or other antihyperglycemic therapy, and with an increase over pretransplant measurement of C-peptide. Good β-cell graft function requires HbA1c less than 7.0% (53 mmol/mol) without severe hypoglycemia and with a significant (>50%) reduction in insulin requirements and restoration of clinically significant C-peptide production. Marginal β-cell graft function is defined by failure to achieve HbA1c less than 7.0% (53 mmol/mol), the occurrence of any severe hypoglycemia, or less than 50% reduction in insulin requirements when there is restoration of clinically significant C-peptide production documented by improvement in hypoglycemia awareness/severity, or glycemic variability/lability. A failed β-cell graft is defined by the absence of any evidence for clinically significant C-peptide production. Optimal and good function are considered successful clinical outcomes.

Beta cell replacement has the potential to restore euglycemia in patients with insulin-dependent diabetes. Although great progress has been made in establishing allogeneic islet transplantation from deceased donors as the standard of care for those with the most labile diabetes, it is also clear that the deceased donor organ supply cannot possibly treat all those who could benefit from restoration of a normal beta cell mass, especially if immunosuppression were not required. Against this background, the International Pancreas and Islet Transplant Association in collaboration with the Harvard Stem Cell Institute, the Juvenile Diabetes Research Foundation (JDRF), and the Helmsley Foundation held a 2-day Key Opinion Leaders Meeting in Boston in 2016 to bring together experts in generating and transplanting beta cells derived from stem cells. The following summary highlights current technology, recent significant breakthroughs, unmet needs and roadblocks to stem cell-derived beta cell therapies, with the aim of spurring future preclinical collaborative investigations and progress toward the clinical application of stem cell-derived beta cells.

Background: The identification of pathway(s) playing a pivotal role in peritransplant detrimental inflammatory events represents the crucial step toward a better management and outcome of pancreatic islet transplanted patients. Recently, we selected the CXCR1/2 inhibition as a relevant strategy in enhancing pancreatic islet survival after transplantation., Methods: Here, the most clinically used anti-inflammatory compounds (IL1-receptor antagonist, steroids, and TNF-α inhibitor) alone or in combination with a CXCR1/2 inhibitor were evaluated in their ability to improve engraftment or delay graft rejection. To rule out bias related to transplantation site, we used well-established preclinical syngeneic (250 C57BL/6 equivalent islets in C57BL/6) and allogeneic (400 Balb/c equivalent islets in C57BL6) intrahepatic islet transplantation platforms., Results: In mice, we confirmed that targeting the CXCR1/2 pathway is crucial in preserving islet function and improving engraftment. In the allogeneic setting, CXCR1/2 inhibitor alone could reduce the overall recruitment of transplant-induced leukocytes and significantly prolong the time to graft rejection both as a single agent and in combination with immunosuppression. No other anti-inflammatory compounds tested (IL1-receptor antagonist, steroids, and TNF-α inhibitor) alone or in combination with CXCR1/2 inhibitor improve islet engraftment and significantly delay graft rejection in the presence of MMF + FK-506 immunosuppressive treatment., Conclusions: These findings indicate that only the CXCR1/2-mediated axis plays a crucial role in controlling the islet damage and should be a target for intervention to improve the efficiency of islet transplantation.

Background: To assess feasibility, safety, and metabolic outcome of islet auto transplantation (IAT) in patients undergoing completion pancreatectomy because of sepsis or bleeding after pancreatic surgery., Methods: From November 2008 to October 2016, approximately 22 patients were candidates to salvage IAT during emergency relaparotomy because of postpancreatectomy sepsis (n = 11) or bleeding (n = 11). Feasibility, efficacy, and safety of salvage IAT were compared with those documented in a cohort of 36 patients who were candidate to simultaneous IAT during nonemergency preemptive completion pancreatectomy through the pancreaticoduodenectomy., Results: The percentage of candidates that received the infusion of islets was significantly lower in salvage IAT than simultaneous IAT (59.1% vs 88.9%, P = 0.008), mainly because of a higher rate of inadequate islet preparations. Even if microbial contamination of islet preparation was significantly higher in candidates to salvage IAT than in those to simultaneous IAT (78.9% vs 20%, P < 0.001), there was no evidence of a higher rate of complications related to the procedure. Median follow-up was 5.45 ± 0.52 years. Four (36%) of 11 patients reached insulin independence, 6 patients (56%) had partial graft function, and 1 patient (9%) had primary graft nonfunction. At the last follow-up visit, median fasting C-peptide was 0.43 (0.19-0.93) ng/mL; median insulin requirement was 0.38 (0.04-0.5) U/kg per day, and median HbA1c was 6.6% (5.9%-8.1%). Overall mortality, in-hospital mortality, metabolic outcome, graft survival, and insulin-free survival after salvage IAT were not different from those documented after simultaneous IAT., Conclusions: Our data demonstrate the feasibility, efficacy, and safety of salvage IAT after relaparotomy.

Background: The aim of this study was to characterize the immune response against intrabone marrow (BM-Tx) or intraliver (liver-Tx) transplanted islets in the presence or in the absence of immunosuppression., Methods: Less (C57BL/6 in Balb/c) and highly (Balb/c in C57BL/6) stringent major histocompatibility complex fully mismatched mouse models were used to evaluate the alloimmune response. Single antigen-mismatched mouse model (C57BL/6 RIP-GP in C57BL/6) was used to evaluate the antigen-specific immune response. Mice received tacrolimus (FK-506, 0.1 mg/kg per day)/mycophenolate mofetil (MMF, 60 mg/kg per day), and anti-CD3 (50 μg/day) either alone or in combination., Results: Transplant site did not impact the timing nor the kinetics of the alloimmune and single antigen-specific memory T cell responses in the absence of immunosuppression or in the presence of MMF/FK-506 combination. On the other hand, the median time to graft rejection was 28 ± 5.2 days and 16 ± 2.6 days (P = 0.14) in the presence of anti-CD3 treatment, 50 ± 12.5 days and 10 ± 1.3 days (P = 0.003) in the presence of anti-CD3/MMF/FK-506 treatment for liver-Tx and BM-Tx, respectively. Anti-CD3 did not differentially reach BM and liver tissues but was more effective in reducing graft associated T cell responses in liver-Tx than in BM-Tx., Conclusions: Islets infused in the BM appear less protected from the adaptive immune response in the presence of the anti-CD3 treatment. This result raises some concerns over the potential of the BM as a site for islet allotransplantation.

Background: The maintenance or expansion of regulatory T (Treg) cells has a fundamental role in the achievement of immunological tolerance after transplantation. Here we aimed to determine mechanisms of human Treg cell depletion and reconstitution after anti-CD25 monoclonal antibody (mAb) treatment., Methods: Seventeen patients with type 1 diabetes who received pancreatic islet transplantation and anti-CD25 mAb as induction therapy were studied., Results: We observed an almost complete depletion of Treg cells after injection of anti-CD25 mAb. The kinetic of Treg cell depletion did not parallel the disappearance of CD25+ T cells as CD25 is also rapidly downregulated and internalized. Regulatory T cell reconstitution is completed within 6 months posttransplantation and appeared to be driven by IL-7-mediated homeostatic T cell proliferation. Anti-CD25 mAb treatment sensitizes Treg cell to the biological effect of IL-7, possibly rendering more common γc-chain available to interact with CD127. Homeostatic Treg cell proliferation is resistant to the inhibitory effect of rapamycin and FK506 but can be blocked by the presence of mycophenolate mofetil., Conclusions: Our data suggest that a compensatory mechanism of IL-7-mediated homeostatic proliferation can restore the inhibitory network of Treg cell after anti-CD25 induction therapy in islet allotransplantation.

Objectives: Our study aims at producing acellular extracellular matrix scaffolds from the human pancreas (hpaECMs) as a first critical step toward the production of a new-generation, fully human-derived bioartificial endocrine pancreas. In this bioartificial endocrine pancreas, the hardware will be represented by hpaECMs, whereas the software will consist in the cellular compartment generated from patient's own cells., Background: Extracellular matrix (ECM)-based scaffolds obtained through the decellularization of native organs have become the favored platform in the field of complex organ bioengineering. However, the paradigm is now switching from the porcine to the human model., Methods: To achieve our goal, human pancreata were decellularized with Triton-based solution and thoroughly characterized. Primary endpoints were complete cell and DNA clearance, preservation of ECM components, growth factors and stiffness, ability to induce angiogenesis, conservation of the framework of the innate vasculature, and immunogenicity. Secondary endpoint was hpaECMs' ability to sustain growth and function of human islet and human primary pancreatic endothelial cells., Results: Results show that hpaECMs can be successfully and consistently produced from human pancreata and maintain their innate molecular and spatial framework and stiffness, and vital growth factors. Importantly, hpaECMs inhibit human naïve CD4 T-cell expansion in response to polyclonal stimuli by inducing their apoptosis and promoting their conversion into regulatory T cells. hpaECMs are cytocompatible and supportive of representative pancreatic cell types., Discussion: We, therefore, conclude that hpaECMs has the potential to become an ideal platform for investigations aiming at the manufacturing of a regenerative medicine-inspired bioartificial endocrine pancreas.

Background: Our final objective is to develop an adoptive therapy with tolerogenic donor-specific type 1 T regulatory cells for patients with type 1 diabetes undergoing islet transplantation. The achievement of this objective depends on the availability of an immunosuppressive treatment compatible with the survival, function, and expansion of type 1 T regulatory cells., Methods: For this purpose, we designed a single-group, phase 1 to 2 trial with an immunosuppression protocol including: (i) rapamycin treatment before the first islet infusion (starting ≥ 30 days before transplantation); (ii) induction therapy with anti-thymocyte globulin (ATG) instead of anti-interleukin-2Ra monoclonal antibody (after the first islet infusion only); (iii) short-term treatment with steroids and interleukin-1Ra (right before and for 2 weeks after each infusion); rapamycin+mycophenolate mofetil treatment as maintenance therapy. The target enrollment was 10 patients., Results: Ten of 15 patients who started the pretransplant rapamycin treatment completed it. Nine of 10 patients did not complete the induction therapy with ATG, and three of 10 required adaptation of maintenance immunosuppression caused by side effects. Four of 10 patients acquired insulin independence which can be maintained up to year 3 after last infusion. All six other patients have lost their graft, and the early graft loss was associated with lower dose of ATG during induction., Conclusion: This protocol resulted feasible, safe but less efficient in maintaining graft survival during the time than other T-cell depletion-based protocols. An adequate induction at the first infusion should be considered to improve the overall clinical outcome.

Objective: Immunosuppression (IS) in islet transplantation (Tx) is a double-edged sword: it prevents immunoreaction but has the potential to impair islet engraftment. The aim of this study was to identify in murine animal models the IS platform with the best balance between these two opposite effects., Methods: To study the impact of IS on islet engraftment diabetic C57BL/6 mice were transplanted with 350 syngeneic islets through the portal vein and treated once-daily with either rapamycin (RAPA; 0.1-0.5-1 mg/kg ip), tacrolimus (FK506; 0.1-0.5-1 mg/kg ip), mycophenolate mofetil (MMF; 60-120-300 mg/kg oral) or vehicle for 14 days. Islet function was evaluated by measuring not-fasting glycemia and by performing an IVGTT on days 15 and 30 post-Tx., Results: RAPA ≥0.5 mg/Kg, FK506 ≥0.5 mg/Kg, and MMF ≥120 mg/kg had detrimental effects on islet engraftment but not on the function of islets already engrafted in the liver. The effect on engraftment was irreversible and persisted even after IS withdrawal. The lower dose of IS that did not affect engraftment was tested for preventing rejection in the full mismatch allogeneic Tx BALB/c to C57BL/6 model. RAPA and/or FK506 were inefficient in preventing rejection, even when anti-IL2R mAb was added to the IS regimen. On the other hand, MMF alone or in association with FK506 significantly prolonged the time to islet rejection., Conclusion: IS showed profound dose-dependent deleterious effects on islet cell engraftment. The MMF/FK506 combination proved the best balance with less toxicity at the time of engraftment and more efficacy in controlling graft rejection.

Objective: To assess metabolic and oncologic outcomes of islet autotransplantation (IAT) in patients undergoing pancreatic surgery for either benign or malignant disease., Background: IAT is performed to improve glycemic control after extended pancreatectomy, almost exclusively in patients with chronic pancreatitis. Limited experience is available for other indications or in patients with pancreatic malignancy., Methods: In addition to chronic pancreatitis, indications for IAT were grade C pancreatic fistula (treated with completion or left pancreatectomy, as indicated); total pancreatectomy as an alternative to high-risk anastomosis during pancreaticoduodenectomy; and distal pancreatectomy for benign/borderline neoplasm of pancreatic body-neck. Malignancy was not an exclusion criterion. Metabolic and oncologic follow-up is presented., Results: From November 2008 to June 2012, 41 patients were candidates to IAT (accounting for 7.5% of all pancreatic resections). Seven of 41 did not receive transplantation for inadequate islet mass (4 pts), patient instability (2 pts), or contamination of islet culture (1 pt). IAT-related complications occurred in 8 pts (23.5%): 4 bleeding, 3 portal thromboses (1 complete, 2 partial), and 1 sepsis. Median follow-up was 546 days. Fifteen of 34 patients (44%) reached insulin independence, 16 patients (47%) had partial graft function, 2 patients (6%) had primary graft nonfunction, and 1 patient (3%) had early graft loss. Seventeen IAT recipients had malignancy (pancreatic or periampullary adenocarcinoma in 14). Two of them had already liver metastases at surgery, 13 were disease-free at last follow-up, and none of 2 patients with tumor recurrence developed metastases in the transplantation site., Conclusions: Although larger data are needed to definitely exclude the risk of disease dissemination, the present study suggests that IAT indications can be extended to selected patients with neoplasm.

Background: Several simple measures of graft function after islet transplantation have been proposed but a comparative evaluation is lacking. Here, we compared the performance of five indices of β-cell function: β-score, transplant estimated function (TEF), homeostasis model assessment (HOMA) 2-B%, C-peptide/glucose ratio, and Secretory Units of Islets in Transplantation (SUIT)., Methods: Two cohorts of transplanted patients were analyzed. Cohort 1 consisted of 14 recipients with type 1 diabetes of islet transplantation whereas cohort 2 consisted of 21 recipients with type 1 diabetes of cultured islet cell graft. The five surrogate indices were compared against the first- and second-phase insulin response to arginine in cohort 1, and against the C-peptide response to a hyperglycemic clamp in cohort 2., Results: We found that the performances of the five surrogate indices were close one to each other in cohort 1. The correlation coefficients ranged 0.62 to 0.67 and 0.62 to 0.68 against the first- and second-phase insulin response to arginine, respectively. In cohort 2, we found that the β-score, TEF, C-peptide/glucose ratio, and SUIT were reasonably well correlated with the clamp response (correlation coefficients were in the range 0.71-0.81), whereas HOMA2-B% showed a modest performance (r=0.54). HOMA2-B% could not be evaluated in one patient whose fasting glucose concentration level was below the lower bound indicated by the HOMA calculator (3 mmol/L). SUIT could not be evaluated in three patients whose fasting glucose concentration was below the glucose threshold of the SUIT formula (3.43 mmol/L)., Conclusion: In summary, no single index outperformed the others. Nevertheless, when the benefit to cost ratio is considered, TEF stands out for its good performance at a very low cost.

Background: The role of recipient hyperglycemia on timing of allograft survival is unknown. In this study, we investigated if and how variation in recipient glycemia affects the ability to achieve and maintain normoglycemia after transplant of C57BL/6 islets into diabetic BALB/c mice., Methods and Results: 85 diabetic BALB/c mice with non-fasting glycaemia ranging between 275 and 600 mg/dL were transplanted with 400 C57BL/6 islets. The time of rejection inversely correlated with the pre-transplant blood glucose concentration (P=0.004). All the 13 mice with normoglycemia beyond 50 days had pretransplant glycemia <450 mg/dL and the presence of autologous beta cell function was demonstrated in 8 (>100 days function) by the persistence of normoglycemia after allograft removal. The presence of immunosuppression (rapamycin plus FK506 plus anti-IL-2Ra chain mAbs, n=31; rapamycin plus IL-10; n=29) removed the influence of pretransplant hyperglycemia but after treatment withdrawn the timing and the probability of graft loss correlate with the pretransplant hyperglycemia. Pretransplant glycemia was inversely correlated with HOMA-B and serum insulin showing that a significant residual beta cell mass was present in mice with glycemia <450 mg/dL., Conclusion: This study demonstrates that the timing of functional loss of islets allotransplantation depends on the degree of recipient hyperglycemia. This potential bias should be kept in count in experimental results and a threshold that excludes moderate diabetes should be used in defining recipient's eligibility.

Background: Appropriate recruitment of dendritic cells (DC) at sites of inflammation and migration to secondary lymphoid organs is of critical importance for the initiation of Ag-specific immune responses. The proper localization of DC in selected tissues is guided primarily by the coordinated expression of chemokine receptors (CKR). Here we show that immunosuppressive drugs have divergent effects on the modulation of CKR in maturing DC., Methods and Results: Dexamethazone (DEX) and IL-10 inhibited human DC migration to CCL19 in vitro and mouse DC migration to lymph nodes (LN) in vivo, by impairing CCR7 expression. The calcineurin inhibitors cyclosporine A (CsA) and tacrolimus (FK506) were characterized by the inability to modulate CKR expression and migratory activity. Rapamycin (RAPA) increased DC migration to CCL19 in vitro and to LN in vivo by enhancing CCR7 expression. This effect could be mediated, in LPS-maturing DC, by the inhibition of autocrine IL-10 production. The in vivo data obtained with ex vivo RAPA treated DC were confirmed in a model of in vivo drug administration in mice, suggesting a potential clinical relevance., Conclusions: These findings demonstrate that immunosuppressive agents differently modulate the CKR switch associated with maturing DC; in particular, RAPA selectively up-regulates CCR7 and enhances the migration of differentiated DC to regional LN. This study contributes to a better understanding of the role of immunosuppressive therapy on DC migration, a potentially relevant check point of immunosuppressive treatment.

Human islets have chemotactic activity toward macrophages mediated by the secretion of monocyte chemoattractant protein-1 (CCL2/MCP-1) that negatively affect clinical outcome in islet after kidney recipients. The aim of the present work was to identify the donor features and the variables involved in the procedures of islet isolation associated with islet CCL2/MCP-1 release in vitro. We used a retrospective approach studying the outcome in 170 islet isolations. The univariate analysis demonstrated that CCL2/MCP-1 release was significantly associated with the surgical team in charge for organ harvesting, the proteins for dilution solution, the type of gradient, the type of enzyme, and the donor noradrenalin treatment. The multivariate analysis confirmed that the surgical team (P = 0.001) and the enzyme (P = 0.001) were independently associated with in vitro CCL2/MCP-1 islet release (r(2) = 17%). Strategies aimed to optimize the procedures of organ harvesting and islet isolation may reduce the pro-inflammatory properties of the preparation and therefore may improve islet engraftment.

Background: Rapamycin is a recently introduced immunosuppressive agent. Its effect on lymphocytes has been extensively studied. Whether it can also modulate dendritic cell (DC) function is unknown., Methods: The effect of rapamycin on differentiation, antigen uptake, and the immunostimulatory capacity of human DC was examined. DC were derived from monocytes upon culture with interleukin (IL)-4 and granulocyte-macrophage colony-stimulating factor in the presence or absence of rapamycin (0.1-100 ng/mL). Surface phenotype and antigen uptake capacity of DC were assessed by flow cytometry. Immunostimulatory capacity was measured by mixed lymphocyte culture., Results: Rapamycin reduced DC recovery and increased DC apoptosis. DC differentiated in the presence of rapamycin (rapa-DC) had increased expression of CD1a, CD1b, and CD1c and decreased expression of MHC I, MHC II, CD80, CD86, and CD40. Antigen uptake receptor expression (mannose receptor, CD32, CD91, CD46) was decreased, and receptor-mediated endocytosis of fluorescein isothiocyanate-dextran was markedly impaired in rapa-DC, as were fluid phase endocytosis of Lucipher Yellow and phagocytic activity of bacteria and dead or apoptotic cells. CD40 ligand-induced production of both IL-12 and IL-10 was reduced in rapa-DC, and allogeneic T lymphocyte responses were moderately impaired when rapa-DC were used as stimulator cells. Neither cyclosporine nor FK506 affected DC function. However, the effects of rapamycin on DC could be completely inhibited by a 10-fold excess of FK506 but not by up to 100-fold excess of cyclosporine., Conclusion: Rapamycin has a unique and profound inhibitory effect on DC function, which seems to be at least in part mediated by the FKBP immunophilins.