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Background. Orthostatic hypotension (OH) is a poorly understood complication of simultaneous pancreas–kidney (SPK) transplantation. We sought to determine the incidence, timing, and relationship of OH to rapid glycemic control in the early posttransplant period. Methods. This was a nonrandomized retrospective single-center review of 75 SPK and 19 kidney-alone (KA) recipients with type 1 diabetes (DM). Results. OH occurred in 57 (76%) SPK versus 2 (10%) KA recipients (odds ratio [OR] 61.72, 95% confidence interval [CI], 9.69-393.01; P < 0.001). The median onset of OH was 12 (interquartile range [IQR] 9–18) days posttransplant and resolved in 85% of SPK recipients after a median of 2.5 (IQR 1.2–6.3) months. Among SPK recipients, independent risk factors for OH were a shorter duration of DM (OR 0.85, 95% CI, 0.73-0.98; P = 0.03) and rapid glycemic control in the early posttransplant period (OR 1.13, 95% CI, 1.01-1.27; P = 0.04), as evidenced by a larger percent change in hemoglobin A1c (HbA1c) from transplant to month 3. OH patients had a higher median baseline HbA1c [8.3% (IQR 7.2–10.0) versus 7.1% (IQR 6.8–8.3); P = 0.07], lower median 3-month HbA1c [4.8% (IQR 4.6–5.2) versus 5.2% (IQR 5.0–5.4); P = 0.02], and a larger reduction in HbA1c over time as compared to recipients without OH (P < 0.01). Conclusions. Our results show that OH is more likely to occur following SPK versus KA transplantation and is strongly associated with rapid glucose normalization within the early posttransplant period.

Background. Pancreas and islet transplantation outcomes are negatively impacted by injury to the endocrine cells from acute stress during donor death, organ procurement, processing, and transplant procedures. Here, we report a novel electron microscopy scoring system, the Newcastle Pancreas Endocrine Stress Score (NPESS). Methods. NPESS was adapted and expanded from our previously validated method for scoring pancreatic exocrine acinar cells, yielding a 4-point scale (0–3) classifying ultrastructural pathology in endocrine cell nuclei, mitochondria, endoplasmic reticulum, cytoplasmic vacuolization, and secretory granule depletion, with a maximum additive score of 15. We applied NPESS in a cohort of deceased organ donors after brainstem (DBD) and circulatory (DCD) death with a wide range of cold ischemic times (3.6–35.9 h) including 3 donors with type 1 and 3 with type 2 diabetes to assess islets in situ (n = 30) in addition to pancreata (n = 3) pre- and postislet isolation. Results. In DBD pancreata, NPESS correlated with cold ischemic time (head: r = 0.55; P = 0.02) and mirrored exocrine score (r = 0.48; P = 0.01). When stratified by endocrine phenotype, cells with granules of heterogeneous morphology had higher scores than α, β, and δ cells (P

In contrast to well-published data with acceptable long-term results in large cohorts of single renal transplant recipients aged >65 y (lit.), combined pancreas-kidney transplantation in recipients >50 y is discussed controversially. Some groups have identified older recipients as a high-risk group, demonstrating decreased patient and graft survival in this population.1-4 Nevertheless, several centers have reported results for pancreatic transplantation in older patients as being comparable to those for younger recipients with the age cutoff ranging from 50 to 60 y.5-10 At our center, we have long-term experience with a total of 655 pancreas transplants performed between 1979 and August 2020, whereby 21 recipients were over 60 y of age; the oldest was age 69 and in remarkably good general condition with good mental adherence and a strong wish to undergo simultaneous kidney-pancreas transplantation (SPK). We retrospectively analyzed patient, pancreas, and kidney graft survival, graft function, and complications at month 38 posttransplant.

Background. Whole pancreas transplantation (Tx) is a successful treatment for type 1 diabetes resulting in independence from antidiabetic therapies. Transplant-related factors contributing to pancreatic islet failure are largely unknown; both recurring insulitis and pancreatitis have been implicated. The aim was to determine if cellular changes in islets and exocrine tissue are evident early in Tx, which could contribute to eventual graft failure using well-preserved tissue of grafts explanted from largely normoglycemic recipients. Methods. Histological specimens of explants (n = 31), Tx duration 1 day–8 years (median 29 d), cold ischemia time 7.2–17.3 hours (median 11.1 h), donor age 13–54 years (median 38 y) were examined; sections were labeled for inflammation, islet amyloidosis, and tissue fibrosis, and morphometry performed on immunolabeled insulin and glucagon positive islet cells. Data were related to clinical details of donor, recipient, and features of Tx. Results. Islet inflammation consistent with recurrent insulitis was not seen in any sample. Insulin-labeled islet cell proportion decreased with donor age (P Conclusions. Explant histological changes after short-term Tx are similar to those seen in type 2 diabetes and occur in the absence of immunologic rejection without causing hyperglycemia. This suggests that factors associated with Tx affect islet stability; persistent deterioration of islet integrity and exocrine tissue fibrosis could impact on sustainability of islet function.

Author(s): Amara, Dominic; Wisel, Steven A; Braun, Hillary J; Collisson, Eric A; Friedlander, Terence; Worner, Giulia; Roll, Garret R; Hirose, Ryutaro; Stock, Peter G | Abstract: Stopping immunosuppression in a transplant patient with donor-derived malignancy offers the theoretical benefit that reconstitution of the patient's immune system will allow "rejection" of the malignancy, as the malignancy also originates from allogeneic tissue. However, this option exists with the caveat that the patient's allograft(s) will likely be rejected too. In simultaneous pancreas-kidney (SPK) recipients, the normal continued functioning and possible absence of malignancy in either the unaffected kidney or pancreas further complicate this decision.MethodsThe charts of 3 patients with donor-derived metastatic malignancies after SPK were retrospectively reviewed in detail. We provide treatment and management recommendations based on successful outcomes and a review of the existing literature.ResultsConsistent with a broad review of the literature, in all 3 cases, complete immunosuppression cessation, removal of both grafts, and in 1 case treatment with an immune checkpoint inhibitor to augment the immune response was successful. One patient is doing well 1 year after successfully undergoing kidney retransplantation, while a second patient is active on the waitlist for SPK retransplantation after no evidence of metastatic disease for 2 years.ConclusionThe successful management of metastatic donor-derived malignancies requires allograft removal, immunosuppression cessation, and adjuvant therapy that includes occasional use of checkpoint inhibitors to augment the immune response.

Supplemental Digital Content is available in the text., Background. Sarcopenia has been identified as a predictive variable for surgical outcomes. We hypothesized that sarcopenia could be a key measure to identify frail patients and potentially predict poorer outcomes among recipients of simultaneous pancreas and kidney (SPK) transplants. Methods. We estimated sarcopenia by measuring psoas muscle mass index (PMI). PMI was assessed on perioperative computed tomography (CT) scans of SPK recipients. Results. Of the 141 patients identified between 2010 and 2018, 107 had a CT scan available and were included in the study. The median follow-up was 4 years (range, 0.5–9.1 y). Twenty-three patients had a low PMI, and 84 patients had a normal PMI. Patient characteristics were similar between the 2 groups except for body mass index, which was significantly lower in low PMI group (P

Background. Complications associated with bladder-drained pancreata necessitating enteric conversion are common. Data on the outcomes after enteric conversion are conflicting. We studied the association between enteric conversion and the pancreas graft rejection, loss, and mortality. Methods. At our center, 1117 pancreas transplants were performed between 2000 and 2016. We analyzed 593 recipients with bladder-drained pancreata, of which 523 received solitary transplants and 70 received simultaneous pancreas-kidney transplants. Kaplan-Meier function was used to estimate time to conversion by transplant type. Cox proportional hazards models were utilized to evaluate patient survival, death-censored graft survival, and acute rejection-free survival while treating conversion as a time-dependent covariate. Subsequently, we examined the association between timing of conversion and the same outcomes in the conversion cohort. Results. At 10 y posttransplant, 48.8% of the solitary pancreas recipients and 44.3% of simultaneous pancreas-kidney transplant recipients had undergone enteric conversion. The enteric conversion was associated with 85% increased risk of acute rejection (hazard ratio [HR] = 1.85; 95% confidence interval [CI] = 1.37-2.49; P < 0.001). However, the conversion was not associated with graft loss or mortality. In the conversion cohort, a longer interval from engraftment to conversion was associated with an 18% lower rejection rate (HR = 0.82; 95% CI = 0.708-0.960; P = 0.013) and a 22% better graft survival (HR = 0.78; 95% CI = 0.646-0.946; P = 0.01). Conclusions. Enteric conversion was associated with increased risk of rejection, but not increased risks of graft loss or mortality. The decision to convert should consider the increased rejection risk. A longer interval from engraftment to conversion appears favorable.

Background Weight change, primarily weight gain, is a common problem among solid organ transplant recipients. The incidence of weight gain or loss after successful pancreas transplant alone (PTA) and the effect on graft survival is unknown. Methods This was a single-center observational study among PTA recipients, transplanted at our center between January 1, 2005, and July 31, 2017, who had a functional pancreas graft for at least 1 year and documented weight change at the 1-year clinic visit. Results In this cohort study of 105 PTA recipients, 28 had significant weight gain, 27 had significant weight loss, and the remaining 50 did not have significant weight change at 1-year posttransplant. When comparing the weight gain and no weight change groups, the weight gain cohort started to gain weight at 3 months posttransplant to 5 years or last follow up. Similarly, the weight loss group lost weight at 3 months posttransplant up to last follow up. Clinically significant weight gain or weight loss were not associated with uncensored or death censored graft failure in univariate regression and Kaplan-Meier survival analysis. Also, there were no significant differences between the groups in the glycated hemoglobin at last follow up. Conclusions Approximately 50% of PTA recipients had a significant weight change at 1-year posttransplant, of which 25% gained significant weight and 25% loss. There was no significant difference in graft survival due to the significant weight changes. Further research is needed in this field.

Supplemental Digital Content is available in the text., Background. The approach to reducing nonspecific inflammation after islet allotransplantation has been designed to improve engraftment, typically using 1 agent. We report results with the use of combination inflammatory blockade consisting of anti-interleukin (IL)-1β and tumor necrosis factor (TNF)-α. Methods. Nine patients underwent islet allotransplantation under a prospective research protocol using double cytokine blockade with anti–TNF-α (etanercept, d 0, 3, 7, 10) and IL-1β (anakinra, d 0–7) at the time of each islet infusion. The primary endpoint, assessed 2 years after the last islet transplant, was the elimination of severe hypoglycemic events and hypoglycemia unawareness, with proper glycemic control, and detectable serum C-peptide. Results. No thrombotic events or infectious complications were associated with combined IL-1β and TNF-α blockade. Six patients became insulin independent, 2 had partial function, and 1 had primary nonfunction. After 24-month follow-up, 6 of 9 patients had excellent glycemic control, hemoglobin A1c ≤6.5%, and no episodes of hypoglycemia unawareness. Eight patients developed HLA alloantibodies at various time points (class 1, 5; class 2, 6), with enhanced T-cell alloreactivity. One patient retained good graft function despite having anti-glutamic acid decarboxylase 65 antibodies. Conclusions. The use of double cytokine blockade is safe, with reduction of inflammation at transplantation and presumably with better engraftment. However, it does not influence later islet loss from T-cell–mediated autoimmunity and alloimmunity, which require other strategies to maintain long-term islet function.

Background. Simultaneous pancreas-kidney (SPK) transplant is usually the best option for the diabetic end-stage renal disease patient. There is limited information about kidney graft outcomes in SPK recipients with isolated pancreas graft failure who do versus do not undergo pancreas retransplantation. Methods. Patients were divided into 2 groups based on whether they underwent pancreas retransplant (ReTx+) or not (ReTx−). Kidney graft function and survival were the primary endpoints. Results. One hundred and nine patients satisfied our selection criteria, 25 in ReTx+ and 84 in ReTx−. Mean interval from SPK to pancreas failure was significantly shorter in the ReTx+ compared with the ReTx− group, 19.3 ± 36.7 versus 45.7 ± 47.0 months (P = 0.01), respectively. There was no significant difference in kidney graft follow-up post SPK between 2 groups (P = 0.48). At last follow-up, 15 of the 25 (60%) of the repeat pancreas graft had failed, with a mean graft survival among these failed pancreas graft of 2.6 ± 2.7 years, ranging from 0 to 8.1 years. Uncensored kidney graft failure was significantly lower in the ReTx+ group compared with the ReTx− group, 44% versus 67% (P = 0.04). Death-censored kidney graft failure was also lower in the ReTx+ group, 24% versus 48% (P = 0.04). The difference in patient survival did not reach statistical significance. In adjusted Cox regression analysis, rejection as a cause of pancreas failure was associated with increased risk of death-censored kidney graft failure, and pancreas retransplantation was associated with decreased risk of kidney graft failure. A similar pattern was seen after 1:1 matching for the interval between SPK and pancreas graft failure. Conclusions. Even though ReTx+ patients accept the risks associated with repeat pancreas surgery, providers should consider this option in suitable otherwise healthy patients.

Supplemental Digital Content is available in the text., Background. We previously demonstrated that the incorporation of the chemokine CXCL12 into alginate microbeads supported long-term survival of microencapsulated auto-, allo-, and xenogeneic islets in murine models of diabetes without systemic immune suppression. The purpose of this study was to test whether CXCL12 could abrogate foreign body responses (FBRs) against alginate microbeads which were empty or contained autologous islets in healthy nonhuman primates (NHPs; n = 4). Methods. Two NHPs received intraperitoneal implants of 400 000 alginate microbeads with or without CXCL12, and postimplantation immunological and histopathological changes were evaluated up to 6 months postimplantation. A similar evaluation of autologous islets in CXCL12-containing alginate microbeads was performed in NHPs (n = 2). Results. CXCL12-containing alginate microbeads were associated with a markedly reduced FBR to microbeads. Host responses to microbead implants were minimal, as assessed by clinical observations, blood counts, and chemistry. Evaluation of encapsulated islets was limited by the development of necrotizing pancreatitis after hemipancreatectomy in 1 NHP. A limited number of functioning islets were detectable at 6 months posttransplantation in the second NHP. In general, empty microbeads or islet-containing beads were found to be evenly distributed through the intraperitoneal cavity and did not accumulate in the Pouch of Douglas. Conclusions. Inclusion of CXCL12 in alginate microbeads minimized localized FBR. The NHP autologous islet implant model had limited utility for excluding inflammatory/immune responses to implanted islets because of the complexity of pancreatic surgery (hemipancreatectomy) before transplantation and the need to microencapsulate and transplant encapsulated autologous islets immediately after pancreatectomy and islet isolation.

Background The impact of functional status on survival among simultaneous pancreas-kidney transplant (SPKT) candidates and recipients is not well described. Methods We examined national Scientific Registry of Transplant Recipients (SRTR) data for patients listed for SPKT in the United States (2006-2019). Functional status was categorized by center-reported Karnofsky Performance Score (KPS). We used Cox regression to quantify associations of KPS at listing and transplant with subsequent patient survival, adjusted for baseline patient and transplant factors (adjusted hazard ratio, 95% LCLaHR95%UCL). We also explored time-dependent associations of SPKT with survival risk after listing compared with continued waiting in each functional status group. Results KPS distributions among candidates (N = 16 822) and recipients (N = 10 316), respectively, were normal (KPS 80-100), 62.0% and 57.8%; capable of self-care (KPS 70), 23.5% and 24.7%; requires assistance (KPS 50-60), 12.4% and 14.2%; and disabled (KPS 10-40), 2.1% and 3.3%. There was a graded increase in mortality after listing and after transplant with lower functional levels. Compared with normal functioning, mortality after SPKT rose progressively for patients capable of self-care (aHR, 1.001.181.41), requiring assistance (aHR, 1.061.311.60), and disabled (aHR, 1.101.552.19). In time-dependent regression, compared with waiting, SPKT was associated with 2-fold mortality risk within 30 days of transplant. However, beyond 30 days, SPKT was associated with reduced mortality, from 52% for disabled patients (aHR, 0.260.480.88) to 70% for patients with normal functioning (aHR, 0.260.300.34). Conclusions While lower functional status is associated with increased mortality risk among SPKT candidates and recipients, SPKT can provide long-term survival benefit across functional status levels in those selected for transplant.

Background. Potential adverse effects, such as functional impairment of islets, render conventional immunosuppressive drugs unsuitable for use in islet transplantation. In addition, as a single therapy, they cannot prolong islet allograft survival. Here, we investigated the utility of the mitogen-activated protein kinase inhibitor trametinib and asked whether it ameliorates acute rejection of transplanted islets without the need for conventional immunosuppressants. Methods. Islets from fully major histocompatibility complex-mismatched BALB/c mice were transplanted into streptozotocin-induced diabetic C57BL/6 mice via the portal vein. These mice received trametinib or vehicle (orally) for 28 days. Isolated islets from BALB/c mice were incubated in vitro with different concentrations of trametinib to determine viability and function. Results. Trametinib (0.1 and 0.3 mg/kg) prolonged graft survival significantly (P = 0.0007 and P = 0.005, respectively) when compared with vehicle. Histologic analyses revealed that cellular infiltration of the graft by lymphocytes was inhibited significantly on day 7 (P

Supplemental Digital Content is available in the text., Background. Patients that have undergone successful simultaneous pancreas/kidney (SPK) transplantation attain normoglycemia and are free from dialysis. However, only a minor improvement in quality of life (QOL) has been demonstrated. Here, we evaluated the role of psychological symptoms in QOL after SPK transplantation. Methods. We assessed patients with type 1 diabetes and end-stage renal disease waitlisted for SPK transplantation (pre-SPK, n = 47), and recipients of an SPK transplant (post-SPK, n = 72). Matched patients with type 1 diabetes without end-stage renal disease were included as reference group (type 1 diabetes [T1D] reference group, n = 42). The brief symptom inventory (BSI) was used to measure psychological symptoms. The Short Form-36 (SF-36) was used to determine QOL. Results. Post-SPK patients scored slightly better on the SF-36 than pre-SPK patients (“General health” 47.2 ± 23.1 versus 37.5 ± 18.1 [P = 0.017]). In the T1D reference group, this score was 60.6 ± 22.3. Post- and pre-SPK patients had similar BSI scores (0.54 ± 0.55 and 0.45 ± 0.42, respectively [P = 0.34]). This score was better in the T1D reference group (BSI score 0.32 ± 0.33). The BSI score inversely correlated with the SF-36 (r = −0.61, P < 0.001). Conclusions. Psychological symptoms are prevalent in both pre-SPK and post-SPK patients and could play an important role in the reduced QOL observed in these groups.

Background This is a synopsis of the registry report from the Australia and New Zealand islet and pancreas transplant registry. The full report is available at http://anziptr.org/reports/. Methods We report data for all solid organ pancreas transplant activity from inception in 1984 to end 2017. Islet-cell transplantation activity is reported elsewhere. Data analysis was performed using Stata software version 14 (StataCorp, College Station, TX). Results From 1984 to 2017 a total of 809 solid organ pancreas transplants have been performed in Australia and New Zealand, in 790 individuals. In 2017, 52 people received a pancreas transplant. By center, this was; Auckland (4), Monash (17), and Westmead (31). In 2017, 51 transplants were simultaneous pancreas kidney, whereas 1 was pancreas after kidney, and none were pancreas transplant alone. Conclusions The number of pancreas transplants performed in Australia and New Zealand was slightly lower in 2017 but continues to increase over time.

This is a registry report from the Australia and New Zealand Islet and Pancreas Transplant Registry. We report data for all solid organ pancreas transplant activity from inception in 1984 to end of 2016. Data analysis was performed using Stata Software version 14 (StataCorp, College Station, Tex). From 1984 to 2016 a total of 756 solid organ pancreas transplants have been performed in Australia and New Zealand, in 738 individuals. In 2016, 55 people received a pancreas transplant. These transplants were performed in Auckland (4), Monash (22), and Westmead (29). In 2016, 50 transplants were simultaneous pancreas kidney, 4 were pancreas after kidney, and 1 was a pancreas transplant alone.

Background Duodenal leak remains a major cause of morbidity and graft loss in pancreas transplant recipients. The role and efficacy of surgical and image-guided interventions to salvage enterically drained grafts with a duodenal leak has yet to be defined. Methods We investigated the incidence, treatment, and outcome of duodenal leak in 426 pancreas transplantation recipients from 2000 to 2015. Results Duodenal leak developed in 33 (7.8%) recipients after a median follow-up of 5.3 (range, 0.5-15.2) years. Most leaks occurred during the first year (n = 22; 67%), and most were located near the proximal and distal duodenal staple line. Graft pancreatectomy was performed in 8 patients as primary therapy because of unfavorable local and/or systemic conditions. Salvage was attempted in 25 patients using percutaneous drainage (n = 4), surgical drainage (n = 4), or surgical repair (n = 17). Percutaneous or surgical drainage failed to control the leak in 7 of these 8 patients, and all 7 ultimately required graft pancreatectomy for persistent leak and sepsis. Surgical repair salvaged 14 grafts, and 13 grafts continue to function after a median follow-up of 2.9 (range, 1.1-6.3) years after repair. Conclusions Our study shows that in selected patients a duodenal leak can be repaired successfully and safely in enterically drained grafts.

Supplemental digital content is available in the text., Background The optimal immunosuppressive regimen in simultaneous pancreas-kidney transplant (SPKT) recipients that prevents acute rejection episodes (AREs) and allows optimal outcome remains elusive. Methods This cohort study assessed incidence and time to AREs in 73 consecutive SPKT recipients receiving alemtuzumab induction and steroid-free maintenance with tacrolimus and mycophenolate mofetil. A cohort with single high-dose antithymocyte globulin (ATG; n = 85) and triple therapy served as controls. In addition, we provided mechanistic insights in AREs after alemtuzumab depletion, including composition and alloreactivity of lymphocytes (flow cytometry and mixed lymphocyte reaction) plasma alemtuzumab levels (enzyme-linked immunosorbent assay), and maintenance drug exposure. Results Overall number of AREs at 3 years was significantly lower with alemtuzumab versus ATG induction (26.0% vs 43.5%; adjusted hazard ratio, 0.38; P = 0.029). Most AREs (94.6%) with ATG occurred within the first month, whereas 84.2% of AREs with alemtuzumab occurred beyond 3 months. Patients with and without an ARE in the steroid-free alemtuzumab group showed no differences in composition of lymphocytes, or in alemtuzumab levels. Of note, more than two thirds of these AREs were preceded by empiric tacrolimus and/or mycophenolate mofetil dose adjustments due to viral infections, leukopenia, or gastrointestinal symptoms. Conclusions Alemtuzumab induction resulted in a significant lower incidence of AREs. Empiric dose adjustments beyond 3 months in the absence of steroids carry a significant risk for subsequent rejection in SPKT recipients.

Islet transplantation is a possible curative treatment for type 1 diabetes (T1D). Currently the liver dominates as implantation site, despite the many challenges encountered at this site.Acute hypoxia in islets transplanted to muscle and omentum, two possible alternative sites, was prevailing. However, it was rapidly reversed at both implantation sites, in contrast to when islets were transplanted intraportally. At the intramuscular site hypoxia was further relieved by co-transplantation of an oxygen carrier, polymerized hemoglobin, which also improved the functional outcome. The complement system was activated after islet transplantation to muscle, but did not hamper graft function.Both mouse and human islets transplanted to omentum become well re-vascularized and have a functional blood flow and oxygenation comparable with that of endogenous islets. Animals transplanted with islets to the omentum had a superior graft function compared with animals receiving intraportal islet grafts.Alloxan-diabetic animals were cured with a low number of islets both when the islets were implanted in the omentum and muscle. The islet grafts responded adequately to both glucose and insulin and displayed a favorable mRNA gene expression profile.A challenge in diabetes research and in islet transplantation is that there are no established techniques for quantifying beta-cell mass in vivo. By using radiolabeled Exendin-4, a GLP-1 receptor agonist, beta-cell mass after transplantation to muscle of mice was quantified. The results may well be translated to the clinical setting.By comparing the pancreatic accumulation of [11C]5-hydroxy tryptophan ([11C]5-HTP) as detected by positron emission tomography (PET) in T1D patients with that of healthy controls, a 66% decrease was observed. This may in fact represent the loss of beta-cells, taking into account that other cells within the islets of Langerhans are largely unaffected in T1D. In conclusion, the data presented support the use of alternative implantation sites for islet transplantation. In addition to improving the functional outcome this may enable more transplantations since the number of transplanted islets may be reduced. The techniques investigated for quantifying transplanted and endogenous beta-cell mass may greatly improve our knowledge of the pathophysiology of T1D and become a valuable tool for evaluation of beta-cell mass.

Background Human allogeneic islet transplantation for treatment of type 1 diabetes provides numerous clinical benefits, such as fewer episodes of hypoglycemic unawareness and tighter control of blood glucose levels. Availability of human pancreas for clinical and research use, however, is severely limited. Porcine pancreas offers an abundant source of tissue for optimization of islet isolation methodology and future clinical transplantation, thereby increasing patient access to this potentially lifesaving procedure. Methods Porcine islet isolations were performed using varying amounts of collagenase (7.5, 3.75, or 2.5 Wunsch units per gram tissue) and neutral protease activity (12 000, 6000, or 4000 neutral protease units per gram tissue) and perfusion volumes (1.7 or 0.85 mL/g tissue) to assess their effects on isolation outcomes. Retention of dissociative enzymes within the pancreas during perfusion and digestion was evaluated, along with distribution of the perfusion solution within the tissue. Results Reducing enzyme usage by as much as 67% and perfusion volume by 50% led to equally successful islet isolation outcomes when compared with the control group (48 ± 7% of tissue digested and 1088 ± 299 islet equivalents per gram of pancreas vs 47 ± 11% and 1080 ± 512, respectively). Using margin-marking dye in the perfusion solution to visualize enzyme distribution demonstrated that increasing perfusion volume did not improve tissue infiltration. Conclusions Current protocols for porcine islet isolation consume excessive amounts of dissociative enzymes, elevating cost and limiting research and development. These data demonstrate that islet isolation protocols can be optimized to significantly reduce enzyme usage while maintaining yield and function and thus accelerating progress toward clinical application.

Background For selected individuals with type 1 diabetes, pancreatic islet transplantation (IT) prevents recurrent severe hypoglycemia and optimizes glycemia, although ongoing systemic immunosuppression is needed. Our aim was to explore candidates and recipients' expectations of transplantation, their experience of being on the waiting list, and (for recipients) the procedure and life posttransplant. Methods Cross-sectional qualitative research design using semistructured interviews with 16 adults (8 pretransplant, 8 posttransplant; from 4 UK centers (n = 13) and 1 Canadian center (n = 3)). Interviews were audio-recorded, transcribed, and underwent inductive thematic analysis. Results Interviewees were aged (mean ± SD) 52 ± 10 years (range, 30-64); duration of diabetes, 36 ± 9 years (range, 21-56); 12 (75%) were women. Narrative accounts centered on expectations, hopes, and realities; decision-making; waiting and uncertainty; the procedure, hospital stay, and follow-up. Expected benefits included fewer severe hypoglycemic episodes, reduced need for insulin, preventing onset/progression of complications and improved psychological well-being. These were realized for most, at least in the short term. Most interviewees described well-informed, shared decision-making with clinicians and family, and managing their expectations. Although life “on the list” could be stressful, and immunosuppressant side effects were severe, interviewees reported “no regrets.” Posttransplant, interviewees experienced increased confidence, through freedom from hypoglycemia and regained glycemic control, which tempered any disappointment about continued reliance on insulin. Most viewed their transplant as a success, though several reflected upon setbacks and hidden hopes for becoming “insulin-free.” Conclusions Independently undertaken interviews demonstrated realistic and balanced expectations of IT and indicate how to optimize the process and support for future IT candidates.

Background Isolation following a good manufacturing practice-compliant, human islet product requires development of a robust islet isolation procedure where effective limits of key reagents are known. The enzymes used for islet isolation are critical but little is known about the doses of class I and class II collagenase required for successful islet isolation. Methods We used a factorial approach to evaluate the effect of high and low target activities of recombinant class I (rC1) and class II (rC2) collagenase on human islet yield. Consequently, 4 different enzyme formulations with divergent C1:C2 collagenase mass ratios were assessed, each supplemented with the same dose of neutral protease. Both split pancreas and whole pancreas models were used to test enzyme targets (n = 20). Islet yield/g pancreas was compared with historical enzymes (n = 42). Results Varying the Wunsch (rC2) and collagen degradation activity (CDA, rC1) target dose, and consequently the C1:C2 mass ratio, had no significant effect on tissue digestion. Digestions using higher doses of Wunsch and CDA resulted in comparable islet yields to those obtained with 60% and 50% of those activities, respectively. Factorial analysis revealed no significant main effect of Wunsch activity or CDA for any parameter measured. Aggregate results from 4 different collagenase formulations gave 44% higher islet yield (>5000 islet equivalents/g) in the body/tail of the pancreas (n = 12) when compared with those from the same segment using a standard natural collagenase/protease mixture (n = 6). Additionally, islet yields greater than 5000 islet equivalents/g pancreas were also obtained in whole human pancreas. Conclusions A broader C1:C2 ratio can be used for human islet isolation than has been used in the past. Recombinant collagenase is an effective replacement for the natural enzyme and we have determined that high islet yield can be obtained even with low doses of rC1:rC2, which is beneficial for the survival of islets.

Pancreatic islet transplantation is a promising approach in treating insulin-dependent diabetes.1-3 Currently, over 900 patients globally have been transplanted with islet allografts.4 Islet transplantation requires isolating islets from mass pancreatic acinar tissue, which involves extensive tissue manipulation and rigorous regulatory approvals to ensure a safe and high-quality final product for treating patients with type 1 diabetes (T1D).5-7 Studies in whole organ transplantation showed that graft failure was attributed to systemic infection due to the contamination in the organ preservation solution.8-10 The contamination issue is further exacerbated in islet isolation, which involves multiple steps, including preservation of the whole pancreas with a portion of the duodenum and/or spleen attached, trimming and decontamination of pancreas, perfusion of enzyme, digestion, collection, washing of pancreatic tissue, purification, culturing, and collection of islets.11 Although, the process of manufacturing islet final product is carried out in a current good manufacturing practice (cGMP) facility, the risk of introducing contamination at any stage of the procedure still remains.12-14 Aside from the media used in pancreas decontamination, all other solutions used throughout the pancreas preservation and islet isolation process are prepared within the cGMP facility without addition of antimicrobial agents to prevent a potential allergic reaction of the recipient. The T1D patients are more vulnerable to infection, especially after islet transplantation with the required immunosuppressive regimen to prevent allograft rejection.15 Thus, it is extremely important to take measures to prevent contamination during manufacturing the final islet product for transplantation. With the advancement of islet transplantation as a standardized treatment strategy in a clinical setting, it eventually may require a biologic license application so that a safe and effective final product would be transplanted into patients.6,16 Therefore, sterility testing of the final product to be transplanted becomes one of the critical checkpoints. Hence, it is important to understand the route and rate of contamination in this whole process to implement an effective prevention plan to ensure the safety and potency of islet preparations. A limited number of large-scale studies have been published regarding the contamination issues during the islet manufacturing process,15,17-19 and little is described regarding the effect of antiseptic agents on the outcome of the islet isolation process. In fact, the most recent article related to this topic was published 10 years ago,18 which evaluated the use of Cefazolin and Amphotericin B for decontamination in the islet isolation process. However, the current protocol from the Clinical Islet Transplantation Consortium centers only uses a single antibiotic (Cefazolin) dip to decontaminate the organ.20 We hypothesize that using multiple antimicrobial agents may further decrease or eliminate the contamination rate of the final product. Herein, we report a comprehensive review and analysis of contamination rates during islet isolation and the frequency of contamination by specific microbial species.