Islet Equivalents Research Articles

Impact of microbial contamination of the islet product during total pancreatectomy with islet autotransplantation.

The combined use of interleukin-1β and tumor necrosis factor-α blockers in the peritransplant period has improved outcomes of total pancreatectomy with islet autotransplantation (TPIAT). However, these drugs may suppress the immune system, resulting in severe infection. We retrospectively investigated the impact of microbial-contaminated islet product on posttransplant complications and metabolic outcomes of TPIAT patients receiving the IL-1β and TNF-blockade treatment at our center. Among 108 TPIAT patients, 37 patients (34%) received contaminated products. Preoperative stent treatment and fibrosis score were independent risk factors for the contamination. There were no significant differences between the contaminated and noncontaminated product groups in posttransplant infectious complication rate, length of hospitalization, or readmission rate. However, islet equivalents (P<.0001) and insulin independence rate (P=.036) at 6months were significantly lower for patients receiving contaminated product. These results suggest that combined anti-inflammatory drug use is safe and well tolerated in TPIAT patients who receive contaminated islet product and does not increase the rate of infectious complications; however, contaminated islet product is associated with poor metabolic outcomes.

Semi-Automated Assessment of Human Islet Viability Predicts Transplantation Outcomes in a Diabetic Mouse Model

In clinical and experimental human pancreatic islet transplantations, establishing pretransplant assessments that accurately predict transplantation outcomes is crucial. Conventional in vitro viability assessment that relies on manual counting of viable islets is a routine pretransplant assessment. However, this method does not correlate with transplantation outcomes; to improve the method, we recently introduced a semi-automated method using imaging software to objectively determine area-based viability. The goal of the present study was to correlate semi-automated viability assessment with posttransplantation outcomes of human islet transplantations in diabetic immunodeficient mice, the gold standard for in vivo functional assessment of isolated human islets. We collected data from 61 human islet isolations and 188 subsequent in vivo mouse transplantations. We assessed islet viability by fluorescein diacetate and propidium iodide staining using both the conventional and semi-automated method. Transplantations of 1,200 islet equivalents under the kidney capsule were performed in streptozotocin-induced diabetic immunodeficient mice. Among the pretransplant variables, including donor factors and post-isolation assessments, viability measured using the semi-automated method demonstrated a strong influence on in vivo islet transplantation outcomes in multivariate analysis. We calculated an optimized cutoff value (96.1%) for viability measured using the semi-automated method and showed a significant difference in diabetes reversal rate for islets with viability above this cutoff (77% reversal) vs. below this cutoff (49% reversal). We performed a detailed analysis to show that both the objective measurement and the improved area-based scoring system, which distinguished between small and large islets, were key features of the semi-automated method that allowed for precise evaluation of viability. Taken together, our results suggest that semi-automated viability assessment offers a promising alternative pretransplant assessment over conventional manual assessment to predict human islet transplantation outcomes.

Optimal Time to Ship Human Islets Post Tissue Culture to Maximize Islet Recovery

Access to functional high-quality pancreatic human islets is critical to advance diabetes research. The Integrated Islet Distribution Program (IIDP), a major source for human islet distribution for over 15 years, conducted a study to evaluate the most advantageous times to ship islets postisolation to maximize islet recovery. For the evaluation, three experienced IIDP Islet Isolation Centers each provided samples from five human islet isolations, shipping 10,000 islet equivalents (IEQ) at four different time periods postislet isolation (no 37°C culture and shipped within 0 to 18 hours; or held in 37°C culture for 18 to 42, 48 to 96, or 144 to 192 hours). A central evaluation center compared samples for islet quantity, quality, and viability for each experimental condition preshipment and postshipment, as well as post 37°C culture 18 to 24 hours after shipment receipt. Additional evaluations included measures of functional potency by static glucose-stimulated insulin release (GSIR), represented as a stimulation index. Comparing the results of the four preshipment holding periods, the greatest IEQ loss postshipment occurred with the shortest preshipment times. Similar patterns emerged when comparing preshipment to postculture losses. In vitro islet function (GSIR) was not adversely impacted by increased tissue culture time. These data indicate that allowing time for islet recovery postisolation, prior to shipping, yields less islet loss during shipment without decreasing islet function.

Transplantation of PEGylated islets enhances therapeutic efficacy in a diabetic nonhuman primate model.

Islet cell transplantation can lead to insulin independence, reduced hypoglycemia, and amelioration of diabetes complications in patients with type 1 diabetes. The systemic delivery of anti-inflammatory agents, while considered crucial to limit the early loss of islets associated with intrahepatic infusion, increases the burden of immunosuppression. In an effort to decrease the pharmaceutical load to the patient, we modified the pancreatic islet surface with long-chain poly(ethylene glycol) (PEG) to mitigate detrimental host-implant interactions. The effect of PEGylation on islet engraftment and long-term survival was examined in a robust nonhuman primate model via three paired transplants of dosages 4300, 8300, and 10000islet equivalents per kg body weight. A reduced immunosuppressive regimen of anti-thymocyte globulin induction plus tacrolimus in the first posttransplant month followed by maintenance with sirolimus monotherapy was employed. To limit transplant variability, two of the three pairs were closely MHC-matched recipients and received MHC-disparate PEGylated or untreated islets isolated from the same donors. Recipients of PEGylated islets exhibited significantly improved early c-peptide levels, reduced exogenous insulin requirements, and superior glycemic control, as compared to recipients of untreated islets. These results indicate that this simple islet modification procedure may improve islet engraftment and survival in the setting of reduced immunosuppression.

Laparoscopic-assisted versus open total pancreatectomy and islet autotransplantation: A case-matched study of pediatric patients

BackgroundTotal Pancreatectomy and Islet Autotransplantation (TPIAT) are a potential treatment for children with severe, refractory chronic pancreatitis. A laparoscopic-assisted approach provides a smaller incision and excellent visualization of the distal pancreas and spleen during resection. A minimally-invasive approach has proven advantageous for other pediatric procedures, but its value is unknown for this rare operation. This retrospective review compares outcomes between patients undergoing laparoscopic-assisted versus open TPIAT. Study designChildren (n = 21) receiving laparoscopic-assisted TPIAT from 2013 to 2015 and children (n = 21) receiving open TPIAT from 2011 to 2015 were matched based on age, gender, symptom duration, previous interventions, and pancreatic fibrosis scores. Data reviewed included postoperative complications, operative time, estimated blood loss (EBL), intraoperative blood transfusions, number of islet equivalents (IEQ)/kg transplanted, hospital length-of-stay, graft function, narcotic use, and Patient Scar Assessment Questionnaire scores. Between-group differences were compared using Fisher's exact, Chi-square, and T-tests. ResultsSurgical complications were similar between surgical groups (p = 0.35) and included wound complications (n = 11), chyle leak (n = 7), bowel obstruction (n = 5), bile leak (n = 3), gastrointestinal bleed (n = 2), and pneumonia (n = 1). There were no significant differences in operative time (p = 0.18), EBL (p = 0.96), blood transfusions (p = 0.34), IEQ/kg transplanted (p = 0.15), and hospital length-of-stay (p = 0.66). Insulin and opioid use was similar except for a slightly higher use of opioids (n = 4) at 2 years in the laparoscopic group. Patient surgical scar satisfaction was similar between groups (p = 0.26). ConclusionsOutcomes for laparoscopic-assisted TPIAT appear comparable to open TPIAT. In children, a minimally-invasive approach does not compromise safety, effectiveness, or operative efficiency and may be used based on surgeon and patient preference.

Excellent Islet Yields after 18-h Porcine Pancreas Preservation by Ductal Injection, Pancreas Preservation with MK Solution, Bottle Purification, and Islet Purification Using Iodixanol with UW Solution and Iodixanol with MK Solution.

Successful islet isolation is the key to successful islet transplantation. Our group recently modified the islet isolation protocol to include pancreatic ductal injection of the preservation solution, pancreas storage in modified extracellular-type trehalose-containing Kyoto (MK) solution, and use of an iodixanol-based purification solution and bottle purification. In this study, we applied these methods to porcine islet isolation after 18-h pancreas preservation and compared two solutions with different compositions in bottle purification. Islet yield before purification was 651,661 ± 157,719 islet equivalents (IE) and 5576 ± 1538 IE/g pancreas weight. An IU solution was made by adding iodixanol to University of Wisconsin solution and an IK solution was made by adding iodixanol to MK solution. The efficacy of the two solutions for islet isolation was compared. There were no significant differences between the two purification methods with regard to islet yield, survival rate, purity, score, or stimulation index. These results indicate that our isolation protocol produces efficient islet yields from prolonged cold-stored pancreas and that IU and IK solutions are equally useful for islet purification.

The Effects of Using Pancreases Obtained from Brain-Dead Donors for Clinical Islet Transplantation in Japan.

Background: The pool of brain-dead donors (BDDs) was increased with the revision to the relevant law in 2010, and islet transplantation from BDDs was started in 2013. The present study assessed the influence of using pancreases from BDDs on islet transplantation in Japan. Methods: The donor information registered with the secretariat of islet transplants from 2012 was reviewed, and the results of 86 clinical islet isolations performed in Japan between 2003 and 2018 with non-heart-beating donors (NHBDs) (n = 71) and BDDs (n = 15) were investigated. Results: The number of cases for which donor information was registered with the secretariat of islet transplants increased to 1.84 cases/month from 2013 to 2018 in comparison to 1.44/month in 2012, when only NHBDs were used. The median pancreatic islet yield was 275,550 IEQ (Islet equivalents) in the NHBD group but 362,700 in the BDD group, which amounted to a statistically significant difference (p = 0.02). As a result, 38/71 cases (53.5%) were achieved successful islet isolation (>5000 IEQ per recipient weight (kg)) was achieved in 38/71 cases (53.5%) in the NHBD group, and 12/15 cases (80.0%) in the BDD group; thus, the rate of successful islet transplantation was higher in the BDD group. Conclusion: The use of pancreases from BDDs has increased the overall number of cases for which donor information is registered with the secretariat of islet transplants and has improved the performance of islet isolation, thereby increasing the probability of successfully achieving islet transplantation.

Utility of arginine stimulation testing in preoperative assessment of children undergoing total pancreatectomy with islet autotransplantation.

Metabolic outcomes after total pancreatectomy with islet autotransplantation (TPIAT) are influenced by the islet mass transplanted. Preclinical and clinical studies indicate that insulin and C-peptide levels measured after intravenous administration of the beta cell secretagogue arginine can be used to estimate the available islet mass. We sought to determine if preoperative arginine stimulation test (AST) results predicted transplanted islet mass and metabolic outcomes in pediatric patients undergoing TPIAT. We evaluated the association of preoperative C-peptide and insulin responses to AST with islet isolation metrics using linear regression, and with postoperative insulin independence using logistic regression. Twenty-six TPIAT patients underwent preoperative AST from 2015 to 2018. The acute C-peptide response to arginine (ACRarg) was correlated with isolated islet equivalents (IEQ; r=0.59, P=0.002) and islet number (IPN; r=0.48, P=0.013). The acute insulin response to arginine (AIRarg) was not significantly correlated with IEQ (r=0.38, P=0.095) or IPN (r=0.41, P=0.071). Neither ACRarg nor AIRarg was associated with insulin use at 6months postoperatively. Preoperative C-peptide response to arginine correlates with islet mass available for transplant in pediatric TPIAT patients. AST represents an additional tool before autotransplant to provide counseling on likely islet mass and to inform quality improvements of islet isolation techniques.

Micro/nanobubbles: Improving Pancreatic Islet Cell Survival for Transplantation.

The preservation of transplantable tissue is directly tied to and limited by the ischemia time. Micro/nanobubbles (MNBs) are miniature gaseous voids that allow for the oxygenation of tissue given their high oxygen-carrying capacity. One of the current limitations of islet cell transplantation for type 1 diabetes is poor islet survival, caused by hypoxia, after harvesting the cells from pancreata. As such, the purpose of this study was to elucidate whether MNBs, when added to standard culture medium, improve islet cell survival postharvest. Islet cells were harvested from Sprague-Dawley rat pancreas tissue via a standard collagenase digestion and gradient purification. To create the MNB solution, a shear-based generation system was used to produce both air- and oxygen-filled MNBs in standard Connaught Medical Research Laboratories (CMRL) medium. Four groups, consisting of 500 islet equivalents, were cultured with either the standard CMRL medium, macrobubble-CMRL, MNB (air)-CMRL, or MNB (O2)-CMRL, and they were incubated at 37°C. Each treatment solution was replenished 24 hours postincubation, and after 48 hours of culture, dithizone staining was used to determine the islet cell counts, and the viability was assessed using Calcein AM/propidium iodide staining. Islet cells that were preserved in macrobubble-CMRL, MNB (air)-CMRL, and MNB (O2)-CMRL conditions showed an increased survival compared with those cultured with standard CMRL. The islet cells cultured in the MNB (air)-CMRL condition demonstrated the greatest cell survival compared with all other groups, including the pure oxygen-carrying MNBs. None of the MNB treatments significantly altered the viability of the islet cells compared to the control condition. The addition of MNBs to culture medium offers an innovative approach for the oxygenation of transplantable tissue, such as islet cells. This study demonstrated that MNBs filled with air provided the most optimal addition to the islet cell culture medium for improving islet cell survival amongst the treatment groups we tested. Given these findings, we hypothesize that MNBs may also improve the oxygenation and survival of a variety of other tissues, including fat grafts from lipoaspirate, chronic wounds, and solid organs.

263-OR: IgM Therapy Reverses Autoimmune Diabetes and Prevents Islet Allo- and Xenotransplant Rejection

Purpose: To determine if IgM therapy promotes islet allo- and xenograft survival. Methods: a) 200ug IgM was injected into new onset diabetic NOD mice (n=14) and blood glucose monitored. b) 2000 human islet equivalents (IEQs) were transplanted under the kidney capsule of diabetic BL/6s with and without IgM therapy (IgM (M) n=5; saline (S) n=6). c) 1000 IEQs were transplanted in NOD/scids (M n=4; S n=4). d) 400 Balb/C islets were transplanted under the kidney capsule (M n=6; S n=6); and 350 islets in the portal vein of diabetic BL/6 mice (M n=6; S n=3). e) 5 weeks-old BL/6 and NODs, BL/6- and NOD-VH125 mice and humanized BLT mice received IgM or Saline (5X) following which spleen and bone-marrow cells were analyzed by Flow cytometry. Results: a) IgM reversed hyperglycemia in 70% of diabetic mice. b) With 2000 IEQS, 5/5 mice in the IgM group returned to normoglycemia, while controls became diabetic in 11±5.5 days (p&amp;lt;0.001). c) Transplantation with 1000 IEQs resulted in restoration of normoglycemia with or without IgM therapy. Removal of islet graft-containing kidney at &amp;gt;60days post-transplant reinstated T1D. d) Following allotransplantation, IgM restored normoglycemia permanently in 6/6 mice. Graft removal at 100 days posttransplant resulted in T1D. Hyperglycemia in controls returned in 10.8±4.7 days. Following intraportal transplantation, all IgM-treated mice were cured. Controls turned diabetic in 6.3±2.5 days. e) IgM mitigated autoimmunity in NODs by reducing % age of marginal zone B cells that perpetuate autoimmunity (p&amp;lt;0.05); by increasing transitional B cell proportions (p&amp;lt;0.01) indicating normalization of B cell homeostatic defects; and inhibiting plasma insulin autoantibody levels (p&amp;lt;0.0001). In NODVH125 mice, IgM eliminated insulin binding B cell population (p&amp;lt;0.0001) and in humanized BLT mice, hIgM therapy expanded the Helios+Foxp3+Treg population. Conclusion: IgM therapy reversed T1D and promoted permanent islet graft survival indicating its clinical relevance for T1D. Disclosure M. Ma: None. K.L. Brayman: None. P. Chhabra: None. Funding American Diabetes Association (1-17-IBS-244 to K.L.B.); University of Virginia

Improved cryopreservation yield of pancreatic islets using combination of lower dose permeable cryoprotective agents

Islet transplantation has been shown to restore normoglycemia in animal models and for type 1 diabetic patients in clinical trials. One method of storing islets intended for transplantation is via cryobanking at very low temperatures (−196 °C). Cryobanking islets without the use of cryoprotecting agents (CPAs) contributes to cellular shear stress and cell death. Although current CPA protocols vary, high concentrations of these agents are toxic to islets cells. This study tested the effects of the permeating CPA dimethyl sulfoxide (Me2SO) with the addition of ethylene glycol (EG), both at reduced concentrations, on rat and human islet cell yield, viability, and glucose stimulated insulin release (GSIR). To test this, islets were treated using three combinations of CPAs (2M ME2SO, 1M ME2SO + 1M EG, and 1M ME2SO + 0.5M EG). Next, fresh islets, 2M ME2SO islets, and 1M ME2SO + 0.5M EG isolated rat islets were transplanted into streptozotocin-induced (STZ) diabetic mice. Our data showed that cryopreservation with a reduced concentration of ME2SO (1M ME2SO + multimolar EG) achieved a higher percent yield and viability when compared to the current standard 2M ME2SO treatment for both rat and human islets. Furthermore, STZ-induced diabetic mice achieved normoglycemia after transplantation with 1000 islet equivalents (IE), an average 12 days sooner, with islets cryopreserved with reduced-concentration (ME2SO + 0.5M EG), compared to islets preserved with 2M ME2SO. In conclusion, reduced concentration of penetrating CPAs during islet cryopreservation increases islet yield and viability in vitro and reduces delay before normoglycemia in diabetic mice.

Evaluation of [68Ga]DO3A-VS-Cys40-Exendin-4 as a PET Probe for Imaging Human Transplanted Islets in the Liver

[68Ga]DO3A-VS-Cys40-Exendin-4, a glucagon-like peptide 1 receptor agonist, was evaluated as a potential PET tracer for the quantitation of human islets transplanted to the liver. The short-lived PET radionuclide 68Ga, available on a regular basis from a 68Ge/68Ga generator, is an attractive choice. Human C-peptide was measured to evaluate human islet function post-transplantation and prior to microPET imaging. [68Ga]DO3A-VS-Cys40-Exendin-4 was radiosynthesized and evaluated for PET imaging of transplanted human islets in the liver of healthy NOD/SCID mice. The biodistribution of the tracer was evaluated to determine the uptake into various organs, and qPCR of liver samples was conducted to confirm engrafted islet numbers after PET imaging. Measurement of human C-peptide indicated that higher engrafted islet mass resulted in higher human C-peptide levels in post-transplantation. The microPET imaging yielded high resolution images of liver-engrafted islets and also showed significant retention in mouse livers at 8 weeks post-transplantation. Biodistribution studies in mice revealed that liver uptake of [68Ga]DO3A-VS-Cys40-Exendin-4 was approximately 6-fold higher in mice that received 1000 islet equivalent (IEQ) than in non-transplanted mice. qPCR analysis of insulin expression suggested that islet engraftment numbers were close to 1000 IEQ transplanted. In conclusion, human islets transplanted into the livers of mice exhibited significant uptake of [68Ga]DO3A-VS-Cys40-Exendin-4 compared to the livers of untreated mice; and imaging of the mice using PET showed the human islets clearly with high contrast against liver tissue, enabling accurate quantitation of islet mass. Further validation of [68Ga]DO3A-VS-Cys40-Exendin-4 as an islet imaging probe for future clinical application is ongoing.

The protective effect of epigallocatechin 3-gallate on mouse pancreatic islets via the Nrf2 pathway.

Epigallocatechin 3-gallate (EGCG), a green tea polyphenol, has been shown to have anti-oxidant and anti-inflammatory effects in vitro and in vivo. The aim of this study was to investigate the effects and mechanism of EGCG on isolated pancreatic islets as pre-conditioning for pancreatic islet transplantation. The pancreatic islets were divided into two groups: an islet culture medium group (control) and an islet culture medium with EGCG (100µM) group. We investigated the islet viability, Nrf2 expression, reactive oxygen species (ROS) production, and heme oxygenase-1 (HO-1) mRNA. Five hundred islet equivalents after 12h of culture for the EGCG 100µM and control group were transplanted under the kidney capsule of streptozotocin-induced diabetic ICR mice. The cell viability and insulin secretion ability in the EGCG group were preserved, and the nuclear translocation of Nrf2 was increased in the EGCG group (p < 0.01). While the HO-1 mRNA levels were also higher in the EGCG group than in the control group (p < 0.05), the ROS production was lower (p < 0.01). An in vivo functional assessment showed that the blood glucose level had decreased in the EGCG group after transplantation (p < 0.01). EGCG protects the viability and function of islets by suppressing ROS production via the Nrf2 pathway.

Cryopreserved Alginate-Encapsulated Islets Can Restore Euglycemia in a Diabetic Animal Model Better than Cryopreserved Non-encapsulated Islets.

Islet transplantation has been shown to restore normoglycemia clinically. One of the current limitations to the widespread clinical use of islet transplantation is culturing and preserving more than 1 million islet equivalents in preparation for transplant. One possible solution is to bank frozen islets and use them when needed. Although promising, the standard islet freezing protocol introduces stress and cell death, resulting in high variability of islet quality post thawing. This study aimed to develop an improved cryopreservation protocol using alginate-encapsulated islets to improve islet survival and function for future transplants. Our data showed that encapsulation improved islet survival and function after thawing the frozen islets. Frozen encapsulated islets have an islet yield recovery of 84% when compared to non-encapsulated islets at 72% after thawing. Post-thaw viability was 78% for non-encapsulated islets compared to 88% for encapsulated islets. The stimulation index values after a static glucose test following thawing were 1.9 ± 0.5, 2.9 ± 0.1, and 3.3 ± 0.3 for the non-encapsulated, 1.75% alginate, and 2.5% alginate groups, respectively. In a transplant study, the mice that received 1.75% alginate-encapsulated cryopreserved islets achieved normoglycemia on average 5 days after transplant. In comparison, control mice that received fresh islets took 4 days, while those receiving unencapsulated cryopreserved islets took 18 days. In conclusion, encapsulating islets in 1.75% alginate prior to freezing was shown to improve islet survival, function post thawing, and graft response significantly when compared to islets frozen without encapsulation.

The Impact of Endoscopic Retrograde Cholangiopancreatography on Islet Cell Yield During Total Pancreatectomy With Islet Autotransplantation.

Many patients with recurrent acute and chronic pancreatitis who are candidates for total pancreatectomy and islet cell autotransplantation (TPIAT) undergo endoscopic retrograde cholangiopancreatography (ERCP). However, little is known on the impact of ERCP on TPIAT outcomes. We aimed to explore the effect of antecedent ERCP on islet yield and postoperative insulin requirement after TPIAT. Through a prospectively maintained database, we identified patients who underwent TPIAT at our institution between 2009 and 2016. After adjusting for confounders, islet cell yield and postoperative insulin requirement were compared between subjects who did and did not undergo ERCP within 2 years prior to TPIAT. Data were available on 167 TPIAT patients during the study period; 105 (62.9%) had undergone ERCP within 2 years prior. Prior ERCP was not associated with a reduction in islet equivalents per patient kilogram (odds ratio, 1.37; 95% confidence interval, 0.75-2.5; P = 0.31). Antecedent ERCP was not associated with increased postoperative insulin requirement among patients with no diabetes undergoing TPIAT (odds ratio, 0.85; 95% confidence interval, 0.39-1.83; P = 0.67). Antecedent ERCP does not appear to have a deleterious impact on islet cell yield during TPIAT. Additional multicenter data are needed to more clearly determine the impact of ERCP in this context.

Validation of a New North American Islet Donor Score for Donor Pancreas Selection and Successful Islet Isolation in a Medium-Volume Islet Transplant Center

The selection of optimal pancreas donors is one of the key factors in determining the ultimate outcome of clinical islet isolation. North American Islet Donor Score (NAIDS) allows for estimating the chance of the success of islet isolation. It was developed based on the data from over 1000 donors from 11 islet isolation centers and validated in the University of Alberta, Edmonton, on the cohort from the most active islet transplant center. Now we aimed to also validate it in our much less active program. Areas under the receiver operating characteristic curves (AUROCs) and logistic regression analyses were obtained to test if NAIDS would better predict successful islet isolation (defined as post-purification islet yield >400,000 islet equivalents (IEQ)) than previously described Edmonton islet donor score (IDS) and our modified version of IDS. We analyzed the donor scores with reference to 82 of our islet isolation outcomes. The success rate increased proportionally as NAIDS increased, from 0% success in NAIDS < 50 points to 40% success in NAIDS ≥ 80 points. AUROCs were 0.67 (95% confidence interval (CI) 0.55–0.79) for NAIDS, 0.58 (95% CI 0.44–0.71) for modified IDS, and 0.51 (95% CI 0.37–0.65) for IDS and did not differ significantly. However, based on logistic regression analyses, NAIDS was the only statistically significant predictor of successful isolation (p = 0.01). The main advantage of NAIDS is an enhanced ability to discriminate poor-quality donors than previously used scoring systems at University of Chicago, with 0% chance for success when NAIDS was <50 as compared with 40% success rate for IDS <50. NAIDS was found to be the most useful available tool for donor pancreas selection in clinical and research practice in our center, allowing for identification and rejection of poor-quality donors, saving time and resources.

In-hospital and 90-day outcomes after total pancreatectomy with islet autotransplantation for pediatric chronic and acute recurrent pancreatitis.

Total pancreatectomy with islet autotransplantation (TPIAT) is used to treat debilitating chronic pancreatitis (CP) and acute recurrent pancreatitis (ARP) that has failed medical and endoscopic therapy. We performed a retrospective review of TPIAT patients at a free-standing children's hospital to evaluate perioperative outcomes. Twenty patients (median age 13, 65% female) underwent TPIAT (2015 through 2017). Of the 20 patients, 95% had CP and 1 patient (5%) had ARP alone. Seventy-five percent of the patients had a pancreatitis-associated genetic mutation; 40% had pancreas divisum. The median surgical time was 757 (IQR 657 to 835) minutes. Median islet equivalents per kg of body weight (IEQ/kg) were 6404 (IQR 5018 to 7554). At 90days postoperatively vs preoperatively, significantly fewer patients were receiving parenteral nutrition (0% vs 25%, P=.006) and opioids (45% vs 75%, P=.01). Short Form 36-Item Health Survey (SF-36) physical health module scores and total scores improved (34.0 preoperatively vs 54.6 at 90days, P=.008, and 47.1 vs 65.3, P=.007, respectively); SF-10 physical health scores also improved (13.4 vs 33.1, P=.02). Insulin requirement decreased from 0.5 unit/kg/day to 0.4 unit/kg/day between discharge and 90days (P=.02). TPIAT is an effective option when debilitating disease persists despite maximal medical and endoscopic therapy. Opioid, parenteral nutrition, and exogenous insulin use can successfully be weaned within 90days after TPIAT, with gains in health-related quality of life.

Comparison of Clostripain and Neutral Protease as Supplementary Enzymes for Human Islet Isolation

Although human islet transplantation has been established as valid and safe treatment for patients with type 1 diabetes, the utilization rates of human pancreases for clinical islet transplantation are still limited and substantially determined by the quality and composition of collagenase blends. While function and integrity of collagenase has been extensively investigated, information is still lacking about the most suitable supplementary neutral proteases. The present study compared islet isolation outcome after pancreas digestion by means of collagenase used alone or supplemented with either neutral protease (NP), clostripain (CP), or both proteases. Decent amounts of islet equivalents (IEQ) were isolated using collagenase alone (3090 ± 550 IEQ/g), or in combination with NP (2340 ± 450 IEQ/g) or CP (2740 ± 280 IEQ/g). Nevertheless, the proportion of undigested tissue was higher after using collagenase alone (21.1 ± 1.1%, P < 0.05) compared with addition of NP (13.3 ± 2.2%) or CP plus NP (13.7 ± 2.6%). Likewise, the percentage of embedded islets was highest using collagenase only (13 ± 2%) and lowest adding NP plus CP (4 ± 1%, P < 0.01). The latter combination resulted in lowest post-culture overall survival (42.7 ± 3.9%), while highest survival was observed after supplementation with CP (74.5 ± 4.8%, P < 0.01). An insulin response toward glucose challenge was present in all experimental groups, but the stimulation index was significantly decreased using collagenase plus NP (2.0 ± 0.12) compared with supplementation with CP (3.16 ± 0.4, P < 0.001). This study demonstrates for the first time that it is possible to isolate significant numbers of human islets combining collagenase only with CP. The supplementation with CP is an effective means to substantially reduce NP activity, which significantly decreases survival and viability after culture. This will facilitate the manufacturing of enzyme blends with less harmful characteristics.

Correction of Hyperglycemia in Diabetic Rats With the Use of Microencapsulated Young Market Pig Islets

ObjectiveThe aim of this work was to investigate the transplantation efficacy of microencapsulated young market pig islets in a diabetic rat model. MethodsIslets were isolated and purified from young market pigs obtained from a local slaughterhouse. The islets were encapsulated in barium alginate and subjected to a glucose-induced insulin release functional assay in culture. Microencapsulated islets were transplanted into diabetic Sprague-Dawley rats and removed after 30 days for histologic examination. ResultsThe mean islet equivalent (IEQ) yield per gram of digested tissue was 3,125 ± 617 IEQ/g after isolation and 2,618 ± 917 IEQ/g after purification, respectively. Host rats' blood glucose concentrations normalized (from 22.3 ± 2.7 mmol/L to 5.1 ± 0.67 mmol/L) following encapsulated islet transplantation. After graft removal, hyperglycemia recurred in the rats, indicating that the grafts were responsible for maintaining euglycemia. Histology revealed viable islets in the capsules 30 days after graft removal. Immunolabeling of insulin verified that β-cells within the capsules remained well granulated. No fibrosis or immune cells were found in histopathology. ConclusionsBarium alginate encapsulation of young market pig islets can normalize glucose regulation in diabetic rats without fibrosis or an immunologic response.

Patient and Procedural Factors Associated With Increased Islet Cell Yield in Total Pancreatectomy With Islet Autotransplantation.

Total pancreatectomy with islet autotransplantation (TPIAT) offers symptom relief to highly selected patients with recurrent acute and/or chronic pancreatitis. However, with variable clinical response, it is important to refine islet manipulation technique and patient selection criteria. This study explores the variables associated with high islet cell yield, a driver of success in TPIAT. This study evaluated patients who underwent TPIAT at Dartmouth-Hitchcock Medical Center from 2012 to 2016. Odds ratios were calculated for various patient and procedural characteristics. The primary clinical outcome was the number of isolated islet equivalents per kilogram body weight. Thirty-eight patients met inclusion criteria. Patients with no computed tomography or magnetic resonance imaging evidence of chronic pancreatitis, without pancreatic duct stones, and without parenchymal stones were associated with higher odds of success (P = 0.02, P = 0.02, and P = 0.002, respectively). Patients with preoperative glycated hemoglobin greater than 5.6, with islet cell suspensions positive for cultures, and with positive gram stains were associated with lower odds of success (P = 0.02, P = 0.01, and P = 0.02, respectively). Factors that diminish a successful islet cell harvest during TPIAT include the presence of infected islets, an elevated preoperative glycated hemoglobin, and the presence of pancreatic duct stones.