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

Hydrogel injection molded complex macroencapsulation device geometry improves long-term cell therapy viability and function in the rat omentum transplant site

Insulin-secreting allogeneic cell therapies are a promising treatment for type 1 diabetes, with the potential to eliminate hypoglycemia and long-term complications of the disease. However, chronic systemic immunosuppression is necessary to prevent graft rejection, and the acute risks associated with immunosuppression limit the number of patients who can be treated with allogeneic cell therapies. Islet macroencapsulation in a hydrogel biomaterial is one proposed method to reduce or eliminate immune suppression; however, macroencapsulation devices suffer from poor oxygen transport and limited efficacy as they scale to large animal model preclinical studies and clinical trials. Hydrogel geometric device designs that optimize nutrient transport combined with methods to promote localized vasculogenesis may improve in vivo macroencapsulated cell viability and function. Here, we demonstrate with finite element modeling that a high surface area-to-volume ratio spiral geometry can increase macroencapsulated islet viability and function relative to a traditional cylindrical design, and we validate these observations in vitro under normoxic and physiological oxygen conditions. Finally, we evaluate macroencapsulated syngeneic islet survival and function in vivo in a diabetic rat omentum transplant model, and demonstrate that high surface area-to-volume hydrogel device designs improved macroencapsulated syngeneic islet function relative to traditional device designs.

Abdominal normothermic regional perfusion after donation after circulatory death improves pancreatic islet isolation yield

Abdominal normothermic regional perfusion (aNRP) is an in situ normothermic oxygenated donor perfusion technique before procurement during controlled donation after circulatory death (cDCD) procedures and allows for organ quality evaluation. There are few data on the effect of aNRP on pancreatic islet isolation and subsequent transplantation outcomes. We aim to evaluate the impact of aNRP on cDCD pancreatic islet isolation and transplantation. A retrospective analysis was performed on pancreatic islet isolation outcomes from aNRP, cDCD, and donation after brain death pancreases. Isolations were compared to previous donor age (60-75 years) matched isolations. Islet function was assessed by a dynamic glucose-stimulated insulin secretion. Donor baseline characteristics did not differ among groups. Isolations from aNRP pancreases (471 739 islet equivalents [IEQ] [655 435-244 851]) yielded more islets compared to cDCD (218 750 IEQ [375 951-112 364], P < .01) and to donation after brain death (206 522 IEQ [385 544-142 446], P = .03) pancreases. Dynamic glucose-stimulated insulin secretion tests in 7 aNRP islet preparations showed a mean stimulation index of 4.91, indicating good functionality. Bilirubin and alanine aminotransferase during aNRP correlated with islet yield (r2 = 0.685, P = .002; r2 = 0.491, P = .016, respectively). Islet isolation after aNRP in cDCD donors results in a high islet yield with viable functional islets. aNRP could increase the utilization of the pancreases for islet transplantation.

The efficiency of stem cell differentiation into functional beta cells for treating insulin-requiring diabetes: Recent advances and current challenges

In recent years, the potential of stem cells (SCs) to differentiate into various types of cells, including β-cells, has led to a significant boost in development. The efficiency of this differentiation process and the functionality of the cells post-transplantation are crucial factors for the success of stem cell therapy in diabetes. Herein, this article reviews the current advances and challenges faced by stem cell differentiation into functional β-cells for diabetes treatment. In vitro, researchers have sought to enhance the differentiation efficiency of functional β-cells by mimicking the normal pancreatic development process, using gene manipulation, pharmacological and culture conditions stimulation, three-dimensional (3D) and organoid culture, or sorting for functional β-cells based on mature islet cell markers. Furthermore, in vivo studies have also looked at suitable transplantation sites, the enhancement of the transplantation microenvironment, immune modulation, and vascular function reconstruction to improve the survival rate of functional β-cells, thereby enhancing the treatment of diabetes. Despite these advancements, developing stem cells to produce functional β-cells for efficacious diabetes treatment is a continuous research endeavor requiring significant multidisciplinary collaboration, for the stem-cell-derived beta cells to evolve into an effective cellular therapy.

Donor- and isolation-related predictive factors of in vitro secretory function of cultured human islets

Background and aims

Human islet preparations designated for research exhibit diverse insulin-secretory profiles. This study aims to assess the impact of donor- and isolation-related factors on in vitro islet secretory function.

Methods

A retrospective analysis of 46 isolations from 23 pancreata discarded for clinical transplantation was conducted. In vitro islet secretory function tests were performed on Day 1 and Day 7 of culture. Linear mixed-effects models (LMMs) were employed to investigate the relationships between various predictors characterizing the patient and donor characteristics as well as the isolation effectiveness and two functional outcomes including the islet stimulation index (SI) and area under the insulin curve (AUC). Fixed effects were introduced to represent the main effects of each predictor, and backward elimination was utilized to select the most significant fixed effects for the final model. Interaction effects between the timepoint (Day 7 vs. Day 1) and the predictors were also evaluated to assess whether predictors were associated with the temporal evolution of SI and AUC. Fold-change (Fc) values associated with each predictor were obtained by exponentiating the corresponding coefficients of the models, which were built on log-transformed outcomes.

Results

Analysis using LMMs revealed that donor body mass index (BMI) (Fc = 0.961, 95% CI = 0.927-0.996, p = 0.05), donor gender (female vs. male, Fc = 0.702, 95% CI = 0.524-0.942, p = 0.04), and donor hypertension (Fc = 0.623, 95% CI = 0.466-0.832, p= <0.01) were significantly and independently associated with SI. Moreover, donor gender (Fc = 0.512, 95% CI = 0.302-0.864, p = 0.02), donor cause of death (cerebrovascular accident vs. cardiac arrest, Fc = 2.129, 95% CI = 0.915-4.946, p = 0.09; trauma vs. cardiac arrest, Fc = 2.129, 95% CI = 1.112-7.106, p = 0.04), pancreas weight (Fc = 1.01, 95% CI = 1.001-1.019, p = 0.03), and islet equivalent (IEQ)/mg (Fc = 1.277, 95% CI = 1.088-1.510, p ≤ 0.01) were significantly and independently associated with AUC. There was no predictor significantly associated with the temporal evolution between Day 1 and Day 7 for both SI and AUC outcomes.

Conclusion

This study identified donor- and isolation-related factors influencing in vitro islet secretory function. Further investigations are essential to validate the applicability of these results in clinical practice.

Insulin independence following islet transplantation improves long-term metabolic outcomes

AIMS

Pancreatic islet allotransplantation is an effective therapy for type 1 diabetes mellitus, restoring glycaemic control and hypoglycaemic awareness in patients with recurrent severe hypoglycaemia. Insulin independence following transplant is being increasingly reported; however, this is not a primary endpoint in the UK. Having surpassed 10 years of islet transplantation in Scotland, we aimed to evaluate the impact of insulin independence following transplant on metabolic outcomes and graft survival.

METHODS

We conducted a retrospective analysis on data collected prospectively between 2011 and 2022. Patients who underwent islet transplantation in Scotland up to the 31st January 2020 were included. Primary endpoint was graft survival (stimulated C-peptide >50 pmol/L). Secondary endpoints included GOLD score, HbA1c, C-peptide and insulin requirement. Outcomes were compared between patients who achieved insulin independence at any point following transplant versus those who did not.

RESULTS

60 patients were included. 74.5% experienced >50 severe hypoglycaemic episodes in the year preceding transplant. There was a 55.0% decrease in insulin requirement following transplant and 30.0% achieved insulin independence. Mean graft survival time was 9.0 years (95% CI 7.2-10.9) in patients who achieved insulin independence versus 4.4 years (95% CI 3.4-5.3) in patients who did not. Insulin independence was associated with significantly improved graft function, glycaemic control and hypoglycaemic awareness at 1 year.

CONCLUSIONS

This is the largest UK single-centre study on islet transplant to date. Our findings demonstrate significantly improved outcomes in patients who achieved insulin independence following islet transplantation.

Stem cells therapy for diabetes: from past to future

Diabetes mellitus is a chronic disease of carbohydrate metabolism characterized by uncontrolled hyperglycemia due to the body's impaired ability to produce or respond to insulin. Oral or injectable exogenous insulin and its analogs cannot mimic endogenous insulin secreted by healthy individuals, and pancreatic and islet transplants face a severe shortage of sources and transplant complications, all of which limit the widespread use of traditional strategies in diabetes treatment. We are now in the era of stem cells and their potential in ameliorating human disease. At the same time, the rapid development of gene editing and cell-encapsulation technologies has added to the wings of stem cell therapy. However, there are still many unanswered questions before stem cell therapy can be applied clinically to patients with diabetes. In this review, we discuss the progress of strategies to obtain insulin-producing cells from different types of stem cells, the application of gene editing in stem cell therapy for diabetes, as well as summarize the current advanced cell encapsulation technologies in diabetes therapy and look forward to the future development of stem cell therapy in diabetes.

Isolation and Purification of Human Pancreatic Islets

Successful islet isolation is the key to islet transplantation in diabetic patients. However, islet isolation is a technically complex and time-consuming manual process. Optimizing the islet isolation process can improve islet yield and quality, reduce operators, and thus reduce costs.The isolation and purification of human islets include pancreas acquisition and preservation, pancreas digestion, islet purification, islet culture, and islet quality identification. Briefly, after the duodenum was removed, the pancreas was trimmed, the main pancreatic duct was intubated at the distal end of the pancreatic head, collagenase was injected into the pancreatic duct, and the perfused pancreatic tissue was cut and then digested in a Ricordi chamber. A digestion temperature of 37 °C was continuously used to assess the number of samples and the integrity of the lysed and released islets. At the end of the digestion process, collect the digested tissue in a 500 mL centrifuge tube prefilled with 25 mL of cold (4 °C) human serum albumin and centrifuge twice at 150 g for 3 min. After mixing with UW solution as islet storage solution, put it on ice (shake occasionally to prevent clumping) after 30 min. Digested pancreatic tissue was centrifuged at 2200 rpm for 5 min in a COBE 2991 cell processor to isolate islets from exocrine tissue using a continuous density gradient. The purified islet fractions were washed twice in HBSS supplemented with 10% human serum albumin and finally collected in CMRL1066 medium supplemented with the corresponding liquid. The purity of purified islets was calculated by DTZ staining, the survival rate of islets was calculated by FDA/PI staining, and islet function was determined by in vitro glucose-stimulated insulin secretion test.

Microwell culture platform maintains viability and mass of human pancreatic islets

Background

Transplantation of the human pancreatic islets is a promising approach for specific types of diabetes to improve glycemic control. Although effective, there are several issues that limit the clinical expansion of this treatment, including difficulty in maintaining the quality and quantity of isolated human islets prior to transplantation. During the culture, we frequently observe the multiple islets fusing together into large constructs, in which hypoxia-induced cell damage significantly reduces their viability and mass. In this study, we introduce the microwell platform optimized for the human islets to prevent unsolicited fusion, thus maintaining their viability and mass in long-term cultures.

Method

Human islets are heterogeneous in size; therefore, two different-sized microwells were prepared in a 35 mm-dish format: 140 µm × 300 µm-microwells for <160 µm-islets and 200 µm × 370 µm-microwells for >160 µm-islets. Human islets (2,000 islet equivalent) were filtered through a 160 µm-mesh to prepare two size categories for subsequent two week-cultures in each microwell dish. Conventional flat-bottomed 35 mm-dishes were used for non-filtered islets (2,000 islet equivalent/2 dishes). Post-cultured islets are collected to combine in each condition (microwells and flat) for the comparisons in viability, islet mass, morphology, function and metabolism. Islets from three donors were independently tested.

Results

The microwell platform prevented islet fusion during culture compared to conventional flat bottom dishes, which improved human islet viability and mass. Islet viability and mass on the microwells were well-maintained and comparable to those in pre-culture, while flat bottom dishes significantly reduced islet viability and mass in two weeks. Morphology assessed by histology, insulin-secreting function and metabolism by oxygen consumption did not exhibit the statistical significance among the three different conditions.

Conclusion

Microwell-bottomed dishes maintained viability and mass of human islets for two weeks, which is significantly improved when compared to the conventional flat-bottomed dishes.

A Low Dose of Ouabain Alters the Metabolic Profile of Adult Rats Experiencing Intrauterine Growth Restriction in a Sex-Specific Manner

Intrauterine growth restriction (IUGR) increases the risk of type 2 diabetes mellitus (T2DM) and metabolic diseases. The pancreas of fetuses with IUGR is usually characterized by pancreatic dysplasia and reduced levels of insulin secretion caused by the diminished replication of β-cells. Previous studies showed that a low dose of ouabain could reduce the apoptosis of embryonic nephric cells during IUGR and partially restore the number of nephrons at birth. The rescued kidneys functioned well and decreased the prevalence of hypertension. Thus, we hypothesized that ouabain could rescue pancreatic development during IUGR and reduce the morbidity of T2DM and metabolic diseases. Maternal malnutrition was used to induce the IUGR model, and then a low dose of ouabain was administered to rats with IUGR during pregnancy. Throughout the experiment, we monitored the pattern of weight increase and evaluated the metabolic parameters in the offspring in different stages. Male, but not female, offspring in the IUGR group presented catch-up growth. Ouabain could benefit the impaired glucose tolerance of male offspring; however, this desirable effect was eliminated by aging. The insulin sensitivity was significantly impaired in male offspring with IUGR, but it was improved by ouabain, even during old age. However, in the female offspring, low birth weight appeared to be a beneficial factor even in old age; administering ouabain exacerbated these favorable effects. Our data suggested that IUGR influenced glucose metabolism in a sex-specific manner and ouabain treatment during pregnancy exerted strongly contrasting effects in male and female rats.

Stem cell therapy for insulin-dependent diabetes: Are we still on the road?

In insulin-dependent diabetes, the islet β cells do not produce enough insulin and the patients must receive exogenous insulin to control blood sugar. However, there are still many deficiencies in exogenous insulin supplementation. Therefore, the replacement of destroyed functional β cells with insulin-secreting cells derived from functional stem cells is a good idea as a new therapeutic idea. This review introduces the development schedule of mouse and human embryonic islets. The differences between mouse and human pancreas embryo development were also listed. Accordingly to the different sources of stem cells, the important research achievements on the differentiation of insulin-secreting β cells of stem cells and the current research status of stem cell therapy for diabetes were reviewed. Stem cell replacement therapy is a promising treatment for diabetes, caused by defective insulin secretion, but there are still many problems to be solved, such as the biosafety and reliability of treatment, the emergence of tumors during treatment, untargeted differentiation and autoimmunity, etc. Therefore, further understanding of stem cell therapy for insulin is needed.

Estimation of Early Graft Function Using the BETA-2 Score Following Clinical Islet Transplantation

Little is known about how early islet graft function evolves in the clinical setting. The BETA-2 score is a validated index of islet function that can be calculated from a single blood sample and lends itself to frequent monitoring of graft function. In this study, we characterized early graft function by calculating weekly BETA-2 score in recipients who achieved insulin independence after single transplant (group 1, n = 8) compared to recipients who required a second transplant before achieving insulin independence (group 2, n = 7). We also determined whether graft function 1-week post-transplant was associated with insulin independence in individuals who received initial transplant between 2000–2017 (n = 125). Our results show that graft function increased rapidly reaching a plateau 4–6 weeks post-transplant. The BETA-2 score was higher in group 1 compared to group 2 as early as 1-week post-transplant (15 + 3 vs. 9 + 2, p = 0.001). In an unselected cohort, BETA-2 at 1-week post-transplant was associated with graft survival as defined by insulin independence during median follow up of 12 months (range 2–119 months) with greater survival among those with BETA-2 score &gt;10 (p &lt; 0.001, log-rank test). These findings suggest that primary graft function is established within 4–6 weeks post-transplant and graft function at 1-week post-transplant predicts long-term transplant outcomes.

Perioperative Coagulation Changes in Total Pancreatectomy and Islet Autotransplantation

OBJECTIVES

Thrombotic complications after total pancreatectomy with islet autotransplantation (TPIAT) are common. However, the systemic changes to coagulation in the perioperative period have not been well studied. Our objective was to evaluate the derangements in coagulation in the perioperative period for this procedure.

METHODS

This was a prospective observational study of patients undergoing elective TPIAT for chronic pancreatitis. Multiple methods of evaluating coagulation, including 2 viscoelastic assays and standard laboratory assays were obtained at defined intraoperative and postoperative intervals.

RESULTS

Fifteen patients were enrolled. Laboratory values demonstrated initial intraoperative hypercoagulability before significant systemic anticoagulation after islet infusion with heparin. Hypercoagulability is again seen at postoperative days 3 and 7. Subgroup analysis did not identify any major coagulation parameters associated with portal vein thrombosis formation.

CONCLUSIONS

Apart from the immediate period after islet cell and heparin infusion, patients undergoing TPIAT are generally hypercoagulable leading to a high rate of thrombotic complications. Portal vein thrombosis development had minimal association with systemic derangements in coagulation as it is likely driven by localized inflammation at the time of islet cell infusion. This study may provide the groundwork for future studies to identify improvements in thrombotic complications.

Possibility of adiponectin use to improve islet transplantation outcomes

Although islet transplantation (ITx) is a promising therapy for severe diabetes mellitus, further advancements are necessary. Adiponectin, an adipokine that regulates lipid and glucose metabolism, exerts favorable effects on islets, such as reinforcement of the insulin-releasing function. This study evaluated the possibility of adiponectin use to improve ITx outcomes. We treated mouse islets with 10 µg/mL recombinant mouse adiponectin by overnight culture and then assessed the insulin-releasing, angiogenic, and adhesion functions of the islets. Furthermore, 80 syngeneic islet equivalents with or without adiponectin treatment were transplanted into the renal subcapsular space of diabetic mice. In in vitro assessment, released insulin at high glucose stimulation, insulin content, and expressions of vascular endothelial growth factor and integrin β1 were improved in adiponectin-treated islets. Furthermore, adiponectin treatment improved the therapeutic effect of ITx on blood glucose levels and promoted angiogenesis of the transplanted islets. However, the therapeutic effect was not pronounced in glucose tolerance test results. In conclusion, adiponectin treatment had preferable effects in the insulin-releasing, angiogenic, and adhesion functions of islets and contributed to the improvement of ITx. The future use of adiponectin treatment in clinical settings to improve ITx outcomes should be investigated.

The impact of islet mass, number of transplants, and time between transplants on graft function in a national islet transplant program

The UK islet allotransplant program is nationally funded to deliver one or two transplants over 12 months to individuals with type 1 diabetes and recurrent severe hypoglycemia. Analyses were undertaken 10 years after program inception to evaluate associations between transplanted mass; single versus two transplants; time between two transplants and graft survival (stimulated C-peptide >50 pmol/L) and function. In total, 84 islet transplant recipients were studied. Uninterrupted graft survival over 12 months was attained in 23 (68%) single and 47 (94%) (p = .002) two transplant recipients (separated by [median (IQR)] 6 (3-8) months). 64% recipients of one or two transplants with uninterrupted function at 12 months sustained graft function at 6 years. Total transplanted mass was associated with Mixed Meal Tolerance Test stimulated C-peptide at 12 months (p < .01). Despite 1.9-fold greater transplanted mass in recipients of two versus one islet infusion (12 218 [9291-15 417] vs. 6442 [5156-7639] IEQ/kg; p < .0001), stimulated C-peptide was not significantly higher. Shorter time between transplants was associated with greater insulin dose reduction at 12 months (beta -0.35; p = .02). Graft survival over the first 12 months was greater in recipients of two versus one islet transplant in the UK program, although function at 1 and 6 years was comparable. Minimizing the interval between 2 islet infusions may maximize cumulative impact on graft function.

Utility of Islet Cell Preparations From Donor Pancreases After Euthanasia

Patients fulfilling criteria for euthanasia can choose to donate their organs after circulatory death [donors after euthanasia (DCD V)]. This study assesses the outcome of islet cell isolation from DCD V pancreases. A procedure for DCD V procurement provided 13 pancreases preserved in Institut Georges Lopez-1 preservation solution and following acirculatory warm ischemia time under 10 minutes. Islet cell isolation outcomes are compared with those from reference donors after brain death (DBD, n = 234) and a cohort of donors after controlled circulatory death (DCD III, n = 29) procured under the same conditions. Islet cell isolation from DCD V organs resulted in better in vitro outcome than for selected DCD III or reference DBD organs. A 50% higher average beta cell number before and after culture and a higher average beta cell purity (35% vs 24% and 25%) was observed, which led to more frequent selection for our clinical protocol (77% of isolates vs 50%). The functional capacity of a DCD V islet cell preparation was illustrated by its in vivo effect following intraportal transplantation in a type 1 diabetes patient: injection of 2 million beta cells/kg body weight (1,900 IEQ/kg body weight) at 39% insulin purity resulted in an implant with functional beta cell mass that represented 30% of that in non-diabetic controls. In conclusion, this study describes procurement and preservation conditions for donor organs after euthanasia, which allow preparation of cultured islet cells, that more frequently meet criteria for clinical use than those from DBD or DCD III organs.

A Multiparametric Assessment of Human Islets Predicts Transplant Outcomes in Diabetic Mice

Prior to transplantation into individuals with type 1 diabetes, in vitro assays are used to evaluate the quality, function and survival of isolated human islets. In addition to the assessments of these parameters in islet, they can be evaluated by multiparametric morphological scoring (0–10 points) and grading (A, B, C, D, and F) based on islet characteristics (shape, border, integrity, single cells, and diameter). However, correlation between the multiparametric assessment and transplantation outcome has not been fully elucidated. In this study, 55 human islet isolations were scored using this multiparametric assessment. The results were correlated with outcomes after transplantation into immunodeficient diabetic mice. In addition, the multiparametric assessment was compared with oxygen consumption rate of isolated islets as a potential prediction factor for successful transplantations. All islet batches were assessed and found to score: 9 points (n = 18, Grade A), 8 points (n = 19, Grade B), and 7 points (n = 18, Grade B). Islets that scored 9 (Grade A), scored 8 (Grade B) and scored 7 (Grade B) were transplanted into NOD/SCID mice and reversed diabetes in 81.2%, 59.4%, and 33.3% of animals, respectively (P < 0.0001). Islet scoring and grading correlated well with glycemic control post-transplantation (P < 0.0001) and reversal rate of diabetes (P < 0.05). Notably, islet scoring and grading showed stronger correlation with transplantation outcome compared to oxygen consumption rate. Taken together, a multiparametric assessment of isolated human islets was highly predictive of transplantation outcome in diabetic mice.

Challenges, highlights, and opportunities in cellular transplantation: A white paper of the current landscape

Although cellular transplantation remains a relatively small field compared to solid organ transplantation, the prospects for advancement in basic science and clinical care remain bountiful. In this review, notable historical events and the current landscape of the field of cellular transplantation are reviewed with an emphasis on islets (allo- and xeno-), hepatocytes (including bioartificial liver), adoptive regulatory immunotherapy, and stem cells (SCs, specifically endogenous organ-specific and mesenchymal). Also, the nascent but rapidly evolving field of three-dimensional bioprinting is highlighted, including its major processing steps and latest achievements. To reach its full potential where cellular transplants are a more viable alternative than solid organ transplants, fundamental change in how the field is regulated and advanced is needed. Greater public and private investment in the development of cellular transplantation is required. Furthermore, consistent with the call of multiple national transplant societies for allo-islet transplants, the oversight of cellular transplants should mirror that of solid organ transplants and not be classified under the unsustainable, outdated model that requires licensing as a drug with the Food and Drug Administration. Cellular transplantation has the potential to bring profound benefit through progress in bioengineering and regenerative medicine, limiting immunosuppression-related toxicity, and providing markedly reduced surgical morbidity.

Clinical use of donation after circulatory death pancreas for islet transplantation

Due to a shortage of donation after brain death (DBD) organs, donation after circulatory death (DCD) is increasingly performed. In the field of islet transplantation, there is uncertainty regarding the suitability of DCD pancreas in terms of islet yield and function after islet isolation. The aim of this study was to investigate the potential use of DCD pancreas for islet transplantation. Islet isolation procedures from 126 category 3 DCD and 258 DBD pancreas were performed in a 9-year period. Islet yield after isolation was significantly lower for DCD compared to DBD pancreas (395 515 islet equivalents [IEQ] and 480 017 IEQ, respectively; p = .003). The decrease in IEQ during 2 days of culture was not different between the two groups. Warm ischemia time was not related to DCD islet yield. In vitro insulin secretion after a glucose challenge was similar between DCD and DBD islets. After islet transplantation, DCD islet graft recipients had similar graft function (AUC C-peptide) during mixed meal tolerance tests and Igls score compared to DBD graft recipients. In conclusion, DCD islets can be considered for clinical islet transplantation.

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

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.

Comparison of Islet Characterization from Use of Standard Crude Collagenase to GMP-Grade Collagenase Enzyme Blends in Preweaned Porcine Islet Isolations

For the advancement of porcine xenotransplantation for clinical use in type 1 diabetes mellitus, the concerns of a sustainable and safe digestion enzyme blend must be overcome. Incorporating good manufacturing practices (GMP) can facilitate this through utilizing GMP-grade enzymes. In conjunction, still taking into account the cost-effectiveness, a wide concern. We evaluated how GMP-grade enzyme blends impact our piglet islets and their long-term effects.  Preweaned porcine islets (PPIs) were isolated from 8- to 10-day-old pigs. Digestion enzyme blends, collagenase type V (Type V), collagenase AF-1 GMP-grade with collagenase NB 6 GMP-grade (AF-1 and NB 6), and collagenase AF-1 GMP-grade with collagenase neutral protease AF GMP-grade (AF-1 and NP AF) were compared. Islet quality control assessments, islet yield, viability, and function, were performed on days 3 and 7, and cell content was performed on day 7.  GMP-grade AF-1 and NB 6 (17,209 ± 2,730 islet equivalent per gram of pancreatic tissue [IE/g] on day 3, 9,001 ± 1,034 IE/g on day 7) and AF-1 and NP AF (17,214 ± 3,901 IE/g on day 3, 8,833 ± 2,398 IE/g on day 7) showed a significant increase in islet yield compared to Type V (4,618 ± 1,240 IE/g on day 3, 1,923 ± 704 IE/g on day 7). Islet size, viability, and function showed comparable results in all enzyme blends. There was no significant difference in islet cellular content between enzyme blends.  This study demonstrated a comparison of GMP-grade collagenase enzyme blends and a standard crude collagenase enzyme in preweaned-aged porcine, a novel topic in this age. GMP-grade enzyme blends of AF-1 and NB 6 and AF-1 and NP AF resulted in substantially higher yields and as effective PPIs compared to Type V. In the long run, considering costs, integrity, and sustainability, GMP-grade enzyme blends are more favorable for clinical application due to high reproducibility in comparison to undefined manufacturing processes of standard enzymes.

Hypothermic oxygenated machine perfusion of the human pancreas for clinical islet isolation: a prospective feasibility study

Due to an increasing scarcity of pancreases with optimal donor characteristics, islet isolation centers utilize pancreases from extended criteria donors, such as from donation after circulatory death (DCD) donors, which are particularly susceptible to prolonged cold ischemia time (CIT). We hypothesized that hypothermic machine perfusion (HMP) can safely increase CIT. Five human DCD pancreases were subjected to 6 h of oxygenated HMP. Perfusion parameters, apoptosis, and edema were measured prior to islet isolation. Five human DBD pancreases were evaluated after static cold storage (SCS). Islet viability, and in vitro and in vivo functionality in diabetic mice were analyzed. Islets were isolated from HMP pancreases after 13.4 h [12.9–14.5] CIT and after 9.2 h [6.5–12.5] CIT from SCS pancreases. Histological analysis of the pancreatic tissue showed that HMP did not induce edema nor apoptosis. Islets maintained >90% viable during culture, and an appropriate in vitro and in vivo function in mice was demonstrated after HMP. The current study design does not permit to demonstrate that oxygenated HMP allows for cold ischemia extension; however, the successful isolation of functional islets from discarded human DCD pancreases after performing 6 h of oxygenated HMP indicates that oxygenated HMP may be a useful technology for better preservation of pancreases.

Comparison of islet isolation result and clinical applicability according to GMP-grade collagenase enzyme blend in adult porcine islet isolation and culture

Background

Porcine islet xenotransplantation is a promising treatment for type 1 diabetes as an alternative to human pancreatic islet transplantation and long‐term insulin therapy. Several research groups have explored porcine islets as an alternative to the inconsistent and chronic shortage of pancreases from human organ donors. Studies have confirmed successful transplant of porcine islets into non‐human primate models of diabetes; however, in most cases, they require more than one adult porcine donor to achieve sufficient viable islet mass for sustained function. The importance of GMP‐grade reagents includes the following: specific enzymes utilized in the pancreatic isolation process were identified as a key factor in successful human clinical islet transplantation trials using cadaveric islets. As xenotransplantation clinical research progresses, isolation reagents and digestion enzymes play a key role in the consistency of the product and ultimately the outcome of the islet xenotransplant. In this study, we evaluated several commercially available enzyme blends that have been used for islet isolation. We evaluated their impact on islet isolation yield and subsequent islet function as part of our plan to bring xenotransplantation into clinical xenotransplantation trials.

Methods

Adult porcine islets were isolated from 16 to 17‐month‐old Yucatan miniature pigs following standard rapid procurement. Pigs weighed on average 48.71 ± 2.85 kg, and the produced pancreases were 39.51 ± 1.80 grams (mean ± SEM). After ductal cannulation, we evaluated both GMP‐grade enzymes (Collagenase AF‐1 GMP grade and Liberase MTF C/T GMP grade) and compared with standard non‐GMP enzyme blend (Collagenase P). Islet quality control assessments including islet yield, islet size (IEQ), membrane integrity (acridine orange/propidium iodide), and functional viability (GSIS) were evaluated in triplicate on day 1 post‐islet isolation culture.

Results

Islet yield was highest in the group of adult pigs where Collagenase AF‐1 GMP grade was utilized. The mean islet yield was 16 586 ± 1391 IEQ/g vs 8302 ± 986 IEQ/g from pancreases isolated using unpurified crude Collagenase P. The mean islet size was higher in Collagenase AF‐1 GMP grade with neutral protease than in Collagenase P and Liberase MTF C/T GMP grade. We observed no significant difference between the experimental groups, but in vitro islet function after overnight tissue culture was significantly higher in Collagenase AF‐1 GMP grade with neutral protease and Liberase MTF C/T GMP grade than the crude control enzyme group. As expected, the GMP‐grade enzyme has significantly lower endotoxin levels than the crude control enzyme group when measured.

Conclusions

This study validates the importance of using specifically blended GMP grade for adult pig islet isolation for xenotransplantation trials and the ability to isolate a sufficient number of viable islets from one adult pig to provide a sufficient number for islets for a clinical islet transplantation. GMP‐grade enzymes are highly efficient in increasing islet yield, size, viability, and function at a lower and acceptable endotoxin level. Ongoing research transplants these islets into animal models of diabetes to validate in vivo function. Also, these defined and reproducible techniques using GMP‐grade enzymes allow for continuance of our plan to advance to xenotransplantation of isolated pig islets for the treatment of type 1 diabetes.

The Feasibility and Applicability of Stem Cell Therapy for the Cure of Type 1 Diabetes

Stem cell therapy using islet-like insulin-producing cells derived from human pluripotent stem cells has the potential to allow patients with type 1 diabetes to withdraw from insulin therapy. However, several issues exist regarding the use of stem cell therapy to treat type 1 diabetes. In this review, we will focus on the following topics: (1) autoimmune responses during the autologous transplantation of stem cell-derived islet cells, (2) a comparison of stem cell therapy with insulin injection therapy, (3) the impact of the islet microenvironment on stem cell-derived islet cells, and (4) the cost-effectiveness of stem cell-derived islet cell transplantation. Based on these various viewpoints, we will discuss what is required to perform stem cell therapy for patients with type 1 diabetes.

Outcomes of Islet Autotransplantation in Chronic Pancreatitis Patients with Complete Acinar Atrophy

Total pancreatectomy with islet autotransplantation (TPIAT) is a promising treatment for refractory chronic pancreatitis (CP). Pathological features of CP include progressive fibrosis in pancreas parenchyma, atrophy, and/or ductal occlusion. Complete acinar atrophy (CAA) caused by chronic fibrosis and necroinflammation results in exocrine sufficiency and may influence islet isolation characteristics during TPIAT. In this analysis of patients who underwent TPIAT at our center, we compared transplant outcomes among those with CAA (n = 5) vs non-acinar atrophy (NAA; matching controls, n = 36). Data were analyzed using one-way analysis of variance with Bonferroni post hoc test or Student's t test. Pancreas digestion was longer in CAA than in NAA cases (18.6 vs 14.6 min) despite a lower pancreas weight (55.2 vs 91.2 g). Obtained tissue volume was 1.0 ml in the CAA group and 12.1 ml in the NAA group. Both groups had similar islet viability (96%) and islet dose (CAA, 3,391 IEQ/kg; NAA, 4141.1 IEQ/kg). During islet infusion, serum cytokine (IL-6, IL-8, and MCP-1) levels and plasma hsa-miR-375 levels were lower in the CAA group than in the NAA group, but not significantly. Serum tumor necrosis factor α levels at 3 h after infusion were significantly higher in CAA group than in NAA group. After TPIAT, the metabolic outcomes of the CAA group were comparable with that of the NAA group. Narcotics usage decreased significantly over 24 months in both groups, with the CAA group reporting being pain free at 12 months. Complete atrophy of acinar cells of pancreas did not significantly impact islet yield or endocrine function after TPIAT.

Surgical management of 10 years delayed recurrent acute pancreatitis post Whipple procedure for chronic pancreatitis: A case report

Introduction

In patients who underwent pancreatoduodenectomy for management of Chronic pancreatitis, early and late anastomotic failure can occur [1]. Nevertheless, taking into consideration that most pancreatic head resections are performed for malignant disease with poor prognosis, long term pancreatico-jejunal anastomotic durability has not been well examined; similarly, the management of its stenosis has not been well assessed [1].

Case

Here we present a case of a 69 years old male patient with history of chronic alcoholic pancreatitis and ampullary fibrosis managed by pancreatico-duodenectomy presenting for 10 years delayed onset of recurrent acute pancreatitis with signs of pancreatico-jejunal anastomotic stenosis, managed surgically with revision of pancreatico-jejunal anastomosis.

Conclusion

Our case report might hold strongly for bringing up a purposeful approach, and be an insight to take into consideration in approaching pancreatic anastomosis, especially when pancreatic resections are utilized for treating benign pathologies.

•

Long term recurrent acute pancreatitis post pancreatic resections for benign pathologies are more and more emerging.

•

Recurrent acute pancreatitis post pancreatic resections manifest as debilitating entities that urges interventions for relief of symptoms, after failure of conservative management.

•

Strictures of pancreatico-jejunostomy, one of the common causes for recurrent acute pancreatitis post pancreatic resections.

•

Revision of anastomosis for relief of symptoms and preservation of gland function shall gain more publicity compared to radical interventions.

Lower beta cell yield from donor pancreases after controlled circulatory death prevented by shortening acirculatory warm ischemia time and by using IGL-1 cold preservation solution

Organs from donors after controlled circulatory death (DCD III) exhibit a higher risk for graft dysfunction due to an initial period of warm ischemia. This procurement condition can also affect the yield of beta cells in islet isolates from donor pancreases, and hence their use for transplantation. The present study uses data collected and generated by our Beta Cell Bank to compare the number of beta cells in isolates from DCD III (n = 141) with that from donors after brain death (DBD, n = 609), before and after culture, and examines the influence of donor and procurement variables. Beta cell number per DCD III-organ was significantly lower (58 x 106 versus 84 x 106 beta cells per DBD-organ; p < 0.001) but their purity (24% insulin positive cells) and insulin content (17 μg / 106 beta cells in DCD III-organs versus 19 μg / 106 beta cells in DBD-organs) were similar. Beta cell number correlated negatively with duration of acirculatory warm ischemia time above 10 min; for shorter acirculatory warm ischemia time, DCD III-organs did not exhibit a lower beta cell yield (74 x 106 beta cells). Use of Institut Georges Lopez-1 cold preservation solution instead of University of Wisconsin solution or histidine-tryptophan-ketoglutarate also protected against the loss in beta cell yield from DCD III-organs (86 x 106 for IGL-1 versus 54 x 106 and 65 x 106 beta cells respectively, p = 0.042). Multivariate analysis indicates that both limitation of acirculatory warm ischemia time and use of IGL-1 prevent the reduced beta cell yield in islet cell isolates from DCD III-organs.

Pancreatic islet transplantation under the kidney capsule of mice: model of refinement for molecular and ex-vivo graft analysis

Diabetes cell therapy by human islet transplantation can restore an endogenous insulin secretion and normal glycaemic control in type 1 diabetic patients for as long as 10 years post transplantation. Before transplantation, each clinical islet preparation undergoes extensive in-vitro and in-vivo quality controls. The in-vivo quality control assay consists of transplanting human islets under the kidney capsule of immunocompromised mice. Currently, it is considered the best predictive factor to qualify clinical transplant efficiency. This chimeric model offers a wide area of study since it combines the possibility of producing not only quantitative but also a maximum of qualitative data. Today's technological advances allow us to obtain more accurate and stronger data from the animals used in research while ensuring their comfort and well-being throughout the protocol, including cage enrichment and pain treatment during and after surgery. As demonstrated in this valuable model, we are able to generate more usable results (Refine), while reducing the number of animals used (Reduce), by focusing on the development of ex-vivo analysis techniques (Replace), which clearly highlights the Burch and Russell 3Rs concept.

Human pluripotent stem cell-derived insulin-producing cells: A regenerative medicine perspective

Tremendous progress has been made over the last two decades in the field of pancreatic beta cell replacement therapy as a curative measure for diabetes. Transplantation studies have demonstrated therapeutic efficacy, and cGMP-grade cell products are currently being deployed for the first time in human clinical trials. In this perspective, we discuss current challenges surrounding the generation, delivery, and engraftment of stem cell-derived islet-like cells, along with strategies to induce durable tolerance to grafted cells, with an eye toward a functional cellular-based therapy enabling insulin independence for patients with diabetes.

Impact of ischemia time on islet isolation success and posttransplantation outcomes: A retrospective study of 452 pancreas isolations

Many variables impact islet isolation, including pancreas ischemia time. The ischemia time upper limit that should be respected to avoid a negative impact on the isolation outcome is not well defined. We have performed a retrospective analysis of all islet isolations in our center between 2008 and 2018. Total ischemia time, cold ischemia time, and organ removal time were analyzed. Isolation success was defined as an islet yield ≥200 000 IEQ. Of the 452 pancreases included, 288 (64%) were successfully isolated. Probability of isolation success showed a significant decrease after 8 hours of total ischemia time, 7 hours of cold ischemia time, and 80 minutes of organ removal time. Although we observed an impact of ischemia time on islet yield, a probability of isolation success of 50% was still present even when total ischemia time exceeds 12 hours. Posttransplantation clinical outcomes were assessed in 32 recipients and no significant difference was found regardless of ischemia time. These data indicate that although shorter ischemia times are associated with better islet isolation outcomes, total ischemia time >12 hours can provide excellent results in appropriately selected donors.

The demise of islet allotransplantation in the United States: A call for an urgent regulatory update

Islet allotransplantation in the United States (US) is facing an imminent demise. Despite nearly three decades of progress in the field, an archaic regulatory framework has stymied US clinical practice. Current regulations do not reflect the state-of-the-art in clinical or technical practices. In the US, islets are considered biologic drugs and "more than minimally manipulated" human cell and tissue products (HCT/Ps). In contrast, across the world, human islets are appropriately defined as "minimally manipulated tissue" and not regulated as a drug, which has led to islet allotransplantation (allo-ITx) becoming a standard-of-care procedure for selected patients with type 1 diabetes mellitus. This regulatory distinction impedes patient access to islets for transplantation in the US. As a result only 11 patients underwent allo-ITx in the US between 2016 and 2019, and all as investigational procedures in the settings of a clinical trials. Herein, we describe the current regulations pertaining to islet transplantation in the United States. We explore the progress which has been made in the field and demonstrate why the regulatory framework must be updated to both better reflect our current clinical practice and to deal with upcoming challenges. We propose specific updates to current regulations which are required for the renaissance of ethical, safe, effective, and affordable allo-ITx in the United States.

Clinical islet transplantation: Current progress and new frontiers

Islet transplantation (IT) is now a robust treatment for selected patients with type 1 diabetes suffering from recurrent hypoglycemia and impaired awareness of hypoglycemia. A global soar of clinical islet transplant programs attests to the commitment of many institutions and researchers to advance IT as a potential cure for this devastating disease. However, many challenges limiting the widespread applicability of clinical IT remain. In this review, we will touch on the milestones in the history of IT and its path to clinical success, discuss the current challenges around IT, propose some possible solutions, and elaborate on the frontiers envisioned in the future of clinical IT.

Use of Culture to Reach Metabolically Adequate Beta-cell Dose by Combining Donor Islet Cell Isolates for Transplantation in Type 1 Diabetes Patients

BACKGROUND

Clinical islet transplantation is generally conducted within 72 hours after isolating sufficient beta-cell mass. A preparation that does not meet the sufficient dose can be cultured until this is reached after combination with subsequent ones. This retrospective study examines whether metabolic outcome is influenced by culture duration.

METHODS

Forty type 1 diabetes recipients of intraportal islet cell grafts under antithymocyte globulin induction and mycophenolate mofetil-tacrolimus maintenance immunosuppression were analyzed. One subgroup (n = 10) was transplanted with preparations cultured for ≥96 hours; in the other subgroup (n = 30) grafts contained similar beta-cell numbers but included isolates that were cultured for a shorter duration. Both subgroups were compared by numbers with plasma C-peptide ≥0.5 ng/mL, low glycemic variability associated with C-peptide ≥1.0 ng/mL, and with insulin independence.

RESULTS

The subgroup with all cells cultured ≥96 hours exhibited longer C-peptide ≥0.5 ng/mL (103 versus 48 mo; P = 0.006), and more patients with low glycemic variability and C-peptide ≥1.0 ng/mL, at month 12 (9/10 versus 12/30; P = 0.005) and 24 (7/10 versus 6/30; P = 0.007). In addition, 9/10 became insulin-independent versus 15/30 (P = 0.03). Grafts with all cells cultured ≥96 hours did not contain more beta cells but a higher endocrine purity (49% versus 36%; P = 0.03). In multivariate analysis, longer culture duration and older recipient age were independently associated with longer graft function.

CONCLUSIONS

Human islet isolates with insufficient beta-cell mass for implantation within 72 hours can be cultured for 96 hours and longer to combine multiple preparations in order to reach the desired beta-cell dose and therefore result in a better metabolic benefit.

Heterogeneity of Human Pancreatic Islet Isolation Around Europe: Results of a Survey Study

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.

Pancreas collagen digestion during islet of Langerhans isolation-a prospective study

The success of pancreas islet isolation largely depends on donor characteristics, including extracellular matrix composition of which collagen is the main element. We hypothesized that isolation yields are proportional to collagen digestion percentage, and aimed to determine a threshold that predicts isolation success. The amount of pancreas collagen (I-V) was determined using colorimetry prior to and after the digestion process in 52 human islet isolations. Collagen I-V and VI were also assessed histologically. We identified a collagen digestion threshold of ≥ 60% as an independent factor beyond which an islet preparation has a ninefold increased odds of yielding ≥ 250 000 islet equivalents (IEQ) (P = 0.009) and a sixfold increased odds of being transplanted (P = 0.015). Preparations with ≥ 60% collagen digestion (n = 35) yielded 283 017 ± 164 214 IEQ versus 180 142 ± 85 397 in the < 60% collagen digestion group (n = 17) (P = 0.016); respectively 62.9% versus 29.4% of those were transplanted (P = 0.024). Common donor characteristics, initial collagen content, enzyme blend, and digestion times were not associated with collagen digestion percentage variations. Donor age positively correlated with the amount of collagen VI (P = 0.013). There was no difference in islet graft survival between high and low digestion groups. We determined that a 60% pancreas collagen digestion is the threshold beyond which an islet isolation is likely to be successful and transplanted.

White Adipose Tissue as a Site for Islet Transplantation

Although islet transplantation is recognized as a useful cellular replacement therapy for severe diabetes, surgeons face difficulties in islet engraftment. The transplant site is a pivotal factor that influences the engraftment. Although the liver is the current representative site for clinical islet transplantation, it is not the best site because of limitations in immunity, inflammation, and hypoxia. White adipose tissue, including omentum, is recognized as a useful candidate site for islet transplantation. Its effectiveness has been evaluated in not only various basic and translational studies using small and large animals but also in some recent clinical trials. In this review, we attempt to shed light on the characteristics and usefulness of white adipose tissue as a transplant site for islets.

White Adipose Tissue as a Site for Islet Transplantation

Although islet transplantation is recognized as a useful cellular replacement therapy for severe diabetes, surgeons face difficulties in islet engraftment. The transplant site is a pivotal factor that influences the engraftment. Although the liver is the current representative site for clinical islet transplantation, it is not the best site because of limitations in immunity, inflammation, and hypoxia. White adipose tissue, including omentum, is recognized as a useful candidate site for islet transplantation. Its effectiveness has been evaluated in not only various basic and translational studies using small and large animals but also in some recent clinical trials. In this review, we attempt to shed light on the characteristics and usefulness of white adipose tissue as a transplant site for islets.

Improved harmonization of critical characterization assays across cell therapies

The field of cell therapy has blossomed, providing exciting new options for treating a variety of diseases. While few cell therapy products have US FDA approval, there are thousands of cell treatments at various stages of development, pointing to a potential revolutionary shift in patient care. The expanding number and nature of cellular therapies necessitate greater standardization. Several international organizations are collaborating to pursue some level of global standardization, especially concerning cell banking. However, less harmonization surrounds assays used for critical quality characterization including: identity, purity, safety and potency. Frequently, there is divergence regarding the terms describing the characterization assays across regulatory authorities and guidances. This review summarizes the critical quality assays currently used for different categories of cell therapies. Areas of harmonization and an absence of standardization are highlighted. We propose potential solutions to facilitate harmonization of critical quality characterization assays and the language used to describe them.

Trisected pancreas model for testing tissue dissociation enzyme combinations: a novel methodology for improving human islet yield for clinical islet transplantation

Purpose

Human islet isolation requires a defined collagenase-protease enzyme combination for obtaining a successful islet yield. While different islet laboratories use different enzyme combinations, a systematic methodology to identify optimal enzyme combinations and their concentrations within a single donor pancreas has not been tested. In this study, we designed a trisected pancreas model to test efficacy of three clinical grade enzyme blends (VitaCyte, Roche, SERVA) within a single pancreas.

Methods

Islet isolations were performed using brain-dead donor pancreases (n = 15) applying the enzyme-related design of experiments (DOEs) and the trisected model approach. After trimming, split each pancreas into three individual lobes (head, body, tail). As per the DOEs, the lobes were altered between different experiments, to minimize anatomical bias. Islets isolated from each lobe (27 lobes totally) were subjected to functional assessments. Insulin staining and islet area fraction were determined for tissue sections obtained from each lobe.

Results

Utilizing the trisected model, we identified that the collagenase dose from three different vendors did not affect the pancreas digestion and islet yield, but islet morphology after isolation with the neutral protease and BP-protease was better than thermolysin. In addition, the head lobe yielded a lower islet mass and higher tissue volume compared to other two lobes, irrespective of enzyme combination used.

Conclusions

This study demonstrates that the trisected model is a promising methodology in assessing donor and isolation associated parameters. Based on this study, we conclude that the donor characteristics and an optimal enzyme dose play a critical role in achieving higher islet yields.

Islet cell transplantation in children

This paper aims to provide an overview of islet cell transplantation in children, with specific attention to pediatric total pancreatectomy with islet autotransplantation (TPIAT). We will summarize the definition and causes of chronic pancreatitis in children, the TPIAT procedure and potential complications, the process of islet cell isolation and autotransplantation, and long-term results after TPIAT. Lastly, we will briefly discuss islet cell allotransplantation in the adult population and its potential role in treating children.

Emerging Nano- and Micro-Technologies Used in the Treatment of Type-1 Diabetes

Type-1 diabetes is characterized by high blood glucose levels due to a failure of insulin secretion from beta cells within pancreatic islets. Current treatment strategies consist of multiple, daily injections of insulin or transplantation of either the whole pancreas or isolated pancreatic islets. While there are different forms of insulin with tunable pharmacokinetics (fast, intermediate, and long-acting), improper dosing continues to be a major limitation often leading to complications resulting from hyper- or hypo-glycemia. Glucose-responsive insulin delivery systems, consisting of a glucose sensor connected to an insulin infusion pump, have improved dosing but they still suffer from inaccurate feedback, biofouling and poor patient compliance. Islet transplantation is a promising strategy but requires multiple donors per patient and post-transplantation islet survival is impaired by inflammation and suboptimal revascularization. This review discusses how nano- and micro-technologies, as well as tissue engineering approaches, can overcome many of these challenges and help contribute to an artificial pancreas-like system.

Targeting CXCR1/2 Does Not Improve Insulin Secretion After Pancreatic Islet Transplantation: A Phase 3, Double-Blind, Randomized, Placebo-Controlled Trial in Type 1 Diabetes

OBJECTIVE

Reparixin is an inhibitor of CXCR1/2 chemokine receptor shown to be an effective anti-inflammatory adjuvant in a pilot clinical trial in allotransplant recipients.

RESEARCH DESIGN AND METHODS

A phase 3, multicenter, randomized, double-blind, parallel-assignment study (NCT01817959) was conducted in recipients of islet allotransplants randomized (2:1) to reparixin or placebo in addition to immunosuppression. Primary outcome was the area under the curve (AUC) for C-peptide during the mixed-meal tolerance test at day 75 ± 5 after the first and day 365 ± 14 after the last transplant. Secondary end points included insulin independence and standard measures of glycemic control.

RESULTS

The intention-to-treat analysis did not show a significant difference in C-peptide AUC at both day 75 (27 on reparixin vs. 18 on placebo, P = 0.99) and day 365 (24 on reparixin vs. 15 on placebo, P = 0.71). There was no statistically significant difference between treatment groups at any time point for any secondary variable. Analysis of patient subsets showed a trend for a higher percentage of subjects retaining insulin independence for 1 year after a single islet infusion in patients receiving reparixin as compared with patients receiving placebo (26.7% vs. 0%, P = 0.09) when antithymocyte globulin was used as induction immunosuppression.

CONCLUSIONS

In this first double-blind randomized trial, islet transplantation data obtained with reparixin do not support a role of CXCR1/2 inhibition in preventing islet inflammation-mediated damage.

Human pancreatic tissue dissociation enzymes for islet isolation: Advances and clinical perspectives

BACKGROUND AND AIMS

Successful clinical human allo or auto-islet transplantation requires the recovery of a sufficient number of functional islets from either brain-dead or chronic pancreatitis pancreases respectively.

METHODS

In the last two decades (2000-2019), significant progress has been made in improving the human islet isolation procedures and in standardizing the use of different tissue dissociation enzyme (TDE; a mixture of collagenase and protease enzymes) blends to recover higher islet yields.

RESULTS AND CONCLUSIONS

This review presents information focusing on properties and role of TDE blends during the islet isolation process, particularly emphasizing on the current developments, associated challenges and future perspectives within the field.

Anti-inflammatory Approach With Early Double Cytokine Blockade (IL-1β and TNF-α) Is Safe and Facilitates Engraftment in Islet Allotransplantation

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.

Glycaemic control in diabetic rats treated with islet transplantation using plasma combined with hydroxypropylmethyl cellulose hydrogel

Islet transplantation is one of the most efficient cell therapies used in clinics and could treat a large proportion of patients with diabetes. However, it is limited by the high requirement of pancreas necessary to provide the sufficient surviving islet mass in the hepatic tissue and restore normoglycaemia. Reduction in organ procurement requirements could be achieved by extrahepatic transplantation using a biomaterial that enhances islet survival and function. We report a plasma-supplemented hydroxypropyl methylcellulose (HPMC) hydrogel, engineered specifically using a newly developed technique for intra-omental islet infusion, known as hOMING (h-Omental Matrix Islet filliNG). The HPMC hydrogel delivered islets with better performance than that of the classical intrahepatic infusion. After the validation of the HPMC suitability for islets in vivo and in vitro, plasma supplementation modified the rheological properties of HPMC without affecting its applicability with hOMING. The biomaterial association was proven to be more efficient both in vitro and in vivo, with better islet viability and function than that of the current clinical intrahepatic delivery technique. Indeed, when the islet mass was decreased by 25% or 35%, glycaemia control was observed in the group of plasma-supplemented hydrogels, whereas no regulation was observed in the hepatic group. Plasma gelation, observed immediately post infusion, decreased anoïkis and promoted vascularisation. To conclude, the threshold mass for islet transplantation could be decreased using HPMC-Plasma combined with the hOMING technique. The simplicity of the hOMING technique and the already validated use of its components could facilitate its transfer to clinics. STATEMENT OF SIGNIFICANCE: One of the major limitations for the broad deployment of current cell therapy for brittle type 1 diabetes is the islets' destruction during the transplantation process. Retrieved from their natural environment, the islets are grafted into a foreign tissue, which triggers massive cell loss. It is mandatory to provide the islets with an 3D environment specifically designed for promoting isletimplantation to improve cell therapy outcomes. For this aim, we combined HPMC and plasma. HPMC provides suitable rheological properties to the plasma to be injectable and be maintained in the omentum. Afterwards, the plasma polymerises around the graft in vivo, thereby allowing their optimal integration into their transplantation site. As a result, the islet mass required to obtain glycaemic control was reduced by 35%.

Change in Viability and Function of Pancreatic Islets after Coculture with Mesenchymal Stromal Cells: A Systemic Review and Meta-Analysis

BACKGROUND

There is no clear consensus on the effect of coculture of islets with mesenchymal stem cells (MSCs) on islet function and viability.

METHODS

We conducted a meta-analysis of relevant studies to evaluate the effect of coculture of islets with MSCs on the function and viability of islets, both in vitro and in vivo. We searched PubMed, Embase, and Web of Science databases for all relevant studies that compared the effect of coculture of islets with MSCs on the function and viability of islets (language of publication: English; reference period: January 2000-May 2019). Data pertaining to islet function and viability, concentrations of some cytokines, and in vivo experimental outcomes were extracted and compared.

RESULTS

Twenty-four articles were included in the meta-analysis. In comparison to islets cultured alone, coculture of islets with MSCs was associated with a significantly higher islet viability [weighted mean difference (WMD), -15.59; -22.34 to -8.83; P < 0.00001], insulin level (WMD, -5.74; -9.29 to -2.19; P = 0.002), insulin secretion index (WMD, -2.45; -3.70 to -1.21; P = 0.0001), and higher concentrations of interleukin-6 (WMD, -1225.66; -2044.47 to -406.86; P = 0.003) and vascular endothelial growth factor (WMD, -1.19; -2.25 to -0.14; P = 0.03). Direct coculture of islets and MSCs significantly increased islet viability (WMD, -19.82; -26.56 to -13.07; P < 0.00001). In the in vivo experiments, coculture of islets with MSCs induced lower fasting blood glucose level (on postoperative days 21 and 28, WMD, 102.60; 27.14 to 178.05; P = 0.008 and WMD, 121.19; 49.56 to 192.82; P = 0.0009) and better glucose tolerance (blood glucose at 30 minutes after intraperitoneal injection of glucose, WMD, 85.92; 5.33 to 166.51; P = 0.04).

CONCLUSION

Coculture of islets with MSCs improves insulin secretory function of islets and enhances islet viability. Direct coculture of two cells significantly increased islet viability. MSC-based strategy may be beneficial for clinical islet transplantation for type 1 diabetes in the future.

Donor age significantly influences the Raman spectroscopic biomolecular fingerprint of human pancreatic extracellular matrix proteins following collagenase-based digestion

Despite the enormous advances in the field of clinical pancreatic islet transplantation over the past two decades, the human islet isolation procedure remains suboptimal. Islets are extracted (isolated) from the exocrine tissue of donor pancreases using neutral protease (NP) and collagenase-based enzymes, which digest the extracellular matrix (ECM) scaffold surrounding human islets. This process remains highly variable and current isolation enzyme blends are ineffective at digesting pancreases from younger donors with low body mass indexes (BMI). However, age-related differences in pancreatic matrix digestion have not been studied in detail at the molecular level. To address this, we investigated ECM digestion in purified ECM proteins and in pancreatic tissue sections from younger (≤30 years; n = 5) and older (>55 years; n = 5) BMI matched donors, using Raman microspectroscopy (RMS). The Raman spectral profiles for purified collagens I, IV, VI and laminins were significantly altered following controlled enzyme treatment. Pancreatic cryosections were treated with Serva collagenase, NP, or the two enzymes combined, at clinically relevant concentrations. RMS demonstrated that the ECM at the islet-exocrine interface was differentially digested with respect to donor age. The action of collagenase was affected to a greater extent than NP. RMS is a powerful, marker-independent technology for characterising the human pancreatic ECM and demonstrating differences between donor types. Ongoing detailed studies using RMS will assist the development of donor-specific enzyme blends, increasing the overall success of human islet isolation and benefiting many people with type 1 diabetes worldwide. STATEMENT OF SIGNIFICANCE: Pancreatic islet transplantation is a minimally invasive treatment, which can reverse Type 1 Diabetes Mellitus (T1DM) in selected patients. Islets of Langerhans are extracted (isolated) from the exocrine tissue of human donor pancreases using neutral protease (NP) and collagenase-based enzymes, which digest the extracellular matrix (ECM) scaffold surrounding human islets. This process remains highly variable and current enzymes are ineffective at digesting pancreases from younger donors. Using Raman microspectroscopy we demonstrate that donor age affects the enzymatic digestion of the pancreatic ECM at the molecular level. Collagenase activity is affected to a greater extent than NP. These findings will assist the development of donor-specific enzymes, thereby increasing the overall success of islet isolation and benefiting many people with T1DM worldwide.

Stem Cell Therapies for Treating Diabetes: Progress and Remaining Challenges

Restoration of insulin independence and normoglycemia has been the overarching goal in diabetes research and therapy. While whole-organ and islet transplantation have become gold-standard procedures in achieving glucose control in diabetic patients, the profound lack of suitable donor tissues severely hampers the broad application of these therapies. Here, we describe current efforts aimed at generating a sustainable source of functional human stem cell-derived insulin-producing islet cells for cell transplantation and present state-of-the-art efforts to protect such cells via immune modulation and encapsulation strategies.

New Insights into Immunotherapy Strategies for Treating Autoimmune Diabetes

Type 1 diabetes mellitus (T1D) is an autoimmune illness that affects millions of patients worldwide. The main characteristic of this disease is the destruction of pancreatic insulin-producing beta cells that occurs due to the aberrant activation of different immune effector cells. Currently, T1D is treated by lifelong administration of novel versions of insulin that have been developed recently; however, new approaches that could address the underlying mechanisms responsible for beta cell destruction have been extensively investigated. The strategies based on immunotherapies have recently been incorporated into a panel of existing treatments for T1D, in order to block T-cell responses against beta cell antigens that are very common during the onset and development of T1D. However, a complete preservation of beta cell mass as well as insulin independency is still elusive. As a result, there is no existing T1D targeted immunotherapy able to replace standard insulin administration. Presently, a number of novel therapy strategies are pursuing the goals of beta cell protection and normoglycemia. In the present review we explore the current state of immunotherapy in T1D by highlighting the most important studies in this field, and envision novel strategies that could be used to treat T1D in the future.