Phase 3 Trial of Transplantation of Human Islets in Type 1 Diabetes Complicated by Severe Hypoglycemia

In situ type I oligomeric collagen macroencapsulation promotes islet longevity and function in vitro and in vivo

Widespread use of pancreatic islet transplantation for treatment of type 1 diabetes (T1D) is currently limited by requirements for long-term immunosuppression, limited donor supply, and poor long-term engraftment and function. Upon isolation from their native microenvironment, islets undergo rapid apoptosis, which is further exacerbated by poor oxygen and nutrient supply following infusion into the portal vein. Identifying alternative strategies to restore critical microenvironmental cues, while maximizing islet health and function, is needed to advance this cellular therapy. We hypothesized that biophysical properties provided through type I oligomeric collagen macroencapsulation are important considerations when designing strategies to improve islet survival, phenotype, and function. Mouse islets were encapsulated at various Oligomer concentrations (0.5 -3.0 mg/ml) or suspended in media and cultured for 14 days, after which viability, protein expression, and function were assessed. Oligomer-encapsulated islets showed a density-dependent improvement in in vitro viability, cytoarchitecture, and insulin secretion, with 3 mg/ml yielding values comparable to freshly isolated islets. For transplantation into streptozotocin-induced diabetic mice, 500 islets were mixed in Oligomer and injected subcutaneously, where rapid in situ macroencapsulation occurred, or injected with saline. Mice treated with Oligomer-encapsulated islets exhibited rapid (within 24 h) diabetes reversal and maintenance of normoglycemia for 14 (immunocompromised), 90 (syngeneic), and 40 days (allogeneic). Histological analysis showed Oligomer-islet engraftment with maintenance of islet cytoarchitecture, revascularization, and no foreign body response. Oligomer-islet macroencapsulation may provide a useful strategy for prolonging the health and function of cultured islets and has potential as a subcutaneous injectable islet transplantation strategy for treatment of T1D.

Differentiation of Sendai Virus-Reprogrammed iPSC into β Cells, Compared with Human Pancreatic Islets and Immortalized β Cell Line

Background:

New sources of insulin-secreting cells are strongly in demand for treatment of diabetes. Induced pluripotent stem cells (iPSCs) have the potential to generate insulin-producing cells (iβ). However, the gene expression profile and secretory function of iβ still need to be validated in comparison with native β cells.

Methods:

Two clones of human iPSCs, reprogrammed from adult fibroblasts through integration-free Sendai virus, were differentiated into iβ and compared with donor pancreatic islets and EndoC-βH1, an immortalized human β cell line.

Results:

Both clones of iPSCs differentiated into insulin⁺ cells with high efficiency (up to 20%). iβ were negative for pluripotency markers (Oct4, Sox2, Ssea4) and positive for Pdx1, Nkx6.1, Chromogranin A, PC1/3, insulin, glucagon and somatostatin. iβ basally secreted C-peptide, glucagon and ghrelin and released insulin in response either to increasing concentration of glucose or a depolarizing stimulus. The comparison revealed that iβ are remarkably similar to donor derived islets in terms of gene and protein expression profile and similar level of heterogeneity. The ability of iβ to respond to glucose instead was more related to that of EndoC-βH1.

Discussion:

We demonstrated that insulin-producing cells generated from iPSCs recapitulate fundamental gene expression profiles and secretory function of native human β cells.

Artificial Pancreas or Novel Beta-Cell Replacement Therapies: a Race for Optimal Glycemic Control?

PURPOSE OF REVIEW

New treatment strategies are needed for patients with type 1 diabetes (T1D). Closed loop insulin delivery and beta-cell replacement therapy are promising new strategies. This review aims to give an insight in the most relevant literature on this topic and to compare the two radically different treatment modalities.

RECENT FINDINGS

Multiple clinical studies have been performed with closed loop insulin delivery devices and have shown an improvement in overall glycemic control and time spent in hypoglycemia. Beta-cell transplantation has been shown to normalize or greatly improve glycemic control in T1D, but the donor organ shortage and the necessity to use immunosuppressive agents are major drawbacks. Donor organ shortage may be solved by the utilization of stem cell-derived beta cells, which has shown great promise in animal models and are now tested in clinical studies. Immunosuppression may be avoided by encapsulation. Closed loop insulin delivery devices are promising treatment strategies and are likely to be used in clinical practice in the short term. But this approach will always suffer from delays in glucose measurement and insulin action preventing it from normalizing glycemic control. In the long term, stem cell-derived beta cell transplantation may be able to achieve this, but wide implementation in clinical practice is still far away.

Defining outcomes for β-cell replacement therapy in the treatment of diabetes: a consensus report on the Igls criteria from the IPITA/EPITA opinion leaders workshop

β-cell replacement therapy, available currently as pancreas or islet transplantation, has developed without a clear definition of graft functional and clinical outcomes. The International Pancreas & Islet Transplant Association (IPITA) and European Pancreas & Islet Transplantation Association (EPITA) held a workshop to develop consensus for an IPITA/EPITA Statement on the definition of function and failure of current and future forms of β-cell replacement therapy. There was consensus that β-cell replacement therapy could be considered as a treatment for β-cell failure, regardless of etiology and without requiring undetectable C-peptide, accompanied by glycemic instability with either problematic hypoglycemia or hyperglycemia. Glycemic control should be assessed at a minimum by glycated hemoglobin (HbA_1c ) and the occurrence of severe hypoglycemia. Optimal β-cell graft function is defined by near-normal glycemic control [HbA_1c  ≤ 6.5% (48 mmol/mol)] without severe hypoglycemia or requirement for insulin or other antihyperglycemic therapy, and with an increase over pretransplant measurement of C-peptide. Good β-cell graft function requires HbA_1c  < 7.0% (53 mmol/mol) without severe hypoglycemia and with a significant (>50%) reduction in insulin requirements and restoration of clinically significant C-peptide production. Marginal β-cell graft function is defined by failure to achieve HbA_1c  < 7.0% (53 mmol/mol), the occurrence of any severe hypoglycemia, or less than 50% reduction in insulin requirements when there is restoration of clinically significant C-peptide production documented by improvement in hypoglycemia awareness/severity, or glycemic variability/lability. A failed β-cell graft is defined by the absence of any evidence for clinically significant C-peptide production. Optimal and good functional outcomes are considered successful clinical outcomes.

Anti-Inflammatory Strategies in Intrahepatic Islet Transplantation: A Comparative Study in Preclinical Models

BACKGROUND

The identification of pathway(s) playing a pivotal role in peritransplant detrimental inflammatory events represents the crucial step toward a better management and outcome of pancreatic islet transplanted patients. Recently, we selected the CXCR1/2 inhibition as a relevant strategy in enhancing pancreatic islet survival after transplantation.

METHODS

Here, the most clinically used anti-inflammatory compounds (IL1-receptor antagonist, steroids, and TNF-α inhibitor) alone or in combination with a CXCR1/2 inhibitor were evaluated in their ability to improve engraftment or delay graft rejection. To rule out bias related to transplantation site, we used well-established preclinical syngeneic (250 C57BL/6 equivalent islets in C57BL/6) and allogeneic (400 Balb/c equivalent islets in C57BL6) intrahepatic islet transplantation platforms.

RESULTS

In mice, we confirmed that targeting the CXCR1/2 pathway is crucial in preserving islet function and improving engraftment. In the allogeneic setting, CXCR1/2 inhibitor alone could reduce the overall recruitment of transplant-induced leukocytes and significantly prolong the time to graft rejection both as a single agent and in combination with immunosuppression. No other anti-inflammatory compounds tested (IL1-receptor antagonist, steroids, and TNF-α inhibitor) alone or in combination with CXCR1/2 inhibitor improve islet engraftment and significantly delay graft rejection in the presence of MMF + FK-506 immunosuppressive treatment.

CONCLUSIONS

These findings indicate that only the CXCR1/2-mediated axis plays a crucial role in controlling the islet damage and should be a target for intervention to improve the efficiency of islet transplantation.

β Cell Replacement Therapy: The Next 10 Years

β cell replacement with either pancreas or islet transplantation has progressed immensely over the last decades with current 1- and 5-year insulin independence rates of approximately 85% and 50%, respectively. Recent advances are largely attributed to improvements in immunosuppressive regimen, donor selection, and surgical technique. However, both strategies are compromised by a scarce donor source. Xenotransplantation offers a potential solution by providing a theoretically unlimited supply of islets, but clinical application has been limited by concerns for a potent immune response against xenogeneic tissue. β cell clusters derived from embryonic or induced pluripotent stem cells represent another promising unlimited source of insulin producing cells, but clinical application is pending further advances in the function of the β cell like clusters. Exciting developments and rapid progress in all areas of β cell replacement prompted a lively debate by members of the young investigator committee of the International Pancreas and Islet Transplant Association at the 15th International Pancreas and Islet Transplant Association Congress in Melbourne and at the 26th international congress of The Transplant Society in Hong Kong. This international group of young investigators debated which modality of β cell replacement would predominate the landscape in 10 years, and their arguments are summarized here.

Ascites formation accompanied by portal vein thrombosis after porcine islet xenotransplantation via the portal vein in Rhesus macaque (Macaca mulatta)

Pig-to-nonhuman primate (NHP) islet transplantation has been widely conducted as a preclinical xenotransplantation model prior to human clinical trial. Portal vein thrombosis is one of the complications associated with islet infusion through the portal vein into the liver. Here, we briefly report severe case of ascites formation accompanied by portal vein thrombi after pig-to-NHP islet xenotransplantation in a rhesus monkey. Meticulous prophylactic treatment such as continuous heparin infusion should be implemented to prevent portal vein thrombi in pig-to-NHP islet transplantation models.

Biomarkers in Islet Cell Transplantation for Type 1 Diabetes

PURPOSE OF REVIEW

Islet transplantation, an important approach to achieve insulin independence for individuals with type 1 diabetes, is limited by the lack of accurate biomarkers to track beta-cell death post islet infusion. In this review, we will discuss existing and recently described biomarkers.

RECENT FINDINGS

As beta cells are killed by the immune system, fragments of beta cell-specific cell-free DNA and proteins are released into the periphery. Several different strategies to identify these fragments have been described. Some circulating, non-coding microRNAs, particularly miRNA-375 are also showing potential to reflect the rate of beta cell loss post-clinical islet transplantation. Recent advances in identifying accurate beta cell-specific biomarkers such as differentially methylated insulin cell-free DNA and circulating miRNA-375 may help predict clinical outcomes. More studies are required to examine the robustness of these biomarkers to detect chronic beta-cell loss in islet transplantation recipients.

Evaluation of encapsulating and microporous nondegradable hydrogel scaffold designs on islet engraftment in rodent models of diabetes

Islet transplantation is a promising therapeutic option for type 1 diabetes mellitus, yet the current delivery into the hepatic portal vasculature is limited by poor engraftment. Biomaterials have been used as a means to promote engraftment and function at extrahepatic sites, with strategies being categorized as encapsulation or microporous scaffolds that can either isolate or integrate islets with the host tissue, respectively. Although these approaches are typically studied separately using distinct material platforms, herein, we developed nondegradable polyethylene glycol (PEG)-based hydrogels for islet encapsulation or as microporous scaffolds for islet seeding to compare the initial engraftment and function of islets in syngeneic diabetic mice. Normoglycemia was restored with transplantation of islets within either encapsulating or microporous hydrogels containing 700 islet equivalents (IEQ), with transplantation on microporous hydrogels producing lower blood glucose levels at earlier times. A glucose challenge test at 1 month after transplant indicated that encapsulated islets had a delay in glucose-stimulated insulin secretion, whereas microporous hydrogels restored normoglycemia in times consistent with native pancreata. Encapsulated islets remained isolated from the host tissue, whereas the microporous scaffolds allowed for revascularization of the islets after transplant. Finally, we compared the inflammatory response after transplantation for the two systems and noted that microporous hydrogels had a substantially increased presence of neutrophils. Collectively, these findings suggest that both encapsulation and microporous PEG scaffold designs allow for stable engraftment of syngeneic islets and the ability to restore normoglycemia, yet the architecture influences islet function and responsiveness after transplantation.

Regenerative Medicine and Diabetes: Targeting the Extracellular Matrix Beyond the Stem Cell Approach and Encapsulation Technology

According to the Juvenile Diabetes Research Foundation (JDRF), almost 1. 25 million people in the United States (US) have type 1 diabetes, which makes them dependent on insulin injections. Nationwide, type 2 diabetes rates have nearly doubled in the past 20 years resulting in more than 29 million American adults with diabetes and another 86 million in a pre-diabetic state. The International Diabetes Ferderation (IDF) has estimated that there will be almost 650 million adult diabetic patients worldwide at the end of the next 20 years (excluding patients over the age of 80). At this time, pancreas transplantation is the only available cure for selected patients, but it is offered only to a small percentage of them due to organ shortage and the risks linked to immunosuppressive regimes. Currently, exogenous insulin therapy is still considered to be the gold standard when managing diabetes, though stem cell biology is recognized as one of the most promising strategies for restoring endocrine pancreatic function. However, many issues remain to be solved, and there are currently no recognized treatments for diabetes based on stem cells. In addition to stem cell resesarch, several β-cell substitutive therapies have been explored in the recent era, including the use of acellular extracellular matrix scaffolding as a template for cellular seeding, thus providing an empty template to be repopulated with β-cells. Although this bioengineering approach still has to overcome important hurdles in regards to clinical application (including the origin of insulin producing cells as well as immune-related limitations), it could theoretically provide an inexhaustible source of bio-engineered pancreases.

BMX-001, a novel redox-active metalloporphyrin, improves islet function and engraftment in a murine transplant model

Islet transplantation has become a well-established therapy for select patients with type 1 diabetes. Viability and engraftment can be compromised by the generation of oxidative stress encountered during isolation and culture. We evaluated whether the administration of BMX-001 (MnTnBuOE-2-PyP⁵⁺ [Mn(III) meso-tetrakis-(N-b-butoxyethylpyridinium-2-yl)porphyrin]) and its earlier derivative, BMX-010 (MnTE-2-PyP [Mn(III) meso-tetrakis-(N-methylpyridinium-2-yl)porphyrin]) could improve islet function and engraftment outcomes. Long-term culture of human islets with BMX-001, but not BMX-010, exhibited preserved in vitro viability. Murine islets isolated and cultured for 24 hours with 34 μmol/L BMX-001 exhibited improved insulin secretion (n = 3 isolations, P < .05) in response to glucose relative to control islets. In addition, 34 μmol/L BMX-001-supplemented murine islets exhibited significantly reduced apoptosis as indicated by terminal deoxynucleotidyl transferase dUTP nick end labeling, compared with nontreated control islets (P < .05). Murine syngeneic islets transplanted under the kidney capsule at a marginal dose of 150 islets revealed 58% of 34 μmol/L BMX-001-treated islet recipients became euglycemic (n = 11 of 19) compared with 19% of nontreated control islet recipients (n = 3 of 19, P < .05). Of murine recipients receiving a marginal dose of human islets cultured with 34 μmol/L BMX-001, 92% (n = 12 of 13) achieved euglycemia compared with 57% of control recipients (n = 8 of 14, P = .11). These results demonstrate that the administration of BMX-001 enhances in vitro viability and augments murine marginal islet mass engraftment.

Advances in drug discovery for human beta cell regeneration

The numbers of insulin-secreting pancreatic beta cells are reduced in people with type 1 and type 2 diabetes. Driving beta cell regeneration in the pancreases of people with diabetes would be an attractive approach to reversing diabetes. While adult human beta cells have long been believed to be terminally differentiated and, therefore, irreversibly quiescent, it has become clear over recent years that this is not true. More specifically, both candidate and unbiased high-throughput screen approaches have revealed several classes of molecules that are clearly able to induce human beta cell proliferation. Here, we review recent approaches and accomplishments in human beta cell regenerative drug discovery. We also list the challenges that this rapidly moving field must confront to translate beta cell regenerative therapy from the laboratory to the clinic.

A model for determining an effective in vivo dose of transplanted islets based on in vitro insulin secretion

BACKGROUND

Allogeneic islet transplantation for the treatment of type 1 diabetes often requires multiple implant procedures, from as many as several human pancreas donors, to achieve lasting clinical benefit. Given the limited availability of human pancreases for islet isolation, porcine islets have long been considered a potential option for clinical use. Agarose-encapsulated porcine islets (macrobeads) permit long-term culture and thus a thorough evaluation of microbiological safety and daily insulin secretory capacity, prior to implantation. The goal of this study was the development of a method for determining an effective dose of encapsulated islets based on their measured in vitro insulin secretion in a preclinical model of type 1 diabetes.

METHODS

Spontaneously diabetic BioBreeding diabetes-prone rats were implanted with osmotic insulin pumps in combination with continuous glucose monitoring to establish the daily insulin dose required to achieve continuous euglycaemia in individual animals. Rats were then implanted with a 1×, 2× or 3× dose (defined as the ratio of macrobead in vitro insulin secretion per 24 hours to the recipient animal's total daily insulin requirement) of porcine islet macrobeads, in the absence of immunosuppression. In vivo macrobead function was assessed by recipient non-fasted morning blood glucose values, continuous glucose monitoring and the presence of peritoneal porcine C-peptide. At the end of the study, the implanted macrobeads were removed and returned to in vitro culture for the evaluation of insulin secretion.

RESULTS

Diabetic rats receiving a 2× macrobead implant exhibited significantly improved blood glucose regulation compared to that of rats receiving a 1× dose during a 30-day pilot study. In a 3-month follow-up study, 2× and 3× macrobead doses initially controlled blood glucose levels equally well, although several animals receiving a 3× dose maintained euglycaemia throughout the study, compared to none of the 2× animals. The presence of porcine C-peptide in rat peritoneal fluid 3 months post-implant and the recurrence of hyperglycaemia following macrobead removal, along with the finding of persistent in vitro insulin secretion from retrieved macrobeads, confirmed long-term graft function.

CONCLUSIONS

Increasing dosages of islet macrobeads transplanted into diabetic rats, based on multiples of in vitro insulin secretion matched to the recipient's exogenous insulin requirements, correlated with improved blood glucose regulation and increased duration of graft function. These results demonstrate the usefulness of a standardized model for the evaluation of the functional effectiveness of islets intended for transplantation, in this case using intraperitoneally implanted agarose macrobeads, in diabetic rats. The results suggest that some features of this islet-dosing methodology may be applicable, and indeed necessary, to clinical allogeneic and xenogeneic islet transplantation.

The Future of Islet Transplantation Is Now

Milestones in the history of diabetes therapy include the discovery of insulin and successful methods of beta cell replacement including whole pancreas and islet cell transplantation options. While pancreas transplantation remains the gold standard for patients who have difficulty controlling their symptoms with exogenous insulin, islet allotransplantation is now able to provide similar results with some advantages that make it an attractive potential alternative. The Edmonton Protocol, which incorporated a large dose of islets from multiple donors with steroid-free immunosuppression helped to establish the modern era of islet transplantation almost 20 years ago. While islet allotransplantation is recognized around the world as a powerful clinical therapy for type 1 diabetes it is not yet recognized by the Federal Drug Administration of the United States. Large-scale clinical trials administered by the Clinical Islet Transplantation Consortium have recently demonstrated that the well-regulated manufacture of a human islet product transplanted into patients with difficult to control type 1 diabetes and with a history of severe hyperglycemic episodes can safely and efficaciously maintain glycemic balance and eliminate the most severe complications associated with diabetes. The results of these clinical trials have established a strong basis for licensure of clinical islet allotransplantation in the US. Recognition by the Federal Drug Administration would likely lead to third party reimbursement for islet allotransplantation as a therapeutic option in the United States and would make the treatment available to many more patients. The high costs of rampant diabetes justify the expense of the treatment, which is in-line with the costs of clinical pancreas transplantation. While much enthusiasm and hope is raised toward the development and optimization of stem cell therapy, the islet transplantation community should push toward licensure, if that means broader access of this procedure to patients who may benefit from it. Even as we prepare to take the first steps in that direction, we must acknowledge the new challenges that a shift from the experimental to clinical will bring. Clinical islet allotransplantation in the United States would be a game-changing event in the treatment of type 1 diabetes and also generate enthusiasm for continued research.

Extracellular matrix scaffold and hydrogel derived from decellularized and delipidized human pancreas

Extracellular matrix (ECM) plays an important developmental role by regulating cell behaviour through structural and biochemical stimulation. Tissue-specific ECM, attained through decellularization, has been proposed in several strategies for tissue and organ replacement. Decellularization of animal pancreata has been reported, but the same methods applied to human pancreas are less effective due to higher lipid content. Moreover, ECM-derived hydrogels can be obtained from many decellularized tissues, but methods have not been reported to obtain human pancreas-derived hydrogel. Using novel decellularization methods with human pancreas we produced an acellular, 3D biological scaffold (hP-ECM) and hydrogel (hP-HG) amenable to tissue culture, transplantation and proteomic applications. The inclusion of a homogenization step in the decellularization protocol significantly improved lipid removal and gelation capability of the resulting ECM, which was capable of gelation at 37 °C in vitro and in vivo, and is cytocompatible with a variety of cell types and islet-like tissues in vitro. Overall, this study demonstrates the characterisation of a novel protocol for the decellularization and delipidization of human pancreatic tissue for the production of acellular ECM and ECM hydrogel suitable for cell culture and transplantation applications. We also report a list of 120 proteins present within the human pancreatic matrisome.

Transplantation of macroencapsulated human islets within the bioartificial pancreas βAir to patients with type 1 diabetes mellitus

Macroencapsulation devices provide the dual possibility of immunoprotecting transplanted cells while also being retrievable, the latter bearing importance for safety in future trials with stem cell-derived cells. However, macroencapsulation entails a problem with oxygen supply to the encapsulated cells. The βAir device solves this with an incorporated refillable oxygen tank. This phase 1 study evaluated the safety and efficacy of implanting the βAir device containing allogeneic human pancreatic islets into patients with type 1 diabetes. Four patients were transplanted with 1-2 βAir devices, each containing 155 000-180 000 islet equivalents (ie, 1800-4600 islet equivalents per kg body weight), and monitored for 3-6 months, followed by the recovery of devices. Implantation of the βAir device was safe and successfully prevented immunization and rejection of the transplanted tissue. However, although beta cells survived in the device, only minute levels of circulating C-peptide were observed with no impact on metabolic control. Fibrotic tissue with immune cells was formed in capsule surroundings. Recovered devices displayed a blunted glucose-stimulated insulin response, and amyloid formation in the endocrine tissue. We conclude that the βAir device is safe and can support survival of allogeneic islets for several months, although the function of the transplanted cells was limited (Clinicaltrials.gov: NCT02064309).

Islet transplantation versus insulin therapy in patients with type 1 diabetes with severe hypoglycaemia or poorly controlled glycaemia after kidney transplantation (TRIMECO): a multicentre, randomised controlled trial

BACKGROUND

Islet transplantation is indicated for patients with type 1 diabetes with severe hypoglycaemia or after kidney transplantation. We did a randomised trial to assess the efficacy and safety of islet transplantation compared with insulin therapy in these patients.

METHODS

In this multicentre, open-label, randomised controlled trial, we randomly assigned (1:1) patients with type 1 diabetes at 15 university hospitals to receive immediate islet transplantation or intensive insulin therapy (followed by delayed islet transplantation). Eligible patients were aged 18-65 years and had severe hypoglycaemia or hypoglycaemia unawareness, or kidney grafts with poor glycaemic control. We used computer-generated randomisation, stratified by centre and type of patient. Islet recipients were scheduled to receive 11 000 islet equivalents per kg bodyweight in one to three infusions. The primary outcome was proportion of patients with a modified β-score (in which an overall score of 0 was not allocated when stimulated C-peptide was negative) of 6 or higher at 6 months after first islet infusion in the immediate transplantation group or 6 months after randomisation in the insulin group. The primary analysis included all patients who received the allocated intervention; safety was assessed in all patients who received islet infusions. This trial is registered with ClinicalTrials.gov, number NCT01148680, and is completed.

FINDINGS

Between July 8, 2010, and July 29, 2013, 50 patients were randomly assigned to immediate islet transplantation (n=26) or insulin treatment (n=24), of whom three (one in the immediate islet transplantation group and two in the insulin therapy group) did not receive the allocated intervention. Median follow-up was 184 days (IQR 181-186) in the immediate transplantation group and 185 days (172-201) in the insulin therapy group. At 6 months, 16 (64% [95% CI 43-82]) of 25 patients in the immediate islet transplantation group had a modified β-score of 6 or higher versus none (0% [0-15]) of the 22 patients in the insulin group (p<0·0001). At 12 months after first infusion, bleeding complications had occurred in four (7% [2-18]) of 55 infusions, and a decrease in median glomerular filtration rate from 90·5 mL/min (IQR 76·6-94·0) to 71·8 mL/min (59·0-89·0) was observed in islet recipients who had not previously received a kidney graft and from 63·0 mL/min (55·0-71·0) to 57·0 mL/min (45·5-65·1) in islet recipients who had previously received a kidney graft.

INTERPRETATION

For the indications assessed in this study, islet transplantation effectively improves metabolic outcomes. Although studies with longer-term follow-up are needed, islet transplantation seems to be a valid option for patients with severe, unstable type 1 diabetes who are not responding to intensive medical treatments. However, immunosuppression can affect kidney function, necessitating careful selection of patients.

FUNDING

Programme Hospitalier de Recherche Clinique grant from the French Government.

Calcium: A Crucial Potentiator for Efficient Enzyme Digestion of the Human Pancreas

Background:

Effective digestive enzymes are crucial for successful islet isolation. Supplemental proteases are essential because they synergize with collagenase for effective pancreatic digestion. The activity of these enzymes is critically dependent on the presence of Ca²⁺ ions at a concentration of 5–10 mM. The present study aimed to determine the Ca²⁺ concentration during human islet isolation and to ascertain whether the addition of supplementary Ca²⁺ is required to maintain an optimal Ca²⁺ concentration during the various phases of the islet isolation process.

Methods:

Human islets were isolated according to standard methods and isolation parameters. Islet quality control and the number of isolations fulfilling standard transplantation criteria were evaluated. Ca²⁺ was determined by using standard clinical chemistry routines. Islet isolation was performed with or without addition of supplementary Ca²⁺ to reach a Ca²⁺ of 5 mM.

Results:

Ca²⁺ concentration was markedly reduced in bicarbonate-based buffers, especially if additional bicarbonate was used to adjust the pH as recommended by the Clinical Islet Transplantation Consortium. A major reduction in Ca²⁺ concentration was also observed during pancreatic enzyme perfusion, digestion, and harvest. Additional Ca²⁺ supplementation of media used for dissolving the enzymes and during digestion, perfusion, and harvest was necessary in order to obtain the concentration recommended for optimal enzyme activity and efficient liberation of a large number of islets from the human pancreas.

Conclusions:

Ca²⁺ is to a large extent consumed during clinical islet isolation, and in the absence of supplementation, the concentration fell below that recommended for optimal enzyme activity. Ca²⁺ supplementation of the media used during human pancreas digestion is necessary to maintain the concentration recommended for optimal enzyme activity. Addition of Ca²⁺ to the enzyme blend has been implemented in the standard isolation protocols in the Nordic Network for Clinical Islet Transplantation.

Comparison of metabolic responses to the mixed meal tolerance test vs the oral glucose tolerance test after successful clinical islet transplantation

Following islet transplantation, mixed meal tolerance tests (MMTs) are routinely utilized to assess graft function, but how the 90-minute MMTT glucose value relates to a 120-minute glucose concentration of ≥11.1 mmol/L used to diagnose diabetes following a standardized 75 g-OGTT, is not known. We examined this relationship further. Thirteen subjects with Type 1 diabetes and stable transplant grafts, not on exogenous insulin with HbA1c < 7% (53 mmol/mol), were studied on 17 occasions with paired OGTTs and MMTTs. Receiver operating characteristic (ROC) curves were constructed to derive the 90-minute MMTT glucose threshold associated with a 120-minute glucose concentration following a 75 g-OGTT (OGTT₁₂₀ ) ≥11.1 mmol/L and their diagnostic accuracy. Studies with OGTT₁₂₀ ≥11.1 mmol/L (n = 5) had diminished C-peptide: glucose, greater integrated glucose and diminished insulin: glucose area under the curve (AUC) ratios (0-120 minutes) and disposition indices; all P < .05, contrasting with MMTTs where no difference in the 90-minute glucose concentrations, C-peptide:glucose, integrated glucose, C-peptide and C-peptide: glucose AUCs (0-90 minutes) was seen; all P > .05. A 90-minute MMTT glucose concentration ≥8.0 mmol/L demonstrated a sensitivity and specificity of ≥80% for the diagnosis of OGTT₁₂₀ ≥11.1 mmol/L; area under ROC curve (mean ± SEM) 73 ± 13%. A 90-minute MMTT glucose ≥8.0 mmol/L, identifies islet transplant recipients who may require closer monitoring for graft dysfunction.

Regulated Cell Death Seen through the Lens of Islet Transplantation

Clinical islet transplantation effectively restores euglycemia and corrects glycosylated hemoglobin in labile type 1 diabetes mellitus (T1DM). Despite marked improvements in islet transplantation outcomes, acute islet cell death remains a substantial obstacle that compromises long-term engraftment outcomes. Multiple organ donors are routinely required to achieve insulin independence. Therapeutic agents that ameliorate cell death and/or control injury-related inflammatory cascades offer potential to improve islet transplant success. Apoptotic cell death has been identified as a major contributor to cellular demise and therapeutic strategies that subvert initiation and consequences of apoptotic cell death have shown promise in pre-clinical models. Indeed, in numerous pathologies and diseases apoptosis has been the most extensively described form of regulated cell death. However, recent identification of novel, alternative regulated cell death pathways in other disease states and solid organ transplantation suggest that these additional pathways may also have substantial relevance in islet transplantation. These regulated, non-apoptotic cell death pathways exhibit distinct biochemical characteristics but have yet to be fully characterized within islet transplantation. We review herein the various regulated cell death pathways and highlight their relative potential contributions to islet viability, engraftment failure and islet dysfunction.

Pancreas regeneration

The pancreas is made from two distinct components: the exocrine pancreas, a reservoir of digestive enzymes, and the endocrine islets, the source of the vital metabolic hormone insulin. Human islets possess limited regenerative ability; loss of islet β-cells in diseases such as type 1 diabetes requires therapeutic intervention. The leading strategy for restoration of β-cell mass is through the generation and transplantation of new β-cells derived from human pluripotent stem cells. Other approaches include stimulating endogenous β-cell proliferation, reprogramming non-β-cells to β-like cells, and harvesting islets from genetically engineered animals. Together these approaches form a rich pipeline of therapeutic development for pancreatic regeneration.

Improved Health-Related Quality of Life in a Phase 3 Islet Transplantation Trial in Type 1 Diabetes Complicated by Severe Hypoglycemia

OBJECTIVE

Attaining glycemic targets without severe hypoglycemic events (SHEs) is a challenging treatment goal for patients with type 1 diabetes complicated by impaired awareness of hypoglycemia (IAH). The CIT Consortium Protocol 07 (CIT-07) trial showed islet transplantation to be an effective treatment for subjects with IAH and intractable SHEs. We evaluated health-related quality of life (HRQOL), functional health status, and health utility before and after pancreatic islet transplantation in CIT-07 trial participants.

RESEARCH DESIGN AND METHODS

Four surveys, the Diabetes Distress Scale (DDS), the Hypoglycemic Fear Survey (HFS), the Short Form 36 Health Survey (SF-36), and the EuroQoL 5 Dimensions (EQ-5D), were administered repeatedly before and after islet transplantation. Summary statistics and longitudinal modeling were used to describe changes in survey scores from baseline and to characterize change in relation to a minimally important difference (MID) threshold of half an SD.

RESULTS

Improvements in condition-specific HRQOL met the MID threshold. Reductions from baseline in the DDS total score and its four DDS subscales (all P ≤ 0.0013) and in the HFS total score and its two subscales (all P < 0.0001) were observed across all time points. Improvements were observed after both 1 and 2 years for the EQ-5D visual analog scale (both P < 0.0001).

CONCLUSIONS

In CIT-07, 87.5% of the subjects achieved the primary end point of freedom from SHE along with glycemic control (HbA_1c <7% [<53 mmol/mol]) at 1 year post-initial islet transplantation. The same subjects reported consistent, statistically significant, and clinically meaningful improvements in condition-specific HRQOL as well as self-assessments of overall health.

A critical review and analysis of ethical issues associated with the artificial pancreas

The artificial pancreas combines a hormone infusion pump with a continuous glucose monitoring device, supported by a dosing algorithm currently installed on the pump. It allows for dynamic infusions of insulin (and possibly other hormones such as glucagon) tailored to patient needs. For patients with type 1 diabetes the artificial pancreas has been shown to prevent more effectively hypoglycaemic events and hyperglycaemia than insulin pump therapy and has the potential to simplify care. However, the potential ethical issues associated with the upcoming integration of the artificial pancreas into clinical practice have not yet been discussed. Our objective was to identify and articulate ethical issues associated with artificial pancreas use for patients, healthcare professionals, industry and policymakers. We performed a literature review to identify clinical, psychosocial and technical issues raised by the artificial pancreas and subsequently analysed them through a common bioethics framework. We identified five sensitive domains of ethical issues. Patient confidentiality and safety can be jeopardized by the artificial pancreas' vulnerability to security breaches or unauthorized data sharing. Public and private coverage of the artificial pancreas could be cost-effective and warranted. Patient selection criteria need to ensure equitable access and sensitivity to patient-reported outcomes. Patient coaching and support by healthcare professionals or industry representatives could help foster realistic expectations in patients. Finally, the artificial pancreas increases the visibility of diabetes and could generate issues related to personal identity and patient agency. The timely consideration of these issues will optimize the technological development and clinical uptake of the artificial pancreas.

[Transplantation strategy in type 1 diabetic patients]

Beta cell replacement by pancreas or Langerhans islets transplantation is the only way to restore glucose homeostasis in type 1 diabetic patients. The counterpart is the need for long-term immunosuppression. These transplantations are therefore mainly indicated for patients candidates for kidney transplantation and for patients with poor quality of life due to unstable diabetes with life-threatening hypoglycemic events. Both beta cell replacement techniques have different benefits and risks and should be adapted to each type 1 diabetic patient. The transplant strategy must be personalized according to parameters assessed in the pre-transplant period, validated by a multidisciplinary team and reassessed regularly until transplantation.

Islet damage during isolation as assessed by miRNAs and the correlation of miRNA levels with posttransplantation outcome in islet autotransplantation

High-quality pancreatic islets are essential for better posttransplantation endocrine function in total pancreatectomy with islet autotransplantation (TPIAT), yet stress during the isolation process affects quality and yield. We analyzed islet-enriched microRNAs (miRNAs) -375 and -200c released during isolation to assess damage and correlated the data with posttransplantation endocrine function. The absolute concentration of miR-375, miR-200c, and C-peptide was measured in various islet isolation steps, including digestion, dilution, recombination, purification, and bagging, in 12 cases of TPIAT. Posttransplantation glycemic control was monitored through C-peptide, hemoglobin A_1c , insulin requirement, and SUITO index. The amount of miR-375 released was significantly higher during enzymatic digestion followed by the islet bagging (P < .001). Mir-200c mirrored these changes, albeit at lower concentrations. In contrast, the C-peptide amount was significantly higher in the purification and bagging steps (P < .001). Lower amounts of miR-375 were associated with a lower 6-month insulin requirement (P = .01) and lower hemoglobin A_1c (P = .04). Measurement of the absolute quantity of miRNA-375 and -200c released during islet isolation is a useful tool to assess islet damage. The quantity of released miRNA is indicative of posttransplantation endocrine function in TPIAT patients.

Expression profiles of stress-related genes in islets from donors with progressively impaired glucose metabolism

It is currently unknown how the islet transcriptional pattern changes as glucose metabolism deteriorates and progresses to fulminant type 2 diabetes (T2D). In this study, we hypothesized that islets from donors with elevated HbA1c levels, but not yet diagnosed with T2D, would show signs of cell stress on a transcriptional level. Laser capture microdissection and qPCR arrays including 330 genes related to mitochondria, oxidative stress, or the unfolded protein response were used to extract and analyze islets from organ donors with HbA1c <5.5% (37 mmol/mol), elevated HbA1c (6.0-6.5% (42-48 mmol/mol)), high HbA1c (>6.5% (48 mmol/mol)) or established T2D. Principal component analysis and hierarchical clustering based on the expression of all 330 genes displayed no obvious separation of the four different donor groups, indicating that the inter-donor variations were larger than the differences between groups. However, 44 genes were differentially expressed (P < 0.05, false discovery rate <30%) between islets from donors with HbA1c <5.5% (37 mmol/mol) compared with islets from T2D subjects. Twelve genes were differentially expressed compared to control islets in both donors with established T2D and donors with elevated HbA1c (6.0-6.5% (42-48 mmol/mol)). Overexpressed genes were related mainly to the unfolded protein response, whereas underexpressed genes were related to mitochondria. Our data on transcriptional changes in human islets retrieved by LCM from high-quality biopsies, as pre-diabetes progresses to established T2D, increase our understanding on how islet stress contributes to the disease development.

Evaluation of collagenase gold plus BP protease in isolating islets from human pancreata

Selection of enzymes for optimal pancreas digestion is essential for successful human islet isolations. The aim of this study was to evaluate the efficacy and outcome of using Collagenase Gold plus BP protease (VitaCyte) (n = 8) by comparing it to two commercially available enzymes, Liberase MTF C/T (Roche) (n = 48) and Collagenase NB1/NP (Serva) (n = 15). The isolation outcomes were assessed by islet counting, viability, glucose-stimulated oxygen consumption rate (OCR), and successful graft-rate following transplantation in diabetic NOD scid mice. The pancreas donor characteristics were not significantly different between the tested enzyme groups regarding their BMI, pancreas weight, cold ischemia time (CIT) and HbA1c. The results show that digested tissue volume was not statistically significant between the VitaCyte enzyme (34.25 ± 5.4 mL) and the Roche enzyme (55.25 ± 3.42 mL, p = 0.073), however, this was significant with Serva enzyme (64.07 ± 7.95 mL, p = 0.020). Interestingly, the islet yields were not statistically different between all enzyme groups. Moreover, when islets were transplanted into NOD scid mice, the reversal rate of diabetes for the VitaCyte enzyme group was similar to all enzyme groups. In conclusion, the effectiveness of Collagenase Gold plus BP protease is comparable to the MTF C/T and the Collagenase NB1/NP enzymes; the low cost could facilitate the use of more pancreata for islet isolations.

Long term (4 years) improved insulin sensitivity following islet cell transplant in type 1 diabetes

BACKGROUND

Impaired insulin sensitivity (IS) predicts complications and mortality in type 1 diabetes (T1D). Insulin sensitivity improves shortly after islet cell transplant for T1D, yet long-term changes in IS and associated factors such as patient characteristics, transplant factors, clinical management, and IS-related biomarkers are unknown.

METHODS

Up to 9 years (mean 4) of longitudinal data were available on 22 adults (18 female) with T1D who received 1 to 3 transplants in Phase 1/2 or 3 clinical trials (2004-2014). Metabolic testing posttransplant estimated IS by the Homeostasis Model Assessment for Insulin Resistance (HOMA-IR; 111 observations) and the Simple Index of Insulin Sensitivity (SIis ; 95 observations).

RESULTS

Simple Index of Insulin Sensitivity significantly increased the first year posttransplant (P = .02), then stabilized (P = .39); HOMA-IR remained stable posttransplant (P = .92). Adjusting for age and BMI, higher SIis was associated with lower HbA1c following transplant (P = .03). Greater IS as measured by lower HOMA-IR and higher SIis was associated with lower fasting C-peptide (both P ≤ .04) and also with higher exenatide dose (both P ≤ .01). More islets transplanted were associated with higher SIis (P < .0001). Lower leptin at transplant predicted lower HOMA-IR and higher SIis after transplant, and lower bone marker receptor activator of nuclear factor kappa-B ligand predicted lower HOMA-IR (all P ≤ .01).

CONCLUSIONS

Insulin sensitivity measured by SIis was improved several years following transplant, while IS measured by HOMA-IR did not worsen. Higher exenatide dose, more islets transplanted, and diet and exercise (lowering leptin and receptor activator of nuclear factor kappa-B ligand) may improve IS, which may enhance glycaemic control and lower metabolic demand on transplanted islets. Long-term clamp studies are needed to confirm these results.

Hope vs hype: where are we in type 1 diabetes?

Much progress has been made in type 1 diabetes research. Biological replacement of islet function has been achieved with pancreas transplantation and with islet transplantation. In the future, human embryonic stem cells and/or induced pluripotent stem cells may offer a potentially unlimited source of cells for islet replacement. Another potential strategy is to induce robust beta cell replication so that regeneration of islets can be achieved. Immune interventions are being studied with the hope of arresting the type 1 diabetes disease process to either prevent the disease or help preserve beta cell function. Mechanical replacement of islet cell function involves the use of glucose sensor-controlled insulin infusion systems. As all of these avenues are pursued, headlines often overstate the case, thus hyping any given advance, which provides enormous hope for patients and families seeking a cure for type 1 diabetes. Often, however, it is an animal study or a pilot trial that is being described. The reality is that translation to successful trials in human beings may not be readily achievable. This article discusses both the hype and the hopes in type 1 diabetes research.

Oxygen-permeable microwell device maintains islet mass and integrity during shipping

Islet transplantation is currently the only minimally invasive therapy available for patients with type 1 diabetes that can lead to insulin independence; however, it is limited to only a small number of patients. Although clinical procedures have improved in the isolation and culture of islets, a large number of islets are still lost in the pre-transplant period, limiting the success of this treatment. Moreover, current practice includes islets being prepared at specialized centers, which are sometimes remote to the transplant location. Thus, a critical point of intervention to maintain the quality and quantity of isolated islets is during transportation between isolation centers and the transplanting hospitals, during which 20-40% of functional islets can be lost. The current study investigated the use of an oxygen-permeable PDMS microwell device for long-distance transportation of isolated islets. We demonstrate that the microwell device protected islets from aggregation during transport, maintaining viability and average islet size during shipping.

Highly Angiogenic, Nonthrombogenic Bone Marrow Mononuclear Cell-Derived Spheroids in Intraportal Islet Transplantation

Highly angiogenic bone marrow mononuclear cell-derived spheroids (BM-spheroids), formed by selective proliferation of the CD31⁺CD14⁺CD34⁺ monocyte subset via three-dimensional (3D) culture, have had robust angiogenetic capacity in rodent syngeneic renal subcapsular islet transplantation. We wondered whether the efficacy of BM-spheroids could be demonstrated in clinically relevant intraportal islet transplantation models without increasing the risk of portal thrombosis. The thrombogenic potential of intraportally infused BM-spheroids was compared with that of mesenchymal stem cells (MSCs) and MSC-derived spheroids (MSC-spheroids). The angiogenic efficacy and persistence in portal sinusoids of BM-spheroids were examined in rodent syngeneic and primate allogeneic intraportal islet transplantation models. In contrast to MSCs and MSC-spheroids, intraportal infusion of BM-spheroids did not evoke portal thrombosis. BM-spheroids had robust angiogenetic capacity in both the rodent and primate intraportal islet transplantation models and improved posttransplant glycemic outcomes. MRI and intravital microscopy findings revealed the persistence of intraportally infused BM-spheroids in portal sinusoids. Intraportal cotransplantation of allogeneic islets with autologous BM-spheroids in nonhuman primates further confirmed the clinical feasibility of this approach. In conclusion, cotransplantation of BM-spheroids enhances intraportal islet transplantation outcome without portal thrombosis in mice and nonhuman primates. Generating BM-spheroids by 3D culture prevented the rapid migration and disappearance of intraportally infused therapeutic cells.

An engineered macroencapsulation membrane releasing FTY720 to precondition pancreatic islet transplantation

Macroencapsulation is a powerful approach to increase the efficiency of extrahepatic pancreatic islet transplant. FTY720, a small molecule that activates signaling through sphingosine-1-phosphate receptors, is immunomodulatory and pro-angiogenic upon sustained delivery from biomaterials. While FTY720 (fingolimod, Gilenya) has been explored for organ transplantation, in the present work the effect of locally released FTY720 from novel nanofiber-based macroencapsulation membranes is explored for islet transplantation. We screened islet viability during culture with FTY720 and various biodegradable polymers. Islet viability is significantly reduced by the addition of high doses (≥500 ng/mL) of soluble FTY720. Among the polymers screened, islets have the highest viability when cultured with poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV). Therefore, PHBV was blended with polycaprolactone (PCL) for mechanical stability and electrospun into nanofibers. Islets had no detectable function ex vivo following 5 days or 12 h of subcutaneous implantation within our engineered device. Subsequently, we explored a preconditioning scheme in which islets are transplanted 2 weeks after FTY720-loaded nanofibers are implanted. This allows FTY720 to orchestrate a local regenerative milieu while preventing premature transplantation into avascular sites that contain high concentrations of FTY720. These results provide a foundation and motivation for further investigation into the use of FTY720 in preconditioning sites for efficacious islet transplantation. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 555-568, 2018.

Beneficial effect of recombinant rC1rC2 collagenases on human islet function: Efficacy of low-dose enzymes on pancreas digestion and yield

A high number of human islets can be isolated by using modern purified tissue dissociation enzymes; however, this requires the use of >20 Wunsch units (WU)/g of pancreas for digestion. Attempts to reduce this dose have resulted in pancreas underdigestion and poor islet recovery but improved islet function. In this study, we achieved a high number of functional islets using a low dose of recombinant collagenase enzyme mixture (RCEM-1200 WU rC2 and 10 million collagen-degrading activity [CDA] U of rC1 containing about 209 mg of collagenase to digest a 100-g pancreas). The collagenase dose used in these isolations is about 42% of the natural collagenase enzyme mixture (NCEM) dose commonly used to digest a 100-g pancreas. Low-dose RCEM was efficient in digesting entire pancreases to obtain higher yield (5535 ± 830 and 2582 ± 925 islet equivalent/g, P < .05) and less undigested tissue (16.7 ± 5% and 37.8 ± 3%, P < .05) compared with low-dose NCEM (12WU/g). Additionally, low-dose RCEM islets retained better morphology (confirmed with scanning electron microscopy) and higher in vitro basal insulin release (2391 ± 1342 and 1778 ± 978 μU/mL; P < .05) compared with standard-dose NCEM. Nude mouse bioassay demonstrated better islet function for low-dose RCEM (area under the curve [AUC] 24 968) compared with low-dose (AUC-38 225) or standard-dose NCEM (AUC-38 685), P < .05. This is the first report indicating that islet function can be improved by using low-dose rC1rC2 (RCEM).

Current issues in allogeneic islet transplantation

PURPOSE OF REVIEW

Transplantation of allogenic pancreatic islets is a minimally invasive treatment option to control severe hypoglycemia and dependence on exogenous insulin among type 1 diabetes (T1D) patients. This overview summarizes the current issues and progress in islet transplantation outcomes and research.

RECENT FINDINGS

Several clinical trials from North America and other countries have documented the safety and efficacy of clinical islet transplantation for T1D patients with impaired hypoglycemia awareness. A recently completed phase 3 clinical trial allows centres in the United States to apply for a Food and Drug Administration Biologics License for the procedure. Introduction of anti-inflammatory drugs along with T-cell depleting induction therapy has significantly improved long-term function of transplanted islets. Research into islet biomarkers, immunosuppression, extrahepatic transplant sites and potential alternative beta cell sources is driving further progress.

SUMMARY

Allogeneic islet transplantation has vastly improved over the past two decades. Success in restoration of glycemic control and hypoglycemic awareness after islet transplantation has been further highlighted by clinical trials. However, lack of effective strategies to maintain long-term islet function and insufficient sources of donor tissue still impose limitations to the widespread use of islet transplantation. In the United States, wide adoption of this technology still awaits regulatory approval and, importantly, a financial mechanism to support the use of this technology.

[Research progress on the donor cell sources of pancreatic islet transplantation for treatment of diabetes mellitus]

Objective

To summarize the research progress on the source and selection of donor cells in the field of islet replacement therapy for diabetes mellitus.

Methods

Domestic and abroad literature concerning islet replacement therapy for diabetes mellitus, as well as donor source and donor selection was reviewed and analyzed thoroughly.

Results

The shortage of donor supply is still a major obstacle for the widely clinical application of pancreatic islet transplantation (PIT). Currently, in addition to the progress on the allogeneic/autologous donor islet supply, some remarkable achievements have been also attained in the application of xenogeneic islet (from pig donor), as well as islet like cells derived from stem cells and islet cell line, potentially enlarging the source of implantable cells.

Conclusion

Adequate and suitable donor cell supply is an essential prerequisite for widely clinical application of PIT therapy for type 1 diabetes mellitus (T1DM). Further perfection of organ donation system, together with development of immune-tolerance induction, gene and bioengineering technology etc. will possibly solve the problem of donor cell shortage and provide a basis for clinical application of cellular replacement therapy for T1DM.

Pancreatic β Cell Regeneration as a Possible Therapy for Diabetes

Diabetes is the result of having inadequate supply of functional insulin-producing β cells. Two possible approaches for replenishing the β cells are: (1) replacement by transplanting cadaveric islets or β cells derived from human embryonic stem cells/induced pluripotent stem cells and (2) induction of endogenous regeneration. This review focuses on endogenous regeneration, which can follow two pathways: enhanced replication of existing β cells and formation of new β cells from cells not expressing insulin, either by conversion from a differentiated cell type (transdifferentiation) or differentiation from progenitors (neogenesis). Exciting progress on both pathways suggest that regeneration may have therapeutic promise.

Glucose-stimulated insulin release: Parallel perifusion studies of free and hydrogel encapsulated human pancreatic islets

To explore the effects immune-isolating encapsulation has on the insulin secretion of pancreatic islets and to improve our ability to quantitatively describe the glucose-stimulated insulin release (GSIR) of pancreatic islets, we conducted dynamic perifusion experiments with isolated human islets. Free (unencapsulated) and hydrogel encapsulated islets were perifused, in parallel, using an automated multi-channel system that allows sample collection with high temporal resolution. Results indicated that free human islets secrete less insulin per unit mass or islet equivalent (IEQ) than murine islets and with a less pronounced first-phase peak. While small microcapsules (d = 700 µm) caused only a slightly delayed and blunted first-phase insulin response compared to unencapsulated islets, larger capsules (d = 1,800 µm) completely blunted the first-phase peak and decreased the total amount of insulin released. Experimentally obtained insulin time-profiles were fitted with our complex insulin secretion computational model. This allowed further fine-tuning of the hormone-release parameters of this model, which was implemented in COMSOL Multiphysics to couple hormone secretion and nutrient consumption kinetics with diffusive and convective transport. The results of these GSIR experiments, which were also supported by computational modeling, indicate that larger capsules unavoidably lead to dampening of the first-phase insulin response and to a sustained-release type insulin secretion that can only slowly respond to changes in glucose concentration. Bioartificial pancreas type devices can provide long-term and physiologically desirable solutions only if immunoisolation and biocompatibility considerations are integrated with optimized nutrient diffusion and insulin release characteristics by design.

6. Glycemic Targets: Standards of Medical Care in Diabetes-2018

The American Diabetes Association (ADA) "Standards of Medical Care in Diabetes" includes ADA's current clinical practice recommendations and is intended to provide the components of diabetes care, general treatment goals and guidelines, and tools to evaluate quality of care. Members of the ADA Professional Practice Committee, a multidisciplinary expert committee, are responsible for updating the Standards of Care annually, or more frequently as warranted. For a detailed description of ADA standards, statements, and reports, as well as the evidence-grading system for ADA's clinical practice recommendations, please refer to the Standards of Care Introduction Readers who wish to comment on the Standards of Care are invited to do so at professional.diabetes.org/SOC.

Pre-clinical results in pig-to-non-human primate islet xenotransplantation using anti-CD40 antibody (2C10R4)-based immunosuppression

BACKGROUND

Islet transplantation is an effective therapy for selected patients with type 1 diabetes with labile glycemic control and hypoglycemic unawareness, but donor organs are limited. Islet xenotransplantation using porcine islets will potentially solve this problem. Although successful proof of concept studies using clinically inapplicable anti-CD154 monoclonal antibody (mAb) in pig-to-non-human primate (NHP) islet xenotransplantation has been demonstrated by several groups worldwide, potentially clinically applicable anti-CD40 (2C10R4) mAb-based studies have not been reported.

METHODS

Nine streptozotocin (STZ)-induced diabetic rhesus monkeys were transplanted with adult porcine islets isolated from designated pathogen-free (DPF) miniature pigs. They were treated with anti-CD40 mAb-based immunosuppressive regimen and were divided into 3 groups: anti-CD40 only group (n = 2), belatacept group (anti-CD40 mAb+belatacept, n = 2), and tacrolimus group (anti-CD40 mAb+tacrolimus, n = 5). All monkeys received anti-thymocyte globulin (ATG), cobra venom factor (CVF), adalimumab, and sirolimus. Blood glucose levels (BGL) and serum porcine C-peptide concentrations were measured. Humoral and cellular immune responses were assessed by ELISA and ELISPOT, respectively. Liver biopsy and subsequent immunohistochemistry were conducted.

RESULTS

All animals restored normoglycemia immediately after porcine islet transplantation and finished the follow-up without any severe adverse effects except for one animal (R092). Most animals maintained their body weight. Median survival, as defined by a serum porcine C-peptide concentration of >0.15 ng/mL, was 31, 27, and 60 days for anti-CD40 only, belatacept, and tacrolimus groups, respectively. Anti-αGal IgG levels in serum and the number of interferon-γ secreting T cells in peripheral blood mononuclear cells did not increase in most animals.

CONCLUSION

These results showed that anti-CD40 mAb combined with tacrolimus was effective in prolonging porcine islet graft survival, but anti-CD40 mAb was not as effective as anti-CD154 mAb in terms of preventing early islet loss.

Cotransplantation of Mesenchymal Stem Cells and Immature Dendritic Cells Potentiates the Blood Glucose Control of Islet Allografts

BACKGROUND

Transplantation of islets is a promising alternative to treat type 1 diabetes (T1D), but graft rejection is the major obstacle to its application in clinical practice. We evaluated the effects of mesenchymal stem cells (MSCs) and immature dendritic cells (imDCs) on islet transplantation in diabetic model.

METHODS

The streptozotocin T1D model was established in BABL/c mice. Rat islets were isolated and identified with dithizone (DTZ) staining. MSCs and imDCs were isolated from bone marrow of syngenic mice. Islets, alone or along with MSCs and/or imDCs, were transplanted to the left kidney capsule of diabetic mice. The blood glucose levels and glycosylated hemoglobin levels after transplantation were monitored.

RESULTS

Cotransplantation significantly decreased blood glucose and glycosylated hemoglobin levels in the diabetes mice. Transplantation of 200 islets + 2 × 105 MSCs + 2 × 105 imDCs could not only restore normal blood glucose levels, but also significantly prolong graft survival for 12.6 ± 3.48 days.

CONCLUSIONS

Cotransplantation of allogenic islets with imDCs and/or MSCs can significantly promote graft survival, reverse hyperglycemia, and effectively control the glycosylated hemoglobin levels.