James J. McGarrigle

Long-term glycemic control using polymer-encapsulated human stem cell–derived beta cells in immune-competent mice

The transplantation of glucose-responsive, insulin-producing cells offers the potential for restoring glycemic control in individuals with diabetes. Pancreas transplantation and the infusion of cadaveric islets are currently implemented clinically, but these approaches are limited by the adverse effects of immunosuppressive therapy over the lifetime of the recipient and the limited supply of donor tissue. The latter concern may be addressed by recently described glucose-responsive mature beta cells that are derived from human embryonic stem cells (referred to as SC-β cells), which may represent an unlimited source of human cells for pancreas replacement therapy. Strategies to address the immunosuppression concerns include immunoisolation of insulin-producing cells with porous biomaterials that function as an immune barrier. However, clinical implementation has been challenging because of host immune responses to the implant materials. Here we report the first long-term glycemic correction of a diabetic, immunocompetent animal model using human SC-β cells. SC-β cells were encapsulated with alginate derivatives capable of mitigating foreign-body responses in vivo and implanted into the intraperitoneal space of C57BL/6J mice treated with streptozotocin, which is an animal model for chemically induced type 1 diabetes. These implants induced glycemic correction without any immunosuppression until their removal at 174 d after implantation. Human C-peptide concentrations and in vivo glucose responsiveness demonstrated therapeutically relevant glycemic control. Implants retrieved after 174 d contained viable insulin-producing cells.

Combinatorial hydrogel library enables identification of materials that mitigate the foreign body response in primates

The foreign body response is an immune-mediated reaction that can lead to the failure of implanted medical devices and discomfort for the recipient. There is a critical need for biomaterials that overcome this key challenge in the development of medical devices. Here we use a combinatorial approach for covalent chemical modification to generate a large library of variants of one of the most widely used hydrogel biomaterials, alginate. We evaluated the materials in vivo and identified three triazole-containing analogs that substantially reduce foreign body reactions in both rodents and, for at least 6 months, in non-human primates. The distribution of the triazole modification creates a unique hydrogel surface that inhibits recognition by macrophages and fibrous deposition. In addition to the utility of the compounds reported here, our approach may enable the discovery of other materials that mitigate the foreign body response.

Neurogenin 3 Expressing Cells in the Human Exocrine Pancreas Have the Capacity for Endocrine Cell Fate

Neurogenin 3 (NGN3) is necessary and sufficient for endocrine differentiation during pancreatic development and is expressed by a population of progenitor cells that give rise exclusively to hormone-secreting cells within islets. NGN3 protein can be detected in the adult rodent pancreas only following certain types of injury, when it is transiently expressed by exocrine cells undergoing reprogramming to an endocrine cell fate. Here, NGN3 protein can be detected in 2% of acinar and duct cells in living biopsies of histologically normal adult human pancreata and 10% in cadaveric biopsies of organ donor pancreata. The percentage and total number of NGN3+ cells increase during culture without evidence of proliferation or selective cell death. Isolation of highly purified and viable NGN3+ cell populations can be achieved based on coexpression of the cell surface glycoprotein CD133. Transcriptome and targeted expression analyses of isolated CD133+ / NGN3+ cells indicate that they are distinct from surrounding exocrine tissue with respect to expression phenotype and Notch signaling activity, but retain high level mRNA expression of genes indicative of acinar and duct cell function. NGN3+ cells have an mRNA expression profile that resembles that of mouse early endocrine progenitor cells. During in vitro differentiation, NGN3+ cells express genes in a pattern characteristic of endocrine development and result in cells that resemble beta cells on the basis of coexpression of insulin C-peptide, chromogranin A and pancreatic and duodenal homeobox 1. NGN3 expression in the adult human exocrine pancreas marks a dedifferentiating cell population with the capacity to take on an endocrine cell fate. These cells represent a potential source for the treatment of diabetes either through ex vivo manipulation, or in vivo by targeting mechanisms controlling their population size and endocrine cell fate commitment.

A microfluidic array for real-time live-cell imaging of human and rodent pancreatic islets

In this study, we present a microfluidic array for high-resolution imaging of individual pancreatic islets. The device is based on hydrodynamic trapping principle and enables real-time analysis of islet cellular responses to insulin secretagogues. This device has significant advantages over our previously published perifusion chamber device including significantly increased analytical power and assay sensitivity, as well as improved spatiotemporal resolution. The islet array, with live-cell multiparametric imaging integration, provides a better tool to understand the physiological and pathophysiological changes of pancreatic islets through the analysis of single islet responses. This platform demonstrates the feasibility of array-based islet cellular analysis and opens up a new modality to conduct informative and quantitive evaluation of islets and cell-based screening for new diabetes treatments.

A multicenter study: North american islet donor score in donor pancreas selection for human islet isolation for transplantation

Selection of an optimal donor pancreas is the first key task for successful islet isolation. We conducted a retrospective multicenter study in 11 centers in North America to develop an islet donor scoring system using donor variables. The data set consisting of 1,056 deceased donors was used for development of a scoring system to predict islet isolation success (defined as postpurification islet yield >400,000 islet equivalents). With the aid of univariate logistic regression analyses, we developed the North American Islet Donor Score (NAIDS) ranging from 0 to 100 points. The c index in the development cohort was 0.73 (95% confidence interval 0.70–0.76). The success rate increased proportionally as the NAIDS increased, from 6.8% success in the NAIDS < 50 points to 53.7% success in the NAIDS ≥ 80 points. We further validated the NAIDS using a separate set of data consisting of 179 islet isolations. A comparable outcome of the NAIDS was observed in the validation cohort. The NAIDS may be a useful tool for donor pancreas selection in clinical practice. Apart from its utility in clinical decision making, the NAIDS may also be used in a research setting as a standardized measurement of pancreas quality.

Use of Glucagon-Like Peptide-1 Agonists to Improve Islet Graft Performance

Human islet transplantation is an effective and promising therapy for type I diabetes. However, long-term insulin independence is both difficult to achieve and inconsistent. De novo or early administration of incretin-based drugs is being explored for improving islet engraftment. In addition to its glucose-dependent insulinotropic effects, incretins also lower postprandial glucose excursion by inhibiting glucagon secretion, delaying gastric emptying, and can protect beta-cell function. Incretin therapy has so far proven clinically safe and tolerable with little hypoglycemic risk. The present review aims to highlight the new frontiers in research involving incretins from both in vitro and in vivo animal studies in the field of islet transplant. It also provides an overview of the current clinical status of incretin usage in islet transplantation in the management of type I diabetes.

A pumpless microfluidic device driven by surface tension for pancreatic islet analysis.

We present a novel pumpless microfluidic array driven by surface tension for studying the physiology of pancreatic islets of Langerhans. Efficient fluid flow in the array is achieved by surface tension-generated pressure as a result of inlet and outlet size differences. Flow properties are characterized in numerical simulation and further confirmed by experimental measurements. Using this device, we perform a set of biological assays, which include real-time fluorescent imaging and insulin secretion kinetics for both mouse and human islets. Our results demonstrate that this system not only drastically simplifies previously published experimental protocols for islet study by eliminating the need for external pumps/tubing and reducing the volume of solution consumption, but it also achieves a higher analytical spatiotemporal resolution due to efficient flow exchanges and the extremely small volume of solutions required. Overall, the microfluidic platform presented can be used as a potential powerful tool for understanding islet physiology, antidiabetic drug development, and islet transplantation.

Alginate encapsulation as long-term immune protection of allogeneic pancreatic islet cells transplanted into the omental bursa of macaques

The transplantation of pancreatic islet cells could restore glycaemic control in patients with type 1 diabetes. Microspheres for islet encapsulation have enabled long-term glycaemic control in rodent models of diabetes; however, humans transplanted with equivalent microsphere formulations have experienced only transient islet graft function owing to a vigorous foreign-body response (FBR), to pericapsular fibrotic overgrowth (PFO) and, in upright bipedal species, to the sedimentation of the microspheres within the peritoneal cavity. Here, we report the results of the testing in non-human primate (NHP) models of seven alginate formulations that were efficacious in rodents, including three that led to transient islet graft function in clinical trials. All formulations elicited significant FBR and PFO 1 month post implantation; however, three chemically modified, immune-modulating alginate formulations elicited a reduced FBR. In conjunction with a minimally invasive transplantation technique into the bursa omentalis of NHPs, the most promising chemically modified alginate derivative (Z1-Y15) protected viable and glucose-responsive allogeneic islets for 4 months without the need for immunosuppression. Chemically modified alginate formulations may enable the long-term transplantation of islets for the correction of insulin deficiency.Transplantation of pancreatic islet cells encapsulated in alginate microspheres into the omental bursa of the peritoneal cavity of NHPs significantly reduces FBRs and extends the longevity of the cells.

Islet Microencapsulation: Strategies and Clinical Status in Diabetes

Purpose of ReviewType 1 diabetes mellitus (T1DM) is an autoimmune disease that results from the destruction of insulin-producing pancreatic β cells in the islets of Langerhans. Islet cell transplantation has become a successful therapy for specific patients with T1DM with hypoglycemic unawareness. The reversal of T1DM by islet transplantation is now performed at many major medical facilities throughout the world. However, many challenges must still be overcome in order to achieve continuous, long-term successful transplant outcomes. Two major obstacles to this therapy are a lack of islet cells for transplantation and the need for life-long immunosuppressive treatment. Microencapsulation is seen as a technology that can overcome both these limitations of islet cell transplantation. This review depicts the present state of microencapsulated islet transplantation.Recent FindingsMicroencapsulation can play a significant role in overcoming the need for immunosuppression and lack of donor islet cells.SummaryThis review focuses on microencapsulation and the clinical status of the technology in combating T1DM.

Effect of Manufacturing Procedures on Human Islet Isolation from Donor Pancreata Standardized by the North American Islet Donor Score

This study investigates manufacturing procedures that affect islet isolation outcomes from donor pancreata standardized by the North American Islet Donor Score (NAIDS). Islet isolations performed at the University of Illinois, Chicago, from pancreata with NAIDS ≥65 were investigated. The research cohort was categorized into two groups based on a postpurification yield either greater than (group A) or less than (group B) 400,000 IEQ. Associations between manufacturing procedures and islet isolation outcomes were analyzed using multivariate logistic or linear regressions. A total of 119 cases were retrieved from 630 islet isolations performed since 2003. Group A is composed of 40 cases with an average postpurified yield of 570,098 IEQ, whereas group B comprised 79 cases with an average yield of 235,987 IEQ. One third of 119 cases were considered successful islet isolations that yielded >400,000 IEQ. The prepurified and postpurified islet product outcome parameters were detailed for future reference. The NAIDS (>80 vs. 65–80) [odds ratio (OR): 2.91, 95% confidence interval (CI): 1.27–6.70], cold ischemic time (≤10 vs. >10 h) (OR: 3.68, 95% CI: 1.61–8.39), and enzyme perfusion method (mechanical vs. manual) (OR: 2.38, 95% CI: 1.01–5.56) were independent determinants for postpurified islet yield ≥400,000 IEQ. The NAIDS (>80, p < 0.001), cold ischemic time (≤10 h, p < 0.05), increased unit of collagenase (p < 0.01), and pancreatic duct cannulation time (<30 min, p < 0.01) all independently correlated with better islet quantity parameters. Furthermore, cold ischemic time (≤10 h, p < 0.05), liberase MTF (p < 0.001), increased unit of collagenase (p < 0.05), duct cannulation time (<30 min, p < 0.05), and mechanical enzyme perfusion (p < 0.05) were independently associated with better islet morphology score. Analysis of islet manufacturing procedures from the pancreata with standardized quality is essential in identifying technical issues within islet isolation. Adequate processing duration in each step of islet isolation, using liberase MTF, and mechanical enzyme perfusion all affect isolation outcomes.