2290-PUB: Donor HLA-DR4 Positivity and Islet Transplantation Outcomes

Encapsulation of pancreatic islets has been proposed and investigated for over three decades to improve islet transplantation outcomes and to eliminate the side effects of immunosuppressive medications. Of the numerous encapsulation systems developed in the past, microencapsulation have been studied most extensively so far. A wide variety of materials has been tested for microencapsulation in various animal models (including nonhuman primates or NHPs) and some materials were shown to induce immunoprotection to islet grafts without the need for chronic immunosuppression. Despite the initial success of microcapsules in NHP models, the combined use of islet transplantation (allograft) and microencapsulation has not yet been successful in clinical trials. This review consists of three sections: introduction to islet transplantation, transplantation of encapsulated pancreatic islets as a treatment for patients with type 1 diabetes mellitus (T1DM), and present challenges and future perspectives.

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

Cell Transplantation ◽

10.1177/0963689720919444 ◽

2020 ◽

Vol 29 ◽

pp. 096368972091944 ◽

Cited By ~ 1

Author(s):

Mayra Salgado ◽

Nelson Gonzalez ◽

Leonard Medrano ◽

Jeffrey Rawson ◽

Keiko Omori ◽

...

Keyword(s):

Islet Transplantation ◽

Human Islet ◽

Viability Assessment ◽

Promising Alternative ◽

Immunodeficient Mice ◽

Automated Method ◽

Significant Difference ◽

Transplantation Outcomes

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

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Current Assessment of Clinical Pancreatic Islet Allotransplantation

10.21926/obm.transplant.2004125 ◽

2020 ◽

Vol 4 (4) ◽

Author(s):

Preeti Chhabra ◽

Kenneth L Brayman ◽

Keyword(s):

Type 1 Diabetes ◽

Islet Transplantation ◽

Human Islets ◽

Current Status ◽

Insulin Independence ◽

Post Transplantation ◽

Widespread Application ◽

Alternative Sources ◽

Transplantation Outcomes

Clinical islet allotransplantation represents a minimally invasive, efficacious alternative to pancreas transplantation for restoring glycemic control and insulin independence in select patients with type 1 diabetes that is complicated by intractable impaired hypoglycemia awareness and/or severe hypoglycemic events refractory to stabilization by other means. Over the last decade, islet transplantation outcomes have steadily improved in part due to refinements in the selection of optimal donors, islet isolation techniques, safer engraftment methods, and effective immunomodulatory and anti-inflammatory therapies. Insulin independence rates at five years post-transplantation at select centers have reached parity with pancreas alone transplantation, and marked progress has been achieved in islet transplantation outcomes using single-donor pancreas. However, widespread application of the procedure is still hindered due to a limited supply of donor pancreases, inadequate engraftment, and the harmful side effects of chronic immunosuppression. Strategies to address some of these challenges involve the use of alternative sources of beta cells or islets, extrahepatic sites of implantation, encapsulation of islets and novel therapies to induce tolerance. While several countries have now transitioned islet transplantation from experimental status to a funded clinical cure for patients with brittle type 1 diabetes that cannot be stabilized by more conventional means, in the US it still awaits regulatory approval and a financial mechanism for sustainable reimbursement. This review details the history and the current status of clinical islet allotransplantation while summarizing improvements that have been made in techniques involving isolation, purification, culture and assessment of human islets as well as the islet transplantation process itself. Furthermore, it discusses the limitations encountered that prevent its widespread application, strategies that address those limitations, and last but not least, clinical trials being conducted that will help position islet transplantation as a mainstay treatment for the cure of type 1 diabetes.

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