Benefits of Islet Transplantation as an Alternative to Pancreas Transplantation: Retrospective Study of More Than 10 Ten Years of Experience in a Single Center

Multifunctional PLGA nanocomposites to improve beta cell replacement therapy in Type 1 diabetes

Diabetes Mellitus is a rapidly growing global health problem, with its prevalence having risen sharply in recent years. Type 1 diabetes (T1D) treatment options are limited, with most of them significantly compromising the quality of life of these patients. This study presents the development and characterization of a multifunctional hybrid nanoformulation (mHNFs) designed to enhance the efficacy of beta cell replacement therapy in T1D. By encapsulating rapamycin and two types of magnetic nanoparticles (MnO and Fe3O4) within PLGA, we aimed to address critical challenges in islet transplantation, including hypoxia and immunosuppression. The synthesized nanoparticles demonstrated dual imaging capabilities as MRI contrast agents, sustained drug release, and in situ oxygen generation, crucial for mitigating islet hypoxia and loss of function. In vitro studies confirmed the cytocompatibility of the system and its efficient internalization by rin-m cells. Additionally, O2 generation studies proved that mHNFs significantly reduced hypoxia levels. These results highlight the potential of these nanocarriers to improve the safety and efficacy of T1D islet transplantation treatments through a multifunctional approach.

Effectiveness of islet transplantation in diabetes mellitus type 1: a systematic review of the recent evidence

INTRODUCTION

Islet transplantation has been introduced as a promising approach for the treatment of diabetes mellitus type 1. Despite many efforts to achieve a perfect treatment, further investigation is still needed to eliminate limitations and challenging issues. The objective of the present systematic review was to evaluate the efficacy of islet transplantation in diabetes mellitus type 1.

EVIDENCE ACQUISITION

We conducted a systematic review on the results of clinical studies on islet cell transplantation between January 2015 and November 2021. The search strategy was designed and conducted in PubMed, Cochrane, Scopus, and Web of Science.

EVIDENCE SYNTHESIS

Studies have indicated that islet transplantation can reduce the daily insulin requirement as well as improving metabolic stability in diabetic patients. Even in some patients, insulin independence was achieved during the first year of transplantation.

CONCLUSIONS

Findings show that islet transplantation has a potential to become a promising treatment for diabetes mellitus type 1. In this regard, to obtain a trustworthy result, it is essential to design clinical studies (RCTs) with large sample size and long follow-up (cohort studies) to achieve a comprehensive and accurate appraisal of islet transplantation.

Current Challenges in Pancreas and Islet Transplantation: A Scoping Review

Type 1 diabetes mellitus is an autoimmune condition characterized by the destruction of pancreatic β-cells, necessitating insulin therapy to prevent life-threatening complications such as diabetic ketoacidosis. Despite advancements in glucose monitoring and pharmacological treatments, managing this disease remains challenging, often leading to long-term complications and psychological burdens, including diabetes distress. Advanced treatment options, such as whole-pancreas transplantation and islet transplantation, aim to restore insulin production and improve glucose control in selected patients with diabetes. The risk of transplant rejection necessitates immunosuppressive therapy, which increases susceptibility to infections and other adverse effects. Additionally, surgical complications, including infection and bleeding, are significant concerns, particularly for whole-pancreas transplantation. Recently, stem cell-derived therapies for type 1 diabetes have emerged as a promising alternative, offering potential solutions to overcome the limitations of formerly established transplantation methods. The purpose of this scoping review was to: (1) summarize the current evidence on achieved insulin independence following various transplantation methods of insulin-producing cells in patients with type 1 diabetes; (2) compare insulin independence rates among whole-pancreas transplantation, islet cell transplantation, and stem cell transplantation; and (3) identify limitations, challenges and potential future directions associated with these techniques. We systematically searched three databases (PubMed, Scopus, and Web of Science) from inception to November 2024, focusing on English-language, peer-reviewed clinical studies. The search terms used were 'transplantation' AND 'type 1 diabetes' AND 'insulin independence'. Studies were included if they reported on achieved insulin independence, involved more than 10 patients with type 1 diabetes, and had a mean follow-up period of at least one year. Reviewers screened citations and extracted data on transplant type, study population size, follow-up duration, and insulin independence rates. We identified 1380 papers, and after removing duplicates, 705 papers remained for title and abstract screening. A total of 139 English-language papers were retrieved for full-text review, of which 48 studies were included in this review. The findings of this scoping review indicate a growing body of literature on transplantation therapy for type 1 diabetes. However, significant limitations and challenges, like insufficient rates of achieved insulin independence, risks related to immunosuppression, malignant diseases, and ethical issues remain with each of the established techniques, highlighting the need for innovative approaches such as stem cell-derived islet transplantation to promote β-cell regeneration and protection.

Pancreas and Islet Transplantation: Comparative Outcome Analysis of a Single-centre Cohort Over 20-years

OBJECTIVE

To provide the largest single-center analysis of islet (ITx) and pancreas (PTx) transplantation.

SUMMARY BACKGROUND DATA

Studies describing long-term outcomes with ITx and PTx are scarce.

METHODS

We included adults undergoing ITx (n=266) and PTx (n=146) at the University of Alberta from January 1999 to October 2019. Outcomes include patient and graft survival, insulin independence, glycemic control, procedure-related complications, and hospital readmissions. Data are presented as medians (interquartile ranges, IQR) and absolute numbers (percentages, %) and compared using Mann-Whitney and χ2 tests. Kaplan-Meier estimates, Cox proportional hazard models and mixed main effects models were implemented.

RESULTS

Crude mortality was 9.4% and 14.4% after ITx and PTx, respectively ( P= 0.141). Sex-adjusted and age-adjusted hazard-ratio for mortality was 2.08 (95% CI, 1.04-4.17, P= 0.038) for PTx versus ITx. Insulin independence occurred in 78.6% and 92.5% in ITx and PTx recipients, respectively ( P= 0.0003), while the total duration of insulin independence was 2.1 (IQR 0.8-4.6) and 6.7 (IQR 2.9-12.4) year for ITx and PTx, respectively ( P= 2.2×10 -22 ). Graft failure ensued in 34.2% and 19.9% after ITx and PTx, respectively ( P =0.002). Glycemic control improved for up to 20-years post-transplant, particularly for PTx recipients (group, P= 7.4×10 -7 , time, P =4.8×10 -6 , group*time, P= 1.2×10 -7 ). Procedure-related complications and hospital readmissions were higher after PTx ( P =2.5×10 -32 and P= 6.4×10 -112 , respectively).

CONCLUSIONS

PTx shows higher sex-adjusted and age-adjusted mortality, procedure-related complications and readmissions compared with ITx. Conversely, insulin independence, graft survival and glycemic control are better with PTx. This study provides data to balance risks and benefits with ITx and PTx, which could improve shared decision-making.

The Optimal Maturation of Subcutaneous Pouch Can Improve Pancreatic Islets Engraftment in Rat Model

BACKGROUND

Transplantation of pancreatic islets into subcutaneous cavities in diabetic rats may be as or even more effective than transplantation into the portal vein. Identifying the optimal timing of the individual steps in this procedure is critical.

METHODS

Macroporous scaffolds were placed in the subcutaneous tissue of diabetic male Lewis rats for 7 or 28 d and the healing of the tissue inside the scaffolds was monitored. A marginal syngeneic graft comprising 4 islets/g of recipient body weight was transplanted at the best timing focusing mainly on vascularization. Recipients were monitored for blood glucose levels and tolerance tests. Histological examination was performed in all implanted scaffolds. The presence of individual endocrine cells was analyzed in detail.

RESULTS

Blood glucose levels remained within the physiological range in all recipients until the end of experiment as well as body weight increase. Coefficients of glucose assimilation were normal or slightly reduced with no statistically significant differences between the groups 40 and 80 d after transplantation. Histological analysis revealed round viable islets in the liver similar to those in pancreas, but alpha cells practically disappeared, whereas islets in the scaffolds formed clusters of cells surrounded by rich vascular network and the alpha cells remained partially preserved.

CONCLUSIONS

Subcutaneous transplantation of pancreatic islets is considerably less invasive but comparably efficient as commonly used islet transplantation into the portal vein. In consideration of alpha and beta cell ratio, the artificial subcutaneous cavities represent a promising site for future islet transplantation therapy.

Considerations and challenges of islet transplantation and future therapies on the horizon

Islet transplantation is a treatment for selected adults with type 1 diabetes and severe hypoglycemia. Islets from two or more donor pancreases, a scarce resource, are usually required to impact glycemic control, but the treatment falls short of a cure. Islets are avascular when transplanted into the hypoxic liver environment and subjected to inflammatory insults, immune attack, and toxicity from systemic immunosuppression. The Collaborative Islet Transplant Registry, with outcome data on over 1,000 islet transplant recipients, has demonstrated that larger islet numbers transplanted and older age of recipients are associated with better outcomes. Induction with T-cell depleting agents and the TNF-α inhibitor etanercept and maintenance systemic immunosuppression with mTOR inhibitors in combination with calcineurin inhibitors also appear advantageous, but concerns remain over immunosuppressive toxicity. We discuss strategies and therapeutics that address specific challenges of islet transplantation, many of which are at the preclinical stage of development. On the horizon are adjuvant cell therapies with mesenchymal stromal cells and regulatory T cells that have been used in preclinical models and in humans in other contexts; such a strategy may enable reductions in immunosuppression in the early peri-transplant period when the islets are vulnerable to apoptosis. Human embryonic stem cell-derived islets are in early-phase clinical trials and hold the promise of an inexhaustible supply of insulin-producing cells; effective encapsulation of such cells or, silencing of the human leukocyte antigen (HLA) complex would eliminate the need for immunosuppression, enabling this therapy to be used in all those with type 1 diabetes.