Islet cell transplantation improves nerve conduction velocity in type 1 diabetes compared with intensive medical therapy over six years

Future directions for adrenal insufficiency: cellular transplantation and genetic therapies

Primary adrenal insufficiency occurs in 1 in 5-7000 adults. Leading aetiologies are autoimmune adrenalitis in adults and congenital adrenal hyperplasia (CAH) in children. Oral replacement of cortisol is lifesaving, but poor quality of life, repeated adrenal crises and dosing uncertainty related to lack of a validated biomarker for glucocorticoid sufficiency, persists. Adrenocortical cell therapy and gene therapy may obviate many of the shortcomings of adrenal hormone replacement. Physiological cortisol secretion regulated by pituitary adrenocorticotropin, could be achieved through allogeneic adrenocortical cell transplantation, production of adrenal-like steroidogenic cells from either stem cells or lineage conversion of differentiated cells, or for CAH, gene therapy to replace or repair a defective gene. The adrenal cortex is a high turnover organ and thus failure to incorporate progenitor cells within a transplant will ultimately result in graft exhaustion. Identification of adrenocortical progenitor cells is equally important in gene therapy where new genetic material must be specifically integrated into the genome of progenitors to ensure a durable effect. Delivery of gene editing machinery and a donor template, allowing targeted correction of the 21-hydroxylase gene, has the potential to achieve this. This review describes advances in adrenal cell transplants and gene therapy that may allow physiological cortisol production for children and adults with primary adrenal insufficiency.

Type 1 diabetes and engineering enhanced islet transplantation

The development of new therapeutic approaches to treat type 1 diabetes mellitus (T1D) relies on the precise understanding and deciphering of insulin-secreting β-cell biology, as well as the mechanisms responsible for their autoimmune destruction. β-cell or islet transplantation is viewed as a potential long-term therapy for the millions of patients with diabetes. To advance the field of insulin-secreting cell transplantation, two main research areas are currently investigated by the scientific community: (1) the identification of the developmental pathways that drive the differentiation of stem cells into insulin-producing cells, providing an inexhaustible source of cells; and (2) transplantation strategies and engineered transplants to provide protection and enhance the functionality of transplanted cells. In this review, we discuss the biology of pancreatic β-cells, pathology of T1D and current state of β-cell differentiation. We give a comprehensive view and discuss the different possibilities to engineer enhanced insulin-secreting cell/islet transplantation from a translational perspective.

A systematic review of the prevalence, risk factors and screening tools for autonomic and diabetic peripheral neuropathy in children, adolescents and young adults with type 1 diabetes

AIMS

We aimed to estimate the prevalence of Diabetic peripheral neuropathy (DPN) and Cardiac autonomic neuropathy (CAN) in youth with type 1 diabetes; identify key risk factors; identify the most useful tests for the diagnostic evaluation of DPN and CAN; identify key treatment options for DPN and CAN.

METHODS

A systematic search was performed including studies published in the last 15 years. PICO framework was used in the selection process and evidence was assessed using the GRADE system.

RESULTS

A total of 758 studies were identified and a final number of 49 studies were included in this systematic review. According to moderate-high level quality studies, the prevalence of probable DPN, ranged between 13.5 and 62%; subclinical DPN between 22 and 88%; confirmed DPN between 2.6 and 11%. The Michigan Neuropathy Screening Instrument was the tool with higher sensitivity and specificity for detecting DPN, which needs to be confirmed by nerve conduction velocity. The prevalence of CAN was 4-39%. Specific treatment options for DPN or CAN in patients younger than 25 years are not available. Key risk factors for DPN and CAN are hyperglycemia/HbA1c, age, diabetes duration, the presence of other microvascular complications, waist/height ratio, lipid profile and blood pressure. For CAN, additional risk factors were cigarette smoking, BMI and total daily insulin.

CONCLUSIONS

Prevalence of neuropathy in youth with type 1 diabetes varies depending on different screening methods and characteristics of the study populations. However, the assessed studies confirmed a relatively high prevalence of subclinical neuropathy, reiterating the importance of early identification of risk factors to prevent this complication.

Cardiac Autonomic Neuropathy Is Not Reversed by Euglycemia Following Islet Transplantation

BACKGROUND

Cardiac autonomic neuropathy (CAN) is a significant cause of morbidity and mortality for people with type 1 (T1D) and type 2 (T2D) diabetes. Heart rate variability (HRV) has been shown to be a marker of CAN with 24-hour Holter monitoring being a robust modality to assess HRV.

METHODS

To investigate the impact of hypoglycemia on CAN and its potential reversibility with islet transplantation, we compared HRV assessment by 24-hour Holter monitor on a total of 109 subjects from 5 cohorts: (1) T1D with recurrent severe hypoglycemia and on waiting list for islet transplant, (2) T1D following islet cell transplantation (ICT), (3) T2D without hypoglycemia, (4) individuals with prediabetes, and (5) controls without diabetes. SD of the normal-normal interval, square root of the mean squared differences of successive normal-normal intervals (rMSSD) and total spectral power were analyzed.

RESULTS

There was no significant difference in HRV parameters between T1D subjects and T1D post ICT suggesting CAN is not reversible at a median of 4 years postislet transplant. There was a significant difference in controls and T1D in rMSSD and between controls and T2D in total power. The differential effect on rMSSD in T1D and T2D suggests potential greater impact of hypoglycemia on rMSSD.

CONCLUSIONS

Achieving euglycemia after ICT may not reverse CAN once established with no significant difference in HRV parameters at a median of 4 years postislet transplant. Differential effects of T1D as compared with T2D on CAN were identified.

Islet transplantation ameliorates diabetes-induced testicular interstitial fibrosis and is associated with inhibition of TGF-β1/Smad2 pathway in a rat model of type 1 diabetes

Islet transplantation (IT) is considered the most effective endocrine replacement therapy for diabetes mellitus (DM). Studies have demonstrated that IT can repair testicular structural injury caused by inflammatory and oxidative stress in a diabetic rat model. However, highly effective exogenous antioxidant and anti-inflammatory drugs can achieve this effect. Testicular interstitial fibrosis caused by long-term hyperglycemia is however difficult to reverse or recover. Thus far, there are no effective drugs that prevent or relieve testicular interstitial fibrosis. Therefore, it is necessary to explore the potential benefit of IT on testicular interstitial fibrosis induced by DM and its underlying molecular mechanisms. In the present study, Wistar rats were used to establish a DM model by intraperitoneal injection of streptozotocin. The diabetic models then underwent IT or received insulin treatment after 12 weeks. IT was more effective than insulin treatment in ameliorating diabetic-induced testicular interstitial fibrosis, Leydig cells apoptosis, testosterone deficiency and poor sperm motility. IT and insulin treatment both significantly inhibited the upregulation of TGF-β1 and phosphorylated Smad2 in DM, with IT being more effective than insulin. The present study's findings proved that IT effectively protects diabetic-induced testicular interstitial fibrosis probably by inhibiting the TGF-β1/Smad2 signaling pathway, which offers hope in male patients with DM complicating with testicular interstitial fibrosis.

Transplant strategies for type 1 diabetes: whole pancreas, islet and porcine beta cell therapies

Whole-organ pancreas and islet transplantations are performed in a highly selected group of patients with diabetes mellitus, primarily those with type 1 diabetes mellitus, complicated by recurrent severe hypoglycaemia or renal failure requiring kidney transplantation. Clinical accessibility to pancreases or islets, and patient characteristics and therapeutic goals, may dictate choice of procedure. Pancreas transplantation is most often performed simultaneous with a kidney transplant, but patients with particularly labile type 1 diabetes may be considered for a pancreas transplant alone. While highly successful at restoring insulin independence, pancreas transplants carry the significant risks of major surgery and immunosuppression. Islet transplantation is a relatively minor procedure, usually performed for labile type 1 diabetes with severe hypoglycaemia. It is highly successful at resolving hypoglycaemia, but more than one pancreas donor may be required for insulin independence. Both pancreas and islet transplantation are limited in applicability by a paucity of deceased donors. Pigs provide one promising replenishable source of islets. Porcine islets can successfully reverse diabetes mellitus in non-human primates under the appropriate immunosuppressive conditions, with promise for eventually translating this success to a larger population of patients with diabetes mellitus in the future. Graphical abstract.

Ten-Year Outcome of Islet Alone or Islet After Kidney Transplantation in Type 1 Diabetes: A Prospective Parallel-Arm Cohort Study

OBJECTIVE

The long-term outcome of allogenic islet transplantation is unknown. The aim of this study was to evaluate the 10-year outcome of islet transplantation in patients with type 1 diabetes and hypoglycemia unawareness and/or a functioning kidney graft.

RESEARCH DESIGN AND METHODS

We enrolled in this prospective parallel-arm cohort study 28 subjects with type 1 diabetes who received islet transplantation either alone (ITA) or after a kidney graft (IAK). Islet transplantation consisted of two or three intraportal infusions of allogenic islets administered within (median [interquartile range]) 68 days (43-92). Immunosuppression was induced with interleukin-2 receptor antibodies and maintained with sirolimus and tacrolimus. The primary outcome was insulin independence with A1C ≤6.5% (48 mmol/mol). Secondary outcomes were patient and graft survival, severe hypoglycemic events (SHEs), metabolic control, and renal function.

RESULTS

The primary outcome was met by (Kaplan-Meier estimates [95% CI]) 39% (22-57) and 28% (13-45) of patients 5 and 10 years after islet transplantation, respectively. Graft function persisted in 82% (62-92) and 78% (57-89) of case subjects after 5 and 10 years, respectively, and was associated with improved glucose control, reduced need for exogenous insulin, and a marked decrease of SHEs. ITA and IAK had similar outcomes. Primary graft function, evaluated 1 month after the last islet infusion, was significantly associated with the duration of graft function and insulin independence.

CONCLUSIONS

Islet transplantation with the Edmonton protocol can provide 10-year markedly improved metabolic control without SHEs in three-quarters of patients with type 1 diabetes, kidney transplanted or not.

Advances in β-cell replacement therapy for the treatment of type 1 diabetes

The main goal of treatment for type 1 diabetes is to control glycaemia with insulin therapy to reduce disease complications. For some patients, technological approaches to insulin delivery are inadequate, and allogeneic islet transplantation is a safe alternative for those patients who have had severe hypoglycaemia complicated by impaired hypoglycaemia awareness or glycaemic lability, or who already receive immunosuppressive drugs for a kidney transplant. Since 2000, intrahepatic islet transplantation has proven efficacious in alleviating the burden of labile diabetes and preventing complications related to diabetes, whether or not a previous kidney transplant is present. Age, body-mass index, renal status, and cardiopulmonary status affect the choice between pancreas or islet transplantation. Access to transplantation is limited by the number of deceased donors and the necessity of immunosuppression. Future approaches might include alternative sources of islets (eg, xenogeneic tissue or human stem cells), extrahepatic sites of implantation (eg, omental, subcutaneous, or intramuscular), and induction of immune tolerance or encapsulation of islets.

Understanding the Signaling Pathways Related to the Mechanism and Treatment of Diabetic Peripheral Neuropathy

Worldwide, the most prevalent metabolic disorder is diabetes mellitus (DM), an important condition that has been widely studied. Diabetic peripheral neuropathy (DPN), a complication that can occur with DM, is associated with pain and can result in foot ulcers and even amputation. DPN treatments are limited and mainly focus on pain management. There is a clear need to develop treatments for DPN at all stages. To make this progress, it is necessary to understand the molecular signaling pathways related to DPN. For this review, we aimed to concentrate on the main signaling cascades that contribute to DPN. In addition, we provide information with regard to treatments that are being explored.

Novel insights into MSC-EVs therapy for immune diseases

Mesenchymal stromal cells (MSC) are a heterogeneous cell population with self-renewal and the ability to differentiate into different lineages. The novel regulatory role of MSC in both adaptive and innate immune responses got extensive investigation and MSC have been widely used in clinical trials as immunosuppressive agents for autoimmune and inflammatory diseases, including graft-versus-host disease (GVHD), multiple sclerosis (MS), systemic lupus erythematosus (SLE), chronic kidney disease, etc. Recent studies have found that MSC exerted their immunomodulation function through secreting extracellular vesicles (EVs), which delivered parent cell cargo to recipient cells without oncogenicity or variability. Since MSC-EVs exhibit most of the properties of MSC and take advantage of their cellular immunomodulatory fuction, MSC-EVs appear to a promising none-cell therapy in various human diseases. In this review, we summarize the pivotal roles of MSC-EVs as agents for immunotherapy in diseases.

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.

Islet transplantation improved penile tissue fibrosis in a rat model of type 1 diabetes

BACKGROUND

Glycaemic control is one of the most effective strategies for the treatment of diabetes-related erectile dysfunction (DMED). Compared to conventional anti-diabetic drugs and insulin, islet transplantation is more effective in the treatment of diabetic complications. The aim of this study was to investigate the efficacy of islet transplantation for reversing advanced-stage DMED in rats and to observe its influence on corpus cavernosum fibrosis.

METHODS

Wistar rats were intraperitoneally injected with streptozotocin to establish a diabetes model. After 12 weeks, the rats were divided into 4 groups: diabetic, insulin, islet transplantation, and normal control. Following supplementation, the changes in blood glucose and weight were determined sequentially. Penile erectile function was evaluated by apomorphine experiments in the fourth week, and the penile corpus cavernosum was also collected for assessment by Masson staining, immunohistochemistry and Western blot to observe the spongy tissue and the related cellular changes at the molecular level.

RESULTS

Islet transplantation significantly ameliorated penile erectile function in advanced-stage diabetic rats. The ratio of corpus cavernosum smooth muscle cells to fibroblasts and the expression level of α-SMA in the islet transplantation group were significantly higher than those in the diabetic and insulin groups. In addition, the expression levels of TGF-β1, p-Samd2, and connective tissue growth factor (CTGF) in the islet transplantation and insulin groups were much lower than those in the diabetic group, while those in the islet transplantation group were significantly lower than those in the insulin group.

CONCLUSIONS

Our findings strongly suggest that islet transplantation can promote the regeneration of smooth muscle cells and ameliorate corpus cavernosum fibrosis to restore its normal structure in advanced-stage diabetic rats. The possible mechanism of ameliorating corpus cavernosum fibrosis by islet transplantation may be associated with improvement of the hyperglycaemic status in diabetic rats, thereby inhibiting the TGF-β1/Samd2/CTGF pathway.

The Flaws and Future of Islet Volume Measurements

When working with isolated islet preparations, measuring the volume of tissue is not a trivial matter. Islets come in a large range of sizes and are often contaminated with exocrine tissue. Many factors complicate the procedure, and yet knowledge of the islet volume is essential for predicting the success of an islet transplant or comparing experimental groups in the laboratory. In 1990, Ricordi presented the islet equivalency (IEQ), defined as one IEQ equaling a single spherical islet of 150 μm in diameter. The method for estimating IEQ was developed by visualizing islets in a microscope, estimating their diameter in 50 μm categories and calculating a total volume for the preparation. Shortly after its introduction, the IEQ was adopted as the standard method for islet volume measurements. It has helped to advance research in the field by providing a useful tool improving the reproducibility of islet research and eventually the success of clinical islet transplants. However, the accuracy of the IEQ method has been questioned for years and many alternatives have been proposed, but none have been able to replace the widespread use of the IEQ. This article reviews the history of the IEQ, and discusses the benefits and failings of the measurement. A thorough evaluation of alternatives for estimating islet volume is provided along with the steps needed to uniformly move to an improved method of islet volume estimation. The lessons learned from islet researchers may serve as a guide for other fields of regenerative medicine as cell clusters become a more attractive therapeutic option.