Restoring insulin production for type 1 diabetes

Advances and challenges of the cell-based therapies among diabetic patients

Diabetes mellitus is a significant global public health challenge, with a rising prevalence and associated morbidity and mortality. Cell therapy has evolved over time and holds great potential in diabetes treatment. In the present review, we discussed the recent progresses in cell-based therapies for diabetes that provides an overview of islet and stem cell transplantation technologies used in clinical settings, highlighting their strengths and limitations. We also discussed immunomodulatory strategies employed in cell therapies. Therefore, this review highlights key progresses that pave the way to design transformative treatments to improve the life quality among diabetic patients.

Current Landscape of Various Techniques and Methods of Gene Therapy through CRISPR Cas9 along with its Pharmacological and Interventional Therapies in the Treatment of Type 2 Diabetes Mellitus

BACKGROUND

Type 2 diabetes mellitus (T2DM) is frequently referred to as a "lifestyle illness". In 2000, India (31.7 million) had the greatest global prevalence of diabetes mellitus, followed by China (20.8 million), the United States (17.7 million), and other countries. In recent years, the treatment of gene therapy (T2DM) has attracted intensive interest.

OBJECTIVE

We aimed to critically review the literature on the various techniques and methods, which may be a possible novel approach through the gene therapy CRISPR Cas9 and some other gene editing techniques for T2DM. Interventional and pharmacological approaches for the treatment of T2DM were also included to identify novel therapies for its treatment.

METHOD

An extensive literature survey was done on databases like PubMed, Elsevier, Science Direct and Springer.

CONCLUSION

It can be concluded from the study that recent advancements in gene-editing technologies, such as CRISPR Cas9, have opened new avenues for the development of novel therapeutic approaches for T2DM. CRISPR Cas9 is a powerful tool that enables precise and targeted modifications of the genome.

A novel hybrid polymer of PCL/Fish gelatin nanofibrous scaffold improves proliferation and differentiation of wharton's jelly-derived mesenchymal cells into islet-like cells

BACKGROUND

Using a different source of stem cells to compensate for the lost beta cells is a promising way to cure diabetic patients. Besides The best efficiency of insulin-producing cells (IPCs) will appear when we culture them in an environment similar to inside the body. Hence, three-dimensional (3D) culture ameliorates the differentiation of diverse kinds of stem cells into IPCs compared to those differentiated in two-dimensional (2D) culture. In this study, we aim to create an ideal differentiation environment by using PCL/Fish gelatin nanofibrous scaffolds to differentiate wharton's jelly-derived mesenchymal cells (WJ-MSCs) to IPCs and compare them with a 2D cultured group.

METHODS

The evaluation of cellular, molecular, and functional properties of differentiated cells on the 3D and 2D cultures were investigated by several assay such as electron microscopy, quantitative PCR, immunochemistry, western blotting, and ELISA.

RESULTS

The in vitro studies showed, WJ-MSCs that differentiated in the 3D culture have strong properties of IPCs such as islet-like cells. The expression of pancreatic-specific genes at both RNA and protein levels showed higher differentiation efficacy of 3D culture. Besides, the results of the elisa tests demonstrates that in both groups the differentiated cells are functional and secreted C-peptide and insulin in glucose stimulation, but the secretion of C-peptide and insulin in the 3D culture group was higher than those cultured in 2D groups.

CONCLUSION

Our findings showed the use of PCL/Fish gelatin nanofibrous scaffolds with optimized differentiation protocols can promote the differentiation of IPCs from WJ-MSCs compared to the 2D culture group.

Emerging Treatment Strategies for Diabetes Mellitus and Associated Complications: An Update

The occurrence of diabetes mellitus (DM) is increasing rapidly at an accelerating rate worldwide. The status of diabetes has changed over the last three generations; whereas before it was deemed a minor disease of older people but currently it is now one of the leading causes of morbidity and mortality among middle-aged and young people. High blood glucose-mediated functional loss, insulin sensitivity, and insulin deficiency lead to chronic disorders such as Type 1 and Type 2 DM. Traditional treatments of DM, such as insulin sensitization and insulin secretion cause undesirable side effects, leading to patient incompliance and lack of treatment. Nanotechnology in diabetes studies has encouraged the development of new modalities for measuring glucose and supplying insulin that hold the potential to improve the quality of life of diabetics. Other therapies, such as β-cells regeneration and gene therapy, in addition to insulin and oral hypoglycemic drugs, are currently used to control diabetes. The present review highlights the nanocarrier-based drug delivery systems and emerging treatment strategies of DM.

Drug Delivery System in the Treatment of Diabetes Mellitus

Diabetes mellitus has been described as a chronic endocrine and metabolic disease, which is characterized by hyperglycemia and the coexistence of multiple complications. At present, the drugs widely applied in clinical treatment of diabetes mellitus mainly include insulin, insulin analogs, non-insulin oral hypoglycemic drugs and genetic drugs. Nevertheless, there is still no complete therapy strategy for diabetes mellitus management by far due to the intrinsic deficiencies of drugs and limits in administration routes such as the adverse reactions caused by long-term subcutaneous injection and various challenges in oral administration, such as enzymatic degradation, chemical instability and poor gastrointestinal absorption. Therefore, it is remarkably necessary to develop appropriate delivery systems and explore complete therapy strategies according to the characters of drugs and diabetes mellitus. Delivery systems have been found to be potentially beneficial in many aspects for effective diabetes treatment, such as improving the stability of drugs, overcoming different biological barriers in vivo to increase bioavailability, and acting as an intelligent automatized system to mimic endogenous insulin delivery and reduce the risk of hypoglycemia. This review aims to provide an overview related with the research advances, development trend of drug therapy and the application of delivery systems in the treatment diabetes mellitus, which could offer reference for the application of various drugs in the field of diabetes mellitus treatment.

Necessities for a Clinical Islet Program

For more than two decades we have been refining advances in islet cell transplantation as a clinical therapy for patients suffering from type 1 diabetes. A great deal of effort has gone to making this a viable therapy for a broader range of patients with type 1 diabetes. Clinical results have progressively improved, demonstrating clinical outcomes on par with other organ transplants, specifically in terms of insulin independence, graft and patient survival. We are now at the point where islet cell transplantation, in the form of allotransplantation, has become accepted as a clinical therapy in adult patients affected by type 1 diabetes, in particular those suffering from severe hypoglycaemic unawareness. This chapter provides an overview on how this has been undertaken over the years to provide outcomes on par with other organ transplantation results. In particular this chapter focuses on the processes and facilities that are required to establish a clinical islet isolation and transplantation program. It also outlines the very important underpinning processes of selection of the organ donor for islet isolation, the processes of organ donor operation and preservation of the pancreas by various means and the ideal ways to best improve outcomes for human islet cell isolation. Providing these more optimal conditions we can underpin the isolation processes to provide islets for transplantation and as such a safe, effective and feasible therapeutic option for an increasing number of patients suffering from type 1 diabetes with severe hypoglycaemic unawareness.

Cellular therapies based on stem cells and their insulin-producing surrogates: a 2015 reality check

Stem cell technology has recently gained a substantial amount of interest as one method to create a potentially limitless supply of transplantable insulin-producing cells to treat, and possibly cure diabetes mellitus. In this review, we summarize the state-of-the art of stem cell technology and list the potential sources of stem cells that have been shown to be useful as insulin-expressing surrogates. We also discuss the milestones that have been reached and those that remain to be addressed to generate bona fide beta cell-similar, insulin-producing surrogates. The caveats, limitations, and realistic expectations are also considered for current and future technology. In spite of the tremendous technical advances realized in the past decade, especially in the field of reprogramming adult somatic cells to become stem cells, the state-of-the art still relies on lengthy and cumbersome in vitro culture methods that yield cell populations that are not particularly glucose-responsive when transplanted into diabetic hosts. Despite the current impediments toward clinical translation, including the potential for immune rejection, the availability of technology to generate patient-specific reprogrammable stem cells has, and will be critical for, important insights into the genetics, epigenetics, biology, and physiology of insulin-producing cells in normal and pathologic states. This knowledge could accelerate the time to reach the desired breakthrough for safe and efficacious beta cell surrogates.

Benefits of healthy adipose tissue in the treatment of diabetes

The major malfunction in diabetes mellitus is severe perturbation of glucose homeostasis caused by deficiency of insulin. Insulin deficiency is either absolute due to destruction or failure of pancreatic β cells, or relative due to decreased sensitivity of peripheral tissues to insulin. The primary lesion being related to insulin, treatments for diabetes focus on insulin replacement and/or increasing sensitivity to insulin. These therapies have their own limitations and complications, some of which can be life-threatening. For example, exogenous insulin administration can lead to fatal hypoglycemic episodes; islet/pancreas transplantation requires life-long immunosuppressive therapy; and anti-diabetic drugs have dangerous side effects including edema, heart failure and lactic acidosis. Thus the need remains for better safer long term treatments for diabetes. The ultimate goal in treating diabetes is to re-establish glucose homeostasis, preferably through endogenously generated hormones. Recent studies increasingly show that extra-pancreatic hormones, particularly those arising from adipose tissue, can compensate for insulin, or entirely replace the function of insulin under appropriate circumstances. Adipose tissue is a versatile endocrine organ that secretes a variety of hormones with far-reaching effects on overall metabolism. While unhealthy adipose tissue can exacerbate diabetes through limiting circulation and secreting of pro-inflammatory cytokines, healthy uninflamed adipose tissue secretes beneficial adipokines with hypoglycemic and anti-inflammatory properties, which can complement and/or compensate for the function of insulin. Administration of specific adipokines is known to alleviate both type 1 and 2 diabetes, and leptin mono-therapy is reported to reverse type 1 diabetes independent of insulin. Although specific adipokines may correct diabetes, administration of individual adipokines still carries risks similar to those of insulin monotherapy. Thus a better approach is to achieve glucose homeostasis with endogenously-generated adipokines through transplantation or regeneration of healthy adipose tissue. Our recent studies on mouse models show that type 1 diabetes can be reversed without insulin through subcutaneous transplantation of embryonic brown adipose tissue, which leads to replenishment of recipients’ white adipose tissue; increase of a number of beneficial adipokines; and fast and long-lasting euglycemia. Insulin-independent glucose homeostasis is established through a combination of endogenously generated hormones arising from the transplant and/or newly-replenished white adipose tissue. Transplantation of healthy white adipose tissue is reported to alleviate type 2 diabetes in rodent models on several occasions, and increasing the content of endogenous brown adipose tissue is known to combat obesity and type 2 diabetes in both humans and animal models. While the underlying mechanisms are not fully documented, the beneficial effects of healthy adipose tissue in improving metabolism are increasingly reported, and are worthy of attention as a powerful tool in combating metabolic disease.

The rise, fall, and resurgence of immunotherapy in type 1 diabetes

Despite considerable effort to halt or delay destruction of β-cells in autoimmune type 1 diabetes (T1D), success remains elusive. Over the last decade, we have seen a proliferation of knowledge on the pathogenesis of T1D that emerged from studies performed in non-obese diabetic (NOD) mice. However, while results of these preclinical studies appeared to hold great promise and boosted patients' hopes, none of these approaches, once tested in clinical settings, induced remission of autoimmune diabetes in individuals with T1D. The primary obstacles to translation reside in the differences between the human and murine autoimmune responses and in the contribution of many environmental factors associated with the onset of disease. Moreover, inaccurate dosing as well as inappropriate timing and uncertain length of drug exposure have played a central role in the negative outcomes of such therapeutic interventions. In this review, we summarize the most important approaches tested thus far in T1D, beginning with the most successful preclinical studies in NOD mice and ending with the latest disappointing clinical trials in humans. Finally, we highlight recent stem cell-based trials, for which expectations in the scientific community and among individuals with T1D are high.

Characterization of polyhormonal insulin-producing cells derived in vitro from human embryonic stem cells

Human embryonic stem cells (hESCs) were used as a model system of human pancreas development to study characteristics of the polyhormonal cells that arise during fetal pancreas development. HESCs were differentiated into fetal-like pancreatic cells in vitro using a 33-day, 7-stage protocol. Cultures were ~90-95% PDX1-positive by day (d) 11 and 70-75% NKX6.1-positive by d17. Polyhormonal cells were scattered at d17, but developed into islet-like clusters that expressed key transcription factors by d33. Human C-peptide and glucagon secretion were first detected at d17 and increased thereafter in parallel with INS and GCG transcript levels. HESC-derived cells were responsive to KCl and arginine, but not glucose in perifusion studies. Compared to adult human islets, hESC-derived cells expressed ~10-fold higher levels of glucose transporter 1 (GLUT1) mRNA, but similar levels of glucokinase (GCK). In situ hybridization confirmed the presence of GLUT1 transcript within endocrine cells. However, GLUT1 protein was excluded from this population and was instead observed predominantly in non-endocrine cells, whereas GCK was co-expressed in insulin-positive cells. In rubidium efflux assays, hESC-derived cells displayed mild potassium channel activity, but no responsiveness to glucose, metabolic inhibitors or glibenclamide. Western blotting experiments revealed that the higher molecular weight SUR1 band was absent in hESC-derived cells, suggesting a lack of functional KATP channels at the cell surface. In addition, KATP channel subunit transcript levels were not at a 1:1 ratio, as would be expected (SUR1 levels were ~5-fold lower than KIR6.2). Various ratios of SUR1:KIR6.2 plasmids were transfected into COSM6 cells and rubidium efflux was found to be particularly sensitive to a reduction in SUR1. These data suggest that an impaired ratio of SUR1:KIR6.2 may contribute to the observed KATP channel defects in hESC-derived islet endocrine cells, and along with lack of GLUT1, may explain the absence of glucose-stimulated insulin secretion.

Maturation and function of human embryonic stem cell-derived pancreatic progenitors in macroencapsulation devices following transplant into mice

AIMS/HYPOTHESIS

Islet transplantation is a promising cell therapy for patients with diabetes, but it is currently limited by the reliance upon cadaveric donor tissue. We previously demonstrated that human embryonic stem cell (hESC)-derived pancreatic progenitor cells matured under the kidney capsule in a mouse model of diabetes into glucose-responsive insulin-secreting cells capable of reversing diabetes. However, the formation of cells resembling bone and cartilage was a major limitation of that study. Therefore, we developed an improved differentiation protocol that aimed to prevent the formation of off-target mesoderm tissue following transplantation. We also examined how variation within the complex host environment influenced the development of pancreatic progenitors in vivo.

METHODS

The hESCs were differentiated for 14 days into pancreatic progenitor cells and transplanted either under the kidney capsule or within Theracyte (TheraCyte, Laguna Hills, CA, USA) devices into diabetic mice.

RESULTS

Our revised differentiation protocol successfully eliminated the formation of non-endodermal cell populations in 99% of transplanted mice and generated grafts containing >80% endocrine cells. Progenitor cells developed efficiently into pancreatic endocrine tissue within macroencapsulation devices, despite lacking direct contact with the host environment, and reversed diabetes within 3 months. The preparation of cell aggregates pre-transplant was critical for the formation of insulin-producing cells in vivo and endocrine cell development was accelerated within a diabetic host environment compared with healthy mice. Neither insulin nor exendin-4 therapy post-transplant affected the maturation of macroencapsulated cells.

CONCLUSIONS/INTERPRETATION

Efficient differentiation of hESC-derived pancreatic endocrine cells can occur in a macroencapsulation device, yielding glucose-responsive insulin-producing cells capable of reversing diabetes.

Adipose tissue, hormones, and treatment of type 1 diabetes

Type 1 diabetes (T1D) is a serious disease with increasing incidence worldwide, with fatal consequences if untreated. Traditional therapies require direct or indirect insulin replacement, which involves numerous limitations and complications. While insulin is the major regulator of blood glucose, recent reports demonstrate the ability of several extra-pancreatic hormones to decrease blood glucose and improve metabolic homeostasis. Such hormones mainly include adipokines originating from adipose tissue (AT), while specific factors from the gut and liver also contribute to glucose homeostasis. Correction of T1D with adipokines is progressively becoming a realistic option, with the potential to overcome many problems associated with insulin replacement. Several recent studies demonstrate insulin-independent reversal or amelioration of T1D through administration of specific adipokines. Our recent work demonstrates the ability of healthy AT to compensate for the function of endocrine pancreas in long-term correction of T1D. This review discusses the potential of AT-related therapies for T1D as viable alternatives to insulin replacement.