An isolated venous sac as a novel site for cell therapy in diabetes mellitus

Generation of Insulin-Producing Multicellular Organoids

Clinical islet transplantation (CIT) is an established noninvasive treatment for type I diabetes (T1D) and has demonstrated improved glycemic control, preventing the occurrence of severe hypoglycemia. However, CIT has several limitations, such as the need for multiple donors, lifelong immunosuppression, and suboptimal long-term graft function. Most of the transplanted islets are lost due to inflammation, ischemic damage, and delayed revascularization.Generation of organoids have gained increasing interest in regenerative medicine in recent years. In the context of beta-cell replacement, it offers a possibility to address limitations of CIT by allowing to produce uniform organoids from single or multiple cell types facilitating revascularization and anti-inflammatory and/or immunomodulatory protection. We have previously generated multicellular insulin-secreting organoids composed of islet cells and the human amniotic epithelial cells (hAECs). These 3D insulin-secreting structures demonstrated improved viability and function both in vitro and in vivo. Here we detail a stepwise methodology to generate insulin-secreting organoids using two different methods. In addition, quality assessment in vitro tests are also described.

From islet of Langerhans transplantation to the bioartificial pancreas

Type 1 diabetes is a disease resulting from autoimmune destruction of the insulin-producing beta cells in the pancreas. When type 1 diabetes develops into severe secondary complications, in particular end-stage nephropathy, or life-threatening severe hypoglycemia, the best therapeutic approach is pancreas transplantation, or more recently transplantation of the pancreatic islets of Langerhans. Islet transplantation is a cell therapy procedure, that is minimally invasive and has a low morbidity, but does not display the same rate of functional success as the more invasive pancreas transplantation because of suboptimal engraftment and survival. Another issue is that pancreas or islet transplantation (collectively known as beta cell replacement therapy) is limited by the shortage of organ donors and by the need for lifelong immunosuppression to prevent immune rejection and recurrence of autoimmunity. A bioartificial pancreas is a construct made of functional, insulin-producing tissue, embedded in an anti-inflammatory, immunomodulatory microenvironment and encapsulated in a perm-selective membrane allowing glucose sensing and insulin release, but isolating from attacks by cells of the immune system. A successful bioartificial pancreas would address the issues of engraftment, survival and rejection. Inclusion of unlimited sources of insulin-producing cells, such as xenogeneic porcine islets or stem cell-derived beta cells would further solve the problem of organ shortage. This article reviews the current status of clinical islet transplantation, the strategies aiming at developing a bioartificial pancreas, the clinical trials conducted in the field and the perspectives for further progress.

Engineering β Cell Replacement Therapies for Type 1 Diabetes: Biomaterial Advances and Considerations for Macroscale Constructs

While significant progress has been made in treatments for type 1 diabetes (T1D) based on exogenous insulin, transplantation of insulin-producing cells (islets or stem cell-derived β cells) remains a promising curative strategy. The current paradigm for T1D cell therapy is clinical islet transplantation (CIT)-the infusion of islets into the liver-although this therapeutic modality comes with its own limitations that deteriorate islet health. Biomaterials can be leveraged to actively address the limitations of CIT, including undesired host inflammatory and immune responses, lack of vascularization, hypoxia, and the absence of native islet extracellular matrix cues. Moreover, in efforts toward a clinically translatable T1D cell therapy, much research now focuses on developing biomaterial platforms at the macroscale, at which implanted platforms can be easily retrieved and monitored. In this review, we discuss how biomaterials have recently been harnessed for macroscale T1D β cell replacement therapies.

Bio-Engineering of Pre-Vascularized Islet Organoids for the Treatment of Type 1 Diabetes

Lack of rapid revascularization and inflammatory attacks at the site of transplantation contribute to impaired islet engraftment and suboptimal metabolic control after clinical islet transplantation. In order to overcome these limitations and enhance engraftment and revascularization, we have generated and transplanted pre-vascularized insulin-secreting organoids composed of rat islet cells, human amniotic epithelial cells (hAECs), and human umbilical vein endothelial cells (HUVECs). Our study demonstrates that pre-vascularized islet organoids exhibit enhanced in vitro function compared to native islets, and, most importantly, better engraftment and improved vascularization in vivo in a murine model. This is mainly due to cross-talk between hAECs, HUVECs and islet cells, mediated by the upregulation of genes promoting angiogenesis (vegf-a) and β cell function (glp-1r, pdx1). The possibility of adding a selected source of endothelial cells for the neo-vascularization of insulin-scereting grafts may also allow implementation of β cell replacement therapies in more favourable transplantation sites than the liver.

Generation of insulin-secreting organoids: a step toward engineering and transplanting the bioartificial pancreas

Diabetes is a major health issue of increasing prevalence. ß‐cell replacement, by pancreas or islet transplantation, is the only long‐term curative option for patients with insulin‐dependent diabetes. Despite good functional results, pancreas transplantation remains a major surgery with potentially severe complications. Islet transplantation is a minimally invasive alternative that can widen the indications in view of its lower morbidity. However, the islet isolation procedure disrupts their vasculature and connection to the surrounding extracellular matrix, exposing them to ischemia and anoikis. Implanted islets are also the target of innate and adaptive immune attacks, thus preventing robust engraftment and prolonged full function. Generation of organoids, defined as functional 3D structures assembled with cell types from different sources, is a strategy increasingly used in regenerative medicine for tissue replacement or repair, in a variety of inflammatory or degenerative disorders. Applied to ß‐cell replacement, it offers the possibility to control the size and composition of islet‐like structures (pseudo‐islets), and to include cells with anti‐inflammatory or immunomodulatory properties. In this review, we will present approaches to generate islet cell organoids and discuss how these strategies can be applied to the generation of a bioartificial pancreas for the treatment of type 1 diabetes.

[Current state of the problem of allotransplantation of Langerhans cells (achievements and prospects)]

Literature data devoted to transplantation of Langerhans cells have been analyzed. The main stages, indications, dissection of islets, immunosuppressive therapy, complications and data of the latest clinical trials were discussed.

Decellularized bovine placentome for portacavally-interposed heterotopic liver transplantation in rats

Scaffolds from healthy placentae offer advantages for tissue engineering with undamaged matrix, associated cytoprotective molecules, and embedded vessels for revascularization. As size disparities in human placenta and small recipients hamper preclinical studies, we studied alternative of bovine placentomes in smaller size ranges. Multiple cow placentomes were decellularized and anatomical integrity was analyzed. Tissue engineering used inbred donor rat livers. Placentomes were hepatized and immediately transplanted in rats with perfusion from portal vein and drainage into inferior vena cava. Cows yielded 99 ± 16 placentomes each. Of these, approximately 25% had 3 to 9 cm diameter and 7 to 63 ml volume, which was suitable for transplantation. After decellularization, angiography and casts documented 100% of vessels and vascular networks were well-perfused without disruptions or leaks. The residual matrix also remained intact for transplantation of placentomes. Perfusion in transplanted placentomes was maintained over up to 30 days. Liver tissue reassembled with restoration of hepatic acinar and sinusoidal structure. Transplanted tissue was intact without apoptosis, or necrosis. Hepatic functions were maintained. Preservation of hepatic homeostasis was verified by cytofluorimetric analysis of hepatocyte ploidy. The prevalence in healthy and transplanted liver of diploid, tetraploid and higher ploidy classes was similar with 57%, 41% and 2% versus 51%, 46.5% and 2.6%, respectively, p = 0.77, ANOVA. CONCLUSIONS: Cow placentomes will allow therapeutic development with disease models in small animals. This will also advance drug or toxicology studies. Portasystemic interposition of engineered liver will be particularly suitable for treating hepatic insufficiencies (metabolic, secretory or detoxification needs), including for children or smaller adults.

Diabetes Is Reversed in a Murine Model by Marginal Mass Syngeneic Islet Transplantation Using a Subcutaneous Cell Pouch Device

Islet transplantation is a successful β-cell replacement therapy for selected patients with type 1 diabetes mellitus. Although high rates of early insulin independence are achieved routinely, long-term function wanes over time. Intraportal transplantation is associated with procedural risks, requires multiple donors, and does not afford routine biopsy. Stem cell technologies may require potential for retrievability, and graft removal by hepatectomy is impractical. There is a clear clinical need for an alternative, optimized transplantation site. The subcutaneous space is a potential substitute, but transplantation of islets into this site has routinely failed to reverse diabetes. However, an implanted device, which becomes prevascularized before transplantation, may alter this equation.

The authors apply a new implanted subcutaneous cell pouch (CP) device in a mouse diabetes model. Mouse islets transplanted into the CP restore glycemic control with well respond to glucose challenge. CP may serve as a potential alternative to clinical intraportal islet transplantation.

Re-engineering islet cell transplantation

We are living exciting times in the field of beta cell replacement therapies for the treatment of diabetes. While steady progress has been recorded thus far in clinical islet transplantation, novel approaches are needed to make cell-based therapies more reproducible and leading to long-lasting success. The multiple facets of diabetes impose the need for a transdisciplinary approach to attain this goal, by targeting immunity, promoting engraftment and sustained functional potency. We discuss herein the emerging technologies applied to this rapidly evolving field.

Ischemic preconditioning affects long-term cell fate through DNA damage-related molecular signaling and altered proliferation

Despite the potential of ischemic preconditioning for organ protection, long-term effects in terms of molecular processes and cell fates are ill defined. We determined consequences of hepatic ischemic preconditioning in rats, including cell transplantation assays. Ischemic preconditioning induced persistent alterations; for example, after 5 days liver histology was normal, but γ-glutamyl transpeptidase expression was observed, with altered antioxidant enzyme content, lipid peroxidation, and oxidative DNA adducts. Nonetheless, ischemic preconditioning partially protected from toxic liver injury. Similarly, primary hepatocytes from donor livers preconditioned with ischemia exhibited undesirably altered antioxidant enzyme content and lipid peroxidation, but better withstood insults. However, donor hepatocytes from livers preconditioned with ischemia did not engraft better than hepatocytes from control livers. Moreover, proliferation of hepatocytes from donor livers preconditioned with ischemia decreased under liver repopulation conditions. Hepatocytes from donor livers preconditioned with ischemia showed oxidative DNA damage with expression of genes involved in MAPK signaling that impose G1/S and G2/M checkpoint restrictions, including p38 MAPK-regulated or ERK-1/2-regulated cell-cycle genes such as FOS, MAPK8, MYC, various cyclins, CDKN2A, CDKN2B, TP53, and RB1. Thus, although ischemic preconditioning allowed hepatocytes to better withstand secondary insults, accompanying DNA damage and molecular events simultaneously impaired their proliferation capacity over the long term. Mitigation of ischemic preconditioning-induced DNA damage and deleterious molecular perturbations holds promise for advancing clinical applications.

Correction of diabetes mellitus by transplanting minimal mass of syngeneic islets into vascularized small intestinal segment

Transplantation of mature islets into portal vein has been most effective thus far, although attrition of transplanted islets constitutes a major limitation, and alternative approaches are required. We analyzed the mechanisms by which islets engrafted, vascularized and functioned over the long term in the small intestinal submucosa. To determine engraftment, survival and function, 350 syngenic islets were transplanted into either intestinal segments or portal vein of diabetic rats. Islet reorganization, vascularization and function were analyzed by histological analysis, RT-PCR analysis as well as glycemic control over up to 1 year. Transplantation of syngeneic islets in marginal numbers successfully restored normoglycemia in diabetic rats. Transplantation of semi-pure islet preparation did not impair their engraftment, vascularization and function. Islets were morphologically intact and expressed insulin as well as glucagon over the year. Expression of angiogenic genes permitted revascularization of transplanted islets. We identified the expression of transcription factors required for maintenance of beta cells. These studies demonstrated that marginal mass of transplanted islets was sufficient to restore euglycemia in streptozotocin-treated rats. These superior results were obtained despite use of an impure preparation of islets in animals with small intestinal segment. Our findings will help advance new horizons for cell therapy in patients with diabetes.

Engineering a local microenvironment for pancreatic islet replacement

Intraportal islet transplantation has emerged as a promising treatment for type 1 diabetes mellitus (T1DM). Nevertheless, long-term efficacy has been limited to a marginal number of patients. Outcomes have been restricted, in part, by challenges associated with the transplant site, poor vascularization, and disruption of the native islet architecture during the isolation process. Engineering a biomaterial platform that recapitulates critical components of the pancreatic environment can serve to address these hurdles. This review highlights the challenges and opportunities in engineering 3D niches for islets, specifically: the importance of site selection; the application of scaffold functionalization to present bioactive motifs; and the development of technologies for enhancing implant nutritional profiles. The potential of these novel approaches to improve islet engraftment and duration of function is discussed.

Transplantation of pancreatic islets to adrenal gland is promoted by agonists of growth-hormone-releasing hormone

Here, we evaluate an alternative approach of preconditioning pancreatic islets before transplantation using a potent agonist of growth-hormone-releasing hormone (GHRH) to promote islet viability and function, and we explore the adrenal gland as an alternative transplantation site for islet engraftment. The endocrine microenvironment of the adrenal represents a promising niche with the unique advantages of exceptional high oxygen tension and local anti-inflammatory and immunosuppressive properties. GHRH agonists have been shown to promote islet graft survival and function, which may help to reduce the islet mass necessary to reverse diabetes. In the present study, the most potent GHRH agonist MR403 was tested on insulinoma cells, isolated rat islets, and adrenal β-cell cocultures in vitro. GHRH receptor is expressed on both adrenal cells and islets. MR403 caused a significant increase in cell viability and proliferation and revealed an antiapoptotic effect on insulinoma cells. Viability of rat islets was increased after treatment with the agonist and in coculture with adrenal cells. Rat islets were transplanted into diabetic mice to the intraadrenal transplant site and compared with the classical transplants underneath the kidney capsule. Graft function and integration were tested by metabolic follow-up and immunohistochemical staining of intraadrenal grafts. A rapid decrease occurred in blood glucose levels in both models, and all animals reached normoglycemia within the first days after transplantation. Our studies demonstrated that the adrenal may be an attractive site for islet transplantation and that GHRH analogs might allow reduction of the islet mass needed to reverse a diabetic status.