Intracutaneous Transplantation of Islets Within a Biodegradable Temporizing Matrix as an Alternative Site for Islet Transplantation.

Intrahepatic islet transplantation for type 1 diabetes is limited by the need for multiple infusions and poor islet viability posttransplantation. The development of alternative transplantation sites is necessary to improve islet survival and facilitate monitoring and retrieval. We tested a clinically proven biodegradable temporizing matrix (BTM), a polyurethane-based scaffold, to generate a well-vascularized intracutaneous "neodermis" within the skin for islet transplantation. In murine models, BTM did not impair syngeneic islet renal-subcapsular transplant viability or function, and it facilitated diabetes cure for over 150 days. Furthermore, BTM supported functional neonatal porcine islet transplants into RAG-1-/- mice for 400 days. Hence, BTM is nontoxic for islets. Two-photon intravital imaging used to map vessel growth through time identified dense vascular networks, with significant collagen deposition and increases in vessel mass up to 30 days after BTM implantation. In a preclinical porcine skin model, BTM implants created a highly vascularized intracutaneous site by day 7 postimplantation. When syngeneic neonatal porcine islets were transplanted intracutaneously, the islets remained differentiated as insulin-producing cells, maintained normal islet architecture, secreted c-peptide, and survived for over 100 days. Here, we show that BTM facilitates formation of an islet-supportive intracutaneous neodermis in a porcine preclinical model, as an alternative islet-transplant site. ARTICLE HIGHLIGHTS: Human and porcine pancreatic islets were transplanted into a fully vascularized biodegradable temporizing matrix (Novosorb) that creates a unique intracutaneous site outside of the liver in a large-animal preclinical model. The intracutaneous prevascularized site supported pancreatic islet survival for 3 months in a syngeneic porcine-transplant model. Pancreatic (human and porcine) islet survival and function were demonstrated in an intracutaneous site outside of the liver for the first time in a large-animal preclinical model.

The Epidemiology and Burden of Childhood Chronic Pancreatitis in South Australia.

OBJECTIVE: To assess longitudinal, population-based data on the prevalence and impact of chronic pancreatitis in children. STUDY DESIGN: Administrative data linkage was used to ascertain an index cohort consisting of all individuals who had an initial diagnosis of chronic pancreatitis before age 19 years in the South Australian public hospital system between June 2000 and June 2019. Age- and sex-matched controls were drawn from the general population of South Australia, children with type 1 diabetes, and children with type 2 diabetes. Main outcomes and measures included hospital visits, days in hospital, emergency department (ED) visits, intensive care unit (ICU) admissions, education comparators, and incidence and prevalence estimates. RESULTS: A total of 73 incident cases were identified. The crude prevalence and incidence of pediatric chronic pancreatitis were estimated at 6.8/100 000 and 0.98/100 000 per year, respectively. Of the index cohort, 24 cases (32.8%) of pediatric chronic pancreatitis were identified as occurring in children of Aboriginal and/or Torres Strait Islander descent. Compared with matched general population controls, children with chronic pancreatitis averaged 11-fold more hospital visits, 5-fold more ED visits, and 9-fold more ICU admissions; spent 10-fold more days in the hospital; and had a 2-fold higher rate of absence from school (P < .001 for all). Similarly, children with chronic pancreatitis used substantially more health resources than children with type 1 or 2 diabetes. CONCLUSIONS: Pediatric patients with chronic pancreatitis consume a high volume of public health services and are significantly impacted in their ability to engage in education.

Australian experience with total pancreatectomy with islet autotransplantation to treat chronic pancreatitis.

BACKGROUND: This study aimed to describe the clinical outcomes of total pancreatectomy with islet autotransplantation (TP-IAT) in Australia. METHODS: Individuals selected for TP-IAT surgery according to the Minnesota Criteria (Appendix) without evidence of diabetes were evaluated including time to transplantation from pancreatectomy, islet numbers infused and post-transplantation HbA1c, C-peptide, total daily insulin and analgesic requirement. RESULTS: Sixteen individuals underwent TP-IAT from Australia and New Zealand between 2010 and 2020. Two recipients are deceased. The median islet equivalents/kg infused was 4244 (interquartile range (IQR) 2290-7300). The median C-peptide 1 month post-TP-IAT was 384 (IQR 210-579) pmol/L and at median 29.5 (IQR 14.5-46.5) months from transplant was 395 (IQR 139-862) pmol/L. Insulin independence was achieved in eight of 15 (53.3%) surviving recipients. A higher islet equivalents transplanted was most strongly associated with the likelihood of insulin independence (P < 0.05). Of the 15 surviving recipients, 14 demonstrated substantial reduction in analgesic requirement. CONCLUSION: The TP-IAT programme in Australia has been a successful new therapy for the management of individuals with chronic pancreatitis including hereditary forms refractory to medical treatment to improve pain management with 50% insulin independence rates.

Ambulatory intravenous insulin and islet cell transplantation to treat severe type III insulin hypersensitivity in a patient with type 1 diabetes mellitus.

Allogenic pancreatic islet cell transplantation is an appropriate treatment option to consider in the management of refractory cases of severe hypersensitivity to insulin in patients with type 1 diabetes mellitus.

Facile preparation of tissue engineering scaffolds with pore size gradients using the muesli effect and their application to cell spheroid encapsulation.

Porous biodegradable scaffolds have many applications in bioengineering, ranging from cell culture and transplantation, to support structures, to induce blood vessel and tissue formation in vivo. While numerous strategies have been developed for the manufacture of porous scaffolds, it remains challenging to control the spatial organization of the pores. In this study, we introduce the use of the granular convection effect, also known as the muesli or brazil nut effect, to rapidly engineer particulate templates with a vertical size gradient. These templates can then be used to prepare scaffolds with pore size gradients. To demonstrate this approach, we prepared templates with particle size gradients, which were then infused with a prepolymer solution consisting of the pentaerythritol ethoxylate (polyol), sebacoyl chloride (acid chloride), and poly(caprolactone). Following curing, the template was dissolved to yield biodegradable polyester-ether scaffolds with pore size gradients that could be tuned depending on the size range of the particulates used. The application of these scaffolds was demonstrated using pancreatic islets, which were loaded via centrifugation and retained within the scaffold's pores without a decrease in viability. The proposed strategy provides a facile approach to prepare templates with spatially organized pores that could potentially be used for cell transplantation, or guided tissue formation.

Australia and New Zealand Islet and Pancreas Transplant Registry Annual Report 2018-Islet Donations, Islet Isolations, and Islet Transplants.

BACKGROUND: This is an excerpt from chapter 4 of the annual registry report from the Australia and New Zealand islet and pancreas transplant registry. The full report is available at http://anziptr.org/reports/. METHODS: We report data for all allogeneic islet isolation and transplant activity from 2002 to end 2017. Solid organ pancreas transplantation activity is reported separately. New Zealand does not have an islet transplant program. Data analysis was performed using Stata software version 14 (StataCorp, College Station, TX). RESULTS: From 2002 to 2017, a total of 104 allogeneic islet transplants were performed in 62 recipients. CONCLUSIONS: The number of islet transplants performed in Australia was slightly lower in 2017 but continues to increase over time.

Oxygen-permeable microwell device maintains islet mass and integrity during shipping.

Islet transplantation is currently the only minimally invasive therapy available for patients with type 1 diabetes that can lead to insulin independence; however, it is limited to only a small number of patients. Although clinical procedures have improved in the isolation and culture of islets, a large number of islets are still lost in the pre-transplant period, limiting the success of this treatment. Moreover, current practice includes islets being prepared at specialized centers, which are sometimes remote to the transplant location. Thus, a critical point of intervention to maintain the quality and quantity of isolated islets is during transportation between isolation centers and the transplanting hospitals, during which 20-40% of functional islets can be lost. The current study investigated the use of an oxygen-permeable PDMS microwell device for long-distance transportation of isolated islets. We demonstrate that the microwell device protected islets from aggregation during transport, maintaining viability and average islet size during shipping.

Local Sphingosine Kinase 1 Activity Improves Islet Transplantation.

Pancreatic islet transplantation is a promising clinical treatment for type 1 diabetes, but success is limited by extensive ß-cell death in the immediate posttransplant period and impaired islet function in the longer term. Following transplantation, appropriate vascular remodeling is crucial to ensure the survival and function of engrafted islets. The sphingosine kinase (SK) pathway is an important regulator of vascular beds, but its role in the survival and function of transplanted islets is unknown. We observed that donor islets from mice deficient in SK1 (Sphk1 knockout) contain a reduced number of resident intraislet vascular endothelial cells. Furthermore, we demonstrate that the main product of SK1, sphingosine-1-phosphate, controls the migration of intraislet endothelial cells in vitro. We reveal in vivo that Sphk1 knockout islets have an impaired ability to cure diabetes compared with wild-type controls. Thus, SK1-deficient islets not only contain fewer resident vascular cells that participate in revascularization, but likely also a reduced ability to recruit new vessels into the transplanted islet. Together, our data suggest that SK1 is important for islet revascularization following transplantation and represents a novel clinical target for improving transplant outcomes.

IGF2: an endocrine hormone to improve islet transplant survival.

In the week following pancreatic islet transplantation, up to 50% of transplanted islets are lost due to apoptotic cell death triggered by hypoxic and pro-inflammatory cytokine-mediated cell stress. Thus, therapeutic approaches designed to protect islet cells from apoptosis could significantly improve islet transplant success. IGF2 is an anti-apoptotic endocrine protein that inhibits apoptotic cell death through the mitochondrial (intrinsic pathway) or via antagonising activation of pro-inflammatory cytokine signalling (extrinsic pathway), in doing so IGF2 has emerged as a promising therapeutic molecule to improve islet survival in the immediate post-transplant period. The development of novel biomaterials coated with IGF2 is a promising strategy to achieve this. This review examines the mechanisms mediating islet cell apoptosis in the peri- and post-transplant period and aims to identify the utility of IGF2 to promote islet survival and enhance long-term insulin independence rates within the setting of clinical islet transplantation.

Insulin-Like growth factor-II (IGF-II) prevents proinflammatory cytokine-induced apoptosis and significantly improves islet survival after transplantation.

BACKGROUND: The early loss of functional islet mass (50-70%) due to apoptosis after clinical transplantation contributes to islet allograft failure. Insulin-like growth factor (IGF)-II is an antiapoptotic protein that is highly expressed in ß-cells during development but rapidly decreases in postnatal life. METHODS: We used an adenoviral (Ad) vector to overexpress IGF-II in isolated rat islets and investigated its antiapoptotic action against exogenous cytokines interleukin-1ß- and interferon-γ-induced islet cell death in vitro. Using an immunocompromised marginal mass islet transplant model, the ability of Ad-IGF-II-transduced rat islets to restore euglycemia in nonobese diabetic/severe combined immunodeficient diabetic recipients was assessed. RESULTS: Ad-IGF-II transduction did not affect islet viability or function. Ad-IGF-II cytokine-treated islets exhibited decreased cell death (40% ± 2.8%) versus Ad-GFP and untransduced control islets (63.2% ± 2.5% and 53.6% ± 2.3%, respectively). Ad-IGF-II overexpression during cytokine treatment resulted in a marked reduction in terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling-positive apoptotic cells (8.3% ± 1.4%) versus Ad-GFP control (41% ± 4.2%) and untransduced control islets (46.5% ± 6.2%). Western blot analysis confirmed that IGF-II inhibits apoptosis via activation of the phosphatidylinositol 3-kinase/Akt signaling pathway. Transplantation of IGF-II overexpressing islets under the kidney capsule of diabetic mice restored euglycemia in 77.8% of recipients compared with 18.2% and 47.5% of Ad-GFP and untransduced control islet recipients, respectively (P<0.05, log-rank [Mantel-Cox] test). CONCLUSIONS: Antiapoptotic IGF-II decreases apoptosis in vitro and significantly improved islet transplant outcomes in vivo. Antiapoptotic gene transfer is a potentially powerful tool to improve islet survival after transplantation.

Ultrastructural analysis, zinc transporters, glucose transporters and hormones expression in New world primate (Callithrix jacchus) and human pancreatic islets.

The New world primates (NWP) Callithrix jacchus separated from man approximately 50 million years ago and is a potential alternative small non-human primate model for diabetes research. Ultrastructure, and gene expression of pancreatic islets and the recently described diabetes auto antigenic zinc transporters families in human, NWP and pig pancreas were studied. Morphologically NWP islets were larger than pig islets and similar in size to human islets. NWP islets alpha cells had high dense core surrounded by a limiting membrane, beta cells by the mixed morphology of the granule core, and delta cells by moderate opaque core. Antibody staining for insulin, glucagon, somatostatin and Glucagon-like peptide-1 (GLP-1) showed that the distribution pattern of the different cell types within islets was comparable to pig and human islets. In all three species protein expression of zinc transporter ZnT8 was detected in most of the insulin producing beta cells whereas Zip14 expression was widely expressed in alpha and beta cells. In both human and NWP little or no expression of Glut2 was observed compared to Glut1 and glucokinase at the protein level, however the messenger RNA level of Glut2 was greater than Glut1 and glucokinase. In contrast all three glucose transporters were expressed in pig islets at the protein level. The expression of Zip14 in islets is reported for the first time. In conclusion NWP pancreatic islets express comparable islet cell types and distribution to humans and pigs. Importantly, marmosets have a similar glucose transporter profile to humans, making this non-endangered primate species a useful animal model for pancreatic biology.

Gene therapy to improve pancreatic islet transplantation for Type 1 diabetes mellitus.

Pancreatic islet transplantation is a promising treatment option for Type 1 Diabetics, offering improved glycaemic control through restoration of insulin production and freedom from life-threatening hypoglycaemic episodes. Implementation of the Edmonton protocol in 2000, a glucocorticoid-free immunosuppressive regimen has led to improved islet transplantation success. >50% of islets are lost post-transplantation primarily through cytokine-mediated apoptosis, ischemia and hypoxia. Gene therapy presents a novel strategy to modify islets for improved survival post-transplantation. Current islet gene therapy approaches aim to improve islet function, block apoptosis and inhibit rejection. Gene transfer vectors include adenoviral, adeno-associated virus, herpes simplex virus vectors, retroviral vectors (including lentiviral vectors) and non-viral vectors. Adeno-associated virus is currently the best islet gene therapy vector, due to the vectors minimal immunogenicity and high safety profile. In animal models, using viral vectors to deliver genes conferring local immunoregulation, anti-apoptotic genes or angiogenic genes to islets can significantly improve islet survival in the early post-transplant period and influence long term engraftment. With recent improvements in gene delivery and increased understanding of the mechanisms underlying graft failure, gene therapy for islet transplantation has the potential to move closer to the clinic as a treatment for patients with Type 1 Diabetes.

Zinc and zinc transporter regulation in pancreatic islets and the potential role of zinc in islet transplantation.

The critical trace element zinc is essential for normal insulin production, and plays a central role in cellular protection against apoptosis and oxidative stress. The regulation of zinc within the pancreas and ß-cells is controlled by the zinc transporter families ZnT and ZIP. Pancreatic islets display wide variability in the occurrence of these molecules. The zinc transporter, ZnT8 is an important target for autoimmunity in type 1 diabetes. Gene polymorphisms of this transporter confer sensitivity for immunosuppressive drugs used in islet transplantation. Understanding the biology of zinc transport within pancreatic islets will provide insight into the mechanisms of ß-cell death, and may well reveal new pathways for improvement of diabetes therapy, including islet transplantation. This review discusses the possible roles of zinc in ß-cell physiology with a special focus on islet transplantation.