Could Transplantation into the Thyroid Gland Benefit Pancreatic Islet Grafting in Unstable Type 1 Diabetes (T1DM), Complicated Type 2 Diabetes (T2DM), and Patients with Total Pancreatectomy?

BACKGROUND: Insular allograft for unstable type 1 diabetes and autograft in pancreatectomy patients are nowadays considered established procedures with precise indications and predictable outcomes. The clinical outcome of islet transplantation is similar to that of pancreas transplantation, avoiding the complications associated with organ transplantation. OBJECTIVE: We hypothesised that transplantation of islets of Langerhans within an endocrine organ could better promote their engraftment and function. This could help to resolve or ameliorate known pathological conditions such as unstable type 1 diabetes and complicated type 2 diabetes. RATIONALE: Pancreatic islet transplantation is currently performed almost exclusively in the liver. The liver provides a sufficiently favourable environment, although not entirely. The hepatic parenchyma has a lower oxygen tension than the pancreatic parenchyma and the vascular structure of the liver is not typical of an exclusively endocrine organ. Moreover, islet transplantation into the liver is not without complications, including hematoma or portal vein thrombosis. PROPOSED PROJECT: The thyroid gland is the endocrine gland proposed as a 'container'. In fact, it has all the characteristics of 'physio-compatibility' which can address the objectives assumed. It is indeed an ideal site because it is an easily accessible anatomical site that allows islets to be implanted using ultrasound-guided transcutaneous inoculation technique. Moreover, it has physiological and anatomical endocrine affinities with pancreatic islets and, if necessary, it can be removed, using hormone supplementation or replacement therapy. CONCLUSIONS: The thyroid gland may be proposed as an ideal site for islet implantation due to its anatomical and physiocompatibility characteristics.

Circularity of islets is a distinct marker for the pathological diagnosis of adult non-neoplastic hyperinsulinemic hypoglycemia using surgical specimens.

BACKGROUND: Adult non-neoplastic hyperinsulinemic hypoglycemia (ANHH), also known as adult-onset nesidioblastosis, is a rare cause of endogenous hyperinsulinemic hypoglycemia in adults. This disease is characterized by diffuse hyperplasia of pancreatic endocrine cells and is diagnosed by a pathological examination. While diagnostic criteria for this disease have already been proposed, we established more quantitative criteria for evaluating islet morphology. METHODS: We measured the number, maximum diameter, total area, and circularity (representing how closely islets resemble perfect spheres) of islets contained in representative sections of ANHH (n = 4) and control cases (n = 5) using the NIS-Elements software program. We also measured the average cell size, percentage of cells with enlarged nuclei, and percentage of cells with recognizable nucleoli for each of three representative islets. We also assessed the interobserver diagnostic concordance of ANHH between five experienced and seven less-experienced pathologists. RESULTS: There was no significant difference in the number, maximum diameter, or total area of islets between the two groups, even after correcting for these parameters per unit area. However, the number of islets with low circularity (< 0.71) per total area of the pancreatic parenchyma was significantly larger in ANHH specimens than in controls. We also found that the percentage of cells with recognizable nucleoli was significantly higher in the ANHH group than in the controls. There were no significant differences in the average cell size or the number of cells with enlarged nuclei between the groups. The correct diagnosis rate with the blind test was 47.5% ± 6.12% for experienced pathologists and 50.0% ± 8.63% for less-experienced pathologists, with no significant differences noted. CONCLUSIONS: Low circularity, which indicates an irregular islet shape, referred to as "irregular shape and occasional enlargement of islets" and "lobulated islet structure" in a previous report, is a useful marker for diagnosing ANHH. An increased percentage of recognizable nucleoli, corresponding to "macronucleoli in ß-cells," has potential diagnostic value.

Current practices in islet cell autotransplantation.

INTRODUCTION: Chronic pancreatitis and recurrent acute pancreatitis comprise a spectrum of disease that results in complications related to exocrine and endocrine insufficiency and chronic pain with narcotic dependence and poor quality of life. The mainstay of therapy has been medical and endoscopic therapy; surgery, especially total pancreatectomy, was historically reserved for few select patients as the obligate exocrine insufficiency and pancreatogenic diabetes (type 3C) are challenging to manage. The addition of islet cell autotransplantation after total pancreatectomy helps to mitigate brittle type 3c diabetes and prevents mortality related to severe hypoglycemic episodes and hypoglycemic unawareness. There have been more recent data demonstrating the safety of surgery and the beneficial long-term outcomes. AREAS COVERED: The purpose of this review is to describe the current practices in the field of islet cell autotransplantation including the selection and evaluation of patients for surgery, their preoperative work up and management, surgical approach, post-operative management and outcomes. EXPERT OPINION: Total pancreatectomy and islet cell autotransplantation has the ability to drastically improve quality of life and prevent brittle diabetes for patients suffering with chronic pancreatitis.

Improvement of Islet Engrafts via Treg Induction Using Immunomodulating Polymeric Tolerogenic Microparticles.

Type 1 diabetes (T1D) is a life-threatening condition for which islet transplantation offers a way to extend longevity and vastly improve quality of life, but the degree and duration of success can vary greatly due to the patient's protective immunity against foreign material. The field is in need of cellular engineering modalities to promote a localized, tolerogenic environment to protect transplanted islet tissue. Artificial antigen-presenting cells (aAPCs) can be designed exogenously to mimic immune cells, such as dendritic cells, and administered to patients, allowing greater control over T cell differentiation. As regulatory T cell (Treg) modulation can reduce the activity of cytotoxic T-effector populations, this strategy can be used to promote immune acceptance of both biomaterials and cellular transplants, such as islets. A new class of poly(lactic-co-glycolic acid) (PLGA) and PLGA/PBAE-blend aAPCs containing transforming growth factor beta and conjugated with anti-CD3 and anti-CD28 antibodies, called tolerogenic aAPCs (TolAPCs), are specifically designed to generate a tolerogenic response by inducing Tregs. We characterized TolAPCs' physical and chemical properties via advanced particle imaging and sizing modalities and investigated their impact on the local and systemic immune system across BALB/c and C57BL/6 mouse strains as well as healthy male and female mice via histologic, gene expression, and immunofluorescence staining methods. Strain-specific differences were observed, whereas sex made no difference in the TolAPC response. TolAPCs stimulated the expansion of FOXP3+ Tregs and provided islet cell protection, maintaining improved glucose-stimulated insulin secretion in vitro when co-cultured with cytotoxic CD8+ T cells. We also explored the ability of this TolAPC platform to promote tolerance in a streptozotocin-induced murine T1D C57BL/6 mouse model. We achieved partial islet protection over the first few days following co-injection with PLGA/PBAE TolAPCs; however, grafts failed soon thereafter. Analysis of the local injection site demonstrated that other immune cell types, including APCs and cytotoxic natural killer cells, increased in the islet injection site. While we aimed to promote a localized tolerogenic microenvironment in vivo using biodegradable TolAPCs to induce Tregs and extend islet transplant durability, further TolAPC improvements will be required to both elongate efficacy and control additional immune cell responders.

Bioengineered omental transplant site promotes pancreatic islet allografts survival in non-human primates.

The transplanting islets to the liver approach suffers from an immediate posttransplant loss of islets of more than 50%, progressive graft dysfunction over time, and precludes recovery of grafts should there be serious complications such as the development of teratomas with grafts that are stem cell-derived islets (SC-islets). The omentum features an attractive extrahepatic alternative site for clinical islet transplantation. We explore an approach in which allogeneic islets are transplanted onto the omentum, which is bioengineered with a plasma-thrombin biodegradable matrix in three diabetic non-human primates (NHPs). Within 1 week posttransplant, each transplanted NHP achieves normoglycemia and insulin independence and remains stable until termination of the experiment. Success was achieved in each case with islets recovered from a single NHP donor. Histology demonstrates robust revascularization and reinnervation of the graft. This preclinical study can inform the development of strategies for ß cell replacement including the use of SC-islets or other types of novel cells in clinical settings.

The Evolution of Pancreatic Islet Function in a Diabetic Patient after Pancreatic Neuroendocrine Neoplasm Surgery: A Case Report.

BACKGROUND: Pancreatic neuroendocrine neoplasms (pNENs) are rare primary tumors of the pancreas. Although these tumors are heterogeneous and can be classified as functional or non-functional according to pancreatic endocrine biomarkers, the more prevalent type is non-functional pNENs with endocrine differentiation but with non-specific symptoms and often late diagnoses. The treatment option for patients often involves surgical management, but the reported outcomes, especially on insulin secretion change and the trend of diabetes in these patients, varied to date. Hence, the purpose of this clinical report is to study the functional change of pancreatic ß- cell corresponding to the mass of tumorectomy of pNEN in a diabetic patient. CASE PRESENTATION: We reported that a 39-year-old man with diabetes was found complicated with neuroendocrine neoplasm. He was admitted to the General Surgery of our hospital for further examination and therapy. The patient received a pancreatectomy + splenectomy + lymphadenectomy on the pancreatic body and tail. We analyzed the pancreatic mass change and performed Oral Glucose Tolerance Test (OGTT) before and after the surgery to evaluate the function of the pancreas. CONCLUSION: This case may provide us a reference to predict the extent of islet function loss before the pancreatectomy, and apply personalized hypoglycemic therapy after surgery in these patients.

Advantages of the retroperitoneal retrocolic space as the transplant site for encapsulated xenogeneic islets.

OBJECTIVE: Islet allotransplantation has demonstrated improved clinical outcomes using the hepatic portal vein as the standard infusion method. However, the current implantation site is not ideal due to the short-term thrombotic and long-term immune destruction. Meanwhile, the shortage of human organ donors further limits its application. To find a new strategy, we tested a new polymer combination for islet encapsulation and transplantation. Meanwhile, we explored a new site for xenogeneic islet transplantation in mice. METHOD: We synthesized a hydrogel combining alginate plus poly-ethylene-imine (Alg/PEI) for the encapsulation of rat, neonatal porcine, and human islets. Transplantation was performed into the retroperitoneal retro-colic space of diabetic mice. Control mice received free islets under the kidney capsule or encapsulated islets into the peritoneum. The biochemical indexes were measured, and the transplanted islets were harvested for immunohistochemical staining of insulin and glucagon. RESULTS: Mice receiving encapsulated rat, porcine and human islets transplanted into the retroperitoneal space maintained normoglycemia for a median of 275, 145.5, and 146 days, respectively. In contrast, encapsulated xenogeneic islets transplanted into the peritoneum, maintained function for a median of 61, 95.5, and 82 days, respectively. Meanwhile, xenogeneic islets transplanted free into the kidney capsule lost their function within 3 days after transplantation. Immunohistochemical staining of encapsulated rat, porcine and human islets, retrieved from the retroperitoneal space, allowed to distinguish morphological normal insulin expressing ß- and glucagon expressing α-cells at 70, 60, and 100 days post-transplant, respectively. CONCLUSION: Transplantation of Alg/PEI encapsulated xenogeneic islets into the retroperitoneal space provides a valuable new implantation strategy for the treatment of type 1 diabetes.

A Prevascularized Sinus Tract on the Liver Surface for Islet Transplantation.

BACKGROUND: The lack of a suitable transplantation site has become a bottleneck restricting the development of islet transplantation. METHODS: In this study, for the first time, a prevascularized sinus tract (PST) for islet transplantation was constructed in a mouse model by temporarily embedding a 4× silk thread between the liver surface and the attached decellularized human amniotic membrane. After which, the characteristics of the PST and the function of the islet graft within the PST were evaluated. RESULTS: The results showed that PST was lined with granulation tissue, the blood vessel density of the local tissue increased, and proangiogenic proteins were upregulated, which mimics the microenvironment of the islets in the pancreas to a certain extent. Transplantation of ~200 syngeneic islets into the PST routinely reversed the hyperglycemia of the recipient mice and maintained euglycemia for >100 d until the islet grafts were retrieved. The islet grafts within the PST achieved better results to those in the nonprevascularized control groups and comparable results to those under the kidney capsule with respect to glycemic control and glucose tolerance. CONCLUSIONS: By attaching a decellularized human amniotic membrane to the surface of mouse liver and temporarily embedding a 4× silk thread, the PST formed on the liver surface has a favorable local microenvironment and is a potential clinical islet transplantation site.

The influence of massive jejunectomy on endocrine pancreas of diabetic Goto-Kakizaki.

OBJECTIVE: Several bariatric surgeries have been related to the T2DM improvement in obese patients. Despite the different mechanism invoked for this improvement, many evidences showed that the pancreas cellularity is conditioned for the homeostatic physiological changes after these surgeries. Many authors reported the changes in beta-cell mass after some surgeries in healthy rats. We purpose to analyze the changes in ß-cell cellularity and ß-cell-mass after a severe malabsorptive surgical method. Thus, we studied several parameters of the islet morphometric composition after a massive jejunal resection. MATERIALS AND METHODS: We employed Goto-Kakizaki diabetic non-obese rats, which underwent the 50% resection of middle portion of the jejunum versus a control group. After 3 months, rats were sacrificed and pancreas was immunohistochemicaly studied. RESULTS: The ß-cell mass was analyzed and several parameters about the endocrine islet size distribution were studied. We report an increase of ß-cell mass in massive resection surgical group versus controls. The islet distribution was significant different between both groups. Endocrine islets of surgical group were bigger with a different cellular distribution. CONCLUSION: According to the enteroendocrine changes related to surgeries in jejunum, as in other gastrointestinal portions, the cellularity of islets changes as an adaptive process to glycemic demands.

OBJETIVO: Varias técnicas quirúrgicas bariátricas han sido relacionadas con el mejoramiento de la T2DM en pacientes obesos. Se han invocado distintos mecanismos de porqué se da este mejoramiento y muchas evidencias apuntan a que la celularidad del páncreas cambia por las condiciones fisiológicas tras estas cirugías. Se han publicado cambios en la celularidad beta en ratas sanas sometidas a estos procesos. Y nos proponemos observar dichos cambios en ratas diabéticas tras una resección jejunal masiva. Estudiamos varios parámetros sobre la masa beta y la morfometría de los islotes, que indiquen los procesos celulares que han tenido lugar. MATERIAL Y METODO: Empleamos Goto-Kakizaki, un modelo de rata diabética no obesa, a la que se sometió a una resección del 50%de la poción media del yeyuno. Tras tres meses de supervivencia, las ratas se estudiaron los páncreas mediante inmunocitoquímica. RESULTADOS: Mostramos un incremento de la masa beta en las ratas resecadas frente a los controles. La distribución de islotes fue significativamente distinta entre los grupos, donde los islotes eran mayores en las ratas diabéticas. CONCLUSIÓN: Los cambios glucémicos tras las resecciones masivas yeyunales cambian la celularidad del páncreas como una muestra de la capacidad adaptativa del mismo a las modificaciones.

Total pancreatectomy and islet cell autotransplantation: a 10-year update on outcomes and assessment of long-term durability.

BACKGROUND: Total pancreatectomy and islet cell autotransplantation (TPIAT) offers an effective, lasting solution for the management of chronic pancreatitis up to 5-years post-operatively. Our aim was to assess durability of TPIAT at 10-years. METHODS: Patients undergoing TPIAT for chronic pancreatitis eligible for 10-year follow-up were included. Primary outcomes, including endocrine function and narcotic requirements, were reported at 5-, 7.5-, and 10-years post-operatively. RESULTS: Of the 231 patients who underwent TPIAT, 142 met inclusion criteria. All patients underwent successful TPIAT with an average of 5680.3 islet equivalents per body weight. While insulin independence tended to decrease over time (25.7% vs. 16.0% vs. 10.9%, p = 0.11) with an increase in HbA1C (7.6% vs. 8.2% vs. 8.4%, p = 0.09), partial islet function persisted (64.9% vs. 68.0% vs. 67.4%, p = 0.93). Opioid independence was achieved and remained durable in the majority (73.3% vs. 72.2% vs. 75.5%, p = 0.93). Quality of life improvements persisted, with 85% reporting improvement from baseline at 10-years. Estimated median overall survival was 202.7 months. CONCLUSION: This study represents one of the largest series reporting on long-term outcomes after TPIAT, demonstrating excellent long-term pain control and durable improvements in quality of life. Islet cell function declines over time however stable glycemic control is maintained.

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.

Adult Pig Islet Isolation.

Type 1 diabetes mellitus (T1DM) is caused by autoimmune destruction of pancreatic ß cells, which results in little or no insulin production. Islet transplantation plays an important role in the treatment of T1DM, with the improved glycometabolic control, the reduced progression of complications, the reduction of hypoglycemic episodes when compared with traditional insulin therapy. The results of phase III clinical trial also demonstrated the safety and efficacy of islet allotransplantation in T1DM. However, the shortage of pancreas donors limits its widespread use. Animals as a source of islets such as the pig offer an alternative choice. Because the architecture of the pig pancreas is different from the islets of mice or humans, the pig islet isolation procedure is still challenging. Since the translation of alternative porcine islet sources (xenogeneic) to the clinical setting for treating T1DM through cellular transplantation is of great importance, a cost-effective, standardized, and reproducible protocol for isolating porcine islets is urgently needed. This manuscript describes a simplified and cost-effective method to isolate and purify adult porcine islets based on the previous protocols that have successfully transplanted porcine islets to non-human primates. This will be a beginners guide without the use of specialized equipment such as a COBE 2991 Cell Processor.

Transcriptomic changes in pancreatic islets, adipose and liver after Roux-en-Y gastric bypass in a diet-induced obese rat model.

Roux-en-Y gastric bypass (RYGB) is the most efficient intervention in morbid obesity and promotes metabolic improvements in several peripheral tissues. However, the underlying molecular mechanisms are still poorly understood. To further understand the effects of RYGB on peripheral tissues transcriptomes, we determined transcriptome signatures in pancreatic islets, adipose and liver tissue from diet-induced obese (DIO) rats model following RYGB. Whereas RYGB led to discrete gene expression changes in pancreatic islets, substantial transcriptome changes were observed in metabolic and immune signaling pathways in adipose tissue and the liver, indicating major gene adaptive responses in fat-storing tissues. Compared to RYGB DIO rats, peripheral tissue transcriptome signatures were markedly different in caloric restricted weight matching DIO rats, implying that caloric restriction paradigms do not reflect transcriptomic regulations of RYGB induced weight loss. The present gene expression study may serve as a basis for further investigations into molecular regulatory effects in peripheral tissues following RYGB-induced weight loss.

A novel prevascularized tissue-engineered chamber as a site for allogeneic and xenogeneic islet transplantation to establish a bioartificial pancreas.

Although sites for clinical or experimental islet transplantation are well established, pancreatic islet survival and function in these locations remain unsatisfactory. A possible factor that might account for this outcome is local hypoxia caused by the limited blood supply. Here, we modified a prevascularized tissue-engineered chamber (TEC) that facilitated the viability and function of the seeded islets in vivo by providing a microvascular network prior to transplantation. TECs were created, filled with Growth Factor-Matrigel™ (Matrigel™) and then implanted into the groins of mice with streptozotocin-induced diabetes. The degree of microvascularization in each TECs was analyzed by histology, real-time PCR, and Western blotting. Three hundred syngeneic islets were seeded into each chamber on days 0, 14, and 28 post-chamber implantation, and 300, 200, or 100 syngeneic islets were seeded into additional chambers on day 28 post-implantation, respectively. Furthermore, allogeneic or xenogeneic islet transplantation is a potential solution for organ shortage. The feasibility of TECs as transplantation sites for islet allografts or xenografts and treatment with anti-CD45RB and/or anti-CD40L (MR-1) was therefore explored. A highly developed microvascularized network was established in each TEC on day 28 post-implantation. Normalization of blood glucose levels in diabetic mice was negatively correlated with the duration of prevascularization and the number of seeded syngeneic islets. Combined treatment with anti-CD45RB and MR-1 resulted in long-term survival of the grafts following allotransplantation (5/5, 100%) and xenotransplantation (16/20, 80%). Flow cytometry demonstrated that the frequency of CD4+Foxp3-Treg and CD4+IL-4+-Th2 cells increased significantly after tolerogenic xenograft transplantation, while the number of CD4+IFN-γ-Th1 cells decreased. These findings demonstrate that highly developed microvascularized constructs can facilitate the survival of transplanted islets in a TECs, implying its potential application as artificial pancreas in the future.

Mechanism of Transplanted Islet Engraftment in Visceral White Adipose Tissue.

BACKGROUND: White adipose tissue (WAT) is a candidate transplantation site for islets. However, the mechanism of islet engraftment in WAT has not been fully investigated. In this study, we attempted to clarify the therapeutic effect and mechanism of islet transplantation into visceral WAT. METHODS: Two hundred mouse islets were transplanted into epididymal WAT of syngeneic diabetic mice by wrapping islets with the tissue (fat-covered group). Mice that received intraperitoneal and renal subcapsular islet transplantations were used as negative and positive control groups, respectively. RESULTS: The transplant efficacy, including improvements in blood glucose and plasma insulin levels and in glucose tolerance tests, of the fat-covered group was superior to the negative control group and almost equal to the positive control group. Vessel density of engrafted islets in the fat-covered group was higher than that in the positive control group. It was speculated that the mechanism of islet engraftment in WAT might consist of trapping islets in WAT, adhesion of islets via a combination of adhesion factors (fibronectin and integrin ß1), and promotion of angiogenesis in islets by expression of angiogenic factors induced by adiponectin. CONCLUSIONS: Visceral WAT is an important candidate for islet transplantation. Adhesion factors and adiponectin might contribute to islet engraftment into WAT. Further studies to elucidate the detailed mechanism are necessary.

Comparative Study of Two Different Islet Transplantation Sites in Mice: Hepatic Sinus Tract vs Splenic Parenchyma.

Although 90% of clinical islet transplantations are performed via the portal vein approach, it is still far from the ideal transplant site. Alternative islet transplant sites are promising to reduce the islet dose required to reverse hyperglycemia, thereby improving the efficiency of islet transplantation. The aim of this study was to compare the differences in survival and metabolic function of islet grafts transplanted into the hepatic sinus tract (HST) and the splenic parenchyma (SP). Approximately 300 syngeneic mouse islets were transplanted into the HST (n = 6) and the SP (n = 6) of recipient diabetic mice, respectively. After transplantation, the glycemic control, glucose tolerance, and morphology of islet grafts were evaluated and compared in each group. The nonfasting blood glucose of the two groups of mice receiving islet transplantation gradually decreased to the normal range and sustained for more than 100 d. There is no significant difference in the time required to restore normoglycemia (P > 0.05). The results of the glucose tolerance test showed that the SP group presented a smaller area under the curve than the HST group (P < 0.05). Histopathological results showed that islet grafts in the HST and the SP were characterized with normal islet morphology and robust insulin production. Compared with the HST, islet transplantation in the SP presents better blood glucose regulation, although there is no significant difference in the time required to restore normoglycemia.

Grafting Islets to a Dissected Peritoneal Pouch to Improve Transplant Survival and Function.

BACKGROUND: Although the liver is the primary site for clinical islet transplantation, it poses several restrictions, especially limited tissue volume due to portal vein pressure. We evaluated the preperitoneal space as an extrahepatic islet transplant site to deliver high tissue volumes and sustain long-term graft function. METHODS: A peritoneal pouch was formed by dissecting the parietal peritoneum from the transversalis fascia of mice. Syngeneic C57BL/6 donor islets were transplanted into the peritoneal pouch of diabetic mouse recipients. Blood glucose was monitored for islet function, and miR-375 was analyzed for islet damage. Islet graft morphology and vascularization were evaluated by immunohistochemistry. [F] fluoro-D-glucose positron emission tomography/computed tomography was used to image islet grafts. RESULTS: Transplantation of 300 syngeneic islets into the peritoneal pouch of recipients reversed hyperglycemia for >60 days. Serum miR-375 was significantly lower in the peritoneal pouch group than in the peritoneal cavity group. Peritoneal pouch islet grafts showed high neovascularization and sustained insulin and glucagon expression up to 80 days posttransplantation. A peritoneal pouch graft with high tissue volume (1000 islets) could be visualized by positron emission tomography/computed tomography imaging. Human islets transplanted into the peritoneal pouch of diabetic nude mice also reversed hyperglycemia successfully. CONCLUSIONS: Islets transplanted into a dissected peritoneal pouch show high efficiency to reverse diabetes and sustain islet graft function. The preperitoneal site has the advantages of capacity for high tissue volume, enriched revascularization and minimal inflammatory damage. It can also serve as an extrahepatic site for transplanting large volume of islets necessitated in islet autotransplantation.

Longitudinal In Vivo Imaging and Quantification of Human Pancreatic Islet Grafting and Contributing Host Cells in the Anterior Eye Chamber.

Imaging beta cells is a key step towards understanding islet transplantation. Although different imaging platforms for the recording of beta cell biology have been developed and utilized in vivo, they are limited in terms of allowing single cell resolution and continuous longitudinal recordings. Because of the transparency of the cornea, the anterior chamber of the eye (ACE) in mice is well suited to study human and mouse pancreatic islet cell biology. Here is a description of how this approach can be used to perform continuous longitudinal recordings of grafting and revascularization of individual human islet grafts. Human islet grafts are inserted into the ACE, using NOD.(Cg)-Gt(ROSA)26Sortm4-Rag2-/-mice as recipients. This allows for the investigation of the expansion of recipient versus donor cells and the contribution of recipient cells in promoting the encapsulation and vascularization of the graft. Further, a step-by-step approach for image analysis and quantification of the islet volume or segmented vasculature and islet capsule forming recipient cells is outlined.

Prolonged bisphenol-A exposure decreases endocrine pancreatic proliferation in response to obesogenic diet in ovariectomized mice.

Research on the deleterious actions of bisphenol (BP)-A have focused on its effects on insulin secretion during pre/perinatal periods or adulthood. Estrogens also modulate endocrine pancreas physiology in females during aging; however, the effects of BPA on islet morphophysiology after menopause have not been investigated. We evaluated the effects of BPA exposure on glucose homeostasis and islet morphofunction in ovariectomized (OVX) mice fed on a high-fat diet (HFD). Adult Swiss female mice were underwent to bilateral ovariectomy, and with the confirmation of the establishment of surgical menopause, the females were then submitted, or not,to a normolipidic diet or HFD [control (CTL) and HFD groups, respectively] without or with 1 µg/mL BPA in their drinking water (CBPA and HBPA groups) for 90 days. HFD females displayed obesity, hyperglycemia, hyperinsulinemia, glucose intolerance and insulin resistance. BPA did not modulate HFD-induced obesity or body glucose impairments in HBPA females, and islets isolated from both the HFD and HBPA groups exhibited insulin hypersecretion. The HBPA islets, however, displayed enlarged islet cells and reduced proliferation, in association with the downregulation of mRNAs encoding PDX-1, NGN3 and CCND2 and upregulation of mRNAs encoding ER-ß, GPR30, TNF-α and IL-1ß in HBPA islets. BPA consumption in OVX mice impaired the islet-cell hyperplasia response to the HFD, partly mediated by increased expression of ER-ß and GPR30, which impaired the expression of major genes involved in islet-cell survival and functionality. Together with higher pro-inflammatory cytokines expression in the islet milieu, these alterations may accelerate ß-cell failure in postmenopause.