Islet cell transplantation today

Differentiation of Human Deceased Donor, Adipose-Derived, Mesenchymal Stem Cells into Functional Beta Cells

There is an emerging need for the rapid generation of functional beta cells that can be used in cell replacement therapy for the treatment of type 1 diabetes (T1D). Differentiation of stem cells into insulin-producing cells provides a promising strategy to restore pancreatic endocrine function. Stem cells can be isolated from various human tissues including adipose tissue (AT). Our study outlines a novel, non-enzymatic process to harvest mesenchymal stem cells (MSC) from research-consented, deceased donor AT. Following their expansion, MSC were characterised morphologically and phenotypically by flow cytometry to establish their use for downstream differentiation studies. MSC were induced to differentiate into insulin-producing beta cells using a step-wise differentiation medium. The differentiation was evaluated by analysing the morphology, dithizone staining, immunocytochemistry, and expression of pancreatic beta cell marker genes. We stimulated the beta cells with different concentrations of glucose and observed a dose-dependent increase in gene expression. In addition, an increase in insulin and c-Peptide secretion as a function of glucose challenge confirmed the functionality of the differentiated beta cells. The differentiation of adipose-derived MSC into beta cells has been well established. However, our data demonstrates, for the first time, that the ready availability and properties of MSC isolated from deceased donor adipose tissue render them well-suited as a source for increased production of functional beta cells. Consequently, these cells can be a promising therapeutic approach for cell replacement therapy to treat patients with T1D.

Differentiation of canine adipose mesenchymal stem cells into insulin-producing cells: comparison of different culture medium compositions

The aim of this study was to differentiate canine adipose-derived mesenchymal stem cells (ADMSCs) into insulin-producing cells by using culture media with different compositions to determine the most efficient media. Stem cells isolated from the fat tissues close to the bitch uterus were distributed into 6 groups: (1) Dulbecco's modified Eagle medium (DMEM)-high glucose (HG), β-mercaptoethanol, and nicotinamide; (2) DMEM-HG, β-mercaptoethanol, nicotinamide, and exendin-4; (3) DMEM-HG, β-mercaptoethanol, nicotinamide, exendin-4, B27, nonessential amino acids, and l-glutamine; (4) DMEM-HG, β-mercaptoethanol, and nicotinamide (for the initial 8-d period), and DMEM-HG, β-mercaptoethanol, nicotinamide, exendin-4, B27, nonessential amino acids, l-glutamine, and basic fibroblast growth factor (for the remaining 8-d period); (5) DMEM-HG and fetal bovine serum; and (6) DMEM-low glucose and fetal bovine serum (standard control group). Adipose-derived mesenchymal stem cells from groups 1 to 5 gradually became round in shape and gathered in clusters. These changes differed between the groups. In group 3, the cell clusters were apparently more in numbers and gathered as bigger aggregates. Dithizone staining showed that groups 3 and 4 were similar in terms of the mean area of each aggregate stained for insulin. However, only in group 4, the number of insulin aggregates and the total area of aggregates stained were significantly bigger than in the other groups. The mRNA expression of PDX1, BETA2, MafA, and Insulin were also confirmed in all the groups. We conclude that by manipulating the composition of the culture medium it is possible to induce canine ADMSCs into insulin-producing cells, and the 2-staged protocol that was used promoted the best differentiation.

Efficacy and safety of stem cells transplantation in patients with type 1 diabetes mellitus-a systematic review and meta-analysis

Stem cells (SCs) therapy is a new promising therapeutic modality for type 1 diabetes (T1DM). We performed a systematic review and meta-analysis to evaluate the efficacy and safety of stem cells transplantation (SCT) in patients with T1DM. We searched five literature databases (MEDLINE, EMBASE, Web of Science, WanFang and CENTRAL) up to 31 October 2019. 29 studies (487 patients with T1DM) were included in our meta-analysis. There was no substantial publication bias. Meta-analysis showed the SCT had significant effect to decrease HbA1c (SMD, 1.40; 95% CI, 0.93 to 1.86; p < 0.00001; I² = 89%) and to improve C-peptide levels (SMD, -0.62; 95% CI, -1.22 to -0.02; p = 0.04; I² = 92%) at 1 year follow-up. Subgroup analyses showed the heterogeneity level of the results was high. Significant improvement of metabolic outcomes was observed in the subgroups of mesenchymal stem cells (MSCs) combined with hematopoietic stem cells (HSCs) and HSCs. The older age showed significant association with the efficacy in HSCs subgroup. The higher GADA positive rate before treatment also significantly associated with the decrease of daily insulin requirement. The transient insulin independence rate at last follow-up was 9.6 per 100 person-years (95% CI: 5.8-13.5%). The mean length of insulin independence was 15.6 months (95% CI: 12.3-18.9). The mortality of SCT was 3.4% (95% CI: 2.1-5.5%). Therefore, SCT is an efficacious and safe method for treating patients with T1DM especially in the subgroups of MSCs + HSCs and HSCs. Well designed, double blind and randomized controlled trails with large sample size and long-term follow-up are needed for further evaluation.

Gastric submucosal alleviated pro-inflammation cytokines mediated initial dysfunction of islets allografts

BACKGROUND

The liver and renal capsule are the most common site for experimental pancreatic islet transplantation, but it is not optimal. Gastric submucosa space may be an ideal site for islet transplantation; however, whether pro-inflammation factors mediated islet dysfunction could be avoided or alleviated is still unclear.

METHODS

Islets of Sprague Dawley (SD) rat were transplanted into the streptozotocin-induced diabetic SD rats. Transplantation sites included gastric submucosa (GS), intraportal vein (PV) and kidney capsule (KC), and the efficiency of glycemic control and site-specific differences of islet grafts were compared.

RESULTS

With limited number of islets (800 IEQ) transplanted, improvement of recipient glycometabolism was superior in the GS group. When transplanted with 1200 IEQ islets, the survival of islet grafts were significantly prolonged in the GS group (25.87 ± 4.08 days, compared to 15.97 ± 0.83 days and 17.33 ± 1.41 days in PV and KC groups, respectively, P < .05). Compared with the PV group, the levels of IL-1β and TNF-α were significantly depressed in GS group after 12 h transplantation (15.5 ± 0.70 pg/mL and 13.28 ± 2.80 pg/mL vs. 262.26 ± 53.37 pg/mL and 138.51 ± 39.58 pg/mL, P < .05).

CONCLUSIONS

Gastric submucosal would be a potential ideal site for islet transplantation in rat. Gastric submucosal might alleviate the early islet dysfunction triggered by the IL-1β and TNF-α, and which requires a low number of transplanted islets and have a good glycemic control in return.

Hypoxia induction in cultured pancreatic islets enhances endothelial cell morphology and survival while maintaining beta-cell function

Background

Pancreatic islets are heavily vascularized in vivo yet lose this vasculature after only a few days in culture. Determining how to maintain islet vascularity in culture could lead to better outcomes in transplanting this tissue for the treatment of type 1 diabetes as well as provide insight into the complex communication between beta-cells and endothelial cells (ECs). We previously showed that islet ECs die in part due to limited diffusion of serum albumin into the tissue. We now aim to determine the impact of hypoxia on islet vascularization.

Methods

We induced hypoxia in cultured mouse islets using the hypoxia mimetic cobalt chloride (100 μM CoCl₂). We measured the impact on islet metabolism (two-photon NAD(P)H and Rh123 imaging) and function (insulin secretion and survival). We also measured the impact on hypoxia related transcripts (HIF-1α, VEGF-A, PDK-1, LDHA, COX4) and confirmed increased VEGF-A expression and secretion. Finally, we measured the vascularization of islets in static and flowing culture using PECAM-1 immunofluorescence.

Results

CoCl₂ did not induce significant changes in beta cell metabolism (NAD(P)H and Rh123), insulin secretion, and survival. Consistent with hypoxia induction, CoCl₂ stimulated HIF-1α, PDK-1, and LDHA transcripts and also stimulated VEGF expression and secretion. We observed a modest switch to the less oxidative isoform of COX4 (isoform 1 to 2) and this switch was noted in the glucose-stimulated cytoplasmic NAD(P)H responses. EC morphology and survival were greater in CoCl₂ treated islets compared to exogenous VEGF-A in both static (dish) and microfluidic flow culture.

Conclusions

Hypoxia induction using CoCl₂ had a positive effect on islet EC morphology and survival with limited impact on beta-cell metabolism, function, and survival. The EC response appears to be due to endogenous production and secretion of angiogenic factors (e.g. VEGF-A), and mechanistically independent from survival induced by serum albumin.

Autologous Mesenchymal Stem Cell Transplant in Patients with Type 1 Diabetes Mellitus

OBJECTIVES

Our goal was to determine the efficacy of autologous mesenchymal stem cell transplant for treatment in patients with type 1 diabetes mellitus.

MATERIALS AND METHODS

We examined 5 patients (4 male, 1 female; age 20-42 y) with type 1 diabetes mellitus who received autologous mesenchymal stem cell transplant (cells were obtained from the patient's iliac crest and cultured for 3-4 weeks) performed by intravenous infusion. The quantity of autologous mesenchymal stem cells infused was 95 to 97 × 106. We analyzed daily insulin dosages and leptin and glycated hemoglobin levels in patients before and 1, 2, and 3 months after their autologous mesenchymal stem cell transplant procedure.

RESULTS

In patients with type 1 diabetes mellitus, autologous mesenchymal stem cell transplant led to a decrease in daily insulin dosage levels, from 63 ± 8.83 to 50.2 ± 12.1 U (P = .064) after 1 month, with significantly increased leptin levels and trend to decreased glycated hemoglobin levels, from 6.86 to 10.77 ng/mL (P = .016) and 9.11% to 8.74% (P = .84) after 3 months, respectively.

CONCLUSIONS

Daily insulin dosage level decreased within 1 month and leptin levels increased significantly within 3 months after autologous mesenchymal stem cell transplant in patients with type 1 diabetes mellitus.

Transforming Growth Factor β1 in Patients with Type 2 Diabetes Mellitus After Fetal Pancreatic Stem Cell Transplant

OBJECTIVES

Our objective was to determine transforming growth factor β1 levels in patients with type 2 diabetes mellitus after fetal pancreatic stem cell transplant.

MATERIALS AND METHODS

We examined 10 patients (age range, 41-65 y) with type 2 diabetes mellitus, which we subsequently divided into 2 groups. Group 1 comprised 5 patients who received fetal pancreatic stem cell transplant (cells were 16-18 wk gestation) performed by intravenous infusion. Group 2 comprised 5 patients (control group) who were on hypoglycemic tablet therapy or insulin therapy. The quantity of fetal stem cells infused was 5 to 6 × 106. We analyzed transforming growth factor β1, C-peptide, and glycated hemoglobin levels in patients before and 3 months after fetal pancreatic stem cell transplant.

RESULTS

In patients with type 2 diabetes mellitus, fetal pancreatic stem cell transplant led to a significant increase in transforming growth factor β1 levels, from 16 364.8 to 35 730.4 ng/mL (P = .008), with trend in decreased glycated hemoglobin levels, from 7.96% to 6.98% (P = .088) after 3 months.

CONCLUSIONS

Transforming growth factor β1 levels increased significantly within 3 months after fetal pancreatic stem cell transplant in patients with type 2 diabetes mellitus.

Role of adipose tissue derived stem cells differentiated into insulin producing cells in the treatment of type I diabetes mellitus

Generation of new β cells is an important approach in the treatment of type 1 diabetes mellitus (type 1 DM). Adipose tissue-derived stem cells (ADSCs) might be one of the best sources for cell replacement therapy for diabetes. Therefore, this work aimed to test the possible role of transplanted insulin-producing cells (IPCs) differentiated from ADSCs in treatment of streptozotocin (STZ) induced type I DM in rats. Type 1 DM was induced by single intra peritoneal injection with STZ (50 mg/kg BW). Half of the diabetic rats were left without treatment and the other half were injected with differentiated IPCs directly into the pancreas. ADSCs were harvested, cultured and identified by testing their phenotypes through flow cytometry. They were further subjected to differentiation into IPCs using differentiation medium. mRNA expression of pancreatic transcription factors (pdx1), insulin and glucose transporter-2 genes by real time PCR was done to detect the cellular differentiation and confirmed by stimulated insulin secretion. The pancreatic tissues from all groups were examined 2 months after IPC transplantation and were subjected to histological, Immunohistochemical and morphometric study. The differentiated IPCs showed significant expression of pancreatic β cell markers and insulin secretion in glucose dependent manner. Treatment with IPCs induced apparent regeneration, diffused proliferated islet cells and significant increase in C-peptide immune reaction. We concluded that transplantation of differentiated IPCs improved function and morphology of Islet cells in diabetic rats. Consequently, this therapy option may be a promising therapeutic approach to patient with type 1 DM if proven to be effective and safe.

Islet Microencapsulation: Strategies and Clinical Status in Diabetes

PURPOSE OF REVIEW

Type 1 diabetes mellitus (T1DM) is an autoimmune disease that results from the destruction of insulin-producing pancreatic β cells in the islets of Langerhans. Islet cell transplantation has become a successful therapy for specific patients with T1DM with hypoglycemic unawareness. The reversal of T1DM by islet transplantation is now performed at many major medical facilities throughout the world. However, many challenges must still be overcome in order to achieve continuous, long-term successful transplant outcomes. Two major obstacles to this therapy are a lack of islet cells for transplantation and the need for life-long immunosuppressive treatment. Microencapsulation is seen as a technology that can overcome both these limitations of islet cell transplantation. This review depicts the present state of microencapsulated islet transplantation.

RECENT FINDINGS

Microencapsulation can play a significant role in overcoming the need for immunosuppression and lack of donor islet cells. This review focuses on microencapsulation and the clinical status of the technology in combating T1DM.

Leptin Levels in Patients with Type 1 Diabetes Mellitus After Fetal Pancreatic Stem Cell Transplant

OBJECTIVES

Our objective was to determine leptin levels in patients with type 1 diabetes mellitus after fetal pancreatic stem cell transplant.

MATERIALS AND METHODS

Seven patients, aged 20 to 42 years, with type 1 diabetes mellitus received a fetal pancreatic stem cell transplant by intravenous infusion. The quantity of fetal stem cells infused was ≥ 5 × 10⁶, and the cells were of 12 to 14 weeks of gestation. We analyzed the levels of leptin, C-peptide, and antibodies to the islets of Langerhans before and 3 months after the transplant procedure.

RESULTS

Fetal pancreatic stem cell transplant led to significant increases in leptin and C-peptide levels, from 4.63 ± 1.17 ng/mL and 0.09 ± 0.02 ng/mL to 7.71 ± 1.45 ng/mL (P < .05) and 0.22 ± 0.05 ng/mL (P < .005), respectively, without an increase in antibodies to the islets of Langerhans, which measured 0.64 ± 0.13 U/mL before transplant and 0.57 ± 0.18 U/mL 3 months later (P > .05).

CONCLUSIONS

Leptin levels increase significantly within 3 months of fetal pancreatic stem cell transplant in patients with type 1 diabetes mellitus.

Fetal Pancreatic Stem-Cell Transplant in Patients With Diabetes Mellitus

OBJECTIVES

To determine the efficacy of fetal stem cell transplant for treating patients with diabetes mellitus types 1 and 2.

MATERIALS AND METHODS

Five patients with diabetes mellitus type 1 and 5 patients with diabetes mellitus type 2 (aged 18-56 years) received a fetal pancreatic stem-cell transplant (cells were 16-18 wk gestation) performed by intravenous infusion at 50 mL/hour. The quantity of fetal stem cells infused was ≥ 5-8*106. We analyzed the patients' C-peptide and glycated hemoglobin levels both before and 3 months after fetal stem cell transplant.

RESULTS

In patients with diabetes mellitus type 1, fetal stem-cell transplant led to a significant increase in C-peptide levels, from 0.09 ± 0.01 ng/mL to 0.20 ± 0.07 ng/mL, after 3 months (P < .008).

CONCLUSIONS

Treatment with fetal pancreatic stem cells may be beneficial for treating patients with type 1 or type 2 diabetes.

Gastric submucosa is inferior to the liver as transplant site for autologous islet transplantation in pancreatectomized diabetic Beagles

Intraportal transplantation of islets is no longer considered to be an ideal procedure and finding the extrahepatic alternative site is becoming a subject of high priority. Herein, in this study, we would introduce our initial outcomes of using gastric submucosa (GS) and liver as sites of islet autotransplantation in pancreatectomized diabetic Beagles. Total pancreatectomy was performed in Beagles and then their own islets extracted from the excised pancreas were transplanted into GS (GS group, n=8) or intrahepatic via portal vein (PV group, n=5). Forty-eight hours post transplantation, graft containing tissue harvested from the recipients revealed the presence of insulin-positive cells. All recipients in GS group achieved euglycemia within 1 day, but returned to a diabetic state at 6 to 8 days post-transplantation (mean survival time, 7.16±0.69 days). However, all of the animals kept normoglycemic until 85 to 155 days post-transplantation in PV group (mean survival time, 120±28.58 days; P<0.01 vs. GS group). The results of intravenous glucose tolerance test (IVGTT) confirmed that the marked improvement in glycometabolism was obtained in intrahepatic islet autotransplantation. Thus, our findings indicate that the liver is still superior to the GS as the site of islet transplantation, at least in our islet autotransplant model in pancreatectomized diabetic Beagles.

Regenerative Therapy of Type 1 Diabetes Mellitus: From Pancreatic Islet Transplantation to Mesenchymal Stem Cells

Type 1 diabetes is an autoimmune disease resulting in the permanent destruction of pancreatic islets. Islet transplantation to portal vein provides an approach to compensate for loss of insulin producing cells. Clinical trials demonstrated that even partial islet graft function reduces severe hypoglycemic events in patients. However, therapeutic impact is restrained due to shortage of pancreas organ donors and instant inflammation occurring in the hepatic environment of the graft. We summarize on what is known about regenerative therapy in type 1 diabetes focusing on pancreatic islet transplantation and new avenues of cell substitution. Metabolic pathways and energy production of transplanted cells are required to be balanced and protection from inflammation in their intravascular bed is desired. Mesenchymal stem cells (MSCs) have anti-inflammatory features, and so they are interesting as a therapy for type 1 diabetes. Recently, they were reported to reduce hyperglycemia in diabetic rodents, and they were even discussed as being turned into endodermal or pancreatic progenitor cells. MSCs are recognized to meet the demand of an individual therapy not raising the concerns of embryonic or induced pluripotent stem cells for therapy.

The effect of endothelial cells on hESC-derived pancreatic progenitors in a 3D environment

Generating transplantable β-like-cells from human embryonic stem cells (hESC) could serve as an ideal cell-based therapy for treatment of type 1 diabetes, which is characterized by the destruction of insulin-secreting pancreatic β-cells. There are several protocols for differentiating hESCs into pancreatic or endocrine precursors. However, so far, production of mature, functional β-like-cells has been achieved mainly by transplanting hESC derived pancreatic progenitors (PPs) and allowing several months for maturation to occur in vivo. One approach, believed to have potential in promoting differentiation into β-like-cells prior to transplantation, is culturing PPs alongside blood vessels. Endothelium and blood vessels have been shown to direct pancreatic development during embryogenesis and also induce endocrine differentiation in vitro. Here we designed a three-dimensional (3D) construct utilizing highly porous polymeric scaffolds that mimic natural conditions and provide cells with mechanical support, and used it in the differentiation protocol. Clusters of hESC derived pancreatic precursor cells were embedded within the scaffolds along with human endothelial cells (ECs) and fibroblasts forming vessel-like networks. Culturing these clusters with ECs for one week significantly increased the population of PPs, characterized by co-expression of the pancreatic markers Pdx1 and Nkx6.1 and also highly induced Ngn3 expression which indicates commitment to endocrine fate. The presence of fibroblasts, however, reduced this cell population. Three months upon implantation of constructs containing clusters and ECs or clusters alone, implanted mice retained normal blood glucose levels after treatment with STZ, while un-implanted mice became diabetic. These findings may lay the foundation for creating an optimal tissue-construct that will support PPs' maturation in vitro and enhance graft function upon implantation.

Improved Islet Purity by the Hypertonic-Hypotonic Method

Introduction

Islet purification is usually performed using the density gradient separation method, but the purity of islets is low because exocrine cells and the embedded islets are hard to remove by using only the density gradient method. The aim of this study was to establish a new islet purification process comprising a hypertonic-hypotonic treatment step followed by a density gradient centrifugation step to improve the purity of islets.

Methods

The Plackett-Burman method was used to determine which factors had a significant influence on the purity of islets obtained after the hypertonic-hypotonic treatment step.

Results

The hypertonic solution concentration and the incubation time were both found to have a significant effect on islet purity. The purity of islets obtained using the modified purification process was significantly higher than that of islets obtained by density gradient alone (97% vs. 87.23%). Importantly, good cell viability and normal insulin secretion ability of islets were maintained following the modified purification.

Conclusions

The new purification process allows isolation of islets with improved purity and does not compromise the viability or function of the islets.

Magnitude and mechanisms of glucose counterregulation following islet transplantation in patients with type 1 diabetes suffering from severe hypoglycaemic episodes

AIMS/HYPOTHESIS

Pancreatic islet transplantation stabilises glycaemic control in type 1 diabetes mellitus patients with neuroglycopoenia, despite them not achieving insulin independence because of limited graft function. However, the extent and underlying metabolic pathways of restored glucose counterregulation are unknown. We therefore compared systemic glucose turnover, including lactate gluconeogenesis (GN) and muscle glucose uptake, in individuals with type 1 diabetes who were transplant recipients with partial graft function (T1DM/ITx(+)), matched non-transplanted individuals with type 1 diabetes (T1DM/ITx(-)) and matched healthy non-diabetic individuals.

METHODS

Participants (n = 12 in each group) underwent a euglycaemic and a hypoglycaemic (2.5-2.8 mmol/l) hyperinsulinaemic clamp (0.8 mU kg(-1) min(-1)) in a randomised crossover fashion. Systemic and skeletal muscle glucose and lactate kinetics were assessed using a combination of isotopic and forearm balance techniques.

RESULTS

Whole-body glucose counterregulation, the difference in glucose infusion rates required to maintain the glycaemic goal between the hypoglycaemic and euglycaemic clamps, was improved in T1DM/ITx(+) (7.8 ± 1.3 μmol kg(-1) min(-1)) compared with T1DM/ITx(-) (0.3 ± 0.9 μmol kg(-1) min(-1)), but was ~45% lower than in controls (14.1 ± 2.1 μmol kg(-1) min(-1)). Increased endogenous glucose production (EGP) and decreased systemic glucose disposal accounted for 49% and 39% of glucose counterregulation in T1DM/ITx(+), respectively, compared with 60% and 36% in controls. Lactate GN increased in T1DM/ITx(+) (2.7 ± 0.4 μmol kg(-1) min(-1)) and controls (1.7 ± 0.5 μmol kg(-1) min(-1)), such that it accounted for 70% and 20% of the increased EGP, respectively. Skeletal muscle accounted for similar proportions of the decrease in systemic glucose disposal in controls (49%) and T1DM/ITx(+) (41%).

CONCLUSIONS/INTERPRETATION

Partial islet graft function improves hypoglycaemia counterregulation by increasing EGP, largely via lactate GN and decreasing systemic glucose disposal. This may explain the reduction in severe hypoglycaemic events in T1DM/ITx(+) individuals.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01668485.

International workshop: islet transplantation without borders enabling islet transplantation in Greece with international collaboration and innovative technology

Recently, initiatives have been undertaken to establish an islet transplantation program in Athens, Greece. A major hurdle is the high cost associated with the establishment and maintenance of a clinical-grade islet manufacturing center. A collaboration was established with the University Hospitals of Geneva, Switzerland, to enable remote islet cell manufacturing with an established and validated fully operational team. However, remote islet manufacturing requires shipment of the pancreas from the procurement to the islet manufacturing site (in this case from anywhere in Greece to Geneva) and then shipment of the islets from the manufacturing site to the transplant site (from Geneva to Athens). To address challenges related to cold ischemia time of the pancreas and shipment time of islets, a collaboration was initiated with the University of Arizona, Tucson, USA. An international workshop was held in Athens, December 2011, to mark the start of this collaborative project. Experts in the field presented in three main sessions: (i) islet transplantation: state-of-the-art and the "network approach"; (ii) technical aspects of clinical islet transplantation and outcomes; and (iii) islet manufacturing - from the donated pancreas to the islet product. This manuscript presents a summary of the workshop.

Goettingen Minipigs (GMP): Comparison of Two Different Models for Inducing Diabetes

PURPOSE

Preclinical experiments on large animals are indispensable for evaluating the effectiveness of diabetes therapies. Miniature swine are well suited for such studies due to their physiological and pathophysiological responses.

METHODS

We compare two methods for inducing diabetes in Goettingen minipigs (GMP), in five with the beta cell toxin streptozotocin (STZ) and in five other GMP by total pancreatectomy (PE). Glucose homeostasis was assessed with the intravenous glucose-tolerance test (IVGTT) and continual monitoring of interstitial glucose levels. At conclusion of the observation period, the pancreata were examined histologically. Three non-diabetic GMP served as control group.

RESULTS

The IVGTT revealed markedly diabetic profiles in both GMP groups. STZ-GMP were found to harbor residual C-peptides and scattered insulin-positive cells in the pancreas. PE-GMP survived the total pancreatectomy only with intensive postoperative care.

CONCLUSIONS

Although both methods reliably induced diabetes in GMP, the PE-GMP clearly had more health problems and required a greater expenditure of time and resources. The PE-GMP model, however, was better at eliminating endogenous insulin and C-peptide than the STZ-GMP model.

Current treatment options for chronic pancreatitis

Chronic pancreatitis (CP) is characterized by progressive and ultimately irreversible pancreatic injury. Alcohol abuse is the most common cause of CP in the Western world. As the pathophysiology of this disorder is better understood, it is probable that the treatment will be more successful. Therapeutic efforts for CP are focused on the treatment of maldigestion, pain, and diabetes. Dosage and timing of enteric-coated pancreatic enzymes are important issues in the treatment of malabsorption due to CP. Non-enteric-coated enzyme preparations along with acid suppression (histamine-2 blockers or proton-pump inhibitors) are of limited to modest effectiveness in treating pain caused by CP but are worth a trial in patients with less advanced disease. Extracorporeal shock wave lithotripsy (ESWL) of calcified stones is sometimes needed to achieve stone fragmentation before endoscopic removal. The role of ESWL alone in relieving calcified CP pain needs further study. Endoscopic therapy is aimed at decompressing the obstructed pancreatic duct and removal of pancreatic stone and is associated with pain relief in many patients. The role of endoscopic ultrasonography-guided celiac plexus block should be limited to treating those patients with CP whose pain has not responded to other modalities. Radiation therapy to the whole pancreas for CP pain relief is a revived treatment option that needs further study to confirm the safety and efficacy. Total pancreatectomy followed by autologous islet cell autotransplantation appears to be a potential therapeutic approach but should be considered as the last option in patients with refractory pain who have failed conventional medical, endoscopic, and surgical options.

Current status of immunomodulatory and cellular therapies in preclinical and clinical islet transplantation

Clinical islet transplantation is a β-cell replacement strategy that represents a possible definitive intervention for patients with type 1 diabetes, offering substantial benefits in terms of lowering daily insulin requirements and reducing incidences of debilitating hypoglycemic episodes and unawareness. Despite impressive advances in this field, a limiting supply of islets, inadequate means for preventing islet rejection, and the deleterious diabetogenic and nephrotoxic side effects associated with chronic immunosuppressive therapy preclude its wide-spread applicability. Islet transplantation however allows a window of opportunity for attempting various therapeutic manipulations of islets prior to transplantation aimed at achieving superior transplant outcomes. In this paper, we will focus on the current status of various immunosuppressive and cellular therapies that promote graft function and survival in preclinical and clinical islet transplantation with special emphasis on the tolerance-inducing capacity of regulatory T cells as well as the β-cells regenerative capacity of stem cells.

Evolution of β-Cell Replacement Therapy in Diabetes Mellitus: Islet Cell Transplantation

Diabetes mellitus remains one of the leading causes of morbidity and mortality worldwide. According to the Centers for Disease Control and Prevention, approximately 23.6 million people in the United States are affected. Of these individuals, 5 to 10% have been diagnosed with Type 1 diabetes mellitus (T1DM), an autoimmune disease. Although it often appears in childhood, T1DM may manifest at any age, leading to significant morbidity and decreased quality of life. Since the 1960s, the surgical treatment for diabetes mellitus has evolved to become a viable alternative to insulin administration, beginning with pancreatic transplantation. While islet cell transplantation has emerged as another potential alternative, its role in the treatment of T1DM remains to be solidified as research continues to establish it as a truly viable alternative for achieving insulin independence. In this paper, the historical evolution, procurement, current status, benefits, risks, and ongoing research of islet cell transplantation are explored.

Culturing pancreatic islets in microfluidic flow enhances morphology of the associated endothelial cells

Pancreatic islets are heavily vascularized in vivo with each insulin secreting beta-cell associated with at least one endothelial cell (EC). This structure is maintained immediately post-isolation; however, in culture the ECs slowly deteriorate, losing density and branched morphology. We postulate that this deterioration occurs in the absence of blood flow due to limited diffusion of media inside the tissue. To improve exchange of media inside the tissue, we created a microfluidic device to culture islets in a range of flow-rates. Culturing the islets from C57BL6 mice in this device with media flowing between 1 and 7 ml/24 hr resulted in twice the EC-density and -connected length compared to classically cultured islets. Media containing fluorescent dextran reached the center of islets in the device in a flow-rate-dependant manner consistent with improved penetration. We also observed deterioration of EC morphology using serum free media that was rescued by addition of bovine serum albumin, a known anti-apoptotic signal with limited diffusion in tissue. We further examined the effect of flow on beta-cells showing dampened glucose-stimulated Ca²⁺-response from cells at the periphery of the islet where fluid shear-stress is greatest. However, we observed normal two-photon NAD(P)H response and insulin secretion from the remainder of the islet. These data reveal the deterioration of islet EC-morphology is in part due to restricted diffusion of serum albumin within the tissue. These data further reveal microfluidic devices as unique platforms to optimize islet culture by introducing intercellular flow to overcome the restricted diffusion of media components.

Porcine aortic endothelial cell genes responsive to selected inflammatory stimulators

Use of porcine tissues has been suggested as a promising solution for severe shortage of transplantable human organs. The immediate hurdle for xenotransplantation is acute immune/inflammatory vascular rejection of the transplant. Because endothelial cells play a key role in the initiation and the amplification of inflammation, alteration of gene expression in human endothelial cells, by various inflammatory stimulators has been studied extensively. However, transcriptional changes induced by human and other inflammatory stimulators in porcine endothelial cells have thus far not been studied. In this study, we treated porcine endothelial cells with human tumor necrosis factor (TNF)-alpha, porcine interferon (IFN)-gamma, H(2)O(2) and lypopolysaccharide (LPS) and profiled transcriptional change at 1 hr, 6 hr and 24 hr, using pig oligonucleotide 13K microarray. We found that mRNA species such as chemokine (C-X-C motif) ligand 6 (CXCL6) and Cathepsin S were significantly induced in porcine endothelial cells, as was previously reported with human endothelial cell. We also found that mRNA species including secreted frizzled-related protein 2 (SFRP2), radical S-adenosyl methionine domain containing 2 (RSAD2), structure specific recognition protein 1 (SSRP1) also were highly overexpressed in porcine endothelial cells. This result shows clues to understand underlying mechanisms of xenotransplantation rejection and the highly responsive porcine genes may serve as novel targets to be regulated for improving the function of grafted porcine donor organs.

Treatment of type 1 diabetes with adipose tissue-derived stem cells expressing pancreatic duodenal homeobox 1

Due to the limited supply of donor pancreas, it is imperative that we identify alternative cell sources that can be used to treat diabetes mellitus (DM). Multipotent adipose tissue-derived stem cells (ADSC) can be abundantly and safely isolated for autologous transplantation and therefore are an ideal candidate. Here, we report the derivation of insulin-producing cells from human or rat ADSC by transduction with the pancreatic duodenal homeobox 1 (Pdx1) gene. RT-PCR analyses showed that native ADSC expressed insulin, glucagon, and NeuroD genes that were up-regulated following Pdx1 transduction. ELISA analyses showed that the transduced cells secreted increasing amount of insulin in response to increasing concentration of glucose. Transplantation of these cells under the renal capsule of streptozotocin-induced diabetic rats resulted in lowered blood glucose, higher glucose tolerance, smoother fur, and less cataract. Histological examination showed that the transplanted cells formed tissue-like structures and expressed insulin. Thus, ADSC-expressing Pdx1 appear to be suitable for treatment of DM.

The immunosuppressive and protective ability of glucose-regulated protein 78 for improvement of alloimmunity in beta cell transplantation

An insulinoma cell line, NIT-1, transfected with glucose-regulated protein 78 (GRP78) was established, namely NIT-GRP78, and used to study the immunosuppressive and protective ability of GRP78. In extended cytotoxic T lymphocyte (CTL) killing assay, NIT-1-primed lymphocytes were more cytotoxic in killing beta cells than NIT-GRP78-primed lymphocytes. Severe necrosis was observed only when the NIT-1-primed lymphocytes were cultured with NIT-1 beta cells, but not with NIT-GRP78 cells. In addition, an increase of interleukin (IL)-4 secretion from beta cell-primed splenocytes when GRP78 presence was observed in cytokine enzyme-linked immunosorbent assay (ELISA). Diabetic mice reached normoglycaemia promptly and gained weight after transplantation of either NIT-1 or NIT-GRP78 cells. However, the recipient mice transplanted with NIT-GRP78 cells lived much longer than those recipients transplanted with NIT-1 cells, which was due apparently to prolonged insulin production by the transplanted NIT-GRP78 cells. In fact, we observed a significant increase of insulin concentration after glucose stimulation of diabetic mice received NIT-GRP78 cells at day 7 post-transplantation. From the results we propose that GRP78 could have a dual function in both protecting NIT-1 cells from CTL-mediated lysis and stimulating a population of T helper 2 cells to down-regulate the immune response to the transplanted beta cells.