Islet cell transplantation for Type 1 diabetes

Efficacy of mesenchymal stromal cells in the treatment of type 1 diabetes: a systematic review

To investigate the efficacy of mesenchymal stromal cells in the treatment of type 1 diabetes. Articles about the effects of mesenchymal stromal cells for T1D were retrieved in PubMed, Web of Science, Embase, and the Cochrane Library databases up to July 2023. Additional relevant studies were manually searched through citations. HbA1c, FBG, PBG, insulin requirement and C-peptide were assessed. The risk of bias was evaluated with the ROB 2.0 and ROBINS-I tools. Six RCTs and eight nRCTs were included. Of the 14 studies included, two evaluated BM-MSCs, three evaluated UC-MSCs, five evaluated AHSCT, two evaluated CB-SCs, and two evaluated UC-SCs plus aBM-MNCs. At the end of follow-up, ten studies found that mesenchymal stromal cells improved glycemic outcomes in T1D, while the remaining four studies showed no significant improvement. Findings support the positive impacts observed from utilizing mesenchymal stromal cells in individuals with T1D. However, the overall methodological quality of the identified studies and findings is heterogeneous, limiting the interpretation of the therapeutic benefits of mesenchymal stromal cells in T1D. Methodically rigorous research is needed to further increase credibility.

Targeted delivery of harmine to xenografted human pancreatic islets promotes robust cell proliferation

Type 1 diabetes (T1D) occurs as a consequence of the autoimmune destruction of insulin-producing pancreatic beta (β) cells and commonly presents with insulin deficiency and unregulated glycemic control. Despite improvements in the medical management of T1D, life-threatening complications are still common. Beta-cell replication to replace lost cells may be achieved by using small-molecule mitogenic drugs, like harmine. However, the safe and effective delivery of such drugs to beta cells remains a challenge. This work aims to deploy an antibody conjugated nanocarrier platform to achieve cell-specific delivery of candidate therapeutic and imaging agents to pancreatic endocrine cells. We approached this goal by generating core-shell type micellar nanocarriers composed of the tri-block copolymer, Pluronic®F127 (PEO₁₀₀-PPO₆₅-PEO₁₀₀). We decorated these nanocarriers with a pancreatic endocrine cell-selective monoclonal antibody (HPi1), with preference for beta cells, to achieve active targeting. The PPO-based hydrophobic core allows encapsulation of various hydrophobic cargoes, whereas the PEO-based hydrophilic shell curbs the protein adhesion, hence prolonging the nanocarriers' systemic circulation time. The nancarriers were loaded with quantum dots (QDots) that allowed nanocarrier detection both in-vitro and in-vivo. In-vitro studies revealed that HPi1 conjugated nanocarriers could target endocrine cells in dispersed islet cell preparations with a high degree of specificity, with beta cells exhibiting a fluorescent quantum dot signal that was approximately five orders of magnitude greater than the signal associated with alpha cells. In vivo endocrine cell targeting studies demonstrated that the HPi1 conjugated nanocarriers could significantly accumulate at the islet xenograft site. For drug delivery studies, the nanocarriers were loaded with harmine. We demonstrated that HPi1 conjugated nanocarriers successfully targeted and delivered harmine to human endocrine cells in a human islet xenograft model. In this model, targeted harmine delivery yielded an ~ 41-fold increase in the number of BrdU positive cells in the human islet xenograft than that observed in untreated control mice. By contrast, non-targeted harmine yielded an ~ 9-fold increase in BrdU positive cells. We conclude that the nanocarrier platform enabled cell-selective targeting of xenografted human pancreatic endocrine cells and the selective delivery of the hydrophobic drug harmine to those cells. Further, the dramatic increase in proliferation with targeted harmine, a likely consequence of achieving higher local drug concentrations, supports the concept that targeted drug delivery may promote more potent biological responses when using harmine and/or other drugs than non-targeting approaches. These results suggest that this targeted drug delivery platform may apply in drug screening, beta cell regenerative therapies, and/or diagnostic imaging in patients with type 1 diabetes.

Stem cell therapy for type1 diabetes with transplantation of stem cells into the Omental pouch, peritoneum, and blood, experimental study

Introduction

Type 1 diabetes is a dreadful autoimmune disease of childhood with incidence of 0.26/1000 children in India. To develop a new, cheap, and effective treatment for this disease, we invented an autologous Stem cell therapy for type 1 diabetes in which stem cells are transplanted into the Omental pouch, peritoneum, and blood. The Omental pouch stem cell operation in the therapy is reported for the first time in the medical literature.

Materials and methods

Last 5 years I treated 21 patients of Type 1 diabetes with autologous stem cell therapy and in the same period, a group of 26 patients of Type 1 diabetes with conventional treatment of Insulin injections was put as a control group. Blood sugar fasting and post prandial, Anti Gad antibody titer, Glycosylated Hb and C peptide levels and weight of patient and total Insulin requirement in 24 h were the variables to be measured before the therapy and after the therapy. Stem cells were harvested from patients own bone marrow and separated by density gradient method. An infusion of 20 mg/kg methylprednisolone in 100 ML normal saline given intravenously over 1 h prior to the therapy. The total average numbers of cells harvested were 7.86 × 107. One third quantity of isolated stem cells were put into the Omental pouch through no. 7 IFT, another one third into peritoneal cavity through no. 10 IFT and remaining third is given IV in 100 ml normal saline.

Results

The minimum follow up was 6 months and maximum of 4 years. In the therapy group, the average weight gain after one year of therapy, daily requirement of Insulin and its drop after therapy, drop in HbA1c levels, drop in fasting and post prandial blood sugar, rise of C peptide levels and drop in Anti-GAD antibody titer were measured and was found to be statistically highly significant. The same parameters were measured in control group and was not statistically significant. There were a few side effects noted after stem cell therapy such as mild skin rash, nausea, and pain in abdomen.

Discussion

In autologous bone marrow derived stem cell therapy, cells are transplanted into the Omental pouch, peritoneum, and blood. Cells transplanted in the Omental pouch get vascularized like a split skin graft. Omental surface has far less cellular immunity than blood, hence, if some of these cells get converted into Islets like cells producing Insulin, then they are less vulnerable to damage by the immune system. It means that the Omental pouch may act as a new biological pancreas producing Insulin. Stem cells injected intravenously reach the pancreases and may get differentiate into Islet like cells due to specific growth factors released by pancreas. Stem cells can reverse autoimmunity by their immunomodulatory function. Stem cells transplanted in peritoneum grow longer due to large surface area and little cellular immunity and secrete growth factors and cytokines for a long time which can rejuvenate existing Islets of Langerhans. The therapy group had substantially good results compared to the control group and the difference was statistically highly significant.

Conclusions

Autologous stem cell therapy was safe, and effective for the long term for the treatment of Type 1 diabetes. We need a greater number of cases and a longer follow up to make it better. The therapy creates a lot of hope for Type 1 diabetes patients as it can be easily repeated any number of times.

Integrating Additive Manufacturing Techniques to Improve Cell-Based Implants for the Treatment of Type 1 Diabetes

The increasing global prevalence of endocrine diseases like type 1 diabetes mellitus (T1DM) elevates the need for cellular replacement approaches, which can potentially enhance therapeutic durability and outcomes. Central to any cell therapy is the design of delivery systems that support cell survival and integration. In T1DM, well-established fabrication methods have created a wide range of implants, ranging from 3D macro-scale scaffolds to nano-scale coatings. These traditional methods, however, are often challenged by their inherent limitations in reproducible and discrete fabrication, particularly when scaling to the clinic. Additive manufacturing (AM) techniques provide a means to address these challenges by delivering improved control over construct geometry and microscale component placement. While still early in development in the context of T1DM cellular transplantation, the integration of AM approaches serves to improve nutrient material transport, vascularization efficiency, and the accuracy of cell, matrix, and local therapeutic placement. This review highlights current methods in T1DM cellular transplantation and the potential of AM approaches to overcome these limitations. In addition, emerging AM technologies and their broader application to cell-based therapy are discussed.

The effects of necrostatin-1 on the in vitro development and function of young porcine islets over 14-day prolonged tissue culture

BACKGROUND

Necrostatin-1 (Nec-1) supplementation to tissue culture media on day 3 has recently been shown to augment the insulin content, endocrine cellular composition, and insulin release of pre-weaned porcine islets (PPIs); however, its effects were only examined for the first 7 days of tissue culture. The present study examined whether the addition of Nec-1 on day 3 could further enhance the in vitro development and function of PPIs after 14 days of tissue culture.

METHODS

PPIs were isolated from 8- to 15-day-old, pre-weaned Yorkshire piglets and cultured in an islet maturation media supplemented with Nec-1 on day 3. The recovery, viability, insulin content, endocrine cellular composition, GLUT2 expression in beta cells, differentiation and proliferation potential, and glucose-stimulated insulin secretion of PPIs were assessed on days 3, 7, and 14 of tissue culture (n = 5 on each day).

RESULTS

Compared with day 7 of tissue culture, islets on day 14 had a lower recovery, GLUT2 expression in beta cells, proliferation capacity of endocrine cells, and glucose-induced insulin stimulation index. Prolonging the culture time to 14 days did not affect islet viability, insulin content, proportion of endocrine cells, and differentiation potential.

CONCLUSION

The growth-inducing effects of Nec-1 on PPIs were most effective on day 7 of tissue culture when added on day 3. Our findings support existing evidence that the in vitro activities of Nec-1 are short-lived and encourage future studies to explore the use of other novel growth factors during prolonged islet tissue culture.

A comparison of the inflammatory response following autologous compared with allogenic islet cell transplantation

Background

The initial response to islet transplantation and the subsequent acute inflammation is responsible for significant attrition of islets following both autologous and allogenic procedures. This multicentre study compares this inflammatory response using cytokine profiles and complement activation.

Methods

Inflammatory cytokine and complement pathway activity were examined in two cohorts of patients undergoing total pancreatectomy followed either by autologous (n=11) or allogenic (n=6) islet transplantation. Two patients who underwent total pancreatectomy alone (n=2) served as controls.

Results

The peak of cytokine production occurred immediately following induction of anaesthesia and during surgery. There was found to be a greater elevation of the following cytokines: TNF-alpha (P<0.01), MCP-1 (P=0.0013), MIP-1α (P=0.001), MIP-1β (P=0.00020), IP-10 (P=0.001), IL-8 (P=0.004), IL-1α (P=0.001), IL-1ra (0.0018), IL-10 (P=0.001), GM-CSF (P=0.001), G-CSF (P=0.0198), and Eotaxin (P=0.01) in the allogenic group compared to autografts and controls. Complement activation and consumption was observed in all three pathways, and there were no significant differences in between the groups although following allogenic transplantation ∆IL-10 and ∆VEGF levels were significantly elevated those patients who became insulin-independent compared with those who were insulin-dependent.

Conclusions

The cytokine profiles following islet transplantation suggests a significantly greater acute inflammatory response following allogenic islet transplantation compared with auto-transplantation although a significant, non-specific inflammatory response occurs following both forms of islet transplantation.

Recent advances in the design of implantable insulin secreting heterocellular islet organoids

Islet transplantation has proved one of the most remarkable transmissions from an experimental curiosity into a routine clinical application for the treatment of type I diabetes (T1D). Current efforts for taking this technology one-step further are now focusing on overcoming islet donor shortage, engraftment, prolonged islet availability, post-transplant vascularization, and coming up with new strategies to eliminate lifelong immunosuppression. To this end, insulin secreting 3D cell clusters composed of different types of cells, also referred as heterocellular islet organoids, spheroids, or pseudoislets, have been engineered to overcome the challenges encountered by the current islet transplantation protocols. β-cells or native islets are accompanied by helper cells, also referred to as accessory cells, to generate a cell cluster that is not only able to accurately secrete insulin in response to glucose, but also superior in terms of other key features (e.g. maintaining a vasculature, longer durability in vivo and not necessitating immunosuppression after transplantation). Over the past decade, numerous 3D cell culture techniques have been integrated to create an engineered heterocellular islet organoid that addresses current obstacles. Here, we first discuss the different cell types used to prepare heterocellular organoids for islet transplantation and their contribution to the organoids design. We then introduce various cell culture techniques that are incorporated to prepare a fully functional and insulin secreting organoids with select features. Finally, we discuss the challenges and present a future outlook for improving clinical outcomes of islet transplantation.

Dose-dependent effects of necrostatin-1 supplementation to tissue culture media of young porcine islets

Previous studies have shown that necrostatin-1 (Nec-1) supplementation improved the viability of murine islets following exposure to nitric oxide, increased the survival of human islets during hypoxic culture, and augmented the maturation of pre-weaned porcine islets (PPIs) after 7 days of tissue culture. A limitation of these studies is that only one concentration of Nec-1 was used, and no studies have determined the optimal dose of Nec-1 for PPIs. Thus, the present study examined the effects of Nec-1 on PPIs at four different doses—0, 25, 50, 100, and 200 μM—after 7 days of tissue culture when supplemented on day 3. PPIs were isolated from pancreata of pre-weaned Yorkshire piglets (8–15 days old) and cultured in a specific islet maturation media added with Nec-1 on day 3 of tissue culture at 4 different doses—0, 25, 50, 100, and 200 μM (n = 6 for each dose). After 7 days of tissue culture, islets were assessed for recovery, viability, endocrine cellular content, GLUT2 expression in beta cells, and insulin secretion after glucose challenge. Nec-1 did not affect the viability of both intact islets and dissociated islets cells during tissue culture regardless of doses. Islets cultured in media supplemented with Nec-1 at 100 μM, but not 25, 50, or 200 μM, had a significantly higher recovery, composition of endocrine cells, GLUT2 expression in beta cells, and insulin secretion capacity than control islets cultured in media without Nec-1 supplementation. Moreover, culturing islets in 200 μM Nec-1 supplemented media not only failed to improve the insulin release but resulted in a lower glucose-induced insulin stimulation index compared to islets cultured in media added with 100 μM Nec-1. Xenotransplantation using porcine islets continues to demonstrate scientific advances to justify this area of research. Our findings indicate that Nec-1 supplementation at 100 μM was most effective to enhance the in vitro maturation of PPIs during tissue culture.

Current situation of clinical islet transplantation from allogeneic toward xenogeneic

Currently, type 1 diabetes requires lifelong insulin injection and careful blood glucose control to prevent secondary complications, but islet transplantation could make a type 1 diabetic patient insulin independent. On the other hand, islet transplantation needs human donors and donor shortage is the most serious issue. To alleviate the donor shortage, non-heart-beating and living donors were used; in addition, the efficacy of islet isolation and transplantation has been improved. However, the donor shortage issue will not be solved as long as human donors are the only source. To solve the donor shortage issue, islet xenotransplantation using porcine islets was initiated in 1994. Islet xenotransplantation has a potential to cure many type 1 diabetic patients, although there is the risk of developing serious or novel infection. Therefore, the World Health Organization has been interested in xenotransplantation, and the International Xenotransplantation Association (IXA) has published consensus statements to initiate xenogeneic islet transplantation. Clinical islet xenotransplantation was conducted under the official regulation, and safety and efficacy data have been accumulated. Currently an efficient method to overcome xenorejection is an important research target. In addition to traditional immunosuppressive drugs and immune isolation methods, the gene modification with CRISPR and blastocyst complementation have been investigated with promising outcomes. Once the xenorejection issue is overcome, islet xenotransplantation should become a curative treatment for type 1 diabetic patients.

Evaluation of Multi-Layered Pancreatic Islets and Adipose-Derived Stem Cell Sheets Transplanted on Various Sites for Diabetes Treatment

Islet cell transplantation is considered an ideal treatment for insulin-deficient diabetes, but implantation sites are limited and show low graft survival. Cell sheet technology and adipose-derived stem cells (ADSCs) can be useful tools for improving islet cell transplantation outcomes since both can increase implantation efficacy and graft survival. Herein, the optimal transplantation site in diabetic mice was investigated using islets and stem cell sheets. We constructed multi-layered cell sheets using rat/human islets and human ADSCs. Cell sheets were fabricated using temperature-responsive culture dishes. Islet/ADSC sheet (AI sheet) group showed higher viability and glucose-stimulated insulin secretion than islet-only group. Compared to islet transplantation alone, subcutaneous AI sheet transplantation showed better blood glucose control and CD31+ vascular traits. Because of the adhesive properties of cell sheets, AI sheets were easily applied on liver and peritoneal surfaces. Liver or peritoneal surface grafts showed better glucose control, weight gain, and intraperitoneal glucose tolerance test (IPGTT) profiles than subcutaneous site grafts using both rat and human islets. Stem cell sheets increased the therapeutic efficacy of islets in vivo because mesenchymal stem cells enhance islet function and induce neovascularization around transplanted islets. The liver and peritoneal surface can be used more effectively than the subcutaneous site in future clinical applications.

Generation of Human Stem Cell-Derived Pancreatic Organoids (POs) for Regenerative Medicine

Insulin-dependent diabetes mellitus or type 1 diabetes mellitus (T1DM) is an auto-immune condition characterized by the loss of pancreatic β-cells. The curative approach for highly selected patients is the pancreas or the pancreatic islet transplantation. Nevertheless, these options are limited by a growing shortage of donor organs and by the requirement of immunosuppression.Xenotransplantation of porcine islets has been extensively investigated. Nevertheless, the strong xenoimmunity and the risk of transmission of porcine endogenous retroviruses, have limited their application in clinic. Generation of β-like cells from stem cells is one of the most promising strategies in regenerative medicine. Embryonic, and more recently, adult stem cells are currently the most promising cell sources exploited to generate functional β-cells in vitro. A number of studies demonstrated that stem cells could generate functional pancreatic organoids (POs), able to restore normoglycemia when implanted in different preclinical diabetic models. Nevertheless, a gradual loss of function and cell dead are commonly detected when POs are transplanted in immunocompetent animals. So far, the main issue to be solved is the post-transplanted islet loss, due to the host immune attack. To avoid this hurdle, nanotechnology has provided a number of polymers currently under investigation for islet micro and macro-encapsulation. These new approaches, besides conferring PO immune protection, are able to supply oxygen and nutrients and to preserve PO morphology and long-term viability.Herein, we summarize the current knowledge on bioengineered POs and the stem cell differentiation platforms. We also discuss the in vitro strategies used to generate functional POs, and the protocols currently used to confer immune-protection against the host immune attack (micro- and macro-encapsulation). In addition, the most relevant ongoing clinical trials, and the most relevant hurdles met to move towards clinical application are revised.

Tissue-engineering approaches in pancreatic islet transplantation

Pancreatic islet transplantation is a promising alternative to whole-pancreas transplantation as a treatment of type 1 diabetes mellitus. This technique has been extensively developed during the past few years, with the main purpose of minimizing the complications arising from the standard protocols used in organ transplantation. By using a variety of strategies used in tissue engineering and regenerative medicine, pancreatic islets have been successfully introduced in host patients with different outcomes in terms of islet survival and functionality, as well as the desired normoglycemic control. Here, we describe and discuss those strategies to transplant islets together with different scaffolds, in combination with various cell types and diffusible factors, and always with the aim of reducing host immune response and achieving islet survival, regardless of the site of transplantation.

The value of glycated albumin for the prediction of graft outcome in the non-human primate porcine islet transplantation model

BACKGROUND

The development of a precise and easy-to-use tool for monitoring islet graft function is important in clarifying the causes of graft loss, identifying appropriate therapy, and ensuring graft survival in the nonhuman primate (NHP) model of porcine islet transplantation (PITx). Glycated albumin (GA) is an indicator of intermediate-term changes in blood glucose control and is useful in clinical diabetes management. The validity of GA for monitoring graft function in NHP recipients of PITx was evaluated using a retrospective analysis of cohort samples.

METHODS

Data from a total of 23 PITxs performed in 20 recipients (3 were retransplanted) were included in this study. Islet clusters purified from adult wild-type pigs were transplanted via the intraportal route into streptozotocin-induced diabetic rhesus monkeys with immune suppression. Blood samples were obtained once per week from the recipients until they lost insulin-independence. Blood samples were also obtained from 69 non-diabetic monkeys that served as a control group. The levels of GA and albumin in stored plasma aliquots were measured using each enzymatic method, and the GA result was expressed as the percentage of GA level to the total albumin level.

RESULTS

The median level of GA in the recipients on the day of PITx (median 18.6%, 95% confidence interval [CI] 16.7%-20.4%) was significantly higher than that of healthy controls (median 9.14%, 95% CI 9.0%-9.3%, P < .0001). However, the level decreased after PITx and remained low or increased depending on the extent of residual graft function. The GA level at a nadir (median 11.6%, 95% CI 10.8%-13.0%) and the time to reach a nadir (median 43 days, 95% CI 21.7-69.3 days) both correlated with the duration of insulin-independence (rho [ρ] = -.605, P = .0028 and ρ = .662, P = .0008, respectively). The GA level strongly correlated with K_G , the glucose disappearance rate during intravenous glucose tolerance testing (ρ = -.76, P < .0001). At post-transplant week (PTW) 3 and at PTW 4, the GA levels in recipients with long-term insulin-independence (>90 days) were significantly lower than those with short-term insulin-independence, which revealed the excellent performance for the prediction of long-term insulin-independence that is comparable to that of porcine C-peptide (historic data).

CONCLUSIONS

As a surrogate indicator for graft function, serial measurement of GA may provide Supporting Information to that obtained from conventional monitoring techniques of graft function for assessing porcine islet grafts in NHP models.

Perioperative management of endocrine insufficiency after total pancreatectomy for neoplasia

PURPOSE

Indications for total pancreatectomy (TP) have increased, including for diffuse main duct intrapapillary mucinous neoplasms of the pancreas and malignancy; therefore, the need persists for surgeons to develop appropriate endocrine post-operative management strategies. The brittle diabetes after TP differs from type 1/2 diabetes in that patients have absolute deficiency of insulin and functional glucagon. This makes glucose management challenging, complicates recovery, and predisposes to hospital readmissions. This article aims to define the disease, describe the cause for its occurrence, review the anatomy of the endocrine pancreas, and explain how this condition differs from diabetes mellitus in the setting of post-operative management. The morbidity and mortality of post-TP endocrine insufficiency and practical treatment strategies are systematically reviewed from the literature. Finally, an evidence-based treatment algorithm is created for the practicing pancreatic surgeon and their care team of endocrinologists to aid in managing these complex patients.

METHODS

A PubMed, Science Citation Index/Social sciences Citation Index, and Cochrane Evidence-Based Medicine database search was undertaken along with extensive backward search of the references of published articles to identify studies evaluating endocrine morbidity and treatment after TP and to establish an evidence-based treatment strategy.

RESULTS

Indications for TP and the etiology of pancreatogenic diabetes are reviewed. After TP, ~80% patients develop hypoglycemic episodes and 40% experience severe hypoglycemia, resulting in 0-8% mortality and 25-45% morbidity. Referral to a nutritionist and endocrinologist for patient education before surgery followed by surgical reevaluation to determine if the patient has the appropriate understanding, support, and resources preoperatively has significantly reduced morbidity and mortality. The use of modern recombinant long-acting insulin analogues, continuous subcutaneous insulin infusion, and glucagon rescue therapy has greatly improved management in the modern era and constitute the current standard of care. A simple immediate post-operative algorithm was constructed.

CONCLUSION

Successful perioperative surgical management of total pancreatectomy and resulting pancreatogenic diabetes is critical to achieve acceptable post-operative outcomes, and we review the pertinent literature and provide a simple, evidence-based algorithm for immediate post-resection glycemic control.

CXCR4 and CXCR7 play distinct roles in cardiac lineage specification and pharmacologic β-adrenergic response

CXCR4 and CXCR7 are prominent G protein-coupled receptors (GPCRs) for chemokine stromal cell-derived factor-1 (SDF-1/CXCL12). This study demonstrates that CXCR4 and CXCR7 induce differential effects during cardiac lineage differentiation and β-adrenergic response in human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). Using lentiviral vectors to ablate CXCR4 and/or CXCR7 expression, hiPSC-CMs were tested for phenotypic and functional properties due to gene knockdown. Gene expression and flow cytometry confirmed the pluripotent and cardiomyocyte phenotype of undifferentiated and differentiated hiPSCs, respectively. Although reduction of CXCR4 and CXCR7 expression resulted in a delayed cardiac phenotype, only knockdown of CXCR4 delayed the spontaneous beating of hiPSC-CMs. Knockdown of CXCR4 and CXCR7 differentially altered calcium transients and β-adrenergic response in hiPSC-CMs. In engineered cardiac tissues, depletion of CXCR4 or CXCR7 had opposing effects on developed force and chronotropic response to β-agonists. This work demonstrates distinct roles for the SDF-1/CXCR4 or CXCR7 network in hiPSC-derived ventricular cardiomyocyte specification, maturation and function.

Microencapsulation in Clinical Islet Xenotransplantation

Allogeneic islet transplantation has become a viable treatment for patients with unstable type 1 diabetes; however, donor shortage and the necessity for immunosuppressive drugs are the major drawbacks of this approach. Microencapsulated porcine islet xenotransplantation could solve these drawbacks. Clinical porcine islet xenotransplantation as well as microencapsulated islet transplantation has been conducted without significant side effects. However, these transplantations are not as efficacious as allogeneic naked islet transplantation. High quality porcine islets, biocompatible capsules, and appropriate implant sites should be the key factors for improving efficacy. With improved efficacy, microencapsulated islet xenotransplantation will solve the major drawbacks associated with current islet transplantation.

Increase in anti-Gal IgM level is associated with early graft failure in intraportal porcine islet xenotransplantation

BACKGROUND

Anti-Gal is a major antibody induced in non-human primates (NHPs) after xenotransplantation. To understand the mechanism of graft rejection, we investigated the association between anti-Gal responses and graft failure in NHP recipients of porcine islet transplantation (PITx).

METHODS

Intraportal PITx was performed in 35 diabetic NHPs, and graft function was monitored. Early graft failure (EGF) was defined as loss of graft function within a month after PITx. Seven, 19, nine NHPs received immunosuppression (IS) without CD40 pathway blockade (Group I), with anti-CD154 (Group II), and with anti-CD40 (Group III), respectively. The anti-Gal levels on day 0 and day 7 of PITx were measured by ELISA.

RESULTS

The frequency of EGF was significantly lower in Group II (26.3%) than in Group I (100%, P=0.0012) and Group III (77.8%, P=0.0166). While levels of anti-Gal IgG in Group I and anti-Gal IgM in Group III increased on day 7 compared with day 0 (P=0.0156 and 0.0273), there was no increase in either on day 7 in Group II. The ratio of anti-Gal IgM or IgG level on day 7 to that on day 0 (Ratio7/0) was significantly higher in recipients with EGF than without EGF (P=0.0009 and 0.0027). ROC curve analysis of anti-Gal IgM Ratio7/0 revealed an area under the curve of 0.789 (P=0.0003).

CONCLUSIONS

IS with anti-CD154 suppressed anti-Gal responses and prevented EGF in PITx. Anti-Gal IgM Ratio7/0, being associated with EGF, is a predictive marker for EGF.

Clinical Benefit of Islet Xenotransplantation for the Treatment of Type 1 Diabetes

BACKGROUND

Allogeneic islet transplantation has become a viable option for the treatment of unstable type 1 diabetes. However, the donor shortage and the necessity of the immunosuppressive drugs are two major issues. To solve these issues, we performed islet xenotransplantation using encapsulated neonatal porcine islets without immunosuppressive drugs.

METHODS

Two different doses (approximately 5000IEQ/kg and 10,000IEQ/kg) of encapsulated neonatal porcine islets were transplanted twice (total approximately 10,000IEQ/kg and 20,000IEQ/kg) into four type 1 diabetic patients in each group (total 8 patients).

FINDINGS

In the higher dose group, all four patients improved HbA1c. This was maintained at a level of <7% for >600days with significant reduction of the frequency of unaware hypoglycemic events.

INTERPRETATION

The clinical benefit of islet xenotransplantation with microencapsulation has been shown.

Current status and future of clinical islet xenotransplantation

β-Cell replacement therapy, including allogeneic pancreas and islet transplantation, can normalize HbA1c levels in unstable type 1 diabetic (T1D) patients, but a donor shortage is a serious issue. To overcome this problem, xenotransplantation is an attractive option. In fact, islet transplantation from porcine pancreata was performed in the 1990s, which opened the door for islet xenotransplantation, but the possibility of porcine endogenous retrovirus (PERV) infection was raised, which has restricted progress in this field. The International Xenotransplantation Association published a consensus statement on conditions for undertaking clinical trials of porcine islet products in T1D to restart islet xenotransplantation safely. Clinical porcine islet xenotransplantation was restarted under comprehensive regulations in New Zealand. In addition, newly emerged gene-editing technologies have activated the xenotransplantation field. Islet xenotransplantation is becoming a clinical reality, with the results of recent studies showing promise to advance this field.

Immunoprotection and Functional Improvement of Allogeneic Islets in Diabetic Mice, Using a Stable Indoleamine 2,3-Dioxygenase Producing Scaffold

BACKGROUND

We have previously shown that an immunomodulatory enzyme, indoleamine 2,3-dioxygenase (IDO) in dermal fibroblasts generates a tryptophan-deficient environment that selectively inhibits proliferation and induces apoptosis of bystander CD4+ and CD8+ T cells, but not pancreatic islets. Because these immune cells are involved in islet allograft rejection, we hypothesized that transplantation of islets embedded in a novel 3-dimensional composite scaffold within which stable IDO-expressing fibroblasts serve as source of local immunosuppression would lead to normoglycemia in a streptozotocin-induced diabetic mouse model.

METHODS

Islet grafts were prepared by embedding stable IDO-expressing fibroblasts and allogeneic islets into a protease-resistant composite scaffold. Islets function and survival were evaluated in vitro using immunohistochemistry. Allografts were transplanted under the kidney capsule of streptozotocin-induced diabetic mice; viability, function, and criteria for graft take were evaluated. Flow cytometry was performed to determine specific intragraft, draining lymph nodes and spleen T-cell population, and splenocytes alloantigen responsiveness of graft recipients.

RESULTS

The results of a series of in vitro experiments revealed that IDO-expressing fibroblasts do not compromise islet function or survival. The expression of IDO suppressed the proliferation of alloantigen-stimulated splenocytes. The in vivo experiments revealed that local IDO expression delivered by lentiviral vector prolonged islet allograft survival (51.0 ± 2.9 days) by increasing the population of FOXP3+ regulatory T cells at the graft site and graft-draining lymph nodes and preventing T-cell infiltration.

CONCLUSIONS

This study shows that incorporation of islets within our novel matrix that is equipped with stable IDO-expressing fibroblasts prolongs allograft survival.

Suspension Culture Alters Insulin Secretion in Induced Human Umbilical Cord Matrix-Derived Mesenchymal Cells

OBJECTIVE

Worldwide, diabetes mellitus (DM) is an ever-increasing metabolic disorder. A promising approach to the treatment of DM is the implantation of insulin producing cells (IPC) that have been derived from various stem cells. Culture conditions play a pivotal role in the quality and quantity of the differentiated cells. In this experimental study, we have applied various culture conditions to differentiate human umbilical cord matrix-derived mesenchymal cells (hUCMs) into IPCs and measured insulin production.

MATERIALS AND METHODS

In this experimental study, we exposed hUCMs cells to pancreatic medium and differentiated them into IPCs in monolayer and suspension cultures. Pancreatic medium consisted of serum-free Dulbecco's modified eagle's medium Nutrient mixture F12 (DMEM/F12) medium with 17.5 mM glucose supplemented by 10 mM nicotinamide, 10 nM exendin-4, 10 nM pentagastrin, 100 pM hepatocyte growth factor, and B-27 serum-free supplement. After differentiation, insulin content was analyzed by gene expression, immunocytochemistry (IHC) and the chemiluminesence immunoassay (CLIA).

RESULTS

Reverse transcription-polymerase chain reaction (RT-PCR) showed efficient expressions of NKX2.2, PDX1 and INSULIN genes in both groups. IHC analysis showed higher expression of insulin protein in the hanging drop group, and CLIA revealed a significant higher insulin production in hanging drops compared with the monolayer group following the glucose challenge test.

CONCLUSION

We showed by this novel, simple technique that the suspension culture played an important role in differentiation of hUCMs into IPC. This culture was more efficient than the conventional culture method commonly used in IPC differentiation and cultivation.

Long-term cultured neonatal islet cell clusters demonstrate better outcomes for reversal of diabetes: in vivo and molecular profiles

BACKGROUND

Porcine neonatal islet-like cell clusters (NICC) are being considered as a source of β-cell replacement. However, the lag time to full function due to hormonal immaturity remains a problem. This study aimed to determine whether time in culture was important for NICC function in vivo.

METHODS

Neonatal islet-like cell clusters were isolated from piglets aged between 1 and 3 days, and cultured for up to 27 days post-isolation. Each week, NICC number, viability, and function were determined.

RESULTS

Neonatal islet-like cell clusters cultured for 12, 19, and 27 days achieved normal blood glucose levels at 46 days (85% of animals), 32 days (100% of animals), and 35 days (81% of animals), respectively. By comparison, standard 6-day culture took a mean of 63 days to achieve normoglycemia in 35% of animals. Longer time in culture resulted in a significant loss of islet equivalent over time. However, insulin gene expression levels were significantly higher at days 12, 19, 27 compared to day 6. Glucagon gene expression was highest at day 12, and significantly higher than day 6 at all time points. Bcl-2 gene expression increased over time, and tissue factor (TF) gene expression was highest on day 6 and then decreased over the remaining time points.

CONCLUSION

Culture of NICC for 12 days provides the best balance in vivo functional outcome for transplantation, shown by better reversal of diabetes, and higher levels of gene expression for insulin, glucagon and Bcl-2 and lower levels of TF expression with acceptable NICC number loss in terms of time and expense.

Mesenchymal stem cells and ligand incorporation in biomimetic poly(ethylene glycol) hydrogels significantly improve insulin secretion from pancreatic islets

The main goal of this study was to investigate pancreatic islet function with mesenchymal stem cells (MSCs) in a ligand-functionalized poly(ethylene glycol) (PEG) hydrogel for the treatment of type 1 diabetes (T1D). Rat bone marrow-derived MSCs (rBM-MSCs) were encapsulated within synthetic PEG hydrogel, and cell viability and apoptosis within this 3D environment was examined in detail. ATP content and caspase-3 activity of encapsulated MSCs showed that fibronectin-derived RGDS, laminin-derived IKVAV and/or insulinotropic glucagon-like peptide (GLP-1) were required to maintain MSC survival. Incorporation of these peptides into the hydrogel environment also improved pancreatic islet viability, where combinations of peptides had altered effects on islet survival. GLP-1 alone was the leading stimulator for insulin secretion. Cell adhesion peptides RGDS and IKVAV improved insulin secretion only when they were used in combination, but could not surpass the effect of GLP-1. Further, when pancreatic islets were co-encapsulated with MSCs within synthetic PEG hydrogel, a two-fold increase in the stimulation index was measured. Synergistic effects of MSCs and peptides were observed, with a seven-fold increase in the stimulation index. The results are promising and suggest that simultaneous incorporation of MSCs and ECM-derived peptides and/or GLP-1 can improve pancreatic islet function in response to altered glucose levels in the physiological environment. Copyright © 2014 John Wiley & Sons, Ltd.

An effective method to release human islets from surrounding acinar cells with agitation in high osmolality solution

INTRODUCTION

Islet purification is mainly performed by the density gradient method. However, purification of the embedded islets that are surrounded by exocrine tissue should be difficult, because their density is similar to exocrine tissue. In this study, we performed chart review to assess the relationship between the ratio of embedded islets and efficacy of purification. Then, we tested several conditions of a new method to free the islets from surrounded exocrine tissues using high osmolality solution with gentle agitation.

MATERIALS AND METHODS

First, we performed chart review of our human islet isolation. Second, embedded islet-enriched human islet fractions (embedded islets >50%) were suspended in University of Wisconsin (UW) solution (UW group, 320 mOsm/kg/H(2)0) or osmolality-adjusted UW solution (400, 500, and 600 mOsm/kg/H(2)0; 400 group, 500 group, and 600 group, respectively). Each tube was gently shaken at 4°C. The tissue samples were taken before shaking and after 15, 30, and 60 minutes. Islet yield, percentage of embedded islets, and viabilities were assessed.

RESULTS

The chart review revealed that high ratio of embedded islets deteriorated the efficacy of islet purification. The islet yield in all groups except for the 600 group did not change at 15 minutes, but it decreased in all groups at 60 minutes. The average percentage of embedded islets before shaking was 62.6%. Although percentage of embedded islets were decreasing in all groups, it was < 20% at 15 minutes in the 500 and 600 groups whereas it was >44% in the UW group, which indicated that higher osmolality would have a greater effect. Viability was >95% in all groups at 30 minutes.

CONCLUSIONS

The embedded islets deteriorated the efficacy of islet purification. Gentle agitation of embedded islets in high osmolality (500 mOsm/kg/H(2)O, 15 minutes) could release islets from surrounded exocrine tissue.

A new method for generating insulin-secreting cells from human pancreatic epithelial cells after islet isolation transformed by NeuroD1

The generation of insulin-secreting cells from nonendocrine pancreatic epithelial cells (NEPEC) has been demonstrated for potential clinical use in the treatment of diabetes. However, previous methods either had limited efficacy or required viral vectors, which hinder clinical application. In this study, we aimed to establish an efficient method of insulin-secreting cell generation from NEPEC without viral vectors. We used nonislet fractions from both research-grade human pancreata from brain-dead donors and clinical pancreata after total pancreatectomy with autologous islet transplantation to treat chronic pancreatitis. It is of note that a few islets could be mingled in the nonislet fractions, but their influence could be limited. The NeuroD1 gene was induced into NEPEC using an effective triple lipofection method without viral vectors to generate insulin-secreting cells. The differentiation was promoted by adding a growth factor cocktail into the culture medium. Using the research-grade human pancreata, the effective method showed high efficacy in the differentiation of NEPEC into insulin-positive cells that secreted insulin in response to a glucose challenge and improved diabetes after being transplanted into diabetic athymic mice. Using the clinical pancreata, similar efficacy was obtained, even though those pancreata suffered chronic pancreatitis. In conclusion, our effective differentiation protocol with triple lipofection method enabled us to achieve very efficient insulin-secreting cell generation from human NEPEC without viral vectors. This method offers the potential for supplemental insulin-secreting cell transplantation for both allogeneic and autologous islet transplantation.

Long-term function of islets encapsulated in a redesigned alginate microcapsule construct in omentum pouches of immune-competent diabetic rats

OBJECTIVE

Our study aim was to determine encapsulated islet graft viability in an omentum pouch and the effect of fibroblast growth factor 1 (FGF-1) released from our redesigned alginate microcapsules on the function of the graft.

METHODS

Isolated rat islets were encapsulated in an inner core made with 1.5% low-viscosity-high-mannuronic-acid alginate followed by an external layer made with 1.25% low-viscosity high-guluronic acid alginate with or without FGF-1, in microcapsules measuring 300 to 400 µm in diameter. The 2 alginate layers were separated by a perm-selective membrane made with 0.1% poly-L-ornithine, and the inner low-viscosity-high-mannuronic-acid core was partially chelated using 55 mM sodium citrate for 2 minutes.

RESULTS

A marginal mass of encapsulated islet allografts (∼2000 islets/kg) in streptozotocin-diabetic Lewis rats caused significant reduction in blood glucose levels similar to the effect observed with encapsulated islet isografts. Transplantation of alloislets coencapsulated with FGF-1 did not result in better glycemic control, but induced greater body weight maintenance in transplant recipients compared with those that received only alloislets. Histological examination of the retrieved tissue demonstrated morphologically and functionally intact islets in the microcapsules, with no signs of fibrosis.

CONCLUSIONS

We conclude that the omentum is a viable site for encapsulated islet transplantation.

Immunological characteristics of human umbilical cord mesenchymal stem cells and the therapeutic effects of their transplantion on hyperglycemia in diabetic rats

Islet transplantation involves the transplantation of pancreatic islets from the pancreas of a donor to another individual. It has proven to be an effective method for the treatment of type 1 diabetes. However, islet transplantation is hampered by immune rejection, as well as the shortage of donor islets. Human umbilical cord Wharton's jelly-derived mesenchymal stem cells (HUMSCs) are an ideal cell source for use in transplantation due to their biological characteristics and their use does not provoke any ethical issues. In this study, we investigated the immunological characteristics of HUMSCs and their effects on lymphocyte proliferation and the secretion of interferon (IFN)-γ, and explored whether direct cell-to-cell interactions and soluble factors, such as IFN-γ were important for balancing HUMSC-mediated immune regulation. We transplanted HUMSCs into diabetic rats to investigate whether these cells can colonize in vivo and differentiate into pancreatic β-cells, and whether the hyperglycemia of diabetic rats can be improved by transplantation. Our results revealed that HUMSCs did not stimulate the proliferation of lymphocytes and did not induce allogeneic or xenogeneic immune cell responses. qRT-PCR demonstrated that the HUMSCs produced an immunosuppressive isoform of human leukocyte antigen (HLA-I) and did not express HLA-DR. Flow cytometry revealed that the HUMSCs did not express immune response-related surface antigens such as, CD40, CD40L, CD80 and CD86. IFN-γ secretion by human peripheral blood lymphocytes was reduced when the cells were co-cultured with HUMSCs. These results suggest that HUMSCs are tolerated by the host in an allogeneic transplant. We transplanted HUMSCs into diabetic rats, and the cells survived in the liver and pancreas. Hyperglycemia of the diabetic rats was improved and the destruction of pancreatic cells was partly repaired by HUMSC transplantation. Hyperglycemic improvement may be related to the immunomodulatory effects of HUMSCs. However, the exact mechanisms involved remain to be further clarified.

Embryonic stem cells and inducible pluripotent stem cells: two faces of the same coin?

Embryonic stem cells (ESCs) are derived from the inner cell mass of the blastocysts and are characterized by the ability to renew themselves (self-renewal) and the capability to generate all the cells within the human body. In contrast, inducible pluripotent stem cells (iPSCs) are generated by transfection of four transcription factors in somatic cells. Like embryonic stem cells, they are able to self-renew and differentiate. Because of these features, both ESCs and iPSCs, are under intense clinical investigation for cell-based therapy. In this review, we revisit stem cell biology and add a new layer of complexity. In particular, we will highlight some of the complexities of the system, but also where there may be therapeutic potential for modulation of intrinsic stem cells and where particular caution may be needed in terms of cell transplantation therapies.

Low temperature condition prevents hypoxia-induced islet cell damage and HMGB1 release in a mouse model

One of the major issues in clinical islet transplantation is the poor efficacy of islet isolation. During pancreas preservation and islet isolation, islets suffer from hypoxia as islets are highly sensitive to hypoxic conditions.Cold preservation has been applied to minimize hypoxia-induced cell damage during organ preservation.However, the studies related to hypoxia-induced islet cell damage during islet isolation are limited. Recently,we demonstrated that mouse islets contain high levels of high-mobility group box 1 protein (HMGB1), and during proinflammatory cytokine-induced damage, islets release HMGB1 outside the cell. The released HMGB1 is involved in the initial events of early islet loss. In the present study, we hypothesize that low temperature conditions could prevent both hypoxia induced islet cell damage and HMGB1 release from islets in a mouse model. Isolated mouse islets underwent normoxic condition (95% air and 5% CO(2)) at 37°C or hypoxic conditions (1% O(2), 5% CO(2), and 94% N(2)) at 37°C (hypoxia-37°C islets), 22°C (hypoxia-22°C islets), or 4°C (hypoxia-4°C islets) for 12 h. In vitro and in vivo viability and functionality tests were performed. HMGB1, IL-6, G-CSF, KC, RANTES, MCP-1, and MIP-1α levels in the medium were measured. Low temperature conditions substantially reduced hypoxia-induced necrosis (p < 0.05) and apoptosis (p < 0.05). In addition, low temperature islet culture significantly increased the insulin secretion from islets by high glucose stimulation (p < 0.05). All of the recipient mice reversed diabetes after receiving the hypoxia-4°C islets but not after receipt of hypoxia-37°C or 22°C islets. The amounts of released HMGB1, IL-6, G-CSF, KC, RANTES, MCP-1, and MIP-1α were significantly reduced in the hypoxia-4°C islets compared to those of the hypoxia-37°C islets (p < 0.05). In conclusion, low temperature conditions could prevent hypoxia-induced islet cell damage, inflammatory reactions in islets, and HMGB1 release and expression. Low temperature conditions should improve the efficacy of isolated islets.

SUITO index for evaluation of clinical islet transplantation

The major endpoints for clinical islet transplantation for type 1 diabetes are insulin independence and reduction of hypoglycemic episodes. Both endpoints are influenced by patients' and physicians' preferences regarding the use of exogenous insulin. Therefore, development of an objective endpoint for assessing clinical islet transplantation is desirable. HOMA-beta score is useful in assessing functional β-cell mass. However, this score uses blood insulin levels that are influenced by exogenous insulin injection and therefore is not suitable for patients who receive exogenous insulin. For assessing functional β-cell mass for type 1 diabetic patients after islet transplantation, we created the Secretory Unit of Islet Transplant Objects (SUITO) index using fasting C-peptide and fasting glucose. The formula of the SUITO index is fasting C-peptide (ng/ml)/[fasting blood glucose − 63 (mg/dl)] × 1500. We demonstrated that, within 1 month of islet transplantation, an average SUITO index of >26 was an excellent predictor of achieving insulin independence. In addition, daily SUITO index scores correlated with a reduction of insulin dose and adversely correlated with blood glucose levels during an intravenous glucose tolerance test. Other important endpoints, reduction of hypoglycemic episodes and quality of life, also correlated with the SUITO index. Thus, the SUITO index is excellent for assessing important endpoints (insulin independence, reduction of hypoglycemia, improved quality of life) after allogeneic islet transplantation.

Correlation of released HMGB1 levels with the degree of islet damage in mice and humans and with the outcomes of islet transplantation in mice

Establishing reliable islet potency assay is a critical and unmet issue for clinical islet transplantation. Recently, we reported that islets contained high levels of high mobility group box 1 (HMGB1) and damaged islets released HMGB1 in a mouse model. In this study, we hypothesized that the amount of released HMGB1 could reflect the degree of islet damage, and could predict the outcome of islet transplantation. Four groups of damaged mouse islets and three groups of damaged human islets were generated by hypoxic conditions. These islets were assessed by in vivo (transplantation) and in vitro (released HMGB1 levels, released C-peptide levels, PI staining, TUNEL staining, ATP/DNA, and glucose-stimulated insulin release test) assays. In addition, the ability of each assay to distinguish between noncured (n = 13) and cured (n = 7) mice was assessed. The curative rates of STZ-diabetic mice after receiving control, hypoxia-3h, hypoxia-6h, and hypoxia-24h mouse islets were 100%, 40%, 0%, and 0%, respectively. Only amounts of released HMGB1 and ratio of PI staining significant increased according to the degree of damages in both human and mouse islets. In terms of predictability of curing diabetic mice, amounts of released HMGB1 showed the best sensitivity (100%), specificity (100%), positive (100%), and negative predictive values (100%) among all the assays. The amount of released HMGB1 reflected the degree of islet damage and correlated with the outcome of islet transplantation in mice. Hence, released HMGB1 levels from islets should be a useful marker to evaluate the potency of isolated islets.

Simultaneous pancreas kidney transplants in diabetic patients with end-stage renal disease: the 20-yr experience

INTRODUCTION

We are reporting the results over a 20 yr period of simultaneous pancreas-kidney transplants in patients with end-stage renal disease and diabetes mellitus. The outcomes of the transplants, performed between 1989 and 2008, are stratified by pretransplant c-peptide value.

METHODS

One hundred and seventy-three patients with end-stage renal disease due to diabetes, and were stratified according to undetectable c-peptide (x < 0.8 ng/mL) and detectable c-peptide (x > 0.8 ng/mL) levels.

RESULTS

Patients with detectable c-peptide (x > 0.8 ng/mL) were the oldest at diabetes diagnosis (24.2 vs. 15.4 yr, p < 0.0001), and oldest at transplant (42.8 vs. 38.5, p < 0.0001) had fewer years of insulin use (19.19 vs. 22.57 yr, p = 0.012), and were heavier pre transplant (BMI: 26.09 vs. 23.1, p < 0.0001), and heavier post transplant (29.8 vs. 24.7, p < 0.0001). Those with detectable c-peptide levels (x > 0.8 ng/mL) had better graft survival than those with an undetectable c-peptide level (x < 0.8 ng/mL), p = 0.064; while those with undetectable levels, had better patient survival than those with detectable c-peptide levels (p = 0.019).

CONCLUSION

Despite the differences between groups by BMI, age of onset of insulin use, and age at transplant, there was a difference in patient but not graft survival within the 20 yr follow-up period.

Islet purification method using large bottles effectively achieves high islet yield from pig pancreas

Porcine islets are a promising resource for xenotransplantation. However, low efficacy of islet isolation because of their marked fragility remains a problem. Recently we found that the standard purification method using COBE 2991 cell processor (COBE) with Ficoll density gradient solution damaged islets mechanically by high shearing force. In this study, we evaluated our new purification method using large plastic bottles for the efficacy of islet purification. Ten porcine pancreata were used. The average warm ischemic time was over 40 min; therefore, these pancreata were considered to be in a marginal condition. After digestion, the digested tissue was divided into three groups. Each group was purified using either top loading method with bottle (top group) or bottom loading method with bottle (bottom group) or standard COBE method (COBE group). Islet yield per pancreas weight (IEQ/g) and the rate of postpurification recovery in the top group were significantly higher than the COBE group (top: 8060 ± 1652 IEQ/g, bottom: 4572 ± 614 IE/g, COBE: 3900 ± 734 IE/g. p < 0.02 in top vs. COBE; top percentage of recovery: 99.3 ± 12.3%, bottom: 62.6 ± 8.8%, COBE: 49.5 ± 6.7%, p < 0.02 in top vs. bottom and COBE). The average sizes of purified islets in the top and bottom groups were significantly larger than COBE group (Average diameter top: 156 ± 8 μm, bottom: 147 ± 6 μm, COBE: 119 ± 6 μm, p < 0.01 in top vs. COBE and in bottom vs. COBE), which indicated that bottle method can reduce shear force during purification. Our new purification using top loading bottle method enabled us to obtain a high yield of porcine islets from marginal pancreata.

Personalized nanomedicine advancements for stem cell tracking

Recent technological developments in biomedicine have facilitated the generation of data on the anatomical, physiological and molecular level for individual patients and thus introduces opportunity for therapy to be personalized in an unprecedented fashion. Generation of patient-specific stem cells exemplifies the efforts toward this new approach. Cell-based therapy is a highly promising treatment paradigm; however, due to the lack of consistent and unbiased data about the fate of stem cells in vivo, interpretation of therapeutic effects remains challenging hampering the progress in this field. The advent of nanotechnology with a wide palette of inorganic and organic nanostructures has expanded the arsenal of methods for tracking transplanted stem cells. The diversity of nanomaterials has revolutionized personalized nanomedicine and enables individualized tailoring of stem cell labeling materials for the specific needs of each patient. The successful implementation of stem cell tracking will likely be a significant driving force that will contribute to the further development of nanotheranostics. The purpose of this review is to emphasize the role of cell tracking using currently available nanoparticles.

"Brittleness" in diabetes: easier spoken than broken

By definition, brittle diabetes (BD) is an unstable condition. Patients with BD suffer chronically from poor metabolic control, characterized by severe instability of glycemic values with frequent and unpredictable hypoglycemic and/or diabetic ketoacidosis episodes that cannot be attributed to failure in management. Quality of life is dramatically compromised because of very frequent acute complications leading to hospital admissions and because of premature chronic complications. It remains difficult to identify all patients with BD as diagnostic criteria are still not well defined. In practice, metabolic instability is manifested most obviously by chaotic glycemic profiles, which show greater and more unpredictable variation than in "stable" patients with diabetes. It is important that patients with BD are not adequately controlled, even by closely supervised, intensive insulin regimens, including continuous subcutaneous and/or intravenous insulin infusion. Their care is often very expensive in terms of time and resources, and their lives are constantly at risk for severe metabolic derangement. Management can also be frustrating and demoralizing for everyone involved, including the patient's family as well as the diabetes care team. Adopting a team approach, involving a broad range of disciplines, is essential in treating patients with BD and helping them to achieve and maintain both normoglycemia and quality of life.

Improvement of collagenase distribution with the ductal preservation for human islet isolation

A delivery of collagenase at the islet-exocrine interface is crucial for successful human islet isolation. In this study, we investigated how the ductal preservation method at the procurement site affected collagenase distribution. At first, we analyzed human islet isolation data among groups using Serva collagenase with or without ductal injection (DI) or using new Liberase MTF with DI. Then, to assess the distribution of collagenase, human pancreata were classified into two groups: without DI (no DI, n = 5) and with DI at the procurement site (DI, n = 5). Collagenase with 1% marking dye was perfused in the same manner as in our clinical isolation. The distension of the pancreas and the microscopic distribution of the dyed collagenase in pancreas sections were examined. For microscopic analysis, islets were counted and classified into three criteria: unreached, dye didn't reach the islet surface; surface, dye resided on the surface of the islet but not inside; and inside, dye was found inside the islet. As a result, DI groups substantially improved islet yields. In addition, Liberase MTF with DI significantly improved efficacy of pancreas digestion. All pancreata were well distended macroscopically. However, microscopically, the majority of islets in the no DI group were untouched by the dyed collagenase. Ductal preservation substantially improved dyed collagenase delivery on the surface of islets. In conclusion, delivery of collagenase on the surface of islets was unexpectedly insufficient without DI, which was substantially improved by DI. Thus, ductal preservation is a potent method to improve collagenase delivery and islet yields.

Impact of tissue volume and purification on clinical autologous islet transplantation for the treatment of chronic pancreatitis

Autologous islet transplantation after total pancreatectomy is an excellent treatment for painful chronic pancreatitis. Traditionally, islets have been isolated without purification; however, purification is applied when the tissue volume is large. Nevertheless, the impact of tissue volume and islet purification on clinical outcomes of autologous islet transplantation has not been well examined. We analyzed 27 cases of autologous islet transplantation performed from October 2006 to January 2011. After examining the relationship between tissue volume and portal pressure at various time points, we compared islet characteristics and clinical outcomes between cases with complications (complication group) and without (noncomplication group), as well as cases with purification (purification group) and without (nonpurification group). Tissue volume significantly correlated with maximum (R = 0.61), final (R = 0.53), and delta (i.e., difference between base and maximum; R = 0.71) portal pressure. The complication group had a significantly higher body mass index, tissue volume, islet yield, and portal pressure (maximum, final, delta), suggesting that complications were associated with high tissue volume and high portal pressure. Only one of four patients (25%) in the complication group became insulin free, whereas 11 of 23 patients (49%) in the noncomplication group became insulin free with smaller islet yields. The purification group had a higher islet yield and insulin independence rate but had similar final tissue volume, portal pressure, and complication rates compared with the nonpurification group. In conclusion, high tissue volume was associated with high portal pressure and complications in autologous islet transplantation. Islet purification effectively reduced tissue volume and had no negative impact on islet characteristics. Therefore, islet purification can reduce the risk of complications and may improve clinical outcome for autologous islet transplantation when tissue volume is large.

Induced pluripotent stem (iPS) cells inhibit apoptosis and fibrosis in streptozotocin-induced diabetic rats

Recent data suggests that transplanted bone marrow stem cells improve cardiac function in streptozotocin induced diabetic cardiomyopathy (SIDC). However, whether modified embryonic stem (ES) cells, induced pluripotent stem (iPS) cells, or factors released from these cells can inhibit apoptosis and fibrosis remains completely unknown. Therefore, we hypothesized that transplanted ES cells overexpressing pancreatic transcription factor 1 a (Ptf1a), a propancreatic endodermal transcription factor, iPS cells, or their respective conditioned media (CM) will attenuate cardiac remodeling and improve cardiac function in SIDC. Experimental diabetes was induced in male Sprague-Dawley rats (8-10 weeks old) by intraperitoneal injections of streptozotocin (STZ) (65 mg/kg body weight). Animals were divided into different groups including control, STZ, stem cells, and CM. Histology, TUNEL, caspase-3 activity, sarcomeric α-actin, and DHE stainings were performed to assess cardiac apoptosis, fibrosis, and oxidative stress. Animals transplanted with ES cells, iPS cells, or both CM showed a significant (p < 0.05) reduction in apoptosis compared with STZ treated animals. Furthermore, our data also shows that active apoptosis was present in cardiac myocytes as confirmed with combined stainings with TUNEL, sarcomeric α-actin, and active caspase-3 antibodies. Increased oxidative stress as evidenced by DHE staining was significantly (p < 0.05) reduced following stem cell or CM transplantation. Moreover, stem cells or CM also attenuated increased interstitial and vascular fibrosis in SIDC hearts. Echocardiography analysis showed a significant (p < 0.05) improvement in fractional shortening in stem cell and CM transplanted groups compared with respective controls. In conclusion, our data suggest that transplanted stem cells or their CM inhibit apoptosis, reduce fibrosis, and improve cardiac function in STZ-treated diabetic rats.