Harnessing cellular therapeutics for type 1 diabetes mellitus: progress, challenges, and the road ahead.

Type 1 diabetes mellitus (T1DM) is a growing global health concern that affects approximately 8.5 million individuals worldwide. T1DM is characterized by an autoimmune destruction of pancreatic ß cells, leading to a disruption in glucose homeostasis. Therapeutic intervention for T1DM requires a complex regimen of glycaemic monitoring and the administration of exogenous insulin to regulate blood glucose levels. Advances in continuous glucose monitoring and algorithm-driven insulin delivery devices have improved the quality of life of patients. Despite this, mimicking islet function and complex physiological feedback remains challenging. Pancreatic islet transplantation represents a potential functional cure for T1DM but is hindered by donor scarcity, variability in harvested cells, aggressive immunosuppressive regimens and suboptimal clinical outcomes. Current research is directed towards generating alternative cell sources, improving transplantation methods, and enhancing cell survival without chronic immunosuppression. This Review maps the progress in cell replacement therapies for T1DM and outlines the remaining challenges and future directions. We explore the state-of-the-art strategies for generating replenishable ß cells, cell delivery technologies and local targeted immune modulation. Finally, we highlight relevant animal models and the regulatory aspects for advancing these technologies towards clinical deployment.

SPIKENET: An Evidence-Based Therapy for Long COVID.

The COVID-19 pandemic has been one of the most impactful events in our lifetime, caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Multiple SARS-CoV-2 variants were reported globally, and a wide range of symptoms existed. Individuals who contract COVID-19 continue to suffer for a long time, known as long COVID or post-acute sequelae of COVID-19 (PASC). While COVID-19 vaccines were widely deployed, both unvaccinated and vaccinated individuals experienced long-term complications. To date, there are no treatments to eradicate long COVID. We recently conceived a new approach to treat COVID in which a 15-amino-acid synthetic peptide (SPIKENET, SPK) is targeted to the ACE2 receptor binding domain of SARS-CoV-2, which prevents the virus from attaching to the host. We also found that SPK precludes the binding of spike glycoproteins with the receptor carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) of a coronavirus, murine hepatitis virus-1 (MHV-1), and with all SARS-CoV-2 variants. Further, SPK reversed the development of severe inflammation, oxidative stress, tissue edema, and animal death post-MHV-1 infection in mice. SPK also protects against multiple organ damage in acute and long-term post-MHV-1 infection. Our findings collectively suggest a potential therapeutic benefit of SPK for treating COVID-19.

Acute and Long COVID Intestinal Changes in an Experimental Model of Coronavirus in Mice.

The COVID-19 pandemic, which emerged in early 2020, has had a profound and lasting impact on global health, resulting in over 7.0 million deaths and persistent challenges. In addition to acute concerns, there is growing attention being given to the long COVID health consequences for survivors of COVID-19 with documented cases of cardiovascular abnormalities, liver disturbances, lung complications, kidney issues, and noticeable cognitive deficits. Recent studies have investigated the physiological changes in various organs following prolonged exposure to murine hepatitis virus-1 (MHV-1), a coronavirus, in mouse models. One significant finding relates to the effects on the gastrointestinal tract, an area previously understudied regarding the long-lasting effects of COVID-19. This research sheds light on important observations in the intestines during both the acute and the prolonged phases following MHV-1 infection, which parallel specific changes seen in humans after exposure to SARS-CoV-2. Our study investigates the histopathological alterations in the small intestine following MHV-1 infection in murine models, revealing significant changes reminiscent of inflammatory bowel disease (IBD), celiac disease. Notable findings include mucosal inflammation, lymphoid hyperplasia, goblet cell hyperplasia, and immune cell infiltration, mirroring pathological features observed in IBD. Additionally, MHV-1 infection induces villous atrophy, altered epithelial integrity, and inflammatory responses akin to celiac disease and IBD. SPIKENET (SPK) treatment effectively mitigates intestinal damage caused by MHV-1 infection, restoring tissue architecture and ameliorating inflammatory responses. Furthermore, investigation into long COVID reveals intricate inflammatory profiles, highlighting the potential of SPK to modulate intestinal responses and restore tissue homeostasis. Understanding these histopathological alterations provides valuable insights into the pathogenesis of COVID-induced gastrointestinal complications and informs the development of targeted therapeutic strategies.

Predictors of lack of glycemic control in persons with type 2 diabetes.

BACKGROUND: Professional guidelines recommend an HbA1c < 7% for most people with diabetes and < 8.5% for those with relaxed glycemic goals. However, many people with type 2 diabetes mellitus (T2DM) are unable to achieve the desired HbA1c goal. This study evaluated factors associated with lack of improvement in HbA1c over 3 years. METHODS: All patients with T2DM treated within a major academic healthcare system during 2015-2020, who had at least one HbA1c value > 8.5% within 3 years from their last HbA1c were included in analysis. Patients were grouped as improved glycemic control (last HbA1c ≤ 8.5%) or lack of improvement (last HbA1c > 8.5%). Multivariate logistic regression analysis was performed to assess independent predictors of lack of improvement in glycemic control. RESULTS: Out of 2,232 patients who met the inclusion criteria, 1,383 had an improvement in HbA1c while 849 did not. In the fully adjusted model, independent predictors of lack of improvement included: younger age (odds ratio, 0.89 per 1-SD [12 years]; 95% CI, 0.79-1.00), female gender (1.30, 1.08-1.56), presence of hypertension (1.29, 1.08-1.55), belonging to Black race (1.32, 1.04-1.68, White as reference), living in low income area (1.86,1.28-2.68, high income area as reference), and insurance coverage other than Medicare (1.32, 1.05-1.66). Presence of current smoking was associated with a paradoxical improvement in HbA1c (0.69, 0.47-0.99). In a subgroup analysis, comparing those with all subsequent HbA1c values > 8.5% (N = 444) to those with all subsequent HbA1c values < 8.5% (N = 341), similar factors were associated with lack of improvement, but smoking was no longer significant. CONCLUSION: We conclude that socioeconomic factors like race, type of insurance coverage and living in low-income areas are associated with lack of improvement in HbA1c over a period of 3-years in people with T2DM. Intervention strategies focused on low-income neighborhoods need to be designed to improve diabetes management.

The anti-CD40L monoclonal antibody AT-1501 promotes islet and kidney allograft survival and function in nonhuman primates.

Prior studies of anti-CD40 ligand (CD40L)-based immunosuppression demonstrated effective prevention of islet and kidney allograft rejection in nonhuman primate models; however, clinical development was halted because of thromboembolic complications. An anti-CD40L-specific monoclonal antibody, AT-1501 (Tegoprubart), was engineered to minimize risk of thromboembolic complications by reducing binding to Fcγ receptors expressed on platelets while preserving binding to CD40L. AT-1501 was tested in both a cynomolgus macaque model of intrahepatic islet allotransplantation and a rhesus macaque model of kidney allotransplantation. AT-1501 monotherapy led to long-term graft survival in both islet and kidney transplant models, confirming its immunosuppressive potential. Furthermore, AT-1501-based regimens after islet transplant resulted in higher C-peptide, greater appetite leading to weight gain, and reduced occurrence of cytomegalovirus reactivation compared with conventional immunosuppression. These data support AT-1501 as a safe and effective agent to promote both islet and kidney allograft survival and function in nonhuman primate models, warranting further testing in clinical trials.

Implantable niche with local immunosuppression for islet allotransplantation achieves type 1 diabetes reversal in rats.

Pancreatic islet transplantation efficacy for type 1 diabetes (T1D) management is limited by hypoxia-related graft attrition and need for systemic immunosuppression. To overcome these challenges, we developed the Neovascularized Implantable Cell Homing and Encapsulation (NICHE) device, which integrates direct vascularization for facile mass transfer and localized immunosuppressant delivery for islet rejection prophylaxis. Here, we investigated NICHE efficacy for allogeneic islet transplantation and long-term diabetes reversal in an immunocompetent, male rat model. We demonstrated that allogeneic islets transplanted within pre-vascularized NICHE were engrafted, revascularized, and functional, reverting diabetes in rats for over 150 days. Notably, we confirmed that localized immunosuppression prevented islet rejection without inducing toxicity or systemic immunosuppression. Moreover, for translatability efforts, we showed NICHE biocompatibility and feasibility of deployment as well as short-term allogeneic islet engraftment in an MHC-mismatched nonhuman primate model. In sum, the NICHE holds promise as a viable approach for safe and effective islet transplantation and long-term T1D management.

Long-Term Sequelae of COVID-19 in Experimental Mice.

We recently reported acute COVID-19 symptoms, clinical status, weight loss, multi-organ pathological changes, and animal death in a murine hepatitis virus-1 (MHV-1) coronavirus mouse model of COVID-19, which were similar to that observed in humans with COVID-19. We further examined long-term (12 months post-infection) sequelae of COVID-19 in these mice. Congested blood vessels, perivascular cavitation, pericellular halos, vacuolation of neuropils, pyknotic nuclei, acute eosinophilic necrosis, necrotic neurons with fragmented nuclei, and vacuolation were observed in the brain cortex 12 months post-MHV-1 infection. These changes were associated with increased reactive astrocytes and microglia, hyperphosphorylated TDP-43 and tau, and a decrease in synaptic protein synaptophysin-1, suggesting the possible long-term impact of SARS-CoV-2 infection on defective neuronal integrity. The lungs showed severe inflammation, bronchiolar airway wall thickening due to fibrotic remodeling, bronchioles with increased numbers of goblet cells in the epithelial lining, and bronchiole walls with increased numbers of inflammatory cells. Hearts showed severe interstitial edema, vascular congestion and dilation, nucleated red blood cells (RBCs), RBCs infiltrating between degenerative myocardial fibers, inflammatory cells and apoptotic bodies and acute myocyte necrosis, hypertrophy, and fibrosis. Long-term changes in the liver and kidney were less severe than those observed in the acute phase. Noteworthy, the treatment of infected mice with a small molecule synthetic peptide which prevents the binding of spike protein to its respective receptors significantly attenuated disease progression, as well as the pathological changes observed post-long-term infection. Collectively, these findings suggest that COVID-19 may result in long-term, irreversible changes predominantly in the brain, lung, and heart.

Mechanism of Multi-Organ Injury in Experimental COVID-19 and Its Inhibition by a Small Molecule Peptide.

Severe disease from SARS-CoV-2 infection often progresses to multi-organ failure and results in an increased mortality rate amongst these patients. However, underlying mechanisms of SARS- CoV-2-induced multi-organ failure and subsequent death are still largely unknown. Cytokine storm, increased levels of inflammatory mediators, endothelial dysfunction, coagulation abnormalities, and infiltration of inflammatory cells into the organs contribute to the pathogenesis of COVID-19. One potential consequence of immune/inflammatory events is the acute progression of generalized edema, which may lead to death. We, therefore, examined the involvement of water channels in the development of edema in multiple organs and their contribution to organ dysfunction in a Murine Hepatitis Virus-1 (MHV-1) mouse model of COVID-19. Using this model, we recently reported multi-organ pathological abnormalities and animal death similar to that reported in humans with SARS-CoV-2 infection. We now identified an alteration in protein levels of AQPs 1, 4, 5, and 8 and associated oxidative stress, along with various degrees of tissue edema in multiple organs, which correlate well with animal survival post-MHV-1 infection. Furthermore, our newly created drug (a 15 amino acid synthetic peptide, known as SPIKENET) that was designed to prevent the binding of spike glycoproteins with their receptor(s), angiotensin- converting enzyme 2 (ACE2), and carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) (SARS-CoV-2 and MHV-1, respectively), ameliorated animal death and reversed altered levels of AQPs and oxidative stress post-MHV-1 infection. Collectively, our findings suggest the possible involvement of altered aquaporins and the subsequent edema, likely mediated by the virus-induced inflammatory and oxidative stress response, in the pathogenesis of COVID- 19 and the potential of SPIKENET as a therapeutic option.

Performance of islets of Langerhans conformally coated via an emulsion cross-linking method in diabetic rodents and nonhuman primates.

Polyethylene glycol (PEG)-based conformal coating (CC) encapsulation of transplanted islets is a promising ß cell replacement therapy for the treatment of type 1 diabetes without chronic immunosuppression because it minimizes capsule thickness, graft volume, and insulin secretion delay. However, we show here that our original CC method, the direct method, requiring exposure of islets to low pH levels and inclusion of viscosity enhancers during coating, severely affected the viability, scalability, and biocompatibility of CC islets in nonhuman primate preclinical models of type 1 diabetes. We therefore developed and validated in vitro and in vivo, in several small- and large-animal models of type 1 diabetes, an augmented CC method-emulsion method-that achieves hydrogel CCs around islets at physiological pH for improved cytocompatibility, with PEG hydrogels for increased biocompatibility and with fivefold increase in encapsulation throughput for enhanced scalability.

Multi-Organ Histopathological Changes in a Mouse Hepatitis Virus Model of COVID-19.

Infection with SARS-CoV-2, the virus responsible for the global COVID-19 pandemic, causes a respiratory illness that can severely impact other organ systems and is possibly precipitated by cytokine storm, septic shock, thrombosis, and oxidative stress. SARS-CoV-2 infected individuals may be asymptomatic or may experience mild, moderate, or severe symptoms with or without pneumonia. The mechanisms by which SARS-CoV-2 infects humans are largely unknown. Mouse hepatitis virus 1 (MHV-1)-induced infection was used as a highly relevant surrogate animal model for this study. We further characterized this animal model and compared it with SARS-CoV-2 infection in humans. MHV-1 inoculated mice displayed death as well as weight loss, as reported earlier. We showed that MHV-1-infected mice at days 7-8 exhibit severe lung inflammation, peribronchiolar interstitial infiltration, bronchiolar epithelial cell necrosis and intra-alveolar necrotic debris, alveolar exudation (surrounding alveolar walls have capillaries that are dilated and filled with red blood cells), mononuclear cell infiltration, hyaline membrane formation, the presence of hemosiderin-laden macrophages, and interstitial edema. When compared to uninfected mice, the infected mice showed severe liver vascular congestion, luminal thrombosis of portal and sinusoidal vessels, hepatocyte degeneration, cell necrosis, and hemorrhagic changes. Proximal and distal tubular necrosis, hemorrhage in interstitial tissue, and the vacuolation of renal tubules were observed. The heart showed severe interstitial edema, vascular congestion, and dilation, as well as red blood cell extravasation into the interstitium. Upon examination of the MHV-1 infected mice brain, we observed congested blood vessels, perivascular cavitation, cortical pericellular halos, vacuolation of neuropils, darkly stained nuclei, pyknotic nuclei, and associated vacuolation of the neuropil in the cortex, as well as acute eosinophilic necrosis and necrotic neurons with fragmented nuclei and vacuolation in the hippocampus. Our findings suggest that the widespread thrombotic events observed in the surrogate animal model for SARS-CoV-2 mimic the reported findings in SARS-CoV-2 infected humans, representing a highly relevant and safe animal model for the study of the pathophysiologic mechanisms of SARS-CoV-2 for potential therapeutic interventions.

Extended survival versus accelerated rejection of nonhuman primate islet allografts: Effect of mesenchymal stem cell source and timing.

Mesenchymal stem cells (MSC) have been shown to be immunomodulatory, tissue regenerative, and graft promoting; however, several questions remain with regard to ideal MSC source and timing of administration. In this study, we utilized a rigorous preclinical model of allogeneic islet cell transplantation, incorporating reduced immune suppression and near to complete mismatch of major histocompatibility antigens between the diabetic cynomolgus monkey recipient and the islet donor, to evaluate both the graft promoting impact of MSC source, that is, derived from the islet recipient, the islet donor or an unrelated third party as well as the impact of timing. Co-transplant of MSC and islets on post-operative day 0, followed by additional IV MSC infusions in the first posttransplant month, resulted in prolongation of rejection free and overall islet survival and superior metabolic control for animals treated with recipient as compared to donor or third-party MSC. Immunological analyses demonstrated that infusion of MSC from either source did not prevent alloantibody formation to the islet or MSC donor; however, treatment with recipient MSC resulted in significant downregulation of memory T cells, decreased anti-donor T cell proliferation, and a trend toward increased Tregulatory:Tconventional ratios.

Umbilical cord mesenchymal stem cells for COVID-19 acute respiratory distress syndrome: A double-blind, phase 1/2a, randomized controlled trial.

Acute respiratory distress syndrome (ARDS) in COVID-19 is associated with high mortality. Mesenchymal stem cells are known to exert immunomodulatory and anti-inflammatory effects and could yield beneficial effects in COVID-19 ARDS. The objective of this study was to determine safety and explore efficacy of umbilical cord mesenchymal stem cell (UC-MSC) infusions in subjects with COVID-19 ARDS. A double-blind, phase 1/2a, randomized, controlled trial was performed. Randomization and stratification by ARDS severity was used to foster balance among groups. All subjects were analyzed under intention to treat design. Twenty-four subjects were randomized 1:1 to either UC-MSC treatment (n = 12) or the control group (n = 12). Subjects in the UC-MSC treatment group received two intravenous infusions (at day 0 and 3) of 100 ± 20 × 106 UC-MSCs; controls received two infusions of vehicle solution. Both groups received best standard of care. Primary endpoint was safety (adverse events [AEs]) within 6 hours; cardiac arrest or death within 24 hours postinfusion). Secondary endpoints included patient survival at 31 days after the first infusion and time to recovery. No difference was observed between groups in infusion-associated AEs. No serious adverse events (SAEs) were observed related to UC-MSC infusions. UC-MSC infusions in COVID-19 ARDS were found to be safe. Inflammatory cytokines were significantly decreased in UC-MSC-treated subjects at day 6. Treatment was associated with significantly improved patient survival (91% vs 42%, P = .015), SAE-free survival (P = .008), and time to recovery (P = .03). UC-MSC infusions are safe and could be beneficial in treating subjects with COVID-19 ARDS.

Experimental Models of COVID-19.

COVID-19 is the most consequential pandemic of the 21st century. Since the earliest stage of the 2019-2020 epidemic, animal models have been useful in understanding the etiopathogenesis of SARS-CoV-2 infection and rapid development of vaccines/drugs to prevent, treat or eradicate SARS-CoV-2 infection. Early SARS-CoV-1 research using immortalized in-vitro cell lines have aided in understanding different cells and receptors needed for SARS-CoV-2 infection and, due to their ability to be easily manipulated, continue to broaden our understanding of COVID-19 disease in in-vivo models. The scientific community determined animal models as the most useful models which could demonstrate viral infection, replication, transmission, and spectrum of illness as seen in human populations. Until now, there have not been well-described animal models of SARS-CoV-2 infection although transgenic mouse models (i.e. mice with humanized ACE2 receptors with humanized receptors) have been proposed. Additionally, there are only limited facilities (Biosafety level 3 laboratories) available to contribute research to aid in eventually exterminating SARS-CoV-2 infection around the world. This review summarizes the most successful animal models of SARS-CoV-2 infection including studies in Non-Human Primates (NHPs) which were found to be susceptible to infection and transmitted the virus similarly to humans (e.g., Rhesus macaques, Cynomolgus, and African Green Monkeys), and animal models that do not require Biosafety level 3 laboratories (e.g., Mouse Hepatitis Virus models of COVID-19, Ferret model, Syrian Hamster model). Balancing safety, mimicking human COVID-19 and robustness of the animal model, the Murine Hepatitis Virus-1 Murine model currently represents the most optimal model for SARS-CoV-2/COVID19 research. Exploring future animal models will aid researchers/scientists in discovering the mechanisms of SARS-CoV-2 infection and in identifying therapies to prevent or treat COVID-19.

Transplantation of PEGylated islets enhances therapeutic efficacy in a diabetic nonhuman primate model.

Islet cell transplantation can lead to insulin independence, reduced hypoglycemia, and amelioration of diabetes complications in patients with type 1 diabetes. The systemic delivery of anti-inflammatory agents, while considered crucial to limit the early loss of islets associated with intrahepatic infusion, increases the burden of immunosuppression. In an effort to decrease the pharmaceutical load to the patient, we modified the pancreatic islet surface with long-chain poly(ethylene glycol) (PEG) to mitigate detrimental host-implant interactions. The effect of PEGylation on islet engraftment and long-term survival was examined in a robust nonhuman primate model via three paired transplants of dosages 4300, 8300, and 10 000 islet equivalents per kg body weight. A reduced immunosuppressive regimen of anti-thymocyte globulin induction plus tacrolimus in the first posttransplant month followed by maintenance with sirolimus monotherapy was employed. To limit transplant variability, two of the three pairs were closely MHC-matched recipients and received MHC-disparate PEGylated or untreated islets isolated from the same donors. Recipients of PEGylated islets exhibited significantly improved early c-peptide levels, reduced exogenous insulin requirements, and superior glycemic control, as compared to recipients of untreated islets. These results indicate that this simple islet modification procedure may improve islet engraftment and survival in the setting of reduced immunosuppression.

We Could Use More Tolerance: Role of Intestinal-Allograft-Derived Human Stem Cells.

Mixed chimerism is associated with allograft acceptance and tolerance. In this issue of Cell Stem Cell, Fu et al. (2019) provide evidence that functional, donor-derived hematopoietic stem and progenitor cells in the intestinal allograft can persist long-term, contribute to multi-lineage chimerism in the circulation, and result in T cell tolerance through host lymphoid organ selection.

Operational immune tolerance towards transplanted allogeneic pancreatic islets in mice and a non-human primate.

AIMS/HYPOTHESIS: Patients with autoimmune type 1 diabetes transplanted with pancreatic islets to their liver experience significant improvement in quality of life through better control of blood sugar and enhanced awareness of hypoglycaemia. However, long-term survival and efficacy of the intrahepatic islet transplant are limited owing to liver-specific complications, such as immediate blood-mediated immune reaction, hypoxia, a highly enzymatic and inflammatory environment and locally elevated levels of drugs including immunosuppressive agents, all of which are injurious to islets. This has spurred a search for new islet transplant sites and for innovative ways to achieve long-term graft survival and efficacy without life-long systemic immunosuppression and its complications. METHODS: We used our previously established approach of islet transplant in the anterior chamber of the eye in allogeneic recipient mouse models and a baboon model of diabetes, which were treated transiently with anti-CD154/CD40L blocking antibody in the peri-transplant period. Survival of the intraocular islet allografts was assessed by direct visualisation in the eye and metabolic variables (blood glucose and C-peptide measurements). We evaluated longitudinally the cytokine profile in the local microenvironment of the intraocular islet allografts, represented in aqueous humour, under conditions of immune rejection vs tolerance. We also evaluated the recall response in the periphery of the baboon recipient using delayed-type hypersensitivity (DTH) assay, and in mice after repeat transplant in the kidney following initial transplant with allogeneic islets in the eye or kidney. RESULTS: Results in mice showed >300 days immunosuppression-free survival of allogeneic islets transplanted in the eye or kidney. Notably, >70% of tolerant mice, initially transplanted in the eye, exhibited >400 days of graft survival after re-transplant in the kidney without immunosuppression compared with ~30% in mice that were initially transplanted in the kidney. Cytokine and DTH data provided evidence of T helper 2-driven local and peripheral immune regulatory mechanisms in support of operational immune tolerance towards the islet allografts in both models. CONCLUSIONS/INTERPRETATION: We are currently evaluating the safety and efficacy of intraocular islet transplantation in a phase 1 clinical trial. In this study, we demonstrate immunosuppression-free long-term survival of intraocular islet allografts in mice and in a baboon using transient peri-transplant immune intervention. These results highlight the potential for inducing islet transplant immune tolerance through the intraocular route. Therefore, the current findings are conceptually significant and may impact markedly on clinical islet transplantation in the treatment of diabetes.

Steroid-Free Immune Suppression Impairs Glycemic Control in a Healthy Cynomolgus Monkey.

The need for chronic immune suppression (IS) is one of the hurdles precluding widespread use of islet cell transplantation to restore glycemic control in patients with type 1 diabetes. We report the case of a healthy nonhuman primate (NHP) treated on and off for over 2.5 years with steroid-free IS, consisting of daclizumab induction and maintenance therapy with rapamycin and low dose tacrolimus. Treatment for 1 year resulted in a striking destabilization of glycemic control, with concomitant decreases in fasting c-peptide and insulin levels. Although these changes gradually reversed during a wash out period of 7 months, retreatment with the same therapy led to accelerated deterioration in glycemic control. Intravenous glucose tolerance and percentage of glycosylated hemoglobin testing further supported a dramatic effect on metabolic control. IS also led to decreases in weight during treatment. Histological evaluation of the pancreas revealed islet hyperplasia, with varying sizes and endocrine cell ratios that differed from normal islet composition, and parenchymal infiltration with adipose tissue. These deleterious effects of IS on glucose control and endocrine components in the native pancreas of a healthy NHP suggest that IS agents commonly utilized for islet transplantation may contribute to failure in islet allograft function in long-term transplant patients.

MRI-Guided, Noninvasive Delivery of Magneto-Electric Drug Nanocarriers to the Brain in a Nonhuman Primate.

A magnetically guided brain delivery method previously demonstrated in mice has not yet been translated for clinical applications due to the mismatch of available static magnet dimensions in relation to the human brain size and shape. To develop a human-compatible methodology, we explored magnetic resonance imaging (MRI) as a tool for the delivery of magneto-electric nanoparticles (MENPs) into the brain of a baboon, as a proof-of-concept study. MRI brain image analysis showed a reduction in T2* value at the basal ganglia, hemisphere, and vertex, thereby confirming successful MENP delivery to the brain. The observation of well-integrated morphologically healthy tissues and no blood toxicity over the study duration confirmed the biocompatibility of MENPs and the delivery procedure. Outcomes of this research present MRI-assisted delivery of MENPs to the brain as a safe and noninvasive method in larger species such as baboons and one step closer to human translation. This MENP-based nanomedicine delivery method can be used for clinical application in order to investigate effective central nervous system (CNS) therapies.

Microencapsulated adult porcine islets transplanted intraperitoneally in streptozotocin-diabetic non-human primates.

BACKGROUND: Xenogeneic donors would provide an unlimited source of islets for the treatment of type 1 diabetes (T1D). The goal of this study was to assess the function of microencapsulated adult porcine islets (APIs) transplanted ip in streptozotocin (STZ)-diabetic non-human primates (NHPs) given targeted immunosuppression. METHODS: APIs were encapsulated in: (a) single barium-gelled alginate capsules or (b) double alginate capsules with an inner, islet-containing compartment and a durable, biocompatible outer alginate layer. Immunosuppressed, streptozotocin-diabetic NHPs were transplanted ip with encapsulated APIs, and graft function was monitored by measuring blood glucose, %HbA1c, and porcine C-peptide. At graft failure, explanted capsules were assessed for biocompatibility and durability plus islet viability and functionality. Host immune responses were evaluated by phenotyping peritoneal cell populations, quantitation of peritoneal cytokines and chemokines, and measurement of anti-porcine IgG and IgM plus anti-Gal IgG. RESULTS: NHP recipients had reduced hyperglycemia, decreased exogenous insulin requirements, and lower percent hemoglobin A1c (%HbA1c) levels. Porcine C-peptide was detected in plasma of all recipients, but these levels diminished with time. However, relatively high levels of porcine C-peptide were detected locally in the peritoneal graft site of some recipients at sacrifice. IV glucose tolerance tests demonstrated metabolic function, but the grafts eventually failed in all diabetic NHPs regardless of the type of encapsulation or the host immunosuppression regimen. Explanted microcapsules were intact, "clean," and free-floating without evidence of fibrosis at graft failure, and some reversed diabetes when re-implanted ip in diabetic immunoincompetent mice. Histology of explanted capsules showed scant evidence of a host cellular response, and viable islets could be found. Flow cytometric analyses of peritoneal cells and peripheral blood showed similarly minimal evidence of a host immune response. Preformed anti-porcine IgG and IgM antibodies were present in recipient plasma, but these levels did not rise post-transplant. Peritoneal graft site cytokine or chemokine levels were equivalent to normal controls, with the exception of minimal elevation observed for IL-6 or IL-1ß, GRO-α, I-309, IP-10, and MCP-1. However, we found central necrosis in many of the encapsulated islets after graft failure, and explanted islets expressed endogenous markers of hypoxia (HIF-1α, osteopontin, and GLUT-1), suggesting a role for non-immunologic factors, likely hypoxia, in graft failure. CONCLUSIONS: With donor xenoislet microencapsulation and host immunosuppression, APIs corrected hyperglycemia after ip transplantation in STZ-diabetic NHPs in the short term. The islet xenografts lost efficacy gradually, but at graft failure, some viable islets remained, substantial porcine C-peptide was detected in the peritoneal graft site, and there was very little evidence of a host immune response. We postulate that chronic effects of non-immunologic factors, such as in vivo hypoxic and hyperglycemic conditions, damaged the encapsulated islet xenografts. To achieve long-term function, new approaches must be developed to prevent this damage, for example, by increasing the oxygen supply to microencapsulated islets in the ip space.