Non-Invasive Multiphoton Imaging of Islets Transplanted Into the Pinna of the NOD Mouse Ear Reveals the Immediate Effect of Anti-CD3 Treatment in Autoimmune Diabetes.
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SUBMITTER: Benson RA
PROVIDER: S-EPMC5968092 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Aims/hypothesisAutoimmune attack against the insulin-producing beta cells in the pancreatic islets results in type 1 diabetes. However, despite considerable research, details of the type 1 diabetes immunopathology in situ are not fully understood mainly because of difficult access to the pancreatic islets in vivo.MethodsHere, we used direct non-invasive confocal imaging of islets transplanted in the anterior chamber of the eye (ACE) to investigate the anti-islet autoimmunity in NOD mice before, during and after diabetes onset. ACE-transplanted islets allowed longitudinal studies of the autoimmune attack against islets and revealed the infiltration kinetics and in situ motility dynamics of fluorescence-labelled autoreactive T cells during diabetes development. Ex vivo immunostaining was also used to compare immune cell infiltrations into islet grafts in the eye and kidney as well as in pancreatic islets of the same diabetic NOD mice.ResultsWe found similar immune infiltration in native pancreatic and ACE-transplanted islets, which established the ACE-transplanted islets as reliable reporters of the autoimmune response. Longitudinal studies in ACE-transplanted islets identified in vivo hallmarks of islet inflammation that concurred with early immune infiltration of the islets and preceded their collapse and hyperglycaemia onset. A model incorporating data on ACE-transplanted islet degranulation and swelling allowed early prediction of the autoimmune attack in the pancreas and prompted treatments to intercept type 1 diabetes.Conclusions/interpretationThe current findings highlight the value of ACE-transplanted islets in studying early type 1 diabetes pathogenesis in vivo and underscore the need for timely intervention to halt disease progression.
| S-EPMC6561836 | biostudies-literature
Project description:Islet transplantation is a novel promising strategy to cure type 1 diabetes. However, the long-term outcome is still poor, because both function and survival of the transplant decline over-time. Non-invasive imaging methods have the potential to enable monitoring of islet survival after transplantation and the effects of immunosuppressive drugs on transplantation outcome. (111)In-labeled exendin-3 is a promising tracer to visualize native and transplanted islets by SPECT (Single Photon Emission Computed Tomography). In the present study, we hypothesized that islet microvasculature plays an important role determining the uptake of exendin-3 in islets when monitoring transplant survival. We observed (111)In-exendin-3 accumulation in the transplant as early as three days after transplantation and an increase in the uptake up to three weeks post-transplantation. Islet-revascularization correlated with the increase in (111)In-exendin-3 uptake, whereas fully re-established islet vasculature coincided with a stabilized uptake of the radiotracer in the transplant. Here, we demonstrate the importance of islet vasculature for in vivo delivery of radiotracers to transplanted islets and we demonstrate that optimal and stable uptake of exendin four weeks after transplantation opens the possibility for long-term monitoring of islet survival by SPECT imaging.
| S-EPMC4614800 | biostudies-other
Project description:Treatment of C57BL/6 or NOD mice with a monoclonal antibody to the CSF-1 receptor resulted in depletion of the resident macrophages of pancreatic islets of Langerhans that lasted for several weeks. Depletion of macrophages in C57BL/6 mice did not affect multiple parameters of islet function, including glucose response, insulin content, and transcriptional profile. In NOD mice depleted of islet-resident macrophages starting at 3 wk of age, several changes occurred: (i) the early entrance of CD4 T cells and dendritic cells into pancreatic islets was reduced, (ii) presentation of insulin epitopes by dispersed islet cells to T cells was impaired, and (iii) the development of autoimmune diabetes was significantly reduced. Treatment of NOD mice starting at 10 wk of age, when the autoimmune process has progressed, also significantly reduced the incidence of diabetes. Despite the absence of diabetes, NOD mice treated with anti-CSF-1 receptor starting at 3 or 10 wk of age still contained variably elevated leukocytic infiltrates in their islets when examined at 20-40 wk of age. Diabetes occurred in the anti-CSF-1 receptor protected mice after treatment with a blocking antibody directed against PD-1. We conclude that treatment of NOD mice with an antibody against CSF-1 receptor reduced diabetes incidence and led to the development of a regulatory pathway that controlled autoimmune progression.
| S-EPMC5715775 | biostudies-literature
Project description:Islet transplantation is an attractive treatment for type 1 diabetic patients. However, transplanted islets suffered from considerable cell death due to inflammatory reactions and oxidative stress. Ferroptosis is a programmed death characterized by iron-dependent lipid peroxidation, which has been implicated in the islet loss and dysfunction. Our previous studies showed that bilirubin displayed protection effect for islets by inhibiting early inflammation and oxidative stress. However, whether bilirubin protects islets by targeting ferroptosis has not yet been elucidated. Here, the isolated islet was exposed to ferroptosis-inducing agents with or without bilirubin. Islet viability, insulin secretion, and oxidative stress levels were assessed. Subsequently, the pretreated islets were transplanted into the subrenal site of streptozotocin-induced diabetic mice. Bilirubin could significantly attenuate ferroptosis in isolated islets, along with reduced oxidative stress, elevated GPX4 expression and upregulation of Nrf2/HO-1. Experimental data also confirmed that bilirubin could chelate iron. In vivo graft study demonstrated that euglycemia was achieved in diabetic mice receiving bilirubin-pretreated islets within 24 hours, while the control islets required at least 7 days. Bilirubin could improve islet viability and function through inhibiting ferroptosis, which could be of clinic interest to apply bilirubin into the islet transplantation system.
| S-EPMC7308534 | biostudies-literature
Project description:Transplantation of islet or beta cells is seen as the cure for type 1 diabetes since it allows physiological regulation of blood glucose levels without requiring any compliance from the patients. In order to circumvent the use of immunosuppressive drugs (and their side effects), semipermeable membranes have been developed to encapsulate and immunoprotect transplanted cells. This review presents the historical developments of immunoisolation and provides an update on the current research in this field. A particular emphasis is laid on the fabrication, characterization and performance of membranes developed for immunoisolation applications.
| S-EPMC4230297 | biostudies-literature
Project description:BackgroundMost studies on regenerative medicine focus on cell-based therapies and transplantations. Small-molecule therapeutics, though proved effective in different medical conditions, have not been extensively investigated in regenerative research. It is known that healing potential decreases with development and developmental changes are driven by epigenetic mechanisms, which suggests epigenetic repression of regenerative capacity.MethodsWe applied zebularine, a nucleoside inhibitor of DNA methyltransferases, to stimulate the regenerative response in a model of ear pinna injury in mice.FindingsWe observed the regeneration of complex tissue that was manifested as improved ear hole repair in mice that received intraperitoneal injections of zebularine. Six weeks after injury, the mean hole area decreased by 83.2 ± 9.4% in zebularine-treated and by 43.6 ± 15.4% in control mice (p < 10-30). Combined delivery of zebularine and retinoic acid potentiated and accelerated this effect, resulting in complete ear hole closure within three weeks after injury. We found a decrease in DNA methylation and transcriptional activation of neurodevelopmental and pluripotency genes in the regenerating tissues.InterpretationThis study is the first to demonstrate an effective induction of complex tissue regeneration in adult mammals using zebularine. We showed that the synergistic action of an epigenetic drug (zebularine) and a transcriptional activator (retinoic acid) could be effectively utilized to induce the regenerative response, thus delineating a novel pharmacological strategy for regeneration. The strategy was effective in the model of ear pinna regeneration in mice, but zebularine acts on different cell types, therefore, a similar approach can be tested in other tissues and organs.
| S-EPMC6710911 | biostudies-literature
Project description:The ear pinna is a complex tissue consisting of the dermis, cartilage, muscles, vessels, and nerves. Ear pinna healing is a model of regeneration in mammals. In some mammals, including rabbits, punch wounds in the ear pinna close spontaneously; in common-use laboratory mice, they remain for life. Agents inducing ear pinna healing are potential regenerative drugs. We tested the effects of selected bioactive agents on 2 mm ear pinna wound closure in BALB/c mice. Our previous research demonstrated that a DNA methyltransferase inhibitor, zebularine, remarkably induced ear pinna regeneration. Although experiments with two other demethylating agents, RG108 and hydralazine, were unsuccessful, a histone deacetylase inhibitor, valproic acid, was another epigenetic agent found to increase ear hole closure. In addition, we identified a pro-regenerative activity of 4-ketoretinoic acid, a retinoic acid metabolite. Attempts to counteract the regenerative effects of the demethylating agent zebularine, with folates as methyl donors, failed. Surprisingly, a high dose of methionine, another methyl donor, promoted ear hole closure. Moreover, we showed that the regenerated areas of ear pinna were supplied with nerve fibre networks and blood vessels. The ear punch model proved helpful in testing the pro-regenerative activities of small-molecule compounds and observations of peripheral nerve regeneration.
| S-EPMC9145447 | biostudies-literature
Project description:Insulin-producing cells (IPCs) generated by our established protocol have reached the non-clinical 'proof of concept' stage. Our strategy for their clinical application is the autotransplantation of IPCs into patients with type 1 diabetes mellitus (T1DM). In this context, the autoimmunity that characterized T1DM is important, rather than allorejection. We aimed to determine how these IPCs respond to T1DM autoimmunity. IPCs were generated from the subcutaneous fat tissue of non-obese diabetic (NOD) mice using our protocol. IPCs derived from NOD mice were transplanted under the kidney capsules of NOD mice at the onset of diabetes and the subsequent changes in blood glucose concentration were characterized. Blood glucose decreased within 30 days of transplantation, but increased again after 40-60 days in three of four recipient NOD mice. In tissue samples, the numbers of CD4+ and CD8+ T cells were significantly higher 60 days after transplantation than 30 days after transplantation. In conclusion, IPCs significantly ameliorate the diabetes of mice in the short term, but are damaged by autoimmunity in the longer term, as evidenced by local T cells accumulation. This study provides new insights into potential stem cell therapies for T1DM.
| S-EPMC8991208 | biostudies-literature
Project description:Background and purposePancreatic islet transplantation is a promising therapeutic approach for Type 1 diabetes. A major prerequisite for the survival of grafted islets is a rapid revascularization after transplantation. Erythropoietin (EPO), the primary regulator of erythropoiesis, has been shown to promote angiogenesis. Therefore, we investigated in this study whether EPO improves the revascularization of transplanted islets.Experimental approachIslets from FVB/N mice were transplanted into dorsal skinfold chambers of recipient animals, which were daily treated with an intraperitoneal injection of EPO (500 IU·kg-1 ) or vehicle (control) throughout an observation period of 14 days. In a second set of experiments, animals were only pretreated with EPO over a 6-day period prior to islet transplantation. The revascularization of the grafts was assessed by repetitive intravital fluorescence microscopy and immunohistochemistry. In addition, a streptozotocin-induced diabetic mouse model was used to study the effect of EPO-pretreatment on the endocrine function of the grafts.Key resultsEPO treatment slightly accelerated the revascularization of the islet grafts. This effect was markedly more pronounced in EPO-pretreated animals, resulting in significantly higher numbers of engrafted islets and an improved perfusion of endocrine tissue without affecting systemic haematocrit levels when compared with controls. Moreover, EPO-pretreatment significantly accelerated the recovery of normoglycaemia in diabetic mice after islet transplantation.Conclusion and implicationsThese findings demonstrate that, particularly, short-term EPO-pretreatment represents a promising therapeutic approach to improve the outcome of islet transplantation, without an increased risk of thromboembolic events.
| S-EPMC7060362 | biostudies-literature
Project description:Humanised xenograft models allow for the analysis of human tissue within a physiological environment in vivo. However, current models often rely on the angiogenesis and ingrowth of recipient vasculature to perfuse tissues, preventing analysis of biological processes and diseases involving human blood vessels. This limits the effectiveness of xenografts in replicating human physiology and may lead to issues with translating findings into human research. We have designed a xenograft model of human vasculature to address this issue. Human subcutaneous fat was cultured in vitro to promote blood vessel outgrowth prior to implantation into immunocompromised mice. We demonstrate that implants survived, retained human vasculature and anastomosed with the circulatory system of the recipient mouse. Significantly, by performing transplants into the ear pinna, this system enabled intravital observation of xenografts by multiphoton microscopy, allowing us to visualise the steps leading to vascular cytoadherence of erythrocytes infected with the human parasite Plasmodium falciparum. This model represents a useful tool for imaging the interactions that occur within human tissues in vivo and permits visualization of blood flow and cellular recruitment in a system which is amenable to intervention for various studies in basic biology together with drug evaluation and mechanism of action studies.
| S-EPMC7004987 | biostudies-literature