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Microencapsulation is a promising strategy to prolong the survival and function of transplanted pancreatic islets for diabetes therapy, albeit its translation has been impeded by incoherent graft performance. The use of decellularized ECM has lately gained substantial research momentum due to its innate capacity to augment the function of cells originating from the same tissue type. In the present study, the advantages of both these approaches are leveraged in a porcine pancreatic ECM (pECM)-based microencapsulation platform, thus significantly enhancing murine pancreatic islet performance. pECM-encapsulated islets sustain high insulin secretion levels in vitro, surpassing those of islets encapsulated in conventional alginate microcapsules. Moreover, pECM-encapsulated islet cells proliferate and produce an enriched intra-islet ECM framework, displaying a distinctive structural rearrangement. The beneficial effect of pECM encapsulation is further reinforced by the temporary protection against cytokine-induced cytotoxicity. In-vivo, this platform significantly improves glucose tolerance and achieves glycemic correction in 100% of immunocompetent diabetic mice without any immunosuppression, compared to only 50% mice achieved glycemic correction by alginate encapsulation. Altogether, the results presented herein reveal that pECM-based microencapsulation offers a natural pancreatic niche that can restore the function of isolated pancreatic islets and deliver them safely, avoiding the need for immunosuppression. STATEMENT OF SIGNIFICANCE: Aiming to improve pancreatic islet transplantation outcomes in diabetic patients, we developed a microencapsulation platform based on pancreatic extracellular matrix (pECM). In these microcapsules the islets are entrapped within a pECM hydrogel that mimics the natural pancreatic microenvironment. We show that pECM encapsulation supports the islets' viability and function in culture, and provides temporal protection against cytokine-induced stress. In a diabetic mouse model, pECM encapsulation significantly improved glucose tolerance and achieved glycemic correction without any immunosuppression. These results reveal the potential of pECM encapsulation as a viable treatment for diabetes, providing a solid scientific basis for more advanced preclinical studies.
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Diabetes Mellitus Experimental , Trasplante de Islotes Pancreáticos , Islotes Pancreáticos , Humanos , Ratones , Animales , Porcinos , Diabetes Mellitus Experimental/terapia , Cápsulas , Trasplante de Islotes Pancreáticos/métodos , Insulina , Matriz Extracelular , Glucosa/farmacología , Alginatos/farmacología , CitocinasRESUMEN
Islets transplantation is a promising treatment for type 1 diabetes mellitus. However, severe host immune rejection and poor oxygen/nutrients supply due to the lack of surrounding capillary network often lead to transplantation failure. Herein, a novel bioartificial pancreas is constructed via islets microencapsulation in core-shell microgels and macroencapsulation in a hydrogel scaffold prevascularized in vivo. Specifically, a hydrogel scaffold containing methacrylated gelatin (GelMA), methacrylated heparin (HepMA) and vascular endothelial growth factor (VEGF) is fabricated, which can delivery VEGF in a sustained style and thus induce subcutaneous angiogenesis. In addition, islets-laden core-shell microgels using methacrylated hyaluronic acid (HAMA) as microgel core and poly(ethylene glycol) diacrylate (PEGDA)/carboxybetaine methacrylate (CBMA) as shell layer are prepared, which provide a favorable microenvironment for islets and simultaneously the inhibition of host immune rejection via anti-adhesion of proteins and immunocytes. As a result of the synergistic effect between anti-adhesive core-shell microgels and prevascularized hydrogel scaffold, the bioartificial pancreas can reverse the blood glucose levels of diabetic mice from hyperglycemia to normoglycemia for at least 90 days. We believe this bioartificial pancreas and relevant fabrication method provide a new strategy to treat type 1 diabetes, and also has broad potential applications in other cell therapies.
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Objective To evaluate the effect of mesenchymal stem cell (MSC) coated-islets on instant blood-mediated inflammatory reaction (IBMIR) after islet transplantation. Methods MSC labeled with tracer and human islets were placed into an ultra-low adsorption cell culture dish, shaken and mixed twice at an interval of 0.5 h, and then incubated at 37 ℃ and 5% CO2 for 24 h to obtain MSC-coated islets. The coating effect of MSC and in vitro function of the islets were assessed. A blood circulation tube-shaped model was established in vitro. In the blank control group, 0.2 mL of islet culture solution was added. In the islet group, 800 islet equivalent quantity (IEQ) of uncoated islets were supplemented. In the MSC-coated islets group, 800 IEQ of MSC-coated islets were added, and circulated for 60 min at 37 ℃. A portion of 0.5 mL blood sample was taken for routine blood test at 0, 30 and 60 min, respectively. After 60 min circulation, the blood sample was filtered with a 70 μm filter to collect plasma, blood clots and islets. Blood clots and islets were subject to hematoxylin-eosin (HE) staining and immunohistochemical staining. Morphological changes and the aggregation of CD11b-positive cells surrounding the islets were observed. The contents of plasma thrombin-antithrombin complex (TAT), tissue factor (TF), C3a, C5b-9, interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF)-α, monocyte chemoattractant protein (MCP)-1 and IL-8 were determined by enzyme-linked immune absorbent assay. Results After 24 h co-incubation, the islets were coated by MSC, with a coating degree of approximately 80%. In the islet and MSC-coated islet group, a large quantity of neutrophils and monocytes were observed surrounding the blood clots and islets, and the quantity of CD11b-positive cells in the MSC-coated islet group was less compared with that in the islet group. After co-incubation with the whole blood for 0, 30 and 60 min, the quantity of platelets, neutrophils and monocytes was declined in the MSC-coated and islet groups, and gradually decreased over time. Compared with the blank control group, the quantity of platelets, monocytes and neutrophils was lower, whereas the TF content was higher in the MSC-coated islet group. Compared with the islet group, the quantity of platelets, monocytes and neutrophils was higher, whereas the TAT and TF contents were less in the MSC-coated islet group, the differences were statistically significant (all P < 0.05). Compared with the blank control group, the expression levels of C3a, C5b-9, IL-6, TNF-α and IL-8 were up-regulated in the MSC-coated islet group. Compared with the islet group, the expression levels of C3a, C5b-9, IL-1β, IL-6, TNF-α, IL-8 and MCP-1 were down-regulated in the MSC-coated islet group, and the differences were statistically significant (all P < 0.05). Conclusions MSC-coated islets may reduce the exposure of islet TF in the blood and prevent the incidence of IBMIR during the coagulation response stage, thereby mitigating the injury and loss of islet allograft in the early stage of islet transplantation.
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As an effective procedure for type 1 diabetes mellitus and end-stage type 2 diabetes mellitus, islet transplantation could enable those patients to obtain proper control of blood glucose levels. Instant blood-mediated inflammatory reaction (IBMIR) is a nonspecific inflammation during early stage after islet transplantation. After IBMIR occurs, coagulation cascade, complement system activation and inflammatory cell aggregation may be immediately provoked, leading to loss of a large quantity of transplant islets, which severely affects clinical efficacy of islet transplantation. How to alleviate the islet damage caused by IBMIR is a hot topic in islet transplantation. Heparin and etanercept, an inhibitor of tumor necrosis factor-α, are recommended as drugs for treating IBMIR following islet transplantation. Recent studies have demonstrated that multiple approaches and drugs may be adopted to mitigate the damage caused by IBMIR to the islets. In this article, the findings in clinical and preclinical researches were reviewed, aiming to provide reference for the management of IBMIR after islet transplantation.
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Type 1 diabetes (T1D) is an autoimmune disease caused by the immune system attacking and destroying insulin-producing ß cells in the pancreas. Islet transplantation is becoming one of the most promising therapies for T1D patients. However, its clinical use is limited by substantial cell loss after islet infusion, closely related to immune reactions, including instant blood-mediated inflammatory responses, oxidative stress, and direct autoimmune attack. Especially the grafted islets are not only exposed to allogeneic immune rejection after transplantation but are also subjected to an autoimmune process that caused the original disease. Due to the development and convergence of expertise in biomaterials, nanotechnology, and immunology, protective strategies are being investigated to address this issue, including exploring novel immune protective agents, encapsulating islets with biomaterials, and searching for alternative implantation sites, or co-transplantation with functional cells. These methods have significantly increased the survival rate and function of the transplanted islets. However, most studies are still limited to animal experiments and need further studies. In this review, we introduced the immunological challenges for islet graft and summarized the recent developments in immune-protective strategies to improve the outcomes of islet transplantation.
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Diabetes Mellitus Tipo 1 , Células Secretoras de Insulina , Trasplante de Islotes Pancreáticos , Animales , Materiales Biocompatibles/metabolismo , Trasplante de Islotes Pancreáticos/efectos adversos , Estrés OxidativoRESUMEN
The purpose of this study was to assess the natural partial oxygen pressure (pO2) of subcutaneous (SC) and intraperitoneal (IP) sites in mice to determine their relative suitability as sites for placement of implants. The pO2 measurements were performed using oxygen imaging of solid probes using lithium phthalocyanine (LiPc) as the oxygen sensitive material. LiPc is a water-insoluble crystalline probe whose spin-lattice and spin-spin relaxation rates (R1 and R2) are sensitive to the local oxygen concentration. To facilitate direct in vivo oxygen imaging, we prepared a solid probe containing encapsulated LiPc crystals in polydimethylsiloxane (PDMS), an oxygen-permeable and bioinert polymer. Although LiPc-PDMS or similar probes have been used in repeated spectroscopic or average oxygen measurements using continuous wave electron paramagnetic resonance (EPR) since the late 1990s and now have advanced to clinical applications, they have not been used for pulse EPR oxygen imaging. One LiPc-PDMS probe of 2 mm diameter and 10 mm length was implanted in SC or IP sites (left or right side) in each animal. The pO2 imaging of implanted LiPc-PDMS probes was performed weekly for 6 weeks using O2M preclinical 25 mT oxygen imager, JIVA-25™, using the pulse inversion recovery electron spin echo method. At week 6, the probes were recovered, and histological examinations were performed. We report in this study, first-ever solid probe oxygen imaging of implanted devices and pO2 assessment of SC and IP sites.
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Oxígeno , Polímeros , Animales , Espectroscopía de Resonancia por Spin del Electrón/métodos , Ratones , Presión Parcial , Marcadores de SpinRESUMEN
Diabetes mellitus refers to a group of metabolic disorders which affect how the body uses glucose impacting approximately 9% of the population worldwide. This review covers the most recent technological advances envisioned to control and/or reverse Type 1 diabetes mellitus (T1DM), many of which will also prove effective in treating the other forms of diabetes mellitus. Current standard therapy for T1DM involves multiple daily glucose measurements and insulin injections. Advances in glucose monitors, hormone delivery systems, and control algorithms generate more autonomous and personalised treatments through hybrid and fully automated closed-loop systems, which significantly reduce hypo- and hyperglycaemic episodes and their subsequent complications. Bi-hormonal systems that co-deliver glucagon or amylin with insulin aim to reduce hypoglycaemic events or increase time spent in target glycaemic range, respectively. Stimuli responsive materials for the controlled delivery of insulin or glucagon are a promising alternative to glucose monitors and insulin pumps. By their self-regulated mechanism, these "smart" drugs modulate their potency, pharmacokinetics and dosing depending on patients' glucose levels. Islet transplantation is a potential cure for T1DM as it restores endogenous insulin and glucagon production, but its use is not yet widespread due to limited islet sources and risks of chronic immunosuppression. New encapsulation strategies that promote angiogenesis and oxygen delivery while protecting islets from recipients' immune response may overcome current limiting factors.
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Diabetes Mellitus Tipo 1 , Dispositivos Electrónicos Vestibles , Glucemia/metabolismo , Diabetes Mellitus Tipo 1/tratamiento farmacológico , Glucagón/uso terapéutico , Glucosa , Humanos , Insulina/uso terapéutico , TecnologíaRESUMEN
Type 1 diabetes (T1D) is caused by low insulin production and chronic hyperglycemia due to destruction of pancreatic ß-cells. Cell transplantation is an attractive alternative approach compared to insulin injection. However, cell therapy has been limited by major challenges, including life-long requirement for immunosuppressive drugs to prevent host immune responses. Encapsulation of the transplanted cells can solve the problem of immune rejection, by providing a physical barrier between the transplanted cells and the recipient's immune cells. Despite current disputes in cell encapsulation approaches, thanks to recent advances in the fields of biomaterials and transplantation immunology, extensive effort has been dedicated to immunoengineering strategies, in combination with encapsulation technologies, to overcome the problem of host's immune responses. This review summarizes the most commonly used encapsulation and immunoengineering strategies combined with cell therapy, which have been applied as a novel approach to improve cell replacement therapies for management of T1D. Recent advances in the fields of biomaterial design, nanotechnology, as well as deeper knowledge about immune modulation had significantly improved cell encapsulation strategies. However, further progress requires combined application of novel immunoengineering approaches and islet/ß-cell transplantation. Impact statement Cell encapsulation shows promising potential in preventing host's immune responses and rejection of islets or ß-cells by providing a selectively permeable barrier between the host and the transplanted cells. Innovative materials, conformal nanocoatings, and immunomodulation have provided promising approaches in the field of encapsulation technology. Novel nanocarriers have been synthesized to release and deliver immunosuppressive agents to islets/ß-cells within the capsules in a controlled manner. The immunoengineering approach (immunosuppressive and immunomodulatory agents) could overcome the challenges of cell replacement therapy in type 1 diabetes.
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Diabetes Mellitus Tipo 1 , Insulinas , Trasplante de Islotes Pancreáticos , Islotes Pancreáticos , Humanos , Diabetes Mellitus Tipo 1/terapia , Diabetes Mellitus Tipo 1/metabolismo , Materiales Biocompatibles , Cápsulas/metabolismo , Islotes Pancreáticos/metabolismo , Inmunosupresores/metabolismo , Insulinas/metabolismoRESUMEN
Islet transplantation provides a promising strategy in treating type 1 diabetes as an autoimmune disease, in which damaged ß-cells are replaced with new islets in a minimally invasive procedure. Although islet transplantation avoids the complications associated with whole pancreas transplantations, its clinical applications maintain significant drawbacks, including long-term immunosuppression, a lack of compatible donors, and blood-mediated inflammatory responses. Biomaterial-assisted islet transplantation is an emerging technology that embeds desired cells into biomaterials, which are then directly transplanted into the patient, overcoming the aforementioned challenges. Among various biomaterials, hydrogels are the preferred biomaterial of choice in these transplants due to their ECM-like structure and tunable properties. This review aims to present a comprehensive overview of hydrogel-based biomaterials that are engineered for encapsulation of insulin-secreting cells, focusing on new hydrogel design and modification strategies to improve ß-cell viability, decrease inflammatory responses, and enhance insulin secretion. We will discuss the current status of clinical studies using therapeutic bioengineering hydrogels in insulin release and prospective approaches.
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Islet transplantation is a promising treatment for type 1 diabetes. However, treatment failure can result from loss of functional cells associated with cell dispersion, low viability, and severe immune response. To overcome these limitations, various islet encapsulation approaches have been introduced. Among them, macroencapsulation offers the advantages of delivering and retrieving a large volume of islets in one system. In this study, we developed a hybrid encapsulation system composed of a macroporous polymer capsule with stagger-type membrane and assemblable structure, and a nanoporous decellularized extracellular matrix (dECM) hydrogel containing pancreatic islet-like aggregates using 3D bioprinting technique. The outer part (macroporous polymer capsule) was designed to have an interconnected porous architecture, which allows insulin-producingß-cells encapsulated in the hybrid encapsulation system to maintain their cellular behaviors, including viability, cell proliferation, and insulin-producing function. The inner part (nanoporous dECM hydrogel), composed of the 3D biofabricated pancreatic islet-like aggregates, was simultaneously placed into the macroporous polymer capsule in one step. The developed hybrid encapsulation system exhibited biocompatibilityin vitroandin vivoin terms of M1 macrophage polarization. Furthermore, by controlling the printing parameters, we generated islet-like aggregates, improving cell viability and functionality. Moreover, the 3D bioprinted pancreatic islet-like aggregates exhibited structural maturation and functional enhancement associated with intercellular interaction occurring at theß-cell edges. In addition, we also investigated the therapeutic potential of a hybrid encapsulation system by integrating human pluripotent stem cell-derived insulin-producing cells, which are promising to overcome the donor shortage problem. In summary, these results demonstrated that the 3D bioprinting approach facilitates the fabrication of a hybrid islet encapsulation system with multiple materials and potentially improves the clinical outcomes by driving structural maturation and functional improvement of cells.
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Bioimpresión , Islotes Pancreáticos , Células Madre Pluripotentes , Bioimpresión/métodos , Humanos , Hidrogeles/química , Insulina/metabolismo , Células Madre Pluripotentes/metabolismo , Polímeros , Impresión Tridimensional , Ingeniería de Tejidos/métodos , Andamios del Tejido/químicaRESUMEN
Encapsulation of insulin-producing cells is a promising strategy for treatment of type 1 diabetes. However, engineering an encapsulation device that is both safe (i.e., no cell escape and no breakage) and functional (i.e., low foreign-body response (FBR) and high mass transfer) remains a challenge. Here, a family of zwitterionic polyurethanes (ZPU) with sulfobetaine groups in the polymer backbone is developed, which are fabricated into encapsulation devices with tunable nanoporous structures via electrospinning. The ZPU encapsulation device is hydrophilic and fouling-resistant, exhibits robust mechanical properties, and prevents cell escape while still allowing efficient mass transfer. The ZPU device also induces a much lower FBR or cellular overgrowth upon intraperitoneal implantation in C57BL/6 mice for up to 6 months compared to devices made of similar polyurethane without the zwitterionic modification. The therapeutic potential of the ZPU device is shown for islet encapsulation and diabetes correction in mice for ≈3 months is demonstrated. As a proof of concept, the scalability and retrievability of the ZPU device in pigs and dogs are further demonstrated. Collectively, these attributes make ZPU devices attractive candidates for cell encapsulation therapies.
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Materiales Biocompatibles/química , Islotes Pancreáticos/química , Nanoporos , Poliuretanos/química , Animales , Tratamiento Basado en Trasplante de Células y Tejidos , Diabetes Mellitus Experimental/terapia , Perros , Interacciones Hidrofóbicas e Hidrofílicas , Islotes Pancreáticos/fisiología , Trasplante de Islotes Pancreáticos/efectos adversos , Masculino , Ratones , Ratones Endogámicos C57BL , PorcinosRESUMEN
Pancreatic islet transplantation to restore insulin production in Type 1 Diabetes Mellitus patients is commonly performed by infusion of islets into the hepatic portal system. However, the risk of portal vein thrombosis or elevation of portal pressure after transplantation introduces challenges to this procedure. Thus, alternative sites have been investigated, among which the omentum represents an ideal candidate. The surgical site is easily accessible, and the tissue is highly vascularized with a large surface area for metabolic exchange. Furthermore, the ability of the omentum to host large volumes of islets represents an intriguing if not ideal site for encapsulated islet transplantation. Research on the safety and efficacy of the omentum as a transplant site focuses on the utilization of biologic scaffolds or encapsulation of islets in a biocompatible semi-permeable membrane. Currently, more clinical trials are required to better characterize the safety and efficacy of islet transplantation into the omentum.
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Diabetes Mellitus Tipo 1 , Trasplante de Islotes Pancreáticos , Islotes Pancreáticos , Diabetes Mellitus Tipo 1/cirugía , Humanos , Insulina , Epiplón/cirugíaRESUMEN
BACKGROUND: Islet transplantation with neonatal porcine islets (NPIs) is a promising treatment for type 1 diabetes (T1D), but immune rejection poses a major hurdle for clinical use. Innate immune-derived reactive oxygen species (ROS) synthesis can facilitate islet xenograft destruction and enhance adaptive immune responses. METHODS: To suppress ROS-mediated xenograft destruction, we utilized nanothin encapsulation materials composed of multilayers of tannic acid (TA), an antioxidant, and a neutral polymer, poly(N-vinylpyrrolidone) (PVPON). We hypothesized that (PVPON/TA)-encapsulated NPIs will maintain euglycemia and dampen proinflammatory innate immune responses following xenotransplantation. RESULTS: (PVPON/TA)-encapsulated NPIs were viable and glucose-responsive similar to non-encapsulated NPIs. Transplantation of (PVPON/TA)-encapsulated NPIs into hyperglycemic C57BL/6.Rag or NOD.Rag mice restored euglycemia, exhibited glucose tolerance, and maintained islet-specific transcription factor levels similar to non-encapsulated NPIs. Gene expression analysis of (PVPON/TA)-encapsulated grafts post-transplantation displayed reduced proinflammatory Ccl5, Cxcl10, Tnf, and Stat1 while enhancing alternatively activated macrophage Retnla, Arg1, and Stat6 mRNA accumulation compared with controls. Flow cytometry analysis demonstrated significantly reduced innate immune infiltration, MHC-II, co-stimulatory molecule, and TNF expression with concomitant increases in arginase-1+ macrophages and dendritic cells. Similar alterations in immune responses were observed following xenotransplantation into immunocompetent NOD mice. CONCLUSION: Our data suggest that (PVPON/TA) encapsulation of NPIs is an effective strategy to decrease inflammatory innate immune signals involved in NPI xenograft responses through STAT1/6 modulation without compromising islet function.
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Trasplante de Islotes Pancreáticos , Islotes Pancreáticos , Animales , Humanos , Inmunidad Innata , Ratones , Ratones Endogámicos C57BL , Ratones Endogámicos NOD , Porcinos , Taninos , Trasplante HeterólogoRESUMEN
The clinical success rate of islet transplantation, namely independence from insulin injections, is limited by factors that lead to graft failure, including inflammation, acute ischemia, acute phase response, and insufficient vascularization. The ischemia and insufficient vascularization both lead to high levels of oxidative stress, which are further aggravated by islet encapsulation, inflammation, and undesirable cell-biomaterial interactions. To identify biomaterials that would not further increase damaging oxidative stress levels and that are also suitable for manufacturing a beta cell encapsulation device, we studied five clinically approved polymers for their effect on oxidative stress and islet (alpha and beta cell) function. We found that 300 poly(ethylene oxide terephthalate) 55/poly(butylene terephthalate) 45 (PEOT/PBT300) was more resistant to breakage and more elastic than other biomaterials, which is important for its immunoprotective function. In addition, it did not induce oxidative stress or reduce viability in the MIN6 beta cell line, and even promoted protective endogenous antioxidant expression over 7 days. Importantly, PEOT/PBT300 is one of the biomaterials we studied that did not interfere with insulin secretion in human islets.
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Células Secretoras de Insulina , Trasplante de Islotes Pancreáticos , Islotes Pancreáticos , Materiales Biocompatibles/metabolismo , Humanos , Insulina/metabolismo , Secreción de Insulina , Células Secretoras de Insulina/metabolismo , Islotes Pancreáticos/metabolismo , Estrés OxidativoRESUMEN
Transplantation technologies of pancreatic islets as well as stem cell-derived pancreatic beta cells encapsulated in hydrogel for the induction of immunoprotection could advance to treat type 1 diabetes mellitus, if the hydrogel transplants acquire retrievability through mitigating foreign body reactions after transplantation. Here, we demonstrate that the diameter of the fiber-shaped hydrogel transplants determines both in vivo cellular deposition onto themselves and their retrievability. Specifically, we found that the in vivo cellular deposition is significantly mitigated when the diameter is 1.0 mm and larger, and that 1.0 mm-thick xenoislet-laden fiber-shaped hydrogel transplants can be retrieved after being placed in the intraperitoneal cavities of immunocompetent diabetic mice for more than 100 days, during which period the hydrogel transplants can normalize the blood glucose concentrations of the mice. These findings could provide an innovative concept of a transplant that would promote the clinical application of stem cell-derived functional cells through improving their in vivo efficacy and safety.
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Diabetes Mellitus Experimental , Trasplante de Islotes Pancreáticos , Islotes Pancreáticos , Animales , Glucemia , Diabetes Mellitus Experimental/terapia , Reacción a Cuerpo Extraño/prevención & control , Control Glucémico , RatonesRESUMEN
Replacement of islets/ß-cells that provide long-lasting glucose-sensing and insulin-releasing functions has the potential to restore extended glycemic control in individuals with type 1 diabetes. Unfortunately, persistent challenges preclude such therapies from widespread clinical use, including cumbersome administration via portal vein infusion, significant loss of functional islet mass upon administration, limited functional longevity, and requirement for systemic immunosuppression. Previously, fibril-forming type I collagen (oligomer) was shown to support subcutaneous injection and in situ encapsulation of syngeneic islets within diabetic mice, with rapid (<24 h) reversal of hyperglycemia and maintenance of euglycemia for beyond 90 days. Here, we further evaluated this macroencapsulation strategy, defining effects of islet source (allogeneic and xenogeneic) and dose (500 and 800 islets), injection microenvironment (subcutaneous and intraperitoneal), and macrocapsule format (injectable and preformed implantable) on islet functional longevity and recipient immune response. We found that xenogeneic rat islets functioned similarly to or better than allogeneic mouse islets, with only modest improvements in longevity noted with dosage. Additionally, subcutaneous injection led to more consistent encapsulation outcomes along with improved islet health and longevity, compared with intraperitoneal administration, whereas no significant differences were observed between subcutaneous injectable and preformed implantable formats. Collectively, these results document the benefits of incorporating natural collagen for islet/ß-cell replacement therapies.
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Encapsulación Celular/métodos , Colágeno , Diabetes Mellitus Tipo 1/terapia , Trasplante de Islotes Pancreáticos/métodos , Aloinjertos , Animales , Glucemia/análisis , Supervivencia Celular , Colágeno/química , Diabetes Mellitus Experimental/terapia , Diabetes Mellitus Tipo 1/sangre , Supervivencia de Injerto , Xenoinjertos , Inyecciones Intraperitoneales , Inyecciones Subcutáneas , Células Secretoras de Insulina/fisiología , Células Secretoras de Insulina/trasplante , Islotes Pancreáticos/fisiología , Ratones , Ratones Endogámicos C57BL , Ratas , Ratas Sprague-DawleyRESUMEN
Islet transplantation has been one promising strategy in diabetes treatment, which can maintain patient's insulin level long-term and avoid periodical insulin injections. However, donor shortage and temporal mismatch between donors and recipients has limited its widespread use. Therefore, searching for islet substitutes and developing efficient cryopreservation technology (providing potential islet bank for transplantation on demand) is in great need. Herein, a novel cryopreservation method is developed for islet ß cells by combining microfluidic encapsulation and cold-responsive nanocapsules (CR-NCs). The cryopreserved cell-laden hydrogels (calcium alginate hydrogel, CAH) can be transplanted for diabetes treatment. During the freezing process, trehalose is released inside ß cells through the CR-NCs and serves as the sole cryoprotectant (CPA). Additionally, CAH helps cells to survive the freeze-thaw process and provide cells with a natural immune barrier in vivo. Different from traditional cryopreservation methods, this method combining the CR-NCs and hydrogel encapsulation replaces the toxic CPAs with natural trehalose. Great preservation results are obtained and transplantation experiments of diabetic rats further prove the excellent glucose regulation ability of such ß cell-laden hydrogels post cryopreservation. This novel cryopreservation method helps to establish a reliable and ready-to-use bank of biological samples for transplantation therapy and other biomedical applications.
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Frío , Criopreservación , Crioprotectores/farmacología , Diabetes Mellitus Experimental/terapia , Hidrogeles/farmacología , Células Secretoras de Insulina/trasplante , Nanocápsulas/química , Trehalosa/farmacología , Animales , Línea Celular , Proliferación Celular/efectos de los fármacos , Células Secretoras de Insulina/efectos de los fármacos , Masculino , Nanocápsulas/ultraestructura , Ratas Sprague-Dawley , Pruebas de ToxicidadRESUMEN
Islet encapsulation and transplantation promises to improve upon current treatments for type 1 diabetes mellitus, though several limitations remain. Macroscale devices have been designed for in vivo transplantation and retrieval, but traditional geometries do not support clinically adequate mass transfer of nutrients to and insulin from the encapsulated tissue. Microcapsule technologies have improved mass transfer properties, but their clinical translation remains challenging as their complete retrieval is difficult, should the graft become a safety concern. Here, the design, characterization and testing of a novel encapsulation structure, comprised of elastomer-reinforced interconnected toroidal hydrogels is reported. These donut-shaped hydrogels feature a high surface area, higher than conventional spherical capsules of the same volume, bestowing suitable mass transport conditions, while allowing interconnection and reversible deformation for intraperitoneal implantation and retrieval. Diabetes correction up to 12 weeks and complete retrieval is achieved in a diabetic mouse model, providing a proof-of-concept for the potential application as a type 1 diabetes cell replacement therapy.
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Hidrogeles/química , Islotes Pancreáticos/fisiología , Células 3T3 , Animales , Materiales Biocompatibles/química , Diabetes Mellitus Experimental/terapia , Humanos , Trasplante de Islotes Pancreáticos , Ratones , Andamios del Tejido/químicaRESUMEN
Islet transplantation is considered the most promising treatment for type 1 diabetes. However, the clinical success is limited by islet dysfunction in long-term culture. In this study, we have utilized the rapid self-gelation and injectability offered by blending of mulberry silk (Bombyx mori) with non-mulberry (Antheraea assama) silk, resulting in a biomimetic hydrogel. Unlike the previously reported silk gelation techniques, the differences in amino acid sequences of the two silk varieties result in accelerated gelation without requiring any external stimulus. Gelation study and rheological assessment depicts tuneable gelation as a function of protein concentration and blending ratio with minimum gelation time. In vitro biological results reveal that the blended hydrogels provide an ideal 3D matrix for primary rat islets. Also, A. assama fibroin with inherent Arg-Gly-Asp (RGD) shows significant influence on islet viability, insulin secretion and endothelial cell maintenance. Furthermore, utility of these hydrogels demonstrate sustained release of Interleukin-4 (IL-4) and Dexamethasone with effective M2 macrophage polarization while preserving islet physiology. The immuno-informed hydrogel demonstrates local modulation of inflammatory responses in vivo. Altogether, the results exhibit promising attributes of injectable silk hydrogel and the utility of non-mulberry silk fibroin as an alternative biomaterial for islet encapsulation.
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Materiales Biomiméticos/química , Hidrogeles/química , Islotes Pancreáticos/fisiología , Macrófagos/efectos de los fármacos , Mariposas Nocturnas/química , Seda/química , Animales , Materiales Biocompatibles , Bombyx/química , Línea Celular , Supervivencia Celular , Dexametasona/administración & dosificación , Dexametasona/química , Dexametasona/inmunología , Fibroínas/administración & dosificación , Fibroínas/química , Fibroínas/inmunología , Inmunomodulación , Inmunosupresores/administración & dosificación , Inmunosupresores/química , Inmunosupresores/inmunología , Secreción de Insulina , Interleucina-4/administración & dosificación , Interleucina-4/química , Islotes Pancreáticos/inmunología , Macrófagos/inmunología , Macrófagos/fisiología , Ratas , Ratas Wistar , Seda/administración & dosificación , Seda/inmunología , Ingeniería de TejidosRESUMEN
Widespread use of pancreatic islet transplantation for treatment of type 1 diabetes (T1D) is currently limited by requirements for long-term immunosuppression, limited donor supply, and poor long-term engraftment and function. Upon isolation from their native microenvironment, islets undergo rapid apoptosis, which is further exacerbated by poor oxygen and nutrient supply following infusion into the portal vein. Identifying alternative strategies to restore critical microenvironmental cues, while maximizing islet health and function, is needed to advance this cellular therapy. We hypothesized that biophysical properties provided through type I oligomeric collagen macroencapsulation are important considerations when designing strategies to improve islet survival, phenotype, and function. Mouse islets were encapsulated at various Oligomer concentrations (0.5 -3.0 mg/ml) or suspended in media and cultured for 14 days, after which viability, protein expression, and function were assessed. Oligomer-encapsulated islets showed a density-dependent improvement in in vitro viability, cytoarchitecture, and insulin secretion, with 3 mg/ml yielding values comparable to freshly isolated islets. For transplantation into streptozotocin-induced diabetic mice, 500 islets were mixed in Oligomer and injected subcutaneously, where rapid in situ macroencapsulation occurred, or injected with saline. Mice treated with Oligomer-encapsulated islets exhibited rapid (within 24 h) diabetes reversal and maintenance of normoglycemia for 14 (immunocompromised), 90 (syngeneic), and 40 days (allogeneic). Histological analysis showed Oligomer-islet engraftment with maintenance of islet cytoarchitecture, revascularization, and no foreign body response. Oligomer-islet macroencapsulation may provide a useful strategy for prolonging the health and function of cultured islets and has potential as a subcutaneous injectable islet transplantation strategy for treatment of T1D.