Beta-cell Replacement Research Articles

In Vivo Mouse Abdominal Oxygen Imaging And Assessment of Subcutaneously Implanted Beta Cell Replacement Devices.

Type 1 diabetes (T1D) is an autoimmune disease that leads to the loss of insulin-producing pancreatic beta cells. Beta cell replacement devices or bioartificial pancreas (BAP) have shown promise in curing T1D and providing long-term insulin independence without the need for immunosuppressants. Hypoxia in BAP devices damages cells and imposes limitations on device dimensions. Noninvasive in vivo oxygen imaging assessment of implanted BAP devices will provide the necessary feedback and improve the chances of success. Pulse-mode electron paramagnetic resonance (EPR) oxygen imaging (EPROI) using injectable trityl OX071 as the oxygen-sensitive agent is an excellent technique for obtaining partial oxygen pressure (pO2) maps in vitro and in vivo. In this study, our goal was to optimize in vivo mouse abdominal EPROI and demonstrate proof-of-concept pO2 imaging of subcutaneously implanted BAP devices. All EPROI experiments were performed using a 25 mT EPROI instrument, JIVA-25®. For in vivo EPROI experiments, trityl OX071, a whole-body mouse resonator (∅32mm × 35mm), C57BL6 mice, and the inversion recovery electron spin echo (IRESE) pulse sequence were utilized. We investigated the signal amplitude and pO2 in mouse abdomen region for intravenous (i.v.) and intraperitoneal (i.p.) injection methods with either only a single bolus (B) or bolus plus infusion (BI) for 72.2mM OX071 and the effect of OX071 concentrations from 18 to 72.2 mM for the i.p.-B injection method. We also investigated the impact of animal respiratory rate on mouse abdominal pO2. Finally, we performed proof-of-concept pO2 imaging of two subcutaneously implanted BAP devices, OxySite and TheraCyte. At the end of the four-week study, the TheraCyte devices were extracted and analyzed for fibrosis, vascular differentiation, and immune cell infiltration. We established that mouse abdominal pO2 remains stable irrespective of trityl injection methods, concentrations, imaging time, or animal breathing rate. We demonstrate that the i.p.-B and i.p.-BI methods are suitable for EPROI, and i.p.-B method provides higher signal amplitude compared to i.v.-BIand up to 75min of imaging. An injection with a reduced trityl concentration and higher volume provides higher signal amplitude for i.p.-B method at the beginning. We also highlight the advantage of milder anesthesia for consistent, reliable mouse pO2 imaging. Finally, we demonstrate that EPROI could provide longitudinal noninvasive oxygen assessment of subcutaneously implanted BAP devices in vivo. In vivo EPROI is a reliable technique for mouse abdominal oxygen imaging and longitudinal assessment of subcutaneously implanted BAP devices noninvasively. This work reports abdominal oxygen imaging in the mouse model and demonstrates its application for the assessment of BAP devices. Even though the application focus of this work was on cell therapy, the techniques developed will have a much broader use in the biomedical field.

Role of the Pancreatic Islet Microvasculature in Health and Disease.

The pancreatic islet vasculature comprises microvascular endothelial cells surrounded by mural cells (pericytes). Both cell types support the islet by providing (1) a conduit for delivery and exchange of nutrients and hormones; (2) paracrine signals and extracellular matrix (ECM) components that support islet development, architecture, and endocrine function; and (3) a barrier against inflammation and immune cell infiltration. In type 2 diabetes, the islet vasculature becomes inflamed, showing loss of endothelial cells, detachment, and/or trans-differentiation of pericytes, vessel dilation, and excessive ECM deposition. While most work to date has focused either on endothelial cells or pericytes in isolation, it is very likely that the interaction between these cell types and disruption of that interaction in diabetes are critically important. In fact, dissociation of pericytes from endothelial cells is an early, key feature of microvascular disease in multiple tissues/disease states. Moreover, in beta-cell replacement therapy, co-transplantation with microvessels versus endothelial cells alone is substantially more effective in improving survival and function of the transplanted cells. Ongoing studies, including characterization of islet vascular cell signatures, will aid in the identification of new therapeutic targets aimed at improving islet function and benefiting people living with all forms of diabetes.

Double transgenic neonatal porcine islets as an alternative source for beta cell replacement therapy

To be clinically efficient, beta cell replacement therapies such as pig islet xenotransplantation must ensure sufficient insulin secretion from grafted islets. While protection from host immune reaction is essential for islet engraftment and their subsequent functioning, intrinsic physiological properties of used cells are also a key factor. We have previously shown that islets with adenoviral-mediated expression of a dipeptidyl peptidase-resistant form of glucagon-like-peptide-1 (GLP-1) and a constitutively activated form of type 3 muscarinic receptor (M3R) in their beta cells have greatly improved insulin secretory response to glucose stimulation that is otherwise 4 to 10 times lower than human islets. Here, we describe in vitro characterization of the secretory function of pancreatic islets, derived from transgenic pigs expressing the GLP-1M3R cassette under the porcine insulin promoter (InsGLP-1M3R), and their usage to treat insulin-dependent diabetes in an immunodeficient mouse model. Our results show that InsGLP-1M3R islets isolated from neonatal and adult pigs secrete up to 15-fold more insulin in response to glucose stimulation compared to wild-type (WT) islets. They also proved to be more efficient in treating diabetes in a preclinical model as shown by a significantly higher percentage of normoglycemic recipients and higher porcine C-peptide levels up to 9 mo post implantation.

Challenges in Beta Cell Replacement for Type 1 Diabetes.

Type 1 diabetes (T1D) presents a significant global health challenge, characterized by immune-mediated destruction of pancreatic beta-cells. Achieving therapeutic goals such as prevention of immune destruction, preservation of beta-cell mass, and automated insulin delivery remains complex due to the disease's heterogeneity. This review explores the advancements and challenges in beta-cell replacement therapies, including pancreas and islet cell transplantation, stem cell-derived β-cell generation, and biotechnological innovations. Pancreas transplantation, especially simultaneous pancreas and kidney transplantation (SPK), has evolved significantly, offering insulin independence and improved quality of life despite surgical and immunological complications. Allogeneic islet transplantation, though less invasive, faces challenges such as donor scarcity, immunosuppressive therapy, and variable long-term success. Innovations in stem cell therapy, particularly using human embryonic stem cells (hESCs) and induced pluripotent stem cells (iPSCs), promise an unlimited source of β-cells. However, translating these advances into clinical applications involves overcoming technical, biological, and ethical hurdles. Strategies such as immunomodulation, encapsulation, and genetic engineering are critical to enhancing the viability and integration of transplanted cells. This review provides a comprehensive overview of the scientific intricacies and potential of β-cell replacement therapies, emphasizing the need for continued research to address the remaining challenges and improve diabetes care outcomes.

Clinical Translation and Implementation of a Bioartificial Pancreas Therapy: A Qualitative Study Exploring the Perspectives of People With Type 1 Diabetes.

The development of a hybrid beta-cell replacement approach, referred to as a personalized, transplantable bioartificial pancreas (BAP), holds promise to treat type 1 diabetes (T1D). This interview study aimed to explore patients' expectations, needs, concerns, and considerations when considering to undergo a BAP transplantation. Semistructured interviews were conducted with 24 participants diagnosed with T1D. Data collection stopped once data saturation was reached. Audio recordings of the interviews were transcribed verbatim. The interviews were independently analyzed by 2 researchers. A qualitative content analysis using an inductive approach was used. Three main themes emerged as follow: (1) hoped-for benefits, (2) concerns and decision-making considerations, and (3) procedural aspects. First, the participants expected benefits across medical, psychological, and social domains. Over these 3 domains, 9 subthemes were identified, including improved clinical outcomes, a cure for diabetes, more headspace, emotional relief, a shift in responsibility, protection of privacy, improved flexibility in daily life, less visible diseases, and improved relationships with others. Second, concerns and considerations about undergoing a BAP transplant comprised adverse events, the functionality of the BAP, the surgery procedure, the biological materials used, the transplant location, and the intrusiveness associated with follow-up care. Finally, procedural considerations included equitable access, patient prioritization, and trust and control. Incorporating insights from this study into the clinical development and implementation of the BAP is crucial to ensure alignment of the product and procedures with the needs and expectations of people with T1D.

Advances in Type 1 Diabetes Mellitus Management in Children.

Recent advancements in the management of type 1 diabetes mellitus (T1DM) have significantly improved outcomes and quality of life for patients, particularly children. Technological innovations, such as continuous glucose monitoring (CGM) systems and insulin pump therapy, including hybrid closed-loop systems, have enhanced glycemic control by providing real-time data and automated insulin delivery. Ultrarapid-acting insulins and adjunctive pharmacotherapies, like sodium-glucose transport protein 2 (SGLT2) inhibitors and glucagon-like peptide 1 (GLP-1) receptor agonists, offer improved postprandial glucose management and reduced insulin requirements. Immunotherapy and beta-cell replacement therapies, including stem cell research and encapsulation devices, aim to preserve or restore endogenous insulin production. Digital health platforms and telemedicine have expanded access to education and support, fostering better self-management. Future directions in precision medicine, artificial intelligence, and microbiome research hold promise for personalized and potentially curative treatments. Collectively, these advances are transforming T1DM management, reducing disease burden, and enhancing the prospects for children with T1DM.

416 The Impact of Pancreas Transplantation on Secondary Diabetic Complications: A Systematic Review

Abstract Aim Pancreas transplantation (PT) provides diabetic cure for patients with complicated Type 1 Diabetes Mellitus (T1DM). We aimed to examine the impact of PT on secondary diabetic complications, including retinopathy, neuropathy, and cardiovascular disease. Method A database search using MedLINE for publications up to April 2023 was conducted employing MeSH terms ‘Pancreas Transplantation’ AND ‘Diabetes Mellitus, Type 1’ AND ‘Diabetic Retinopathy’ OR ‘Heart Disease’ OR ‘Cardiovascular Diseases’ OR ‘Peripheral Vascular Disease’ OR “Amputation’ OR ‘Neuropathy.” Results 223 articles were screened, with 172 excluded as per study design (total included 51). 64.7% (n=33) of studies were retrospective case control studies, 35.3% (n=18) of studies were retrospective cohort studies. A total of 5616 patients with a mean of 99.1 (SD± 262.4) simultaneous kidney transplant (SPK) patients and 48.2 (SD± 262.4) pancreas transplant alone (PTA) patients per article were studied. All articles examining diabetic retinopathy concluded that retinopathy improved or stabilized. 69% (n=11) of papers demonstrated no significant change to visual acuity. An equal number of articles (n=4) demonstrated increased peripheral nerve conduction velocity after SPK and PTA. 40% (n=2) of articles examining vibration perception studies demonstrated an increase post-transplantation. Improvements in cardiac events incidence, metabolic factors, and heart structure were seen in 79% (n=15) of cardiovascular articles. Conclusions Despite significant heterogeneity in outcome measures observed, PT provides benefits in mitigating the complication profile of T1DM. Standardised outcome measurement should be adopted to allow assessment of the impact of beta-cell replacement with the potential for objective evidence reversibility of secondary complications.

Prevention and treatment of type 1 diabetes: in search of the ideal combination therapy targeting multiple immunometabolic pathways

Type 1 diabetes (T1D) represents an autoimmune disease caused by the gradual immune-mediated destruction of the insulin-producing beta cells within the pancreatic islets of Langerhans, resulting in the lifelong need for exogenous insulin therapy. According to recent estimates, T1D currently affects about 8.4 million individuals worldwide. Since a definitive biological cure for this disease is not available yet, there is a great need for novel therapeutic strategies aimed at safely and effectively altering the natural history of the disease during its sequential stages. Ideal therapeutic goals in T1D include the prevention of autoimmune beta-cell destruction, the preservation of residual beta-cell mass and endogenous insulin secretion, the replacement and/or regeneration of beta cells, as well as automated insulin delivery through advanced closed-loop artificial pancreas systems. With this regard, an important research area focused on the identification of a definitive biological cure for T1D is represented by the investigation of immunotherapeutic and beta-cell-protective agents used as disease-modifying therapies to forestall or eliminate insulin dependence. In this commentary, we discuss the reasons why the use of combination therapies targeting the multiple immunometabolic dysfunctions associated with T1D (other than beta-cell autoimmunity) is likely to be more effective in preserving beta cell function in individuals at different stages of T1D, as compared to the use of single therapeutic agents.

Human Pancreatic β Cell Regenerative Therapy: Exploring the Role of Chicoric Acid as a Phytochemical Candidate

Diabetes is a global health issue, impacting life expectancy and productivity. Pathogenesis of diabetes mellitus involves decreased functional beta cells, making beta cell replacement and regeneration a crucial area of research. However, current methods like whole pancreas transplant or stem cell-derived beta cells have limitations for diabetic patients. Exploring pharmacological approaches to stimulate regeneration of residual beta cells is valuable, as many diabetic patients retain some beta cells. Finding drugs that target and regenerate these cells effectively is a challenge, with no approved options available currently. Nature provides several therapeutic agents, and chicoric acid (CA) found in medicinal plants like Cichorium intybus, and shows potential for beta cell regeneration. Cichorium intybus possesses antioxidants, phenolics, and flavonoids, aiding its antidiabetic activity by targeting hyperglycemia, oxidative stress, inflammation, and hyperlipidemia. CA's multifaceted effects on glucose homeostasis are attributed to its involvement in various interconnected processes and pathways. This comprehensive review explores the molecular-level mechanisms through which chicoric acid facilitates beta cell regeneration, insulin release, and glucose uptake. The findings suggest that chicoric acid holds promise as a phytochemical agent for diabetes prevention and treatment. Its natural origin, antidiabetic properties, and multi-dimensional effects make it a potential candidate. Hence, further research to fully elucidate the efficacy and safety of chicoric acid for β cell regeneration as an antidiabetic agent is essential. In summary, this extensive review at the molecular level, concludes that chicoric acid is a phytochemical with great antidiabetic potential and may be indicated both as a preventive and therapeutic agent.

An unmet need: Pancreatic beta cell replacement.

Diabetes mellitus (DM) is a growing public health concern in South Africa (SA) and poses a substantial economic burden on healthcare globally. A century has passed since the discovery of insulin, and despite advances in diabetes management, exogenous insulin remains a primary treatment for type 1 DM, posing challenges of hyperglycaemia and hypoglycaemia. Pancreas transplantation should be considered a treatment for insulin-deficient DM, offering sustained euglycaemia and preventing complications associated with the disease. However, there has been a global decrease in the number of transplants performed. In SA, only a few pancreas transplants have been performed, primarily because of surgical risks and the need for immunosuppression. Islet transplantation is an alternative but faces limitations due to donor scarcity and immunosuppression requirements. This review explores recent progress in pancreas and islet transplants for DM, with the aim of providing insights into expanding treatment options for people with insulin-deficient DM.

The role of genetic risk factors, diet, and gut microbiota in type 1 diabetes mellitus, pancreas and pancreatic islet transplantation.

Despite advances in insulin delivery and glucose monitoring technology, prevention of the progression of secondary complications in patients with type 1 diabetes (T1DM) remains a challenge. Beta cell replacement therapy in the form of islet or pancreas transplantation can restore long-term normoglycaemia with sustained periods of insulin independence among T1DM patients. However, the same genetic, behavioural, or gut microbiota-related factors that promoted autoimmunity and primary islet destruction may also affect the function of transplanted islets and the ultimate results of transplant procedures. In such cases, identifying genetic risk factors and modifying behavioural factors and those related to gut microbiota may be beneficial for the outcomes of transplant procedures. Herein, we review related literature to the identified current gap in knowledge to be addressed in future clinical trials.

Efficient Vascular and Neural Engraftment of Stem Cell-Derived Islets.

Pluripotent stem cell-derived islets (SC-islets) now emerge as a new source for beta-cell replacement therapy. While the function of human islet transplants is hampered by excessive cell death post-transplantation, contributing factors include inflammatory reactions, insufficient revascularization and islet amyloid formation, there is a gap in knowledge on the engraftment process of the SC-islets. In this experimental study, we investigated the engraftment capability of SC-islets at three months post-transplantation, and observed that the cell apoptosis rates were lower, but the vascular density was similar in SC-islets to that of human islets. While the human islet transplant vascular structures were a mixture of remnant donor endothelium and ingrowing blood vessels, the SC-islets contained ingrowing blood vessels only. The oxygenation of the SC-islet grafts was twice as high as in the corresponding grafts of human islets, suggesting better vascular functionality. Similar to the blood vessel ingrowth, also the reinnervation of the SC-islets was four- to five-fold higher than the human islets. Both SC-islets and the human islets contained amyloid at one and three months post-transplantation. We conclude that the vascular and neural engraftment of SC-islets is superior to human islets, but that grafts of both origins develop amyloid with potential long-term consequences.

Molecular Retention Limitations for Prevascularized Subcutaneous Sites for Islet Transplantation.

Beta cell replacement therapies utilizing the subcutaneous space have inherent advantages to other sites: the potential for increased accessibility, noninvasive monitoring, and graft extraction. Site prevascularization has been developed to enhance islet survivability in the subcutaneous zone while minimizing potential foreign body immune responses. Molecular communication between the host and prevascularized implant site remains ill-defined. Poly(ethylene oxide)s (PEOs) of various hydrated radii (i.e., ∼11-62 Å) were injected into prevascularized subcutaneous sites in C57BL/6 mice, and the clearance and organ biodistribution were characterized. Prevascularization formed a barrier that confined the molecules compared with the unmodified site. Molecular clearance from the prevascularized site was inversely proportional to the molecular weight. The upper limit in molecular size for entering the vasculature to be cleared was determined to be 35 kDa MW PEO. These findings provide insight into the impact of vascularization on molecular retention at the injection site and the effect of molecular size on the mobility of hydrophilic molecules from the prevascularized site to the host. This information is necessary for optimizing the transplantation site for increasing the beta cell graft survival.

Targeted mapping and utilization of the perihepatic surface for therapeutic beta cell replacement and retrieval in diabetic non-human primates.

Successful diabetes reversal using pancreatic islet transplantation by various groups illustrates the significant achievements made in cell-based diabetes therapy. While clinically, intraportal islet delivery is almost exclusively used, it is not without obstacles, including instant blood-mediated inflammatory reaction (IBMIR), relative hypoxia, and loss of function over time, therefore hindering long-term success. Here we demonstrate the perihepatic surface of non-human primates (NHPs) as a potential islet delivery site maximizing favorable characteristics, including proximity to a dense vascular network for adequate oxygenation while avoiding IBMIR exposure, maintenance of portal insulin delivery, and relative ease of accessibility through minimally invasive surgery or percutaneous means. In addition, we demonstrate a targeted mapping technique of the perihepatic surface, allowing for the testing of multiple experimental conditions, including a semi-synthetic hydrogel as a possible three-dimensional framework to improve islet viability. Perihepatic allo-islet cell transplants were performed in immunosuppressed cynomolgus macaques using a targeted mapping technique to test multiple conditions for biocompatibility. Transplant conditions included islets or carriers (including hydrogel, autologous plasma, and media) alone or in various combinations. Necropsy was performed at day 30, and histopathology was performed to assess biocompatibility, immune response, and islet viability. Subsequently, single-injection perihepatic allo-islet transplant was performed in immunosuppressed diabetic cynomolgus macaques. Metabolic assessments were measured frequently (i.e., blood glucose, insulin, C-peptide) until final graft retrieval for histopathology. Targeted mapping biocompatibility studies demonstrated mild inflammatory changes with islet-plasma constructs; however, significant inflammatory cell infiltration and fibrosis were seen surrounding sites with the hydrogel carrier affecting islet viability. In diabetic NHPs, perihepatic islet transplant using an autologous plasma carrier demonstrated prolonged function up to 6 months with improvements in blood glucose, exogenous insulin requirements, and HbA1c. Histopathology of these islets was associated with mild peri-islet mononuclear cell infiltration without evidence of rejection. The perihepatic surface serves as a viable site for islet cell transplantation demonstrating sustained islet function through 6 months. The targeted mapping approach allows for the testing of multiple conditions simultaneously to evaluate immune response to biomaterials at this site. Compared to traditional intraportal injection, the perihepatic site is a minimally invasive approach that allows the possibility for graft recovery and avoids IBMIR.

Pig Xenotransplantation in Beta Cell Replacement: Addressing Challenges and Harnessing Potential for Type 1 Diabetes Therapy.

This opinion paper evaluates the potential of porcine islets as a promising alternative in beta cell replacement therapy for Type 1 Diabetes (T1D), juxtaposed with the current limitations of human donor islets. It analyzes the compatibility of pig islets with human glucose metabolism, their prospects as a limitless and high-quality source of beta cells, and the unique immunogenic challenges they present in xenotransplantation. Additionally, the paper discusses the regulatory and ethical considerations pertinent to the use of porcine islets. By synthesizing current research and expert perspectives, the paper highlights both the opportunities and significant barriers that need addressing to advance pig islets as a viable therapeutic option. The findings advocate for a balanced and forward-looking approach to the integration of pig islets in T1D treatment, underscoring the need for continued research and dialogue in this evolving field.

Imaging in Type 1 Diabetes, Current Perspectives and Directions.

Type 1 diabetes (T1D) is characterized by the autoimmune-mediated attack of insulin-producing beta cells in the pancreas, leading to reliance on exogenous insulin to control a patient's blood glucose levels. As progress is being made in understanding the pathophysiology of the disease and how to better develop therapies to treat it, there is an increasing need for monitoring technologies to quantify beta cell mass and function throughout T1D progression and beta cell replacement therapy. Molecular imaging techniques offer a possible solution through both radiologic and non-radiologic means including positron emission tomography, magnetic resonance imaging, electron paramagnetic resonance imaging, and spatial omics. This commentary piece outlines the role of molecular imaging in T1D research and highlights the need for further applications of such methodologies in T1D.

Adipose-Derived Stromal Cells Preserve Pancreatic Islet Function in a Transplantable 3D Bioprinted Scaffold.

Intra-portal islet transplantation is currently the only clinically approved beta cell replacement therapy, but its outcome is hindered by limited cell survival due to a multifactorial reaction against the allogeneic tissue in liver. Adipose-derived stromal cells (ASCs) can potentially improve the islet micro-environment by their immunomodulatory action. The challenge is to combine both islets and ASCs in a relatively easy and consistent long-term manner in a deliverable scaffold. Manufacturing the 3D bioprinted double-layered scaffolds with primary islets and ASCs using a mix of alginate/nanofibrillated cellulose (NFC) bioink is reported. The diffusion properties of the bioink and the supportive effect of human ASCs on islet viability, glucose sensing, insulin secretion, and reducing the secretion of pro-inflammatory cytokines are demonstrated. Diabetic mice transplanted with islet-ASC scaffolds reach normoglycemia seven days post-transplantation with no significant difference between this group and the group received islets under the kidney capsules. In addition, animals transplanted with islet-ASC scaffolds stay normoglycemic and show elevated levels of C-peptide compared to mice transplanted with islet-only scaffolds. The data present a functional 3D bioprinted scaffold for islets and ASCs transplanted to the extrahepatic site and suggest a possible role of ASCs on improving the islet micro-environment.

338.6: A conceptual supportive cell based implant for beta cell replacement therapy

338.6: A conceptual supportive cell based implant for beta cell replacement therapy

336.3: Identification of novel cell surface markers for the characterization of human beta cell replacement therapies

336.3: Identification of novel cell surface markers for the characterization of human beta cell replacement therapies

In vitro oxygen imaging of acellular and cell-loaded beta cell replacement devices

Type 1 diabetes (T1D) is an autoimmune disease that leads to the loss of insulin-producing beta cells. Bioartificial pancreas (BAP) or beta cell replacement strategies have shown promise in curing T1D and providing long-term insulin independence. Hypoxia (low oxygen concentration) that may occur in the BAP devices due to cell oxygen consumption at the early stages after implantation damages the cells, in addition to imposing limitations to device dimensions when translating promising results from rodents to humans. Finding ways to provide cells with sufficient oxygenation remains the major challenge in realizing BAP devices’ full potential. Therefore, in vitro oxygen imaging assessment of BAP devices is crucial for predicting the devices’ in vivo efficiency. Electron paramagnetic resonance oxygen imaging (EPROI, also known as electron MRI or eMRI) is a unique imaging technique that delivers absolute partial pressure of oxygen (pO2) maps and has been used for cancer hypoxia research for decades. However, its applicability for assessing BAP devices has not been explored. EPROI utilizes low magnetic fields in the mT range, static gradients, and the linear relationship between the spin–lattice relaxation rate (R1) of oxygen-sensitive spin probes such as trityl OX071 and pO2 to generate oxygen maps in tissues. With the support of the Juvenile Diabetes Research Foundation (JDRF), an academic-industry partnership consortium, the “Oxygen Measurement Core” was established at O2M to perform oxygen imaging assessment of BAP devices originated from core members’ laboratories. This article aims to establish the protocols and demonstrate a few examples of in vitro oxygen imaging of BAP devices using EPROI. All pO2 measurements were performed using a recently introduced 720 MHz/25 mT preclinical oxygen imager instrument, JIVA-25™. We began by performing pO2 calibration of the biomaterials used in BAPs at 25 mT magnetic field since no such data exist. We compared the EPROI pO2 measurement with a single-point probe for a few selected materials. We also performed trityl OX071 toxicity studies with fibroblasts, as well as insulin-producing cells (beta TC6, MIN6, and human islet cells). Finally, we performed proof-of-concept in vitro pO2 imaging of five BAP devices that varied in size, shape, and biomaterials. We demonstrated that EPROI is compatible with commonly used biomaterials and that trityl OX071 is nontoxic to cells. A comparison of the EPROI with a fluorescent-based point oxygen probe in selected biomaterials showed higher accuracy of EPROI. The imaging of typically heterogenous BAP devices demonstrated the utility of obtaining oxygen maps over single-point measurements. In summary, we present EPROI as a quality control tool for developing efficient cell transplantation devices and artificial tissue grafts. Although the focus of this work is encapsulation systems for diabetes, the techniques developed in this project are easily transferable to other biomaterials, tissue grafts, and cell therapy devices used in the field of tissue engineering and regenerative medicine (TERM). In summary, EPROI is a unique noninvasive tool to experimentally study oxygen distribution in cell transplantation devices and artificial tissues, which can revolutionize the treatment of degenerative diseases like T1D.