Human hypoimmune primary pancreatic islets avoid rejection and autoimmunity and alleviate diabetes in allogeneic humanized mice

A cloaked human stem-cell-derived neural graft capable of functional integration and immune evasion in rodent models

Human pluripotent stem cell (hPSC)-derived therapies are a realistic possibility for numerous disorders, including Parkinson's disease. While generating replacement neurons is achievable, immunosuppressive drug challenges, to prevent rejection, remain. Here we adopted a hPSC line (termed H1-FS-8IM), engineered to overexpress 8 immunomodulatory transgenes, to enable transplant immune evasion. In co-cultures, H1-FS-8IM PSC-derived midbrain neurons evaded rejection by T lymphocytes, natural killer cells, macrophages, and dendritic cells. In humanized mice, allogeneic H1-FS-8IM neural grafts evaded rejection, while control hPSC-derived neural grafts evoked activation of human immune cells, elevated inflammatory cytokines in blood and cerebrospinal fluid, and caused spleen and lymph node enlargement. H1-FS-8IM neural grafts retained functionality, reversing motor deficits in Parkinsonian rats. Additional incorporation of a suicide gene into the H1-FS-8IM hPSC line enabled proliferative cell elimination within grafts. Findings demonstrate feasibility of generating a population-wide applicable, safe, off-the-shelf cell product, suitable for treating diseases for which cell-based therapies are a viable option.

Inhibition of polymorphonuclear cells averts cytotoxicity against hypoimmune cells in xenotransplantation

Allogeneic, immune-evasive hypoimmune (HIP) cell therapeutics that are HLA-depleted and overexpress CD47 create the opportunity to treat immunocompetent patients with cancer, degenerative, or autoimmune diseases. However, HIP cell therapy has not yet been established for xenotransplantation. Here we engineer, for human-to-non-human primate studies, human HIP* endothelial cells (EC) that are HLA-depleted and express macaque CD47 to allow compatibility with the macaque SIRPα immune checkpoint. Although no T cell, NK cell, or macrophage responses and no antibody-dependent cytotoxicity is observed in cynomolgus recipients, we reveal that macaque polymorphonuclear cells (PMN) show strong xenogeneic cytotoxicity against HIP* ECs. Inhibition of PMN killing using a multi-drug regimen leads to improved xenogeneic human HIP* EC survival in cynomolgus monkeys. Similarly, human PMNs show xenoreactivity against pig ECs, which has implications for clinical xenotransplantation. Accordingly, our engineered pig HIP* ECs that are SLA-depleted, overexpress human CD47, and additionally overexpress the PMN-inhibitory ligands CD99 and CD200, are protected against all human adaptive and innate cytotoxicity, including PMNs. In summary, specific targeting of PMN-mediated killing of the transplanted cells might improve outcomes for clinical pig-to-human xenotransplantation.

Hypoimmunogenic hPSC-derived cardiac organoids for immune evasion and heart repair

Human pluripotent stem cell (hPSC)-derived cardiac therapies hold great promise for heart regeneration but face major translational barriers due to allogeneic immune rejection. Here, we engineered hypoimmunogenic hPSCs using a two-step CRISPR-Cas9 strategy: (1) B2M knockout, eliminating HLA class I surface expression, and (2) knock-in of HLA-E or HLA-G trimer constructs in the AAVS1 safe harbor locus to confer robust immune evasion. Hypoimmunogenic hPSCs maintained pluripotency, efficiently differentiated into cardiac cell types that resisted both T and NK cell-mediated cytotoxicity in vitro , and self-assembled into engineered cardiac organoids. Comprehensive analyses of the hypoimmunogenic cells and organoids revealed preservation of transcriptomic, structural, and functional properties with minimal off-target effects from gene editing. In vivo , hypoimmunogenic cardiac organoids restored contractile function in infarcted rat hearts and demonstrated superior graft retention and immune evasion in humanized mice compared to wild-type counterparts. These findings establish the therapeutic potential of hypoimmunogenic hPSC-CMs in the cardiac organoid platform, laying the foundation for off-the-shelf cardiac cell therapies to treat cardiovascular disease, the leading cause of death worldwide.

Bioprinting and synthetic biology approaches to engineer functional endocrine pancreatic constructs

Diabetes is a complex disease affecting over 500 million people worldwide. Traditional approaches, such as insulin delivery, are mainstay treatments, but do not cure the disease. Recent advances in biofabrication and synthetic biology offer new hope for the development of tissue constructs recapitulating salient organ functions. Here, we discuss recent progress in bioprinting a functional endocrine pancreas, ranging from cell sources to main advances in biomaterials. We review innovative areas for the development of this field, with a particular focus on the convergence of synthetic biology and cell engineering with bioprinting, which opens new avenues for developing advanced in vitro models and regenerative, transplantable grafts, with the potential to provide independence from exogenous insulin administration.

Progress and challenges in developing allogeneic cell therapies

The new era of cell therapeutics has started with autologous products to avoid immune rejection. However, therapeutics derived from allogeneic cells could be scaled and made available for a much larger patient population if immune rejection could reliably be overcome. In this review, we outline gene engineering concepts aimed at generating immune-evasive cells. First, we summarize the current state of allogeneic immune cell therapies, and second, we compile the still limited data for allogeneic cell replacement therapies. We emphasize the advances in this fast-developing field and provide an optimistic outlook for future allogeneic cell therapies.

T Cell Development and Responses in Human Immune System Mice

Human Immune System (HIS) mice constructed with mature human immune cells or with human hematopoietic stem cells and thymic tissue have provided an important tool for human immunological research. In this article, we first review the different types of HIS mice based on human tissues transplanted and sources of the tissues. We then focus on knowledge of human T cell development and responses obtained using HIS mouse models. These areas include the development of human T cell subsets, with a focus on αβ conventional T cells and regulatory T cells, and human T cell responses in the settings of infection, transplantation rejection and tolerance, autoimmune disease, cancer immunotherapy, and regulatory T cell therapy. We also discuss the limitations and potential future applications of HIS mouse models.

Regulating islet stress responses through CD47 activation

AIMS/HYPOTHESIS

Diabetes is a global health burden characterised by incremental beta cell loss. Islet transplantation is a recognised treatment for individuals with type 1 diabetes and hypoglycaemia unawareness but broader application is constrained by limited islet survival and function post-transplantation. The underlying molecular mechanisms that induce beta cell dysfunction and demise remain unclear, and therapeutic agents that protect against cellular loss and maintain insulin secretion are in demand as potential treatment options. CD47 is a cell surface protein implicated in cellular stress responses but its role in beta cell function remains relatively unexplored. We hypothesised that modulating CD47 expression would demonstrate a cytoprotective effect in beta cells.

METHODS

We used primary murine islets with/without genetic deletion of CD47, as well as human islets and MIN6 cells subjected to pharmacological disruption of CD47 signalling (siRNA or blocking antibody). Metabolic stress was induced in cells by exposure to hypoxia, hyperglycaemia or thapsigargin, and markers of the unfolded protein response, cell survival and insulin secretory function were assessed. Human pancreases from individuals with and without diabetes were examined for evidence of CD47 signalling.

RESULTS

Expression of CD47 and its high affinity ligand thrombospondin-1 (TSP1) was robustly upregulated by exogenous stressors. Limiting CD47 signalling improved markers of senescence, apoptosis, endoplasmic reticulum stress, unfolded protein response, self-renewal and autophagy, and maintained insulin secretory responses. We also found concurrent upregulated expression of CD47 and senescence markers in the endocrine pancreas of aged donors and those with type 2 diabetes. Both CD47 and TSP1 expression were increased in pancreases of humans with type 1 diabetes, as were plasma levels of TSP1.

CONCLUSIONS/INTERPRETATION

Our study provides key insights into the essential role of CD47 as a novel regulator of islet dysfunction, regulating cytoprotective responses to stress. CD47 may contribute to beta cell damage during the development of diabetes and failure of islet transplant function. Therefore, limiting CD47 activation may be a potential therapeutic tool in conditions where islet function is inadequate.

Efficient transduction of pancreas tissue slices with genetically encoded calcium integrators

This study combines live pancreas tissue slices with adenoviral transduction of the Calcium Modulated Photoactivatable Ratiometric Integrator 2 (CaMPARI2) biosensor for high-throughput analysis of islet calcium responses. Pancreas slices preserve islets within their native microenvironment, adding tissue context to the study of islet function and pathology. A key challenge of the pancreas slice model has been efficient transgene delivery while maintaining viability and function. Here, we demonstrate a robust adenoviral gene delivery approach using targeted and universal promoters. By transducing slices with CaMPARI2 and applying 405 nm photoconverting light, we permanently marked glucose-induced calcium activity across entire islet populations while preserving the in situ tissue context. Applied to nPOD donor tissues, including from individuals with type 1 diabetes, type 2 diabetes, and non-diabetic controls, this approach demonstrated glucose responsive CaMPARI2 labeling that correlated with insulin secretion. Integrating CaMPARI2 with pancreas slices enables multiplexed analyses, linking a functional readout with spatial context through immunostaining or gene expression to advance understanding of human islet behavior.

The future of islet transplantation beyond the BLA approval: challenges and opportunities

This opinion paper explores the path forward for islet transplantation as a cell therapy for type 1 diabetes, following the Biologics License Application (BLA) approval. The authors review key challenges and opportunities that lie ahead. After a brief overview of the history of human islet transplantation, the paper examines the FDA's regulatory stance on isolated islet cells and the requirements for obtaining a BLA. The authors discuss the significance of this approval and the critical steps necessary to broaden patient access, such as scaling up production, clinical integration, reimbursement frameworks, post-marketing surveillance, and patient education initiatives. The paper highlights that the approval of LANTIDRA as an allogeneic cell transplant for uncontrolled type 1 diabetes marks the beginning of new chapters in improving islet transplantation. The authors emphasize essential areas for development, including advancements in islet manufacturing, optimization of transplant sites, islet encapsulation, exploration of unlimited cell sources, and gene editing technologies. In conclusion, the future of islet transplantation beyond the BLA approval presents challenges and opportunities. While significant regulatory milestones have been reached, hurdles remain. Innovations in stem cell-derived islets, cell encapsulation, and gene editing show promise in enhancing graft survival, expanding the availability of transplantable cells, and reducing the reliance on immunosuppressive drugs. These advancements could pave the way for more accessible, durable, and personalized diabetes treatments.

Islet Cell Replacement and Regeneration for Type 1 Diabetes: Current Developments and Future Prospects

Type 1 diabetes (T1D) is a chronic autoimmune disorder characterized by the destruction of insulin-producing beta cells in the pancreas, leading to insulin deficiency and chronic hyperglycemia. The main current therapeutic strategies for clinically overt T1D - primarily exogenous insulin administration combined with blood glucose monitoring - fail to fully mimic physiological insulin regulation, often resulting in suboptimal or insufficient glycemic control. Islet cell transplantation has emerged as a promising avenue for functionally replacing endogenous insulin production and achieving long-term glycemic stability. Here, we provide an overview of current islet replacement strategies, ranging from islet transplantation to stem cell-derived islet cell transplantation, and highlight emerging approaches such as immunoengineering. We examine the advancements in immunosuppressive protocols to enhance graft survival, innovative encapsulation, and immunomodulation techniques to protect transplanted islets, and the ongoing challenges in achieving durable and functional islet integration. Additionally, we discuss the latest clinical outcomes, the potential of gene editing technologies, and the emerging strategies for islet cell regeneration. This review aims to highlight the potential of these approaches to transform the management of T1D and improve the quality of life of individuals affected by this condition.

Bioengineering of a human iPSC-derived vascularized endocrine pancreas for type 1 diabetes

Intrahepatic islet transplantation in patients with type 1 diabetes is limited by donor availability and lack of engraftment. Alternative β cell sources and transplantation sites are needed. We demonstrate the feasibility to repurpose a decellularized lung as an endocrine pancreas for β cell replacement. We bioengineer an induced pluripotent stem cell (iPSC)-based version, fabricating a human iPSC-based vascularized endocrine pancreas (iVEP) using iPSC-derived β cells (iPSC-derived islets [SC-islets]) and endothelial cells (iECs). SC-islets and iECs are aggregated into vascularized iβ spheroids (ViβeSs), and over 7 days of culture, spheroids integrate into the bioengineered vasculature, generating a functional, perfusable human endocrine organ. In vitro, the vascularized extracellular matrix (ECM) sustained SC-islet engraftment and survival with a significantly preserved β cell mass and a physiologic insulin release. In vivo, iVEP restores normoglycemia in diabetic NSG mice. We report a human iVEP providing a controlled in vitro insulin-secreting phenotype and in vivo function.

Beyond cancer: The potential application of CD47-based therapy in non-cancer diseases

CD47 is an immune checkpoint widely regarded as a 'don't eat me' signal. CD47-based anti-cancer therapy has received considerable attention, with a significant number of clinical trials conducted. While anti-cancer therapies based on CD47 remain a focal point of interest among researchers, it is noteworthy that an increasing number of studies have found that CD47-based therapy ameliorated the pathological status of non-cancer diseases. This review aims to provide an overview of the recent progress in comprehending the role of CD47-based therapy in non-cancer diseases, including diseases of the circulatory system, nervous system, digestive system, and so on. Furthermore, we sought to delineate the promising mechanisms of CD47-based therapy in treating non-cancer diseases. Our findings suggest that CD47-based agents may exert their effect by regulating phagocytosis, regulating T cells, dendritic cells, and neutrophils, and regulating the secretion of cytokines and chemokines. Additionally, we put forward the orientation of further research to bring to light the potential of CD47 and its binding partners as a target in non-cancer diseases.

The HIP mouse and all of its organs are completely invisible to allogeneic immune cells

Hypoimmune (HIP) allogeneic cell therapeutics hold the promise to allow off-the-shelf treatments for a broad patient population. Our HIP approach includes the depletion of major histocompatibility complex (MHC) class I and II molecules and the overexpression of Cd47. Here, we report the engineering of HIP mice that stably exhibit the HIP phenotype in all cell types. Parabiosis experiments were designed to broadly assess immune evasiveness of all HIP blood cells in fully allogeneic BALB/c mice. HIP blood cells did not induce any immune response and achieved stable engraftment in BALB/c mice. Parabiosis experiments with irradiated HIP mice served as a model for full-body transplantation. There was no measurable cellular or antibody response in immunocompetent, allogeneic BALB/c parabionts. Transplantation of HIP islets into diabetic, allogeneic BALB/c mice reliably treated diabetes in all animals. Together, these data suggest that all allogeneic tissues can be HIP engineered and HIP cell therapy may be envisioned for many more indications.

From stem cells to pancreatic β-cells: strategies, applications, and potential treatments for diabetes

Loss and functional failure of pancreatic β-cells results in disruption of glucose homeostasis and progression of diabetes. Although whole pancreas or pancreatic islet transplantation serves as a promising approach for β-cell replenishment and diabetes therapy, the severe scarcity of donor islets makes it unattainable for most diabetic patients. Stem cells, particularly induced pluripotent stem cells (iPSCs), are promising for the treatment of diabetes owing to their self-renewal capacity and ability to differentiate into functional β-cells. In this review, we first introduce the development of functional β-cells and their heterogeneity and then turn to highlight recent advances in the generation of β-cells from stem cells and their potential applications in disease modeling, drug discovery and clinical therapy. Finally, we have discussed the current challenges in developing stem cell-based therapeutic strategies for improving the treatment of diabetes. Although some significant technical hurdles remain, stem cells offer great hope for patients with diabetes and will certainly transform future clinical practice.

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 β 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 β 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.

Microfluidic chip systems for characterizing glucose-responsive insulin-secreting cells equipped with FailSafe kill-switch

BACKGROUND

Pluripotent cell-derived islet replacement therapy offers promise for treating Type 1 diabetes (T1D), but concerns about uncontrolled cell proliferation and tumorigenicity present significant safety challenges. To address the safety concern, this study aims to establish a proof-of-concept for a glucose-responsive, insulin-secreting cell line integrated with a built-in FailSafe kill-switch.

METHOD

We generated β cell-induced progenitor-like cells (βiPLCs) from primary mouse pancreatic β cells through interrupted reprogramming. Then, we transcriptionally linked our FailSafe (FS) kill-switch, HSV-thymidine kinase (TK), to Cdk1 gene using a CRISPR/Cas9 knock-in strategy, resulting in a FailSafe βiPLC line, designated as FSβiPLCs. Subsequently we evaluated and confirmed the functionality of the drug-inducible kill-switch in FSβiPLCs at different ganciclovir (GCV) concentrations using our PDMS-based transcapillary microfluidic system. Finally, we assessed the functionality of FSβiPLCs by characterizing the dynamics of insulin secretion in response to changes in glucose concentration using our microfluidic perfusion glucose-stimulated insulin secretion (GSIS) assay-on- chip.

RESULTS

The βiPLCs exhibited Ins1, Pdx1 and Nkx6.1 expression, and glucose responsive insulin secretion, the essential properties of pancreatic beta cells. The βiPLCs were amenable to genome editing which allowed for the insertion of the kill-switch into the 3'UTR of Cdk1, confirmed by PCR genotyping. Our transcapillary microfluidic system confirmed the functionality of the drug-inducible kill-switch in FSβiPLCs, showing an effective cell ablation of dividing cells from a heterogeneous cell population at different ganciclovir (GCV) concentrations. The Ki67 expression assessment further confirmed that slow- or non-dividing cells in the FSβiPLC population were resistant to GCV. Our perfusion glucose-stimulated insulin secretion (GSIS) assay-on-chip revealed that the resistant non-dividing FSβiPLCs exhibited higher levels of insulin secretion and glucose responsiveness compared to their proliferating counterparts.

CONCLUSIONS

This study establishes a proof-of-concept for the integration of a FailSafe kill-switch system into a glucose-responsive, insulin-secreting cell line to address the safety concerns in stem cell-derived cell replacement treatment for T1D. The microfluidic systems provided valuable insights into the functionality and safety of these engineered cells, demonstrating the potential of the kill-switch to reduce the risk of tumorigenicity in pluripotent cell-derived insulin-secreting cells.

Emerging Diabetes Therapies: Regenerating Pancreatic β Cells

The incidence of diabetes mellitus (DM) is steadily increasing annually, with 537 million diabetic patients as of 2021. Restoring diminished β cell mass or impaired islet function is crucial in treating DM, particularly type 1 DM. However, the regenerative capacity of islet β cells, which primarily produce insulin, is severely limited, and natural regeneration is only observed in young rodents or children. Hence, there is an urgent need to develop advanced therapeutic approaches that can regenerate endogenous β cells or replace them with stem cell (SC)-derived or engineered β-like cells. Current strategies for treating insulin-dependent DM mainly include promoting the self-replication of endogenous β cells, inducing SC differentiation, reprogramming non-β cells into β-like cells, and generating pancreatic-like organoids through cell-based intervention. In this Review, we discuss the current state of the art in these approaches, describe associated challenges, propose potential solutions, and highlight ongoing efforts to optimize β cell or islet transplantation and related clinical trials. These effective cell-based therapies will generate a sustainable source of functional β cells for transplantation and lay strong foundations for future curative treatments for DM.

Hypoimmunogenic CD19 CAR-NK cells derived from embryonic stem cells suppress the progression of human B-cell malignancies in xenograft animals

Background

Chimeric antigen receptor (CAR) engineered natural killer (NK) cells exhibit advantages such as MHC-independent recognition and strong anti-tumor functions. However, allogeneic CAR-NK cells derived from human tissues are heterogeneous and susceptible to clearance by hosts.

Methods

We generated a B2M knockout, HLA-E and CD19 CAR ectopic expressing embryonic stem cell (ESC) line, which differentiated normally and gave rise to homogeneous CD19 CAR-NK (CD19 CAR-UiNK) cells using an organoid aggregate induction method. The CD19 CAR-UiNK were co-cultured with T cells or NK cells derived from peripheral blood mononuclear cells (PBMC) with the mismatched HLA to evaluate the immunogenicity of CD19 CAR-UiNK cells. We further assessed the therapeutic effects of CD19 CAR-UiNK cells on CD19+ tumor cells through in vitro cytotoxicity assays and in vivo animal models.

Results

The CD19 CAR-UiNK cells exhibited typical expression patterns of activating and inhibitory receptors, and crucial effector molecules of NK cells, similar to those of unmodified NK cells. In co-culture assays, the CD19 CAR-UiNK cells evaded allogeneic T cell response and suppressed allogeneic NK cell response. Functionally, the CD19 CAR-UiNK cells robustly secreted IFN-γ and TNF-α, and upregulated CD107a upon stimulation with Nalm-6 tumor cells. The CD19 CAR-UiNK cells effectively eliminated CD19+ tumor cells in vitro, including B-cell cancer cell lines and primary tumor cells from human B-cell leukemia and lymphoma. Further, the CD19 CAR-UiNK cells exhibited strong anti-tumor activity in xenograft animals.

Conclusion

We offer a strategy for deriving homogeneous and hypoimmunogenic CD19 CAR-iNK cells with robust anti-tumor effects from ESCs. Our study has significant implications for developing hypoimmunogenic CD19 CAR-NK cell therapy using human ESC as an unlimited cell source.

Recent progress in modeling and treating diabetes using stem cell-derived islets

Stem cell-derived islets (SC-islets) offer the potential to be an unlimited source of cells for disease modeling and the treatment of diabetes. SC-islets can be genetically modified, treated with chemical compounds, or differentiated from patient derived stem cells to model diabetes. These models provide insights into disease pathogenesis and vulnerabilities that may be targeted to provide treatment. SC-islets themselves are also being investigated as a cell therapy for diabetes. However, the transplantation process is imperfect; side effects from immunosuppressant use have reduced SC-islet therapeutic potential. Alternative methods to this include encapsulation, use of immunomodulating molecules, and genetic modification of SC-islets. This review covers recent advances using SC-islets to understand different diabetes pathologies and as a cell therapy.

Hydrogel-Encapsulated Pancreatic Islet Cells as a Promising Strategy for Diabetic Cell Therapy

Islet transplantation has now become a promising treatment for insulin-deficient diabetes mellitus. Compared to traditional diabetes treatments, cell therapy can restore endogenous insulin supplementation, but its large-scale clinical application is impeded by donor shortages, immune rejection, and unsuitable transplantation sites. To overcome these challenges, an increasing number of studies have attempted to transplant hydrogel-encapsulated islet cells to treat diabetes. This review mainly focuses on the strategy of hydrogel-encapsulated pancreatic islet cells for diabetic cell therapy, including different cell sources encapsulated in hydrogels, encapsulation methods, hydrogel types, and a series of accessorial manners to improve transplantation outcomes. In addition, the formation and application challenges as well as prospects are also presented.

Identification of unique cell type responses in pancreatic islets to stress

Diabetes involves the death or dysfunction of pancreatic β-cells. Analysis of bulk sequencing from human samples and studies using in vitro and in vivo models suggest that endoplasmic reticulum and inflammatory signaling play an important role in diabetes progression. To better characterize cell type-specific stress response, we perform multiplexed single-cell RNA sequencing to define the transcriptional signature of primary human islet cells exposed to endoplasmic reticulum and inflammatory stress. Through comprehensive pair-wise analysis of stress responses across pancreatic endocrine and exocrine cell types, we define changes in gene expression for each cell type under different diabetes-associated stressors. We find that β-, α-, and ductal cells have the greatest transcriptional response. We utilize stem cell-derived islets to study islet health through the candidate gene CIB1, which was upregulated under stress in primary human islets. Our findings provide insights into cell type-specific responses to diabetes-associated stress and establish a resource to identify targets for diabetes therapeutics.

Beta cells deficient for Renalase counteract autoimmunity by shaping natural killer cell activity

Type 1 diabetes (T1D) arises from autoimmune-mediated destruction of insulin-producing pancreatic beta cells. Recent advancements in the technology of generating pancreatic beta cells from human pluripotent stem cells (SC-beta cells) have facilitated the exploration of cell replacement therapies for treating T1D. However, the persistent threat of autoimmunity poses a significant challenge to the survival of transplanted SC-beta cells. Genetic engineering is a promising approach to enhance immune resistance of beta cells as we previously showed by inactivating the Renalase (Rnls) gene. Here, we demonstrate that Rnls loss of function in beta cells shapes autoimmunity by mediating a regulatory natural killer (NK) cell phenotype important for the induction of tolerogenic antigen-presenting cells. Rnls-deficient beta cells mediate cell-cell contact-independent induction of hallmark anti-inflammatory cytokine Tgfβ1 in NK cells. In addition, surface expression of regulatory NK immune checkpoints CD47 and Ceacam1 is markedly elevated on beta cells deficient for Rnls. Altered glucose metabolism in Rnls mutant beta cells is involved in the upregulation of CD47 surface expression. These findings are crucial to better understand how genetically engineered beta cells shape autoimmunity, giving valuable insights for future therapeutic advancements to treat and cure T1D.

CRISPR-Cas9 immune-evasive hESCs are rejected following transplantation into immunocompetent mice

Although current stem cell therapies exhibit promising potential, the extended process of employing autologous cells and the necessity for donor-host matching to avert the rejection of transplanted cells significantly limit the widespread applicability of these treatments. It would be highly advantageous to generate a pluripotent universal donor stem cell line that is immune-evasive and, therefore, not restricted by the individual's immune system, enabling unlimited application within cell replacement therapies. Before such immune-evasive stem cells can be moved forward to clinical trials, in vivo testing via transplantation experiments in immune-competent animals would be a favorable approach preceding preclinical testing. By using human stem cells in immune competent animals, results will be more translatable to a clinical setting, as no parts of the immune system have been altered, although in a xenogeneic setting. In this way, immune evasiveness, cell survival, and unwanted proliferative effects can be assessed before clinical trials in humans. The current study presents the generation and characterization of three human embryonic stem cell lines (hESCs) for xenogeneic transplantation in immune-competent mice. The major histocompatibility complexes I- and II-encoding genes, B2M and CIITA, have been deleted from the hESCs using CRISPR-Cas9-targeted gene replacement strategies and knockout. B2M was knocked out by the insertion of murine CD47. Human-secreted embryonic alkaline phosphatase (hSEAP) was inserted in a safe harbor site to track cells in vivo. The edited hESCs maintained their pluripotency, karyotypic normality, and stable expression of murine CD47 and hSEAP in vitro. In vivo transplantation of hESCs into immune-competent BALB/c mice was successfully monitored by measuring hSEAP in blood samples. Nevertheless, transplantation of immune-evasive hESCs resulted in complete rejection within 11 days, with clear immune infiltration of T-cells on day 8. Our results reveal that knockout of B2M and CIITA together with species-specific expression of CD47 are insufficient to prevent rejection in an immune-competent and xenogeneic context.

Innovations in bio-engineering and cell-based approaches to address immunological challenges in islet transplantation

Human allogeneic pancreatic islet transplantation is a life-changing treatment for patients with severe Type 1 Diabetes (T1D) who suffer from hypoglycemia unawareness and high risk of severe hypoglycemia. However, intensive immunosuppression is required to prevent immune rejection of the graft, that may in turn lead to undesirable side effects such as toxicity to the islet cells, kidney toxicity, occurrence of opportunistic infections, and malignancies. The shortage of cadaveric human islet donors further limits islet transplantation as a treatment option for widespread adoption. Alternatively, porcine islets have been considered as another source of insulin-secreting cells for transplantation in T1D patients, though xeno-transplants raise concerns over the risk of endogenous retrovirus transmission and immunological incompatibility. As a result, technological advancements have been made to protect transplanted islets from immune rejection and inflammation, ideally in the absence of chronic immunosuppression, to improve the outcomes and accessibility of allogeneic islet cell replacement therapies. These include the use of microencapsulation or macroencapsulation devices designed to provide an immunoprotective environment using a cell-impermeable layer, preventing immune cell attack of the transplanted cells. Other up and coming advancements are based on the use of stem cells as the starting source material for generating islet cells 'on-demand'. These starting stem cell sources include human induced pluripotent stem cells (hiPSCs) that have been genetically engineered to avoid the host immune response, curated HLA-selected donor hiPSCs that can be matched with recipients within a given population, and multipotent stem cells with natural immune privilege properties. These strategies are developed to provide an immune-evasive cell resource for allogeneic cell therapy. This review will summarize the immunological challenges facing islet transplantation and highlight recent bio-engineering and cell-based approaches aimed at avoiding immune rejection, to improve the accessibility of islet cell therapy and enhance treatment outcomes. Better understanding of the different approaches and their limitations can guide future research endeavors towards developing more comprehensive and targeted strategies for creating a more tolerogenic microenvironment, and improve the effectiveness and sustainability of islet transplantation to benefit more patients.

Hypoimmune islets achieve insulin independence after allogeneic transplantation in a fully immunocompetent non-human primate

Allogeneic transplantation of pancreatic islets for patients with difficult-to-control diabetes mellitus is severely hampered by the requirement for continuous immunosuppression and its associated morbidity. We report that allogeneic transplantation of genetically engineered (B2M-/-, CIITA-/-, CD47+), primary, hypoimmune, pseudo-islets (p-islets) results in their engraftment into a fully immunocompetent, diabetic non-human primate wherein they provide stable endocrine function and enable insulin independence without inducing any detectable immune response in the absence of immunosuppression. Hypoimmune primary p-islets may provide a curative cell therapy for type 1 diabetes mellitus.

Beta Cells Deficient for Renalase Counteract Autoimmunity by Shaping Natural Killer Cell Activity

Type 1 diabetes (T1D) arises from autoimmune-mediated destruction of insulin-producing pancreatic beta cells. Recent advancements in the technology of generating pancreatic beta cells from human pluripotent stem cells (SC-beta cells) have facilitated the exploration of cell replacement therapies for treating T1D. However, the persistent threat of autoimmunity poses a significant challenge to the survival of transplanted SC-beta cells. Genetic engineering is a promising approach to enhance immune resistance of beta cells as we previously showed by inactivating of the Renalase (Rnls) gene. Here we demonstrate that Rnls loss-of-function in beta cells shape autoimmunity by mediating a regulatory Natural Killer (NK) cell phenotype important for the induction of tolerogenic antigen presenting cells. Rnls-deficient beta cells mediate cell-cell-contact-independent induction of hallmark anti-inflammatory cytokine Tgfβ1 in NK cells. In addition, surface expression of key regulatory NK immune checkpoints CD47 and Ceacam1 are markedly elevated on beta cells deficient for Rnls. Enhanced glucose metabolism in Rnls mutant beta cells is responsible for upregulation of CD47 surface expression. These findings are crucial to a better understand how genetically engineered beta cells shape autoimmunity giving valuable insights for future therapeutic advancements to treat and cure T1D.

Immunoprotection of cellular transplants for autoimmune type 1 diabetes through local drug delivery

Type 1 diabetes mellitus (T1DM) is an autoimmune condition that results in the destruction of insulin-secreting β cells of the islets of Langerhans. Allogeneic islet transplantation could be a successful treatment for T1DM; however, it is limited by the need for effective, permanent immunosuppression to prevent graft rejection. Upon transplantation, islets are rejected through non-specific, alloantigen specific, and recurring autoimmune pathways. Immunosuppressive agents used for islet transplantation are generally successful in inhibiting alloantigen rejection, but they are suboptimal in hindering non-specific and autoimmune pathways. In this review, we summarize the challenges with cellular immunological rejection and therapeutics used for islet transplantation. We highlight agents that target these three immune rejection pathways and how to package them for controlled, local delivery via biomaterials. Exploring macro-, micro-, and nano-scale immunomodulatory biomaterial platforms, we summarize their advantages, challenges, and future directions. We hypothesize that understanding their key features will help identify effective platforms to prevent islet graft rejection. Outcomes can further be translated to other cellular therapies beyond T1DM.

Remyelination in the Central Nervous System

The inability of the mammalian central nervous system (CNS) to undergo spontaneous regeneration has long been regarded as a central tenet of neurobiology. However, while this is largely true of the neuronal elements of the adult mammalian CNS, save for discrete populations of granule neurons, the same is not true of its glial elements. In particular, the loss of oligodendrocytes, which results in demyelination, triggers a spontaneous and often highly efficient regenerative response, remyelination, in which new oligodendrocytes are generated and myelin sheaths are restored to denuded axons. Yet remyelination in humans is not without limitation, and a variety of demyelinating conditions are associated with sustained and disabling myelin loss. In this work, we will (1) review the biology of remyelination, including the cells and signals involved; (2) describe when remyelination occurs and when and why it fails, including the consequences of its failure; and (3) discuss approaches for therapeutically enhancing remyelination in demyelinating diseases of both children and adults, both by stimulating endogenous oligodendrocyte progenitor cells and by transplanting these cells into demyelinated brain.

Engineering human pluripotent stem cell lines to evade xenogeneic transplantation barriers

Successful allogeneic human pluripotent stem cell (hPSC)-derived therapies must overcome immunological rejection by the recipient. To build reagents to define these barriers, we genetically ablated β2M, TAP1, CIITA, CD74, MICA, and MICB to limit expression of HLA-I, HLA-II, and natural killer (NK) cell activating ligands in hPSCs. Transplantation of these cells that also expressed covalent single chain trimers of Qa1 and H2-Kb to inhibit NK cells and CD55, Crry, and CD59 to inhibit complement deposition led to persistent teratomas in wild-type mice. Transplantation of HLA-deficient hPSCs into mice genetically deficient in complement and depleted of NK cells also led to persistent teratomas. Thus, T cell, NK cell, and complement evasion are necessary to prevent immunological rejection of hPSCs and their progeny. These cells and versions expressing human orthologs of immune evasion factors can be used to define cell type-specific immune barriers and conduct preclinical testing in immunocompetent mouse models.

Translation of cell therapies to treat autoimmune disorders

Autoimmune diseases are a diverse and complex set of chronic disorders with a substantial impact on patient quality of life and a significant global healthcare burden. Current approaches to autoimmune disease treatment comprise broadly acting immunosuppressive drugs that lack disease specificity, possess limited efficacy, and confer undesirable side effects. Additionally, there are limited treatments available to restore organs and tissues damaged during the course of autoimmune disease progression. Cell therapies are an emergent area of therapeutics with the potential to address both autoimmune disease immune dysfunction as well as autoimmune disease-damaged tissue and organ systems. In this review, we discuss the pathogenesis of common autoimmune disorders and the state-of-the-art in cell therapy approaches to (1) regenerate or replace autoimmune disease-damaged tissue and (2) eliminate pathological immune responses in autoimmunity. Finally, we discuss critical considerations for the translation of cell products to the clinic.

Tolerating CD47

Cluster of differentiation 47 (CD47) occupies the outer membrane of human cells, where it binds to soluble and cell surface receptors on the same and other cells, sculpting their topography and resulting in a pleiotropic receptor-multiligand interaction network. It is a focus of drug development to temper and accentuate CD47-driven immune cell liaisons, although consideration of on-target CD47 effects remain neglected. And yet, a late clinical trial of a CD47-blocking antibody was discontinued, existent trials were restrained, and development of CD47-targeting agents halted by some pharmaceutical companies. At this point, if CD47 can be exploited for clinical advantage remains to be determined. Herein an airing is made of the seemingly conflicting actions of CD47 that reflect its position as a junction connecting receptors and signalling pathways that impact numerous human cell types. Prospects of CD47 boosting and blocking are considered along with potential therapeutic implications for autoimmune diseases and cancer.

Advancements in innate immune regulation strategies in islet transplantation

As a newly emerging organ transplantation technique, islet transplantation has shown the advantages of minimal trauma and high safety since it was first carried out. The proposal of the Edmonton protocol, which has been widely applied, was a breakthrough in this method. However, direct contact between islets and portal vein blood will cause a robust innate immune response leading to massive apoptosis of the graft, and macrophages play an essential role in the innate immune response. Therefore, therapeutic strategies targeting macrophages in the innate immune response have become a popular research topic in recent years. This paper will summarize and analyze recent research on strategies for regulating innate immunity, primarily focusing on macrophages, in the field of islet transplantation, including drug therapy, optimization of islet preparation process, islet engineering and Mesenchymal stem cells cotransplantation. We also expounded the heterogeneity, plasticity and activation mechanism of macrophages in islet transplantation, providing a theoretical basis for further research.

Stem and progenitor cell-based therapy of myelin disorders

Much of clinical neurology is concerned with diseases of-or involving-the brain's subcortical white matter. Common to these disorders is the loss of myelin, reflecting the elimination or dysfunction of oligodendrocytes and fibrous astrocytes. As such, the introduction of glial progenitor cells, which can give rise to new oligodendrocytes and astrocytes alike, may be a feasible strategy for treating a broad variety of conditions in which white matter loss is causally involved. This review first covers the sourcing and production of human glial progenitor cells, and the preclinical evidence for their efficacy in achieving myelin restoration in vivo. It then discusses both pediatric and adult disease targets for which transplanted glial progenitors may prove of therapeutic value, those challenges that remain in the clinical application of a glial cell replacement strategy, and the clinical endpoints by which the efficacy of this approach may be assessed.

Allo Beta Cell transplantation: specific features, unanswered questions, and immunological challenge

Type 1 diabetes (T1D) presents a persistent medical challenge, demanding innovative strategies for sustained glycemic control and enhanced patient well-being. Beta cells are specialized cells in the pancreas that produce insulin, a hormone that regulates blood sugar levels. When beta cells are damaged or destroyed, insulin production decreases, which leads to T1D. Allo Beta Cell Transplantation has emerged as a promising therapeutic avenue, with the goal of reinstating glucose regulation and insulin production in T1D patients. However, the path to success in this approach is fraught with complex immunological hurdles that demand rigorous exploration and resolution for enduring therapeutic efficacy. This exploration focuses on the distinct immunological characteristics inherent to Allo Beta Cell Transplantation. An understanding of these unique challenges is pivotal for the development of effective therapeutic interventions. The critical role of glucose regulation and insulin in immune activation is emphasized, with an emphasis on the intricate interplay between beta cells and immune cells. The transplantation site, particularly the liver, is examined in depth, highlighting its relevance in the context of complex immunological issues. Scrutiny extends to recipient and donor matching, including the utilization of multiple islet donors, while also considering the potential risk of autoimmune recurrence. Moreover, unanswered questions and persistent gaps in knowledge within the field are identified. These include the absence of robust evidence supporting immunosuppression treatments, the need for reliable methods to assess rejection and treatment protocols, the lack of validated biomarkers for monitoring beta cell loss, and the imperative need for improved beta cell imaging techniques. In addition, attention is drawn to emerging directions and transformative strategies in the field. This encompasses alternative immunosuppressive regimens and calcineurin-free immunoprotocols, as well as a reevaluation of induction therapy and recipient preconditioning methods. Innovative approaches targeting autoimmune recurrence, such as CAR Tregs and TCR Tregs, are explored, along with the potential of stem stealth cells, tissue engineering, and encapsulation to overcome the risk of graft rejection. In summary, this review provides a comprehensive overview of the inherent immunological obstacles associated with Allo Beta Cell Transplantation. It offers valuable insights into emerging strategies and directions that hold great promise for advancing the field and ultimately improving outcomes for individuals living with diabetes.

Electrocatalytic on-site oxygenation for transplanted cell-based-therapies

Implantable cell therapies and tissue transplants require sufficient oxygen supply to function and are limited by a delay or lack of vascularization from the transplant host. Previous exogenous oxygenation strategies have been bulky and had limited oxygen production or regulation. Here, we show an electrocatalytic approach that enables bioelectronic control of oxygen generation in complex cellular environments to sustain engineered cell viability and therapy under hypoxic stress and at high cell densities. We find that nanostructured sputtered iridium oxide serves as an ideal catalyst for oxygen evolution reaction at neutral pH. We demonstrate that this approach exhibits a lower oxygenation onset and selective oxygen production without evolution of toxic byproducts. We show that this electrocatalytic on site oxygenator can sustain high cell loadings (>60k cells/mm3) in hypoxic conditions in vitro and in vivo. Our results showcase that exogenous oxygen production devices can be readily integrated into bioelectronic platforms, enabling high cell loadings in smaller devices with broad applicability.

Synthetic immune checkpoint engagers protect HLA-deficient iPSCs and derivatives from innate immune cell cytotoxicity

Immune rejection of allogeneic cell therapeutics remains a major problem for immuno-oncology and regenerative medicine. Allogeneic cell products so far have inferior persistence and efficacy when compared with autologous alternatives. Engineering of hypoimmune cells may greatly improve their therapeutic benefit. We present a new class of agonistic immune checkpoint engagers that protect human leukocyte antigen (HLA)-depleted induced pluripotent stem cell-derived endothelial cells (iECs) from innate immune cells. Engagers with agonistic functionality to their inhibitory receptors TIM3 and SIRPα effectively protect engineered iECs from natural killer (NK) cell and macrophage killing. The SIRPα engager can be combined with truncated CD64 to generate fully immune evasive iECs capable of escaping allogeneic cellular and immunoglobulin G (IgG) antibody-mediated rejection. Synthetic immune checkpoint engagers have high target specificity and lack retrograde signaling in the engineered cells. This modular design allows for the exploitation of more inhibitory immune pathways for immune evasion and could contribute to the advancement of allogeneic cell therapeutics.

Current and future therapies to treat impaired awareness of hypoglycemia

In order to achieve optimal glycemic control, intensive insulin regimes are needed for individuals with Type 1 Diabetes (T1D) and insulin-dependent Type 2 Diabetes (T2D). Unfortunately, intensive glycemic control often results in insulin-induced hypoglycemia. Moreover, recurrent episodes of hypoglycemia result in both the loss of the characteristic warning symptoms associated with hypoglycemia and an attenuated counterregulatory hormone responses. The blunting of warning symptoms is known as impaired awareness of hypoglycemia (IAH). Together, IAH and the loss of the hormonal response is termed hypoglycemia associated autonomic failure (HAAF). IAH is prevalent in up to 25% in people with T1D and up to 10% in people with T2D. IAH and HAAF increase the risk of severe hypoglycemia 6-fold and 25-fold, respectively. To reduce this risk for severe hypoglycemia, multiple different therapeutic approaches are being explored that could improve awareness of hypoglycemia. Current therapies to improve awareness of hypoglycemia include patient education and psychoeducation, the use of novel glycemic control technology, pancreas/islet transplantation, and drug therapy. This review examines both existing therapies and potential therapies that are in pre-clinical testing. Novel treatments that improve awareness of hypoglycemia, via improving the counterregulatory hormone responses or improving hypoglycemic symptom recognition, would also shed light on the possible neurological mechanisms that lead to the development of IAH. To reduce the risk of severe hypoglycemia in people with diabetes, elucidating the mechanism behind IAH, as well as developing targeted therapies is currently an unmet need for those that suffer from IAH.

Microneedle-based cell delivery and cell sampling for biomedical applications

Cell-based therapeutics are novel therapeutic strategies that can potentially treat many presently incurable diseases through novel mechanisms of action. Cell therapies may benefit from the ease, safety, and efficacy of administering therapeutic cells. Despite considerable recent technological and biological advances, several barriers remain to the clinical translation and commercialization of cell-based therapies, including low patient compliance, personal handling inconvenience, poor biosafety, and limited biocompatibility. Microneedles (MNs) are emerging as a promising biomedical device option for improved cell delivery with little invasion, pain-free administration, and simplicity of disposal. MNs have shown considerable promise in treating a wide range of diseases and present the potential to improve cell-based therapies. In this review, we first summarized the latest advances in the various types of MNs developed for cell delivery and cell sampling. Emphasis was given to the design and fabrication of various types of MNs based on their structures and materials. Then we focus on the recent biomedical applications status of MNs-mediated cell delivery and sampling, including tissue repair (wound healing, heart repair, and endothelial repair), cancer treatment, diabetes therapy, cell sampling, and other applications. Finally, the current status of clinical application, potential perspectives, and the challenges for clinical translation are also highlighted.

Cell Therapy Drug Product Development: Technical Considerations and Challenges

Cell therapy uses living cells as a drug to treat diseases. To develop a cell therapy drug product (DP), cryopreservation plays a central role in extending the shelf life of these living medicines by pausing their biological activities, especially preventing degradation, at a temperature as low as liquid nitrogen. This helps overcome the temporal and geographical gaps between centralized manufacturing and clinical administration, as well as allowing sufficient time for full release testing and flexibility in scheduling patients for administration. Cryopreservation determines or influences several key manufacturing, logistical, or clinical in-use processes, including formulation, filling, controlled rate freezing, cryogenic storage and transportation, thawing, and dose preparation. This article overviews the key technical aspects of cell therapy DP development and elucidates fundamental principles of cryobiology that should be considered when we design and optimize the relevant processes. This article also discusses the challenges that motivate continued innovation for cell therapy drug product development.

The pathogenic "symphony" in type 1 diabetes: A disorder of the immune system, β cells, and exocrine pancreas

Type 1 diabetes (T1D) is widely considered to result from the autoimmune destruction of insulin-producing β cells. This concept has been a central tenet for decades of attempts seeking to decipher the disorder's pathogenesis and prevent/reverse the disease. Recently, this and many other disease-related notions have come under increasing question, particularly given knowledge gained from analyses of human T1D pancreas. Perhaps most crucial are findings suggesting that a collective of cellular constituents-immune, endocrine, and exocrine in origin-mechanistically coalesce to facilitate T1D. This review considers these emerging concepts, from basic science to clinical research, and identifies several key remaining knowledge voids.

The TSP1-CD47-SIRPα interactome: an immune triangle for the checkpoint era

The use of treatments, such as programmed death protein 1 (PD1) or cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) antibodies, that loosen the natural checks upon immune cell activity to enhance cancer killing have shifted clinical practice and outcomes for the better. Accordingly, the number of antibodies and engineered proteins that interact with the ligand-receptor components of immune checkpoints continue to increase along with their use. It is tempting to view these molecular pathways simply from an immune inhibitory perspective. But this should be resisted. Checkpoint molecules can have other cardinal functions relevant to the development and use of blocking moieties. Cell receptor CD47 is an example of this. CD47 is found on the surface of all human cells. Within the checkpoint paradigm, non-immune cell CD47 signals through immune cell surface signal regulatory protein alpha (SIRPα) to limit the activity of the latter, the so-called trans signal. Even so, CD47 interacts with other cell surface and soluble molecules to regulate biogas and redox signaling, mitochondria and metabolism, self-renewal factors and multipotency, and blood flow. Further, the pedigree of checkpoint CD47 is more intricate than supposed. High-affinity interaction with soluble thrombospondin-1 (TSP1) and low-affinity interaction with same-cell SIRPα, the so-called cis signal, and non-SIRPα ectodomains on the cell membrane suggests that multiple immune checkpoints converge at and through CD47. Appreciation of this may provide latitude for pathway-specific targeting and intelligent therapeutic effect.

Engineering Human Pluripotent Stem Cell Lines to Evade Xenogeneic Transplantation Barriers

Allogeneic human pluripotent stem cell (hPSC)-derived cells and tissues for therapeutic transplantation must necessarily overcome immunological rejection by the recipient. To define these barriers and to create cells capable of evading rejection for preclinical testing in immunocompetent mouse models, we genetically ablated β2m, Tap1, Ciita, Cd74, Mica, and Micb to limit expression of HLA-I, HLA-II, and natural killer cell activating ligands in hPSCs. Though these and even unedited hPSCs readily formed teratomas in cord blood-humanized immunodeficient mice, grafts were rapidly rejected by immunocompetent wild-type mice. Transplantation of these cells that also expressed covalent single chain trimers of Qa1 and H2-Kb to inhibit natural killer cells and CD55, Crry, and CD59 to inhibit complement deposition led to persistent teratomas in wild-type mice. Expression of additional inhibitory factors such as CD24, CD47, and/or PD-L1 had no discernible impact on teratoma growth or persistence. Transplantation of HLA-deficient hPSCs into mice genetically deficient in complement and depleted of natural killer cells also led to persistent teratomas. Thus, T cell, NK cell, and complement evasion are necessary to prevent immunological rejection of hPSCs and their progeny. These cells and versions expressing human orthologs of immune evasion factors can be used to refine tissue- and cell type-specific immune barriers, and to conduct preclinical testing in immunocompetent mouse models.