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Beta cell replacement therapy (BCRT) for patients with type 1 diabetes (T1D) improves blood glucose regulation by replenishing the endogenous beta cells destroyed by autoimmune attack. Several limitations, including immune isolation, prevent this therapy from reaching its full potential. Cell encapsulation devices used for BCRT provide a protective physical barrier for insulin‐producing beta cells, thereby protecting transplanted cells from immune attack. However, poor device engraftment posttransplantation leads to nutrient deprivation and hypoxia, causing metabolic strain on transplanted beta cells. Prevascularization of encapsulation devices at the transplantation site can help establish a host vascular network around the implant, increasing solute transport to the encapsulated cells. Here, we present a replenishable prevascularized implantation methodology (RPVIM) that allows for the vascular integration of replenishable encapsulation devices in the subcutaneous space. Empty encapsulation devices were vascularized for 14 days, after which insulin‐producing cells were inserted without disrupting the surrounding vasculature. The RPVIM devices were compared with nonprevascularized devices (Standard Implantation Methodology [SIM]) and previously established prevascularized devices (Standard Prevascularization Implantation Methodology [SPVIM]). Results show that over 75% of RPVIM devices containing stem cell‐derived insulin‐producing beta cell clusters showed a signal after 28 days of implantation in subcutaneous space. Notably, not only was the percent of RPVIM devices showing signal significantly greater than SIM and SPVIM devices, but the intraperitoneal glucose tolerance tests and histological analyses showed that encapsulated stem‐cell derived insulin‐producing beta cell clusters retained their function in the RPVIM devices, which is crucial for the successful management of T1D. [ABSTRACT FROM AUTHOR]

Type 1 diabetes results from an autoimmune attack directed at pancreatic beta cells predominantly mediated by T cells. Transplantation of stem cell derived beta-like cells (sBC) have been shown to rescue diabetes in preclinical animal models. However, how sBC will respond to an inflammatory environment with diabetogenic T cells in a strict human setting has not been determined. This is due to the lack of model systems that closely recapitulates human T1D. Here, we present a reliable in vitro assay to measure autologous CD8 T cell stimulation against sBC in a human setting. Our data shows that upon pro-inflammatory cytokine exposure, sBC upregulate Human Leukocyte Antigen (HLA) class I molecules which allows for their recognition by diabetogenic CD8 T cells. To protect sBC from this immune recognition, we utilized genome engineering to delete surface expression of HLA class I molecules and to integrate an inducible overexpression system for the immune checkpoint inhibitor Programmed Death Ligand 1 (PD-L1). Genetically engineered sBC that lack HLA surface expression or overexpress PD-L1 showed reduced stimulation of diabetogenic CD8 T cells when compared to unmodified cells. Here, we present evidence that manipulation of HLA class I and PD-L1 receptors on sBC can provide protection from diabetes-specific immune recognition in a human setting. [ABSTRACT FROM AUTHOR]

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Stem cell-based replacement therapies hold the promise to restore function of damaged or degenerated tissue such as the pancreatic islets in people with type 1 diabetes. Wide application of these therapies requires overcoming the fundamental roadblock of immune rejection. To address this issue, we use genetic engineering to create human pluripotent stem cells (hPSCs) in which the majority of the polymorphic human leukocyte antigens (HLAs), the main drivers of allogeneic rejection, are deleted. We retain the common HLA class I allele HLA-A2 and less polymorphic HLA-E/F/G to allow immune surveillance and inhibition of natural killer (NK) cells. We employ a combination of in vitro assays and humanized mouse models to demonstrate that these gene manipulations significantly reduce NK cell activity and T-cell-mediated alloimmune response against hPSC-derived islet cells. In summary, our approach produces hypoimmunogenic hPSCs that can be readily matched with recipients to avoid alloimmune rejection. [Display omitted] • Deletion of individual HLA genes protects β cells from T-cell-mediated rejection • Genome editing of stem cells does not affect their β cell differentiation potential • Retention of HLA-A2 promotes surface expression of HLA-E and reduces NK cell activity • HLA-A2 retention reduces rejection while allowing immune surveillance of the graft Parent et al. create immune-evasive human pluripotent stem cells by individually deleting all classical human leukocyte antigens except for the highly prevalent allele HLA-A2. This strategy significantly reduces NK- and T-cell-mediated rejection of stem cell-derived pancreatic β cells while retaining immune surveillance of the cells through HLA-A2. [ABSTRACT FROM AUTHOR]

Pancreatic islet transplantation is a promising treatment for type I diabetes, which is a chronic autoimmune disease in which the host immune cells attack insulin‐producing beta cells. The impact of this therapy is limited due to tissue availability and dependence on immunosuppressive drugs that prevent immune rejection of the transplanted cells. These issues can be solved by encapsulating stem cell‐derived insulin‐producing cells in an immunoprotective device. However, encapsulation exacerbates ischemia, and the lack of vasculature at the implantation site post‐transplantation worsens graft survival. Here, an encapsulation device that supplements nutrients to the cells is developed to improve the survival of encapsulated stem cell‐derived insulin‐producing cells in the poorly vascularized subcutaneous space. An internal compartment in the device is fabricated to provide zero‐order release of alanine and glutamine for several weeks. The amino acid reservoir sustains viability of insulin‐producing cells in nutrient limiting conditions in vitro. Moreover, the reservoir also increases cell survival by 30% after transplanting the graft in the subcutaneous space. [ABSTRACT FROM AUTHOR]