Engineering human stem cell-derived islets to evade immune rejection and promote localized immune tolerance.

Immunological protection of transplanted stem cell-derived islet (SC-islet) cells is yet to be achieved without chronic immunosuppression or encapsulation. Existing genetic engineering approaches to produce immune-evasive SC-islet cells have so far shown variable results. Here, we show that targeting human leukocyte antigens (HLAs) and PD-L1 alone does not sufficiently protect SC-islet cells from xenograft (xeno)- or allograft (allo)-rejection. As an addition to these approaches, we genetically engineer SC-islet cells to secrete the cytokines interleukin-10 (IL-10), transforming growth factor ß (TGF-ß), and modified IL-2 such that they promote a tolerogenic local microenvironment by recruiting regulatory T cells (Tregs) to the islet grafts. Cytokine-secreting human SC-ß cells resist xeno-rejection and correct diabetes for up to 8 weeks post-transplantation in non-obese diabetic (NOD) mice. Thus, genetically engineering human embryonic SCs (hESCs) to induce a tolerogenic local microenvironment represents a promising approach to provide SC-islet cells as a cell replacement therapy for diabetes without the requirement for encapsulation or immunosuppression.

Whole-genome CRISPR screening identifies genetic manipulations to reduce immune rejection of stem cell-derived islets.

Human embryonic stem cells (hESCs) provide opportunities for cell replacement therapy of insulin-dependent diabetes. Therapeutic quantities of human stem cell-derived islets (SC-islets) can be produced by directed differentiation. However, preventing allo-rejection and recurring autoimmunity, without the use of encapsulation or systemic immunosuppressants, remains a challenge. An attractive approach is to transplant SC-islets, genetically modified to reduce the impact of immune rejection. To determine the underlying forces that drive immunogenicity of SC-islets in inflammatory environments, we performed single-cell RNA sequencing (scRNA-seq) and whole-genome CRISPR screen of SC-islets under immune interaction with allogeneic peripheral blood mononuclear cells (PBMCs). Data analysis points to "alarmed" populations of SC-islets that upregulate genes in the interferon (IFN) pathway. The CRISPR screen in vivo confirms that targeting IFNγ-induced mediators has beneficial effects on SC-islet survival under immune attack. Manipulating the IFN response by depleting chemokine ligand 10 (CXCL10) in SC-islet grafts confers improved survival against allo-rejection compared with wild-type grafts in humanized mice. These results offer insights into the nature of immune destruction of SC-islets during allogeneic responses and provide targets for gene editing.

Generation of a heterozygous GAPDH-Luciferase human ESC line (HVRDe008-A-1) for in vivo monitoring of stem cells and their differentiated progeny.

Human stem cell-derived beta (SC-ß) cells are a candidate for cell replacement therapy for type 1 diabetes. Whilst refinements to the differentiation protocol have resulted in the production of SC-ß cells that resemble adult beta cells, the unsolved challenge to protect transplanted SC-ß cells from the host immune system remains. To monitor the survival of SC-ß cells in vivo, we knocked-in the Firefly luciferase gene into the GAPDH locus of the HUES8 human embryonic stem cell (hESC) line, such that differentiated islet cells constitutively express luciferase.

The Past, Present and Future of Immunotherapy for Metastatic Renal Cell Carcinoma.

The treatment of renal cell carcinoma (RCC) has evolved tremendously over the past decades. Localized disease is often curative with surgical resection of the malignancy. However, in cases where the primary tumor has metastasized, immunotherapy is becoming a more prevalent means to combat metastatic renal cell carcinoma (mRCC). Cytokine and checkpoint inhibitor immunotherapy have been demonstrated to stimulate the immune response through a number of different mechanisms. These drugs have been used as a monotherapy, combination therapy, or as successive treatments to systemic therapies. This review summarizes the success of previous and current therapeutic targets, while also leading to the direction of future therapies. This review might be helpful in improving the management of mRCC.