Whole-genome CRISPR screening identifies genetic modifiers of stem cell-derived islet transplantation

Genetically engineering human pluripotent stem cell (hPSC)-derived islets is a promising strategy for improving transplantation for diabetes cell therapy; however, genetic perturbations that modulate transplantation outcomes have yet to be systematically explored.

To identify potential targets, we performed an unbiased whole-genome CRISPR-activation screen in transplanted stem cell-derived islets (SC-islets). Specifically, we created a stem cell line with CRISPR-activation components (HUES8-VPR) and then transduced these stem cells with a lentiviral guide RNA library targeting the whole human genome. Following transduction, the stem cells were differentiated into SC-islets, which were subsequently transplanted into NOD.Cg-PrkdcscidIl2rgtm1Wjl/SzJ (NSG) immunodeficient mice. After transplantation, SC-islets were extracted for next-generation sequencing.

The screen identified multiple candidates, including the Fc alpha/mu receptor (FCAMR). In vitro characterization revealed that FCAMR overexpression did not negatively affect SC-islet function or transcriptomic identity. Mice subcutaneously transplanted with SC-islets overexpressing FCAMR had reduced blood glucose levels and increased C-peptide compared to controls. Additionally, mice receiving FCAMR-modified grafts into the kidney capsule or hindleg muscle maintained a higher body weight compared to controls in a diabetic setting.

In conclusion, this study demonstrats improved glucose regulation at a subcutaneous transplant site. In addition, we show that FCAMR SC-islets could play a role in systemic metabolism when transplanted into the kidney capsule or hindleg muscle. Overall, our study establishes a functional screening approach to identify gene candidates to improve SC-islet transplantation.