# Disruption of Cell-Adhesion Signaling Resolves Unwanted Progenitor Specification in Stem Cell-Derived α and β Cell Grafts

## TL;DR

Disrupting cell-adhesion signaling in stem cell-derived α and β cells reduces unwanted growth after transplantation, improving their safety for treating type 1 diabetes.

## Contribution

This study identifies shared outgrowth-driving populations in SC-α and SC-β cells and shows that disrupting cell-adhesion signaling improves their safety profile.

## Key findings

- SC-α cells generate outgrowths similar to SC-β cells, marked by SOX9, CDX2, or SOX2.
- Cell-adhesion signaling is enriched in outgrowth-driving populations identified via single-cell RNA sequencing.
- Dispersing and reaggregating cells reduces outgrowth propensity in both SC-α and SC-β grafts.

## Abstract

What are the main findings?
An enrichment in cell-adhesion signaling is identified via single-cell RNA sequencing in the outgrowth-driving populations of transplanted stem cell-derived β and α cell products.The interruption of cell-adhesion signaling via Notch inhibition or single-cell dissociation disrupts outgrowth-driving populations in transplant-ready cell populations.

An enrichment in cell-adhesion signaling is identified via single-cell RNA sequencing in the outgrowth-driving populations of transplanted stem cell-derived β and α cell products.

The interruption of cell-adhesion signaling via Notch inhibition or single-cell dissociation disrupts outgrowth-driving populations in transplant-ready cell populations.

What are the implications of the main findings?
The dispersion and reaggregation of stem cell-derived β and α cells enhances their safety profiles following transplantation in mice.

The dispersion and reaggregation of stem cell-derived β and α cells enhances their safety profiles following transplantation in mice.

Directed differentiation protocols have recently been developed to produce stem cell-derived α (SC-α) cells as a potential component of a complete cell-based therapy for T1D, to complement the more widely studied stem cell-derived β (SC-β) cells. Differentiation protocols for SC-β cells produce off-target cell populations implicated in the development of outgrowths in SC-β cell grafts, but outgrowths from SC-α cells have not been explored. This study identifies that engrafted SC-α cells generate outgrowths of similar composition to SC-β cell outgrowths. Both cell types share outgrowth-driving populations marked by SOX9, CDX2, or SOX2. Single-cell RNA sequencing was used to reveal an enrichment in cell-adhesion signaling events in outgrowth-driving populations. Small-molecule inhibition of the Notch pathway was insufficient to disrupt all three outgrowth-driving populations. A comprehensive disruption of cell-adhesion signaling via single-cell dispersion and reaggregation is found to reduce the outgrowth propensity in engrafted SC-α and SC-β cells. Together, these results suggest that disrupting residual progenitor cells with SC-α and SC-β cell clusters can enhance the safety profile of these cell therapy products for T1D therapy.