CD98hc marks a precursor of human stem cell-derived alpha cells primed for functional maturation.

Introduction: Pluripotent stem cell-derived alpha cells (SC-α cells) represent a promising component of next-generation cell therapies designed to more fully recapitulate human islet function; however, heterogeneity and the presence of undesired side populations limit their functional maturity and therapeutic potential. Here, we identify the cell surface protein CD98hc (SLC3A2), that when highly expressed in precursor cells, is associated with differentiation toward a more transcriptionally and functionally mature population of human SC-α cells. Methods: Directed differentiation was used to generate SC-α cells from pluripotent stem cells, which were assessed via single cell RNA sequencing, flow cytometry, and immunofluorescence imaging. Following magnetic activated cell sorting (MACS) of CD98hc enriched precursors, SC-α cell function was assessed using glucose stimulated glucagon secretion (GSGS). Results: We show that CD98hc is upregulated in SC-α cells expressing high levels of genes known to play important roles in α cell identity and function, and that CD98hc expression is elevated at the pre-α precursor stage relative to non-α cell populations. We demonstrate that magnetic enrichment of CD98hc⁺ pre-α cells derived from multiple pluripotent stem cell lines selectively increases the proportion of the highest CD98hc expressing glucagon-copositive precursors while depleting multiple undesired side populations, including somatostatin-positive and SOX9-positive cells. Although total α cell yield equalizes following complete differentiation, SC-α cells derived from high-CD98hc enriched precursors exhibit significantly enhanced glucose-responsive glucagon secretion compared to sham-sorted controls, indicating improved functional maturation of this precursor population. Discussion: Together, these findings establish that high expression levels of CD98hc marks a functionally superior α cell precursor, that enrichment at the precursor stage can bias differentiation toward higher functional α cell output, that stem cell-derived α cell populations harbor intrinsic functional heterogeneity, and that selective targeting of precursor populations represents a generalizable strategy to improve the quality and performance of stem cell-derived endocrine cell products.