Glucagon and GLP-1 Accelerate Pseudo-Islet Assembly and Unmask Sex-Specific Islet Fragmentation Dynamics

Pancreatic hormones are best known for their role in regulating blood sugar levels as well as islet cell function and proliferation. However, their impact on maintaining and inducing cell aggregation in culture remains under-explored. In this study, we investigated the effects of glucagon (GCG) and glucagon-like-peptide 1(GLP-1) on the formation and integrity of human islet clusters. Native human islets were dissociated and sorted into pure α-, β-, and δ-cell populations using antibody-based fluorescence-activated cell sorting (FACS). The sorted cells were then co-cultured with mouse endothelial MS1 cells in suspension to generate pseudo-islets of varying cell composition. Hormonal supplementation with GCG or GLP-1 versus blank was administered during the tissue culture phase. Hormone-treated pseudo-islets formed faster, dependent on the cellular composition and the sex of the donor. In parallel, we also exposed native islets, maintained in suspension without prior dissociation or sorting, to hormone supplementation. These islets exhibited accelerated fragmentation under hormone treatment compared to controls, again dependent on donor sex with islets from female donors fragmenting faster than from male donors. These findings suggest that GCG and GLP-1 enhance pseudo-islet formation and affect the structural integrity of native islets in a sex-specific manner, offering insights into islet biology and implications for diabetes research and therapy.

We established a manipulatable, expandable human pseudo-islet platform to investigate islet morphogenesis, architecture, and intercellular signaling. We examined the contribution of individual α-, β-, and δ-cell populations and assessed how glucagon (GCG) and glucagon-like peptide-1 (GLP-1) modulate islet integrity in culture. In native islets, hormonal supplementation attenuated fragmentation in male donors but accelerated it in females. In pseudo-islets, cellular composition was the predominant determinant of maturation versus fragmentation, with donor sex exerting a secondary influence. We present methodological guidelines for generating and maintaining human pseudo-islets, thereby providing a framework to optimize donor selection, culture conditions, and experimental design in diabetes research.