Stimulation of rodent and human beta-cell proliferation using synthetic modified mRNAs encoding cell cycle regulators

Pancreatic beta cells exhibit marked resistance to proliferation, posing a barrier to therapeutic strategies aimed at restoring beta-cell mass in diabetes. Here, we present a transient, non-integrative approach to stimulate beta-cell proliferation using in vitro transcribed (IVT) mRNAs encoding cell cycle regulators. In rodent beta cells and human-beta cell derived EndoC-BH5 cells, chemically modified IVT mRNAs activated cell cycle entry and subsequent mitosis. A single dose of cyclin D1 and CDK4 IVT mRNAs nearly doubled the number of rat beta cells. However, achieving cell division in human beta cells required co-delivery of MYC IVT mRNA. The mitogenic response of beta cells peaked within 36–60 hours, and declined thereafter, reflecting the transient nature of IVT mRNA. Transcriptomic profiling revealed temporary activation of proliferative pathways and reversible downregulation of beta-cell maturation markers. Importantly, we detected no evidence of sustained proliferation. Our findings demonstrate that mRNA-based delivery of cell cycle regulators can overcome the intrinsic cell cycle block in beta cells and may provide a controllable approach for beta-cell regeneration.