Heterogeneity in cell-cycle dynamics of synthetic mRNA-induced β-cell proliferation

The study investigates the cell-cycle dynamics of synthetic mRNA-induced β-cell proliferation in adult pancreatic β-cells, which are typically locked in a quiescent state, limiting comprehensive cell cycle analysis. Synthetic in vitro transcribed mRNAs encoding Cyclin D1 and CDK4 were employed to stimulate proliferation in up to 70% of primary rat β-cells.

Flow cytometry analysis revealed significant heterogeneity in β-cell cell-cycle progression, with five distinct groups of proliferating β-cells identified based on G1 entry timing. The total cell-cycle length varied from approximately 26 to 34 hours, primarily determined by variability in G1 duration (13-19 hours). Fastest-dividing β-cells exhibited a shorter G1 phase (13 hours), followed by S and G2M phases of approximately 6 and 7 hours, respectively.

Later-entering β-cells had progressively longer G1 phases. Additionally, a small subpopulation of β-cells failed to complete division and may have exited the cell cycle. The findings underscore cell-cycle entry and G1 progression as major contributors to β-cell proliferation heterogeneity and provide a quantitative benchmark for devising strategies to facilitate controlled β-cell regeneration in diabetes.