Extended Data Figure 7: Characterization of δ-cell-derived regenerated insulin⁺ cells.

a, Once differentiated from δ-cells (YFP⁺), the newly formed β-cells re-enter the cell cycle (Ki67⁺ cells). Two waves of massive replication occur, at 3 and 4 months after injury, respectively (Supplementary Table 23). b, qPCR for β-cell-specific genes using RNA extracted from islets isolated from control and DT-treated mice, either 2 weeks or 4 months after DT administration (0.5 mpa and 4 mpa). Note that after an initial extreme downregulation of all the β-cell-specific markers explored, their levels significantly recover after 4 months, which correlates with the observed robust regeneration and diabetes recovery. Values represent the ratio between each regeneration time-point and its age-matched control. c, Experimental design. d, qPCR comparison between regenerated mCherry⁺/insulin⁺ cells isolated from mice 4 months after β-cell ablation, and mCherry⁺ β-cells obtained from age-matched controls (4.5-month-old). All markers tested are expressed at identical levels in both groups; non-β-cell markers are expressed at extremely reduced levels (threshold cycle (CT) ranging from 28 to 31), showing the same degree of purity in both types of cell preparations. e, f, Interestingly, in contrast to bona fide β-cells isolated from 4.5-month-old controls, regenerated insulin⁺ cells have lower levels of cyclin-dependent kinase inhibitors, FoxO1 and Smad3. This correlates with their increased proliferative capacity at this specific time-point. Scale bars, 20 µm. qPCRs: n = 3 mice per group; each individual sample of each experimental group was run in triplicate, in three independent reactions; built-in Welch’s test. Error bars show s.d.