Fig 2: Schematic illustration of the effects of α-Spinasterol isolated from A. pseudoglehnii on glucose-stimulated insulin secretion in pancreatic β-cells and glucose uptake in skeletal muscle cells. IRS-1, insulin receptor substrate-1; IRS-2, insulin receptor substrate-2; AMPK, AMP-activated protein kinase; PDX-1, pancreatic and duodenal homeobox 1; GLUT-4, glucose transporter type 4; PPARγ, peroxisome proliferator-activated receptor γ.

Fig 3: Morphology of the generated NOD-IPCs. (a–d) Immunofluorescence staining of insulin (a), C-peptide (b), PDX-1 (c), and NKX6.1 (d) in NOD-IPCs on day 28. Green: insulin, C-peptide, PDX-1, or NKX6.1; blue: DAPI. Scale bar, 200 μm; scale bar of the larger image, 25 μm. (e–g) Immunofluorescence staining of autoantigens (ICA, GAD65, and ZnT8) in NOD-IPCs on day 28. ICA and ZnT8 were highly expressed, whereas GAD65 was not expressed. Green: ICA, ZnT8, or GAD65; blue: DAPI. Scale bar, 200 μm; scale bar of the larger image, 25 μm. (h) Immunofluorescence staining of PD-L1, which was highly expressed in NOD-IPCs. Green: PD-L1; blue: DAPI. Scale bar, 200 μm; scale bar of the larger image, 25 μm. Islets of NOD mice were used as a control.

Fig 4: KY19334 treatment restores β‐cell mass and functions in HFD‐fed and STZ‐induced diabetes mellitus (DM) mice. C57BL/6 mice fed NCD or HFD for 4 weeks followed by injection with STZ (50 mg/kg/d) for 1 week. Afterward, mice were p.o. administered KY19334 (25 mg/kg/d) or sitagliptin (50 mg/kg/d) for 4 weeks (n = 6 per group). (A) Non‐fasting blood glucose levels. (B) Glucose tolerance and insulin tolerance test and AUC. (C–E) The concentration of plasma C‐peptide (C), insulin (D) and serum active GLP‐1 (E). (F–H) Isolated islets from the pancreas of NCD or DM mice treated with DMSO or KY19334 for 72 h. The concentration of secreted insulin (F) and C‐peptide (G) from islets in response to different concentrations measured after incubation for 1 h with either low (2.8 mM) or high (16.7 mM) glucose in KRBH buffer. (H) Representative images of immunofluorescent staining for insulin and Ki67 (upper panel). Quantitative analyses of insulin‐ and Ki67‐positive cells, respectively, in the islets (lower panel). (I) Representative images of IHC staining of the pancreas for insulin, β‐catenin, PCNA, Pdx‐1 and Ki67. Arrows indicate proliferating β‐cells (upper panel). Quantitative analyses of insulin‐positive β‐cell mass, PCNA, Pdx‐1 and Ki67 positive cells in pancreatic tissues (lower panel). (J) Relative mRNA expression of Wnt/β‐catenin signalling target genes. Expression levels of mRNA were normalized by vehicle‐treated HFD mice group. Scale bars = 100 μm. All data are presented as the mean ± SD. *p < 0.05, **p < 0.01, ***p < 0.001 determined by Student's t‐test. DM: Diabetes mellitus; β‐cat: β‐catenin

Fig 5: Quality of the generated NOD-IPCs. (a) Schema of our differentiation protocol for the generation of NOD-IPCs from ADSCs. (b) Morphology of ADSCs isolated from the fat tissue of NOD mice. Scale bar, 100 μm. (c) FACS analysis of ADSCs isolated from the fat tissue of NOD mice. NOD DM- ADSCs: ADSCs isolated from normoglycemic NOD mice. NOD DM + ADSCs: ADSCs isolated from diabetic NOD mice. ADSCs were positive for CD90 and CD105, and negative for CD31, CD34, CD45 and CD146. (d) Morphology of a NOD-IPC cluster on days 1, 7, 14, 21, and 28. NOD-IPC clusters formed sphere-like structures within 24 h of the start of the 3D culture, and their morphology was maintained for at least 28 days. NOD-IPCs showed strong staining with dithizone on day 28. Scale bar, 200 μm. (e, f) mRNA expression of Insulin and MafA in the generated NOD-IPCs on day 28. The lines in the boxes show the median values (*P < 0.05, Mann–Whitney U test). (g) Western blots for insulin and PDX-1 in ADSCs and NOD-IPCs. The gels/blots were cropped from different parts of the different gels and grouped. The original blots/gels are presented in Supplementary Fig. 1. (h) Glucose-stimulated insulin secretion by NOD-IPCs. The mean insulin secretion by cells cultured in basal 2.2 mM glucose-containing medium was 0.50 ng/mL and that by cells cultured in 22 mM glucose-containing medium was 1.86 ng/mL. The SI for the NOD-IPCs was 3.7.