Figure 6.

5-IT treatment promotes human β-cell proliferation in vivo. A: Immunohistochemistry of vehicle or 5-IT–treated kidney sections grafted with human islets (10×) showing BrdU (green), insulin (red), and DAPI (blue). Yellow arrows define the kidney and human islet grafts. White arrows mark proliferating β-cells. Magnified images (×40) show each immunofluorescent staining separately (indicating nuclear gap for replicating β-cell surrounded by insulin) for the proliferating β-cell. Representative experiment from n = 3–4. Quantification of proliferating β-cells for BrdU/insulin (B), Ki67/insulin (C), and pHH3/insulin (D) double-positive cells from human islet grafts from A. Between 1,000 and 2,000 β-cells were counted in each section. E: Immunohistochemistry for another β-cell marker (PDX-1) in human islet–grafted kidney sections treated with or without 5-IT, using PDX-1 (red), Ki67/BrdU (green), and DAPI (blue). Representative experiment from n = 4. Quantification of proliferating β-cells for BrdU/PDX-1 (F) and Ki67/BrdU (G) double-positive cells. Error bars indicate ±SEM. P values were determined by unpaired Student t test. *P < 0.05; **P < 0.01. Absolute numbers of β-cells counted are provided in Supplementary Fig. 13. HI, human islet; HI Tx, vehicle treated; HI Tx + 5IT, 5-IT treated.