Pancreatic islets are able to attract BM-derived cells. (A) Confocal microscopy analysis of GFP⁺ BM-derived cells in pancreas 2 weeks after BMT. GFP⁺ BM cells localized around and at lower extent inside the islet. Immunostaining for insulin (red) and glucagons (blue). DAPI: nuclear staining. (Aii-iii) Close-up view of the region marked in panel Ai. White arrows point to the GFP⁺ cells localized around the islet that are confirmed by the nuclear staining. (B-C) Islet isolated from mice that underwent transplantation with GFP⁺ BM after 11 (exp 1), 12 (exp 2), and 13 weeks (exp 3). (B) Low-power magnification (× 5) of islet representative of the 3 experiments; left panel: phase contrast image; right panel: fluorescence image. (C) GFP⁺ cells inside the islets were counted directly in floating isolated islets. Data are expressed as number of GFP⁺ cells/islet (mean ± SE); 150 islets were evaluated for each experiment.