BM-derived CD45^– can be isolated and expanded from pancreatic islets. (A) GFP⁺ cells inside and outside islets after islet isolation and 4 weeks of culture. Low-power magnification of islets representative of the 3 experiments photographed under an inverted microscope after 1 week of culture. (i) Phase contrast. (ii) Fluorescence image. Islets were photographed under an inverted microscope at different time points during culture. The number of GFP⁺ cells was calculated with Scion Imaging Software (Scion, Frederick, MD) (iii-iv). For cells found inside islets (iii), data at each time point are expressed as the mean ± SE GFP⁺ cell/islet determined for 100 islets. For cells found outside islets (iv), an area from the islet center corresponding to twice the islet diameter was outlined and cells scored in the area not occupied by the islet. The data at each time point are expressed as the mean ± SE GFP⁺ cell/100 μm² non–islet area determined for 50 islets. (B) Staining for CD45 (red) and GFP (green) of cells found outside isolated islets after 24 hours or 48 hours of culture. (Left) Confocal microscopy showing GFP⁺/CD45⁺ and GFP⁺/CD45^– cells at 24 hours. (Right) Results (mean ± SE) of cell counting are expressed as number of cells/field. At least 20 fields for each time point were counted.