Prevention of diabetes and insulitis in NOD mice after intrathymic injection of a preproinsulin-2–expressing lentiviral vector. (A) Cumulative diabetes incidence (Kaplan-Meier survival curve) in unmanipulated mice (CTRL, n = 11) or after intrathymic injection of a GFP-expressing (LvGFP, n = 10) or preproinsulin-2–expressing (LvPpins2, n = 14) lentiviral vector. Indicated for LvGFP and LvPpins2 survival curves are the P values calculated with a log-rank test relative to the untreated NOD mice. (B) Sections of formalin-fixed pancreas from 10-week-old untreated nondiabetic mice (top left: original magnification, ×20), 36-week-old LvGFP-treated diabetic mice (top right: original magnification, ×100), and LvPpins-2–treated nondiabetic mice (bottom left and right: original magnification, ×20). Paraffinembedded sections of pancreas from NOD mice were stained with hematoxylin for 5 minutes followed by eosin for 30 seconds to reveal nucleated cells. Images were taken with either a 10×/0.3 PL or a 20×/0.5 FLUOTAR AB objective of a DM RB microscope (Leica Microsystems, Wetzlar, Germany). Image digitization was performed by a DXC930P CDD color video camera (Sony France, Clichy, France) with TRIBVN ICS software v. 1.2.0.9 (TRIBVN, Châtillon, France). Images were processed for contrast and luminosity using Adobe Photoshop CS.