Apoptosis of Hurler MAPCs in presence of FGF-2. (A) Apoptosis was determined in Hurler MAPCs grown on coverslips placed in 6-well plates. Color definitions are as follows: green indicates viable cells; yellow, apoptotic cells (arrow); red, dead cells (arrowhead). Images were acquired on an Olympus BX60 fluorescent microscope using an UPlanApo 10×/0.4 dry objective lens at room temperature (final magnification, × 100). Fluorochromes were Cy3 (red) and 6-CF (green). Multiple fields were photographed using an Olympus U-ULS100HG digital camera system and SPOT 2.12 software (Diagnostics Instruments). Red and green images were merged and the composite figure made using Adobe Photoshop CS software. (i) Normal MAPCs grown on coverslips in standard MAPC medium (containing serum, EGF, and PDGF-BB). (ii) Hurler MAPCs grown on coverslips in standard MAPC medium (as in panel i). (iii) Hurler MAPCs grown on coverslips in FGF-2–supplemented serum-free medium, in presence of Hurler MAPCs in Transwells (TW) for 5 days. (iv) Hurler MAPCs grown on coverslips in FGF-2–supplemented serum-free medium, in presence of normal MAPCs in Transwells for 5 days. (B) Apoptotic and dead cells on the coverslips in the lower chambers of wells were counted on the indicated days after changing to FGF-2–supplemented serum-free medium and placement of Transwells with either Hurler or normal MAPCs. Data in the columns show the percentages of apoptotic and dead cells (upper and lower sections of the columns, respectively). The total height of the columns indicates the percentages of apoptotic and dead cells. The upper and lower error bars indicate the standard error (SE) of the mean for apoptotic and dead cells, respectively. Comparison between wells with Hurler MAPCs in the Transwells versus wells with normal MAPCs in Transwells: ^*P < .02 for apoptotic cells; ^**P < .05 for apoptotic and dead cells.