(a) Representative gross
photos of a mouse showing tumors (highlighted
by dashed white circles) at 14 d after treatment with the conditions
described for groups 1–4. Scale bars, 10 mm. (b) Tumor volumes
in the four treatment groups at 6, 8, 10, 12, and 14 d after treatment
to determine the effectiveness of the treatment in terms of tumor
cell growth inhibition. (c) TUNEL staining of tissue sections from
the treatment groups at 24 h after treatment to determine the effectiveness
of the treatment in terms of tumor cell death by apoptosis. DAPI counterstaining
indicates the nuclear region, and upconversion fluorescence imaging
indicates the position of the injected UCNP-labeled cell (400×
magnification). Scale bar, 20 μm. (d) The apoptotic index charted
as the percentage of TUNEL-positive apoptotic nuclei divided by the
total number of nuclei visualized by counterstaining with DAPI obtained
from counts of randomly chosen microscopic fields. (Reprinted with
permission from ref (49). Copyright 2012 Nature Publishing Group.)