Photothermal therapy, a type of
laser application, has the ability to eradicate
tumor cells by a local thermal effect and elicit a
tumor specific immune response.
Indocyanine green (ICG), a
photosensitizer, can effectively elevate the local temperature by absorbing energy from the
laser. The present study aimed to investigate the characteristics of temperature changes during
photothermal therapy with an infrared thermometer in an ICG
solution and in
tumor-bearing mice treated with a combination of
laser and ICG. Additionally, the present study observed the morphological changes of
tumor tissue by
hematoxylin-
eosin staining following
photothermal therapy. In the
solution experiment, when the
laser power density was 1 W/cm2 and the concentration of ICG was 0 or 0.0187 mg/ml, the temperature of the water was elevated by 3 and 28°C, respectively. In the
tumor-bearing mice experiment, when the
laser power density was 1 W/cm2 and the concentration of ICG was 0 and 0.1 mg/ml, the temperature of the
tumor-bearing mice was elevated by 6.9 and 28.5°C, respectively. With an increase in
laser power density, including 0.6, 0.8 and 1.0 W/cm2, the temperature was 23.3, 26.7 and 28.5°C, respectively. Pathological tissue sections demonstrated that a large number of
tumor cells experienced
necrosis, and the envelope of the
tumor was destroyed. Numerous inflammatory cells, in particular lymphocytes, infiltrated into the
tumor tissue following
tumor tissue treatment with a combination of
laser and ICG. These results indicated that a combination treatment with
laser and ICG may significantly increase the temperature of the water solutions and in the
tumor-bearing mice. The concentration of ICG and
laser power density contributed to the temperature elevation, in particular to the concentration of ICG.