Dynamic tracing of immune cells in an orthotopic gastric carcinoma mouse model using near-infrared fluorescence live imaging.

Adoptive cellular immunotherapy (ACI) has been demonstrated to be a promising cancer therapeutic, however, the distribution of immune cells injected into a tumor-bearing body is unclear. In this study, we investigated the tumor-targeting capacity of cytokine-induced killer (CIK) cells and cytotoxic T lymphocytes (CTLs) in a human gastric carcinoma orthotopic mouse model using a near-infrared fluorescence imaging system. CIK cells and tumor-specific CTLs were prepared with the near-infrared fluorescent dye DiR. As expected, no significant change in the proliferation rate or antitumor activity of CIK cells and CTLs was noted after labeling with DiR. Furthermore, a gastric carcinoma orthotopic model was established using a fibrinogen-thrombin method in nude mice followed by intraperitoneal infusion of the labeled immune cells into nude mice with established gastric carcinoma. Dynamic tracing of the immune cells was performed using a fluorescence-based live imaging system. Concentrated fluorescence signals were observed for a minimum of two weeks at the tumor site in mice infused with either CIK cells or CTLs with a peak signal at 48 h. Notably, CTLs were more persistent at the tumor site and exhibited a more intense antitumor activity than CIK cells following infusion. These results provided visual evidence of the tumor-targeting capacity of immune cells in live animals.