EXPERIMENTAL AND THERAPEUTIC MEDICINE 4: 221-225, 2012
Abstract. 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 brinogen-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 uorescence-
based live imaging system. Concentrated uorescence 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.
Introduction
The high morbidity and mortality of gastric cancer makes it
particularly concerning. Recent advances in tumor immunology
have led to the development of novel immunotherapies for
cancer. Adoptive cellular immunotherapy (ACI), a developing
cancer therapeutic, can mobilize and strengthen the body's
immune system to kill cancer cells in both a specic and non-
specic manner. Furthermore, adverse effects stemming from
ACI are milder than both radiotherapy and chemotherapy. While
clinical trials using cancer vaccines have yielded low objective
response rates (1), recent approaches based on ACI have shown
signicantly higher efcacy. Dudley et al demonstrated partial
and complete responses in ~50% of patients with metastatic
melanoma treated with adoptive transfer of ex vivo-expanded
autologous tumor-inltrating lymphocytes and a lymphode-
pleting host conditioning regime (2,3). While this method was
demonstrated to improve quality of life and prolong survival
time, the distribution of immune cells injected into a tumor-
bearing body has yet to be described. Furthermore, the ability of
intraperitoneally infused immune cells to target in situ gastric
cancer is also unknown. Thus, it would be worthwhile to nd
visual evidence of the tumor-targeting ability of immune cells.
With modern fluorescence imaging techniques, we are
able to trace the migration of cells in living animal models.
Unfortunately, the results of monitoring immune cells injected
into the gastric cancer orthotopic model were unsatisfactory due
to a low signal-to-noise ratio (4). In recent years, however, the
development of a near-infrared uorescence imaging technique
has made it possible to better trace living cells in deep tissue (5).
In the present study, we established an orthotopic gastric
carcinoma nude mouse model and dynamically monitored
cytokine-induced killer (CIK) cells and cytotoxic T lympho-
cytes (CTLs) labeled with the near-infrared uorescent dye,
DiR (1,1'-dioctadecyl-3,3,3',3'-tetramethyl indotricarbocya-
nine iodide).
Materials and methods
Cell line. Human gastric adenocarcinoma cell line BGC-823
(maintained in our laboratory) was grown in Dulbecco's modi-
ed Eagle's medium (DMEM) (Sigma, St. Louis, MO, USA)
with 10% fetal bovine serum and 1 U/ml gentamicin and
maintained in a humidied atmosphere of 5% CO
2
at 37˚C.
Dynamic tracing of immune cells in an orthotopic gastric
carcinoma mouse model using near-infrared
uorescence live imaging
XIAOHUI DU
1,2
, XIANGYU WANG
3
, NING NING
1,2
, SHAOYOU XIA
1,2
, JUCHAO LIU
3
,
WENTAO LIANG
3
, HUIWEI SUN
3
and YINGXIN XU
1,3
1
General Surgery Department, Chinese PLA General Hospital, Beijing;
2
General Surgery Department,
Chinese PLA General Hospital Hainan Branch, Hainan;
3
Institute of General Surgery,
Chinese PLA General Hospital, Beijing, P.R. China
Received February 15, 2012; Accepted May 4, 2012
DOI: 10.3892/etm.2012.579
Correspondence to: Professor Yingxin Xu, General Surgery
Department and Institute of General Surgery, Chinese PLA General
Hospital, 28 Fuxing Road, Haidian, Beijing 100853, P.R. China
E-mail: xuyingxin301@yeah.net
Key words: gastric carcinoma orthotopic model, cytokine-induced
killer cells, cytotoxic T lymphocytes, antitumor effect, near-infrared
fluorescence live imaging