Probe-Based Confocal Laser Endomicroscopy for Imaging TRAIL-Expressing Mesenchymal Stem Cells to Monitor Colon Xenograft Tumors In Vivo.
BACKGROUND
Mesenchymal stem cells (MSCs) can serve as vehicles for therapeutic genes. However, little is known about MSC behavior in vivo. Here, we demonstrated that probe-based confocal laser endomicroscopy (pCLE) can be used to track MSCs in vivo and individually monitor tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) gene expression within carcinomas.


METHODS
Isolated BALB/c nu/nu mice MSCs (MSCs) were characterized and engineered to co-express the TRAIL and enhanced green fluorescent protein (EGFP) genes. The number of MSCs co-expressing EGFP and TRAIL (TRAIL-MSCs) at tumor sites was quantified with pCLE in vivo, while their presence was confirmed using immunofluorescence (IF) and quantitative polymerase chain reaction (qPCR). The therapeutic effects of TRAIL-MSCs were evaluated by measuring the volumes and weights of subcutaneous HT29-derived xenograft tumors.


RESULTS
Intravital imaging of the subcutaneous xenograft tumors revealed that BALB/c mice treated with TRAIL-MSCs exhibited specific cellular signals, whereas no specific signals were observed in the control mice. The findings from the pCLE images were consistent with the IF and qPCR results.


CONCLUSIONS
The pCLE results indicated that endomicroscopy could effectively quantify injected MSCs that homed to subcutaneous xenograft tumor sites in vivo and correlated well with the therapeutic effects of the TRAIL gene. By applying pCLE for the in vivo monitoring of cellular trafficking, stem cell-based anticancer gene therapeutic approaches might be feasible and attractive options for individualized clinical treatments.
Department of Gastroenterology, Qilu Hospital, Shandong University, Jinan, China.|Laboratory of Translational Gastroenterology, Qilu Hospital, Shandong University, Jinan, China.
Zhen
Z
Zhang
Department of Gastroenterology, Qilu Hospital, Shandong University, Jinan, China.
Ming
M
Li
Department of Gastroenterology, Qilu Hospital, Shandong University, Jinan, China.
Feixue
F
Chen
Laboratory of Translational Gastroenterology, Qilu Hospital, Shandong University, Jinan, China.
Lixiang
L
Li
Department of Gastroenterology, Qilu Hospital, Shandong University, Jinan, China.
Jun
J
Liu
Department of Gastroenterology, Qilu Hospital, Shandong University, Jinan, China.
Zhen
Z
Li
Department of Gastroenterology, Qilu Hospital, Shandong University, Jinan, China.
Rui
R
Ji
Department of Gastroenterology, Qilu Hospital, Shandong University, Jinan, China.
Xiuli
X
Zuo
Department of Gastroenterology, Qilu Hospital, Shandong University, Jinan, China.
Yanqing
Y
Li
D000818:Animals; D003110:Colonic Neoplasms / Q000473:pathology*; D005260:Female; D019073:HT29 Cells; D064593:Heterografts; D006801:Humans; D059630:Mesenchymal Stem Cells / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D018613:Microscopy, Confocal / Q000379:methods*; D015335:Molecular Probes; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000378:metabolism*
D015335:Molecular Probes; D053221:TNF-Related Apoptosis-Inducing Ligand; C505654:Tnfsf10 protein, mouse