The Effects of Placental Mesenchymal Stem Cells Labeled With Ultrasmall Superparamagnetic Iron Oxides on the Growth of Colorectal Cancer Cells.

OBJECTIVE: Colorectal cancer (CRC) is one of the most common malignant tumors worldwide, with effective intervention and treatment being essential for CRC management. This study investigated the effects of human placental mesenchymal stem cells (PMSCs) labeled with ultrasmall superparamagnetic iron oxides (USPIOs) on the growth of CRC cells and the feasibility of 3.0-T magnetic resonance (MR) imaging as an in vivo tracer. METHODS: Twenty subcutaneous CRC HT-29 xenograft model in immunodeficient mice was established. Mice injected with labeled PMSCs were considered as the experimental group. Thereafter, the growth and MR signal changes of xenograft tumors of every nude mouse were measured. Then, growth curve was plotted, and the MR image quality in different sequences was analyzed. Pathological staining was performed after MR scan. RESULTS: Ultrasmall superparamagnetic iron oxides-labeled PMSCs had no significant influence on biological characteristics ( P > 0.05). The growth of tumors in mice in the experimental group before the injection of PMSCs was similar to that of the control group. Contrarily, the tumor growth rate in the experimental group on day 5 post-PMSCs injection was slightly lower than that of the control group. Moreover, the tumor volume on day 14 was noticeably smaller than in the control group. The tracing ability of T2* mapping sequences for USPIOs-labeled cells was significantly more effective than T2-weighted image and T2 mapping sequences. CONCLUSIONS: Ultrasmall superparamagnetic iron oxides-labeled PMSCs injected into CRC transplanted tumors can be studied for a long period of time. Furthermore, 3.0-T MRI in vivo molecular imaging was demonstrated to be effective for CRC intervention.