Original Article
Copyright ©2011 Baishideng Publishing Group Co., Limited. All rights reserved.
World J Gastroenterol. Aug 21, 2011; 17(31): 3614-3622
Published online Aug 21, 2011. doi: 10.3748/wjg.v17.i31.3614
Bimodal visualization of colorectal uptake of nanoparticles in dimethylhydrazine-treated mice
Tao Wu, Wei-Liang Zheng, Shi-Zheng Zhang, Ji-Hong Sun, Hong Yuan
Tao Wu, Wei-Liang Zheng, Shi-Zheng Zhang, Department of Radiology, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, No. 3 Qingchun Road East, Hangzhou 310016, Zhejiang Province, China
Tao Wu, Department of Radiology, Jining Medical College, Jining 272067, Shandong Province, China
Ji-Hong Sun, Department of Radiology, Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310009, Zhejiang Province, China
Hong Yuan, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310009, Zhejiang Province, China
Author contributions: Wu T, Zheng WL, and Zhang SZ designed the research; Wu T, Zheng WL and Sun JH performed the research; Yuan H designed and evaluated the nanoparticles; Wu T analyzed the data and wrote the paper; Zhang SZ guaranteed the integrity of the research.
Supported by National Natural Science Foundation of China, No. 30670610.
Correspondence to: Shi-Zheng Zhang, MD, Professor of Radiology, Department of Radiology,Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, No. 3 Qingchun Road East, Hangzhou 310016, Zhejiang Province, China. paper.wutao@gmail.com
Telephone: +86-571-86006751 Fax: +86-571-86032876
Received: December 4, 2010
Revised: March 24, 2011
Accepted: April 3, 2011
Published online: August 21, 2011

AIM: To investigate colorectal uptake of solid lipid nanoparticles (SLNs) in mice receiving different doses of 1,2-dimethylhydrazine (DMH) using magnetic resonance (MR) and laser-scanning confocal fluorescence microscope (LSCFM) imaging.

METHODS: Eight mice were sacrificed in a pilot study to establish the experimental protocol and to visualize colorectal uptake of SLNs in normal mice. Gadopentetate dimeglumine and fluorescein isothiocyanate (FITC)-loaded SLN (Gd-FITC-SLN) enemas were performed on mice receiving DMH for 10 wk (group 1, n = 9) or 16 wk (group 2, n = 7) and FITC-SLN enema was performed on 4 DMH-treated mice (group 3). Pre- and post-enema MR examinations were made to visualize the air-inflated distal colorectum. Histological and LSCFM examinations were performed to verify colorectal malignancy and to track the distribution of SLNs.

RESULTS: Homogeneous enhancement and dense fluorescence (FITC) deposition in colorectal wall were observed in normal mice and 1 DMH-treated mouse (group 1) on fluid attenuated inversion recovery (FLAIR) and LSCFM images, respectively. Heterogeneous mural enhancement was found in 6 mice (4 in group 1; 2 in group 2). No visible mural enhancement was observed in the other mice. LSCFM imaging revealed linear fluorescence deposition along the colorectal mucosa in all groups. Nine intraluminal masses and one prolapsed mass were detected by MR imaging with different enhancement modes and pathologies. Interstitial FITC deposition was identified where obvious enhancement was observed in FLAIR images. Bladder imaging agent accumulations were observed in 11 of 16 DMH-treated mice of groups 1 and 2.

CONCLUSION: There are significant differences in colorectal uptake and distribution of SLNs between normal and DMH-treated mice, which may provide a new mechanism of contrast for MR colonography.

Keywords: Solid lipid nanoparticles, Colorectal cancer, Magnetic resonance colonography