title: Bimodal visualization of colorectal uptake of nanoparticles in dimethylhydrazine-treated mice.
abstract: OBJECTIVE
  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.
  
  
  CONCLUSIONS
  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.
authors: School of Medicine, Zhejiang University, No. 3 Qingchun Road East, Hangzhou 310016, Zhejiang Province, China.
authors: Tao
authors: T
authors: Wu
authors: Wei-Liang
authors: WL
authors: Zheng
authors: Shi-Zheng
authors: SZ
authors: Zhang
authors: Ji-Hong
authors: JH
authors: Sun
authors: Hong
authors: H
authors: Yuan
mesh_terms: D019813:1,2-Dimethylhydrazine / Q000008:administration & dosage / Q000494:pharmacology*; D000230:Adenocarcinoma / Q000139:chemically induced / Q000378:metabolism / Q000473:pathology; D000818:Animals; D002273:Carcinogens / Q000494:pharmacology*; D003106:Colon / Q000187:drug effects* / Q000378:metabolism* / Q000473:pathology; D015179:Colorectal Neoplasms / Q000139:chemically induced / Q000378:metabolism / Q000473:pathology; D004733:Enema; D019793:Fluorescein / Q000378:metabolism; D005456:Fluorescent Dyes / Q000378:metabolism; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D051379:Mice; D018613:Microscopy, Confocal / Q000379:methods; D053758:Nanoparticles; D010865:Pilot Projects; D012007:Rectum / Q000187:drug effects* / Q000378:metabolism* / Q000473:pathology
chemical_list: D002273:Carcinogens; D005456:Fluorescent Dyes; D019813:1,2-Dimethylhydrazine; D019793:Fluorescein