title: Mesenchymal stem cells administered in the early phase of tumorigenesis inhibit colorectal tumor development in rats.
abstract: To investigate the differences between the effects of mesenchymal stem cells (MSCs) administered in the early and late phases of tumorigenesis, MSCs were isolated from bone marrow and colorectal tumors were produced by exposing 7-week-old F344 rats to 1,2-dimethylhydrazine and dextran sulfate sodium. We evaluated tumor number and volume (week 25), MSC localization, number of aberrant crypt foci (ACF), transforming growth factor (TGF)-β1 protein levels in the rectum after administration of MSCs (week 5 or 15), and the effects of MSC-conditioned medium on ACL15 cell proliferation. Administered MSCs labeled with PKH26 were observed in the rectum. Administered MSCs in the early phase (week 5) before tumor occurrence (week 12) significantly decreased tumor number and volume (1.5 vs 4 and 21 mm(3) vs 170 mm(3); p<0.01), but not administered MSCs in the late phase (week 15). Administered MSCs in the early phase reduced ACF number on days 14 and 35 (1.9 vs 4.1 and 3.7 vs 7.3; p<0.01). Rectal TGF-β1 increased 1.3 fold on day 3, and MSC-conditioned medium containing TGF-β1 abundantly inhibited ACL15 cell proliferation. MSCs administered in the early phase but not late phase inhibited colorectal tumor development in a rat model.
authors.affiliation: Department of Gastroenterology, Osaka City University Graduate School of Medicine, 1-4-3 Asahimachi, Abeno-ku, Osaka 545-8585, Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Katsuno
authors.forename: Masahiro
authors.initials: M
authors.lastname: Ochi
authors.forename: Kazunari
authors.initials: K
authors.lastname: Tominaga
authors.forename: Fumio
authors.initials: F
authors.lastname: Tanaka
authors.forename: Mitsue
authors.initials: M
authors.lastname: Sogawa
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Tanigawa
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Yamagami
authors.forename: Masatsugu
authors.initials: M
authors.lastname: Shiba
authors.forename: Kenji
authors.initials: K
authors.lastname: Watanabe
authors.forename: Toshio
authors.initials: T
authors.lastname: Watanabe
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Fujiwara
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Arakawa
keywords: aberrant crypt foci; colorectal tumor; mesenchymal stem cell; transforming growth factor β1