title: Three-dimensional assessment of bystander effects of mesenchymal stem cells carrying a cytosine deaminase gene on glioma cells.
abstract: Stem cells carrying a suicide gene have emerged as therapeutic candidates for their cytotoxic bystander effects on neighboring cancers, while being non-toxic to other parts of the body. However, traditional cytotoxicity assays are unable to adequately assess the therapeutic effects of bystander cells. Here, we report a method to assess bystander effects of therapeutic stem cells against 3-dimensionally grown glioma cells in real time. U87 glioma cells were stably transduced to express a green fluorescence protein and co-cultivated with mesenchymal stem cells engineered to carry a bacterial cytosine deaminase gene (MSC/CD). Following addition of a 5-fluorocytine (5-FC) prodrug to the co-culture, fluorescence from U87 cells was obtained and analyzed in real time. Notably, the IC50 of 5-FC was higher when U87 cells were grown 3-dimensionally in soft agar medium for 3 weeks, as compared to those grown for one week in two-dimensional monolayer cultures. Additionally, more MSC/CD cells were required to maintain a similar level of efficacy. Since three-dimensional growth of glioma cells under our co-culture condition mimics the long-term expansion of cancer cells in vivo, our method can extend to an in vitro assay system to assess stem cell-mediated anti-cancer effects before advancing into preclinical animal studies.
authors.affiliation: Department of Biomedical Sciences, Ajou Graduate School Suwon, South Korea.
authors.forename: Jin Hwa
authors.initials: JH
authors.lastname: Jung
authors.affiliation: Wake Forest University Winston-Salem, NC, USA.
authors.forename: Andrew Aujin
authors.initials: AA
authors.lastname: Kim
authors.affiliation: Department of Anatomy, Ajou University School of Medicine Suwon Korea.
authors.forename: Da-Young
authors.initials: DY
authors.lastname: Chang
authors.affiliation: Yonsei University Seoul, South Korea.
authors.forename: Yoo Ra
authors.initials: YR
authors.lastname: Park
authors.affiliation: Department of Biomedical Sciences, Ajou Graduate School Suwon, South Korea ; Department of Anatomy, Ajou University School of Medicine Suwon Korea.
authors.forename: Haeyoung
authors.initials: H
authors.lastname: Suh-Kim
authors.affiliation: Department of Anatomy, Ajou University School of Medicine Suwon Korea.
authors.forename: Sung-Soo
authors.initials: SS
authors.lastname: Kim
keywords: 3D culture; Bystander effect; gene therapy; stem cell; suicide gene