title: Culture medium refinement by dialysis for the expansion of human induced pluripotent stem cells in suspension culture.
abstract: Human induced pluripotent stem cells (hiPSCs) secrete essential autocrine factors that are removed along with toxic metabolites when the growth medium is exchanged daily. In this study, after determining the minimum inhibitory level of lactic acid for hiPSCs, a medium refining system was constructed by which toxic metabolites were removed from used culture medium and autocrine factors as well as other growth factors were recycled. Specifically, about 87 % of the basic fibroblast growth factor and 80 % of transforming growth factor beta 1 were retained in the refined medium after dialysis. The refined medium efficiently potentiated the proliferation of hiPS cells in adherent culture. When the refining system was used to refresh medium in suspension culture, a final cell density of (1.1 ± 0.1) × 106cells mL-1was obtained, with 99.5 ± 0.2 % OCT 3/4 and 78.3 ± 1.1 % TRA-1-60 expression, on day 4 of culture. These levels of expression were similar to those observed in the conventional suspension culture. With this method, culture medium refinement by dialysis was established to remove toxic metabolites, recycle autocrine factors as well as other growth factors, and reduce the use of macromolecules for the expansion of hiPSCs in suspension culture.
authors.affiliation: Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka, 565-0871, Japan.
authors.forename: Suman Chandra
authors.initials: SC
authors.lastname: Nath
authors.affiliation: Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka, 565-0871, Japan.
authors.forename: Eiji
authors.initials: E
authors.lastname: Nagamori
authors.affiliation: Division of Biochemical Engineering, Radioisotope Research Centre, Kyoto University, Kyoto, 606-8501, Japan.
authors.forename: Masanobu
authors.initials: M
authors.lastname: Horie
authors.affiliation: Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka, 565-0871, Japan. kino-oka@bio.eng.osaka-u.ac.jp.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Kino-Oka
mesh_terms: D018929:Cell Culture Techniques / Q000295:instrumentation* / Q000379:methods*; D003470:Culture Media / Q000737:chemistry*; D003956:Dialysis; D006801:Humans; D057026:Induced Pluripotent Stem Cells / Q000166:cytology / Q000378:metabolism*
chemical_list: D003470:Culture Media
keywords: Autocrine factors; Culture medium; Dialysis; Lactic acid; Refining method; hiPSC expansion