title: Significant increase in Young's modulus of ATDC5 cells during chondrogenic differentiation induced by PAMPS/PDMAAm double-network gel: comparison with induction by insulin.
abstract: A double-network (DN) gel, which was composed of poly(2-acrylamido-2-methylpropanesulfonic acid) and poly(N,N'-dimethyl acrylamide) (PAMPS/PDMAAm), has the potential to induce chondrogenesis both in vitro and in vivo. The present study investigated the biomechanical and biological responses of chondrogenic progenitor ATDC5 cells cultured on the DN gel. ATDC5 cells were cultured on a polystyrene surface without insulin (Culture 1) and with insulin (Culture 2), and on the DN gel without insulin (Culture 3). The cultured cells were evaluated using micropipette aspiration for cell Young's modulus and qPCR for gene expression of chondrogenic and actin organization markers on days 3, 7 and 14. On day 3, the cells in Culture 3 formed nodules, in which the cells exhibited an actin cortical layer inside them, and gene expression of type-II collagen, aggrecan, and SOX9 was significantly higher in Culture 3 than Cultures 1 and 2 (p<0.05). Young's modulus in Culture 3 was significantly higher than that in Culture 1 throughout the testing period (p<0.05) and that in Culture 2 on day 14 (p<0.01). There was continuous expression of actin organization markers in Culture 3. This study highlights that the cells on the DN gel increased the modulus and mRNA expression of chondrogenic markers at an earlier time point with a greater magnitude compared to those on the polystyrene surface with insulin. This study also demonstrates a possible strong interrelation among alteration of cell mechanical properties, changes in actin organization and the induction of chondrogenic differentiation.
authors.affiliation: Laboratory of Micro and Nanomechanics, Division of Human Mechanical Systems and Design, Graduate School of Engineering, Hokkaido University, N13 W8, Kita-ku, Sapporo, Hokkaido 060-8628, Japan. Electronic address: e.maeda@eng.hokudai.ac.jp.
authors.forename: Eijiro
authors.initials: E
authors.lastname: Maeda
authors.affiliation: Laboratory of Micro and Nanomechanics, Division of Human Mechanical Systems and Design, Graduate School of Engineering, Hokkaido University, N13 W8, Kita-ku, Sapporo, Hokkaido 060-8628, Japan.
authors.forename: Takehiro
authors.initials: T
authors.lastname: Tsutsumi
authors.affiliation: Department of Sports Medicine and Joint Surgery, Graduate School of Medicine, Hokkaido University, N15 W7, Kita-ku, Sapporo, Hokkaido 060-8638, Japan.
authors.forename: Nobuto
authors.initials: N
authors.lastname: Kitamura
authors.affiliation: Laboratory of Soft and Wet Matter, Department of Advanced Transdisciplinary Sciences, Faculty of Advanced Life Science, Hokkaido University, N10, W8, Kita-ku, Sapporo, Hokkaido 060-0810, Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Kurokawa
authors.affiliation: Laboratory of Soft and Wet Matter, Department of Advanced Transdisciplinary Sciences, Faculty of Advanced Life Science, Hokkaido University, N10, W8, Kita-ku, Sapporo, Hokkaido 060-0810, Japan.
authors.forename: Jian
authors.initials: J
authors.lastname: Ping Gong
authors.affiliation: Department of Sports Medicine and Joint Surgery, Graduate School of Medicine, Hokkaido University, N15 W7, Kita-ku, Sapporo, Hokkaido 060-8638, Japan.
authors.forename: Kazunori
authors.initials: K
authors.lastname: Yasuda
authors.affiliation: Laboratory of Micro and Nanomechanics, Division of Human Mechanical Systems and Design, Graduate School of Engineering, Hokkaido University, N13 W8, Kita-ku, Sapporo, Hokkaido 060-8628, Japan.
authors.forename: Toshiro
authors.initials: T
authors.lastname: Ohashi
mesh_terms: D000178:Acrylamides / Q000737:chemistry*; D008841:Actin Cytoskeleton / Q000187:drug effects / Q000378:metabolism; D015415:Biomarkers / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects*; D045744:Cell Line, Tumor; D019902:Chondrocytes / Q000166:cytology / Q000187:drug effects; D020219:Chondrogenesis / Q000187:drug effects*; D055119:Elastic Modulus / Q000187:drug effects*; D005782:Gels; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D007328:Insulin / Q000494:pharmacology*; D011108:Polymers / Q000737:chemistry* / Q000494:pharmacology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013451:Sulfonic Acids / Q000737:chemistry* / Q000494:pharmacology*
chemical_list: D000178:Acrylamides; D015415:Biomarkers; D005782:Gels; D007328:Insulin; D011108:Polymers; D012333:RNA, Messenger; D013451:Sulfonic Acids; C429790:poly(N,N-dimethylacrylamide); C077118:poly(2-acrylamido-2-methyl-1-propanesulfonic acid)
keywords: ATDC5; Actin cortical layer; Chondrogenic differentiation; Double-network hydrogel; Young׳s modulus