title: Cell survival and gene expression under compressive stress in a three-dimensional in vitro human periodontal ligament-like tissue model.
abstract: This study investigated cell survival and gene expression under various compressive stress conditions mimicking orthodontic force by using a newly developed in vitro model of human periodontal ligament-like tissue (HPdLLT). The HPdLLT was developed by three-dimensional culturing of human periodontal ligament fibroblasts in a porous poly-L-lactide matrix with threefold increased culture media permeability due to hydrophilic modification. In vitro HPdLLTs in experimental groups were subjected to 5, 15, 25 and 35 g/cm(2) compressive stress for 1, 3, 7 or 14 days; controls were cultured over the same periods without compressive stress. Cell morphology and cell apoptosis in the experimental and control groups were investigated using scanning electron microscopy and caspase-3/7 detection. Real-time polymerase chain reaction was performed for seven osteogenic and osteoclastic genes. Similar extracellular matrix and spindle-shaped cells were observed inside or on the surface of in vitro HPdLLTs, with no relation to compressive stress duration or intensity. Similar caspase-3/7 activity indicating comparable apoptosis levels was observed in all samples. Receptor activator of nuclear factor kappa-B ligand and bone morphogenetic protein 2 genes showed characteristic "double-peak" expression at 15 and 35 g/cm(2) on day 14, and alkaline phosphatase and periodontal ligament-associated protein 1 expression peaked at 5 g/cm(2) on day 14; other genes also showed time-dependent and load-dependent expression patterns. The in vitro HPdLLT model system effectively mimicked the reaction and gene expression of the human periodontal ligament in response to orthodontic force. This work provides new information on the effects of compressive stress on human periodontal ligament tissue.
authors.affiliation: Department of Orthodontics, Graduate School of Dentistry, Osaka Dental University, 8-1 Kuzuha-hanazono-cho, Hirakata-shi, Osaka, 573-1121, Japan. liaowenssw@gmail.com.
authors.forename: Wen
authors.initials: W
authors.lastname: Liao
authors.affiliation: Department of Biomaterials, Osaka Dental University, 8-1 Kuzuha-hanazono-cho, Hirakata-shi, Osaka, 573-1121, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Okada
authors.affiliation: Department of Orthodontics, Osaka Dental University, 8-1 Kuzuha-hanazono-cho, Hirakata-shi, Osaka, 573-1121, Japan.
authors.forename: Kaoru
authors.initials: K
authors.lastname: Inami
authors.affiliation: Department of Biomaterials, Osaka Dental University, 8-1 Kuzuha-hanazono-cho, Hirakata-shi, Osaka, 573-1121, Japan. yoshiya@cc.osaka-dent.ac.jp.
authors.forename: Yoshiya
authors.initials: Y
authors.lastname: Hashimoto
authors.affiliation: Department of Orthodontics, Osaka Dental University, 8-1 Kuzuha-hanazono-cho, Hirakata-shi, Osaka, 573-1121, Japan.
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Matsumoto
keywords: Cell living condition; Compressive stress; Gene expression; Human periodontal ligament-like tissue; Orthodontic force
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