title: Hydrostatic pressure induces apoptosis of chondrocytes cultured in alginate beads.
abstract: The purpose of this study was to investigate the influence of hydrostatic pressure (HP) on apoptosis and expression of heat-shock protein 70 (HSP70) in chondrocytes cultured in alginate beads. Chondrocytes were isolated from the articular cartilage of rabbit joints and seeded in alginate beads. The beads in Group A were cultured for less than 24 h after being embedded with the chondrocytes, while those in Group B were cultured for 2 weeks. Both groups were exposed to HP of 10 or 50 MPa for 12 or 24 h. The beads in Groups A and B that were not exposed to HP were regarded as controls. Apoptotic cells induced by exposure to HP were quantified using the TUNEL method. Immunohistochemical analysis for HSP70 and in situ TUNEL analysis were also performed. Apoptotic chondrocytes were not observed in the control cells under atmospheric pressure, whereas apoptosis was observed in the beads in Group A, and the number of apoptotic cells increased as the duration and magnitude of HP increased. On the other hand, we observed no significant population of apoptotic cells in the beads in Group B. Chondrocytes expressing HSP70 were not TUNEL positive in the histological analysis. Excessively strong HP could evoke apoptosis when the extracellular matrix did not accumulate around the chondrocytes. HSP70 expression was related to occurrence of apoptosis that resulted from HP. These findings suggest a mechanism for the pathogenesis of cartilage degeneration in osteoarthritis.
authors.affiliation: Department of Orthopaedics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto 602-8566, Japan.
authors.forename: Shu
authors.initials: S
authors.lastname: Nakamura
authors.forename: Yuji
authors.initials: Y
authors.lastname: Arai
authors.forename: Kenji A
authors.initials: KA
authors.lastname: Takahashi
authors.forename: Ryu
authors.initials: R
authors.lastname: Terauchi
authors.forename: Suzuyo
authors.initials: S
authors.lastname: Ohashi
authors.forename: Osam
authors.initials: O
authors.lastname: Mazda
authors.forename: Jiro
authors.initials: J
authors.lastname: Imanishi
authors.forename: Atsuo
authors.initials: A
authors.lastname: Inoue
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Tonomura
authors.forename: Toshikazu
authors.initials: T
authors.lastname: Kubo
mesh_terms: D000464:Alginates; D000818:Animals; D017209:Apoptosis; D002478:Cells, Cultured; D019902:Chondrocytes / Q000473:pathology*; D020723:Glucuronic Acid; D006025:Glycosaminoglycans / Q000032:analysis; D050884:HSP72 Heat-Shock Proteins / Q000235:genetics; D006603:Hexuronic Acids; D006874:Hydrostatic Pressure; D008297:Male; D012333:RNA, Messenger / Q000032:analysis; D011817:Rabbits
chemical_list: D000464:Alginates; D006025:Glycosaminoglycans; D050884:HSP72 Heat-Shock Proteins; D006603:Hexuronic Acids; D012333:RNA, Messenger; D020723:Glucuronic Acid