title: Study on the effects of gradient mechanical pressures on the proliferation, apoptosis, chondrogenesis and hypertrophy of mandibular condylar chondrocytes in vitro.
abstract: OBJECTIVE
  To investigate the effects of gradient mechanical pressure on chondrocyte proliferation, apoptosis, and the expression of markers of chondrogenesis and chondrocyte hypertrophy.
  
  
  METHODS
  Mandibular condylar chondrocytes from 5 rabbits were cultured in vitro, and pressed with static pressures of 50kPa, 100kPa, 150kPa and 200kPa for 3h, respectively. The chondrocytes cultured without pressure (0kPa) were used as control. Cell proliferation, apoptosis, and the expression of aggrecan (AGG), collagen II (COL2), collagen X (COL10), alkaline phosphatase (ALP) were investigated. Ultrastructures of the pressurized chondrocytes under transmission electron microscopy (TEM) were observed.
  
  
  RESULTS
  Chondrocyte proliferation increased at 100kPa and decreased at 200kPa. Chondrocyte apoptosis increased with peak pressure at 200kPa in a dose-dependent manner. Chondrocyte necrosis increased at 200kPa. The expression of AGG increased at 200kPa. The expression of COL2 decreased at 50kPa and increased at 150kPa. The expression of COL10 and ALP increased at 150kPa. Ultrastructure of the pressurized chondrocytes under TEM showed: at 100kPa, cells were enlarged with less cellular microvillus and a bigger nucleus; at 200kPa, cells shrank with the sign of apoptosis, and apoptosis cells were found.
  
  
  CONCLUSIONS
  The mechanical loading of 150kPa is the moderate pressure for chondrocyte: cell proliferation and apoptosis is balanced, necrosis is reduced, and chondrogenesis and chondrocyte hypertrophy are promoted. When the pressure is lower, chondrogenesis and chondrocyte hypertrophy are inhibited. At 200kPa, degeneration of cartilage is implied.
authors: Department of Oral and Maxillofacial Surgery, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai 200011, China.
authors: Hui
authors: H
authors: Li
authors: Department of Oral and Maxillofacial Surgery, The Second Affiliated Hospital Zhejiang University School of Medicine, Hangzhou 310009, China.
authors: Linjian
authors: L
authors: Huang
authors: Department of Oral and Maxillofacial Surgery, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai 200011, China.
authors: Qianyang
authors: Q
authors: Xie
authors: Department of Oral and Maxillofacial Surgery, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai 200011, China.
authors: Xieyi
authors: X
authors: Cai
authors: Department of Oral and Maxillofacial Surgery, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai 200011, China. Electronic address: yangchi63@hotmail.com.
authors: Chi
authors: C
authors: Yang
authors: Department of Oral and Maxillofacial Surgery, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai 200011, China.
authors: Shaoyi
authors: S
authors: Wang
authors: Department of General Dentistry & Emergency, School of Stomatology, Fourth Military Medical University, Xi'an 710032, China.
authors: Min
authors: M
authors: Zhang
mesh_terms: D053674:Aggrecans / Q000096:biosynthesis / Q000378:metabolism; D000469:Alkaline Phosphatase / Q000096:biosynthesis / Q000378:metabolism; D000818:Animals; D017209:Apoptosis / Q000502:physiology; D002454:Cell Differentiation / Q000502:physiology; D049108:Cell Enlargement; D049109:Cell Proliferation / Q000502:physiology; D019902:Chondrocytes / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D020219:Chondrogenesis / Q000502:physiology*; D003094:Collagen / Q000096:biosynthesis / Q000378:metabolism; D006984:Hypertrophy / Q000209:etiology / Q000473:pathology; D008335:Mandibular Condyle / Q000166:cytology / Q000378:metabolism / Q000473:pathology / Q000502:physiology*; D009336:Necrosis; D011312:Pressure; D011817:Rabbits
chemical_list: D053674:Aggrecans; D003094:Collagen; D000469:Alkaline Phosphatase
keywords: Apoptosis; Chondrocyte hypertrophy; Chondrogenesis; Mandibular condylar chondrocytes; Mechanical pressure; Proliferation