Cyclic tensile stretch loaded on bovine chondrocytes causes depolymerization of hyaluronan: involvement of reactive oxygen species.
OBJECTIVE
We have previously demonstrated that reactive oxygen species (ROS) are involved in cartilage degradation. Decreased size of hyaluronan (HA), the major macromolecule in synovial fluid, to which it imparts viscosity, is reported in patients with arthritis. The purpose of this study was to determine the alteration in the molecular weight range of HA as a result of mechanical deformation loaded on the chondrocytes, as well as the involvement of ROS in this action.


METHODS
ROS were generated via the oxidation of hypoxanthine by xanthine oxidase. Cyclic tensile stretch was loaded using a vacuum-operated instrument. Levels of HA were measured using a sandwich enzyme-binding assay. Superoxide dismutase (SOD) activity and ROS were measured using water-soluble tetrazolium and a chemiluminescent probe, respectively.


RESULTS
ROS depolymerized HA molecules. Cyclic tensile stretch depolymerized HA and induced ROS. SOD inhibited not only ROS induction but also HA depolymerization caused by the mechanical stress.


CONCLUSIONS
ROS play an important role in mechanical stress-induced HA depolymerization.
Yamazaki
K
K
Kinki University School of Medicine, Osaka, Japan.
Fukuda
K
K
Matsukawa
M
M
Hara
F
F
Matsushita
T
T
Yamamoto
N
N
Yoshida
K
K
Munakata
H
H
Hamanishi
C
C
D000818:Animals; D002417:Cattle; D019902:Chondrocytes / Q000187:drug effects / Q000378:metabolism*; D006820:Hyaluronic Acid / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D019271:Hypoxanthine / Q000378:metabolism; D008970:Molecular Weight; D011108:Polymers / Q000737:chemistry / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism* / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013314:Stress, Mechanical; D013482:Superoxide Dismutase; D013718:Tensile Strength / Q000502:physiology; D014969:Xanthine Oxidase / Q000378:metabolism
D011108:Polymers; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D019271:Hypoxanthine; D006820:Hyaluronic Acid; D013482:Superoxide Dismutase; D014969:Xanthine Oxidase