Mechanical Injury Kills Cartilage Far from Impact Site
Reactive oxygen species and infiltration of leukocytes kill chondrocytes
MONDAY, May 1 (HealthDay News) -- After mechanical injury, cartilage cells as far as 10 mm away from the impact site die due to the generation of reactive oxygen species and infiltration of inflammatory leukocytes, according to a report in the May issue of Arthritis & Rheumatism.
Holly H. Birdsall, M.D., Ph.D., from Baylor College of Medicine in Houston, and colleagues subjected the hind knee joints of 24 adult dogs to a 20-25 MPa impact injury within an hour of death. Chondrocytes were cultured with autologous blood mononuclear leukocytes and their viability at various distances from the impact site was assessed over time.
The researchers found that while 92 percent of chondrocytes from uninjured bones survived, 45 percent of chondrocytes from the injured bones died within seven days, even those more than 10 mm away from the impact site. This death could be inhibited by blocking nitric oxide generation. Inhibiting the generation of reactive oxygen species or using antibodies against CD18 blocked the attachment of leukocytes to chondrocytes in the impact zone.
"Our data suggest that after mechanical injury, chondrocytes distant from the site may be killed through the generation of nitric oxide," Birdsall and colleagues conclude. "Patients may benefit from therapies that reduce infiltration of inflammatory leukocytes into acutely injured cartilage."