Ac. Kim et M. Spector, Distribution of chondrocytes containing alpha-smooth muscle actin in humanarticular cartilage, J ORTHOP R, 18(5), 2000, pp. 749-755
Relatively little is known about the contractile behavior of the human arti
cular chondrocyte. Other connective tissue cells are known to express a con
tractile actin isoform, alpha -smooth muscle actin, in response to injury,
at selected stages of wound healing, and in certain pathological conditions
. This and recent work demonstrating contractile behavior in adult canine a
rticular chondrocytes in vitro prompted the present study of the distributi
on of alpha -smooth muscle actin-containing chondrocytes in human articular
cartilage. Approximately 75% of the chondrocytes in the superficial region
of cartilage expressed alpha -smooth muscle actin as demonstrated by immun
ohistochemistry. In contrast, only approximately 10% of the cells in the de
ep region stained fur this contractile actin isoform. There was no correlat
ion of the percentage of alpha -smooth muscle actin-positive cells in eithe
r region with Mankin grade or with age. This is the first report of a contr
actile potential for human articular chondrocytes. The roles of a-smooth mu
scle actin in these cells warrant further investigation. The question of wh
ether it is necessary to refer to these cells as myochondrocytes is conside
red.