This study was designed to examine whether human articular chondrocytes express heat shock protein 27 (hsp27) and to evaluate the relation between hsp27 and the apoptosis of chondrocytes.

Knee joint articular cartilage was obtained from femoral condyle in osteoarthritis patients who underwent joint replacement surgery. Chondrocytes were isolated, cultured and then exposed to heat shock (42℃) for 1 hour to induce the expression of hsp27. 20 mM of sodium nitroprusside (SNP) was then added for 12 hours to evaluate the ability of hsp27 to prevent SNPinduced chondrocyte apoptosis. The expression of hsp27 was verified by Western blot and the rate of apoptosis was determined by flow cytometric analysis.

Heat shock resulted in the increased expression of hsp27 in chondrocytes. Heat-shocked groups had smaller numbers of apoptotic cells than control groups when both were exposed to apoptosis inducing stimuli.

We conclude that hsp27 was expressed in human articular chondrocytes by heat shock and that the expression of hsp27 in chondrocytes increases their resistance to apoptosis. This result presents clues, which suggest that the induction of hsp27 could be a desirable future therapeutic strategy in human osteoarthritis.