To evaluate the expression of CD44v6 on chondrocytes from hyaline cartilage over the course of osteoarthritis (OA).
In 12 NZW rabbits, the anterior cruciate ligament (ACL) was resected to create anterior instability of the knee. In 12 control rabbits, only a sham operation, without resection of the ACL, was performed. Four animals from each group were killed at 3, 6, and 12 weeks. After opening the knee joint, OA was macroscopically graded and hyaline cartilage of the load-bearing area was evaluated histologically according to the Mankin scale and by immunostaining for CD44v6.
There was a positive linear correlation between the time after surgery and the macroscopic and histologic OA scores. The scores in the control group were constant over the time course. Immunostaining showed constant expression of CD44v6 in the control group. In the experimental group, a positive linear correlation between CD44v6 expression and macroscopic and histologic grades was found.
The results show an in vivo increase in the expression of the hyaluronan receptor CD44 over the time course of OA. Further studies are needed to evaluate whether this pattern applies to humans and whether new treatment approaches could evolve from this knowledge.