Elevated aggrecan mRNA in early murine osteoarthritis.

Male STR/ort mice develop osteoarthritis in the tibial articular cartilage. Low grade histological lesions first appear between 10-20 weeks of age. A previous study showed that the level of aggrecan, the major cartilage proteoglycan, is approximately twofold greater in the tibial cartilage of 16-19-week-old STR/ort mice compared with that in normal cartilage in control CBA mice. In the present investigation aggrecan gene transcription was investigated in 20-week-old STR/ort and CBA tibial cartilage using a quantitative reverse transcription-polymerase chain reaction (RT-PCR). The amount of aggrecan cDNA obtained from the STR/ort medial and lateral plateau was 2.8- and 4.6-fold greater per milligram of wet cartilage than that from the CBA tibial plateau. The difference was not due to differences in cellularity of tibial cartilage in the two strains and indicates that aggrecan gene transcription is elevated in early osteoarthritis.