Age-related changes in the synthesis and mRNA expression of decorin and aggrecan in human meniscus and articular cartilage.
OBJECTIVE
To determine if the biosynthesis of aggrecan and decorin in the human meniscus and the potential of the cells to express these macromolecules (mRNA), is affected by the age of the individual and that if any changes are observed are they different to those measured in articular cartilage obtained from the same joint.


METHODS
Radiolabelling of tissue explants, anion-exchange chromatography and agarose-polyacrylamide gel electrophoresis were used to analyze newly synthesized proteoglycans. A quantitative, competitive reverse-transcriptase polymerase chain reaction was developed and applied to the tissue to measure the expression of decorin and aggrecan mRNA.


RESULTS
Proteoglycan synthesis in the meniscus was higher in young donors (1-5 mmoles sulfate incorporated/h/mgDNA, under 20 years of age) than in adult tissues (0.5-1 mmoles incorporated/h/mgDNA, 20-62 years of age) and decorin was the major proteoglycan synthesized at this time. An age-related increase in the proportion of aggrecan synthesis in the meniscus was also observed using agarose-polyacrylamide gel electrophoresis. Both decorin (five-fold) and aggrecan (eight-fold) mRNA expression increased with age in meniscus whereas levels were relatively constant in articular cartilage. In addition, the synthesis of decorin and aggrecan and the expression of their mRNA was different in meniscus and articular cartilage from the same knee joint.


CONCLUSIONS
The synthesis and turnover of aggrecan and decorin in the human meniscus is influenced by the age of the individual and is not the same as that observed for articular cartilage.
McAlinden
A
A
Department of Orthopaedic Surgery, Washington University School of Medicine, St Louis, Missouri 63110, USA.
Dudhia
J
J
Bolton
M C
MC
Lorenzo
P
P
Heinegård
D
D
Bayliss
M T
MT
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D053674:Aggrecans; D002358:Cartilage, Articular / Q000166:cytology; D002648:Child; D058575:Decorin; D016326:Extracellular Matrix Proteins; D006801:Humans; D007719:Knee Joint / Q000166:cytology; D037181:Lectins, C-Type; D008592:Menisci, Tibial / Q000166:cytology; D008875:Middle Aged; D011509:Proteoglycans / Q000096:biosynthesis*; D012333:RNA, Messenger / Q000378:metabolism*
D053674:Aggrecans; C546878:DCN protein, human; D058575:Decorin; D016326:Extracellular Matrix Proteins; D037181:Lectins, C-Type; D011509:Proteoglycans; D012333:RNA, Messenger