Open AccessPresence of cartilage‐derived morphogenetic proteins in articular cartilage and enhancement of matrix replacement in vitro
Author(s) -
Erlacher Ludwig,
Ng CheeKeng,
Ullrich Robert,
Krieger Sigurd,
Luyten Frank P.
Publication year - 1998
Publication title -
arthritis & rheumatism
Language(s) - English
Resource type - Journals
eISSN - 1529-0131
pISSN - 0004-3591
DOI - 10.1002/1529-0131(199802)41:2<263::aid-art10>3.0.co;2-5
Subject(s) - aggrecan , cartilage , proteoglycan , matrix (chemical analysis) , explant culture , type ii collagen , in vitro , articular cartilage , microbiology and biotechnology , western blot , chemistry , anatomy , pathology , medicine , osteoarthritis , biochemistry , biology , chromatography , alternative medicine , gene
Objective To investigate the effects of the cartilage‐derived morphogenetic proteins (CDMPs) in an in vitro cartilage explant model that mimics the chondrocytic response to matrix depletion, and to demonstrate their presence in articular cartilage. Methods Adult bovine articular cartilage and postmortem specimens from adult human donors with and without osteoarthritic (OA) lesions were stained by immunohistochemistry using polyclonal antibodies specific for CDMP‐1 and CDMP‐2. Extracts of bovine articular cartilage were analyzed by Western blotting for the presence of the CDMPs. Bovine articular cartilage explants were depleted of their matrix by trypsin digestion, followed by a 7‐day culture period in a chemically defined serum‐free basal medium (BM), with or without recombinant CDMPs 1 and 2. The metabolic activity of chondrocytes was measured by 35 S‐sulfate incorporation into macromolecules. Newly synthesized proteoglycans (PGs) were analyzed using Sephacryl S‐500 HR gel chromatography. The expression levels of the messenger RNA (mRNA) for chondrogenic markers were investigated by Northern analysis. Results CDMP‐1 and CDMP‐2 were detected in both bovine and human healthy and OA articular cartilage. Treatment of matrix‐depleted cartilage explants with CDMPs 1 and 2 increased equally the incorporation of 35 S‐sulfate into PGs compared with tissue maintained in BM. Gel chromatography analysis indicated that aggrecan was the predominant PG species. Northern blot analysis showed that the expression of link protein, type II collagen, and aggrecan mRNA transcripts was not modulated by CDMP treatment. Conclusion This study shows the presence of CDMP‐1 and CDMP‐2 in adult bovine and human articular cartilage. In addition, our in vitro data indicate that CDMPs 1 and 2 stimulate the metabolic activity of articular chondrocytes. Therefore, these signaling molecules may be contributing to the maintenance of the integrity of the joint surface.