To investigate the expression of bcl-2 in healthy and osteoarthritic articular cartilage at the transcriptional level and at the protein level.
bcl-2 mRNA was detected by reverse transcriptase/polymerase chain reaction. The expression of bcl-2 protein was studied using flow cytometry analysis with a monoclonal antibody against intracellular bcl-2 and by immunohistochemistry.
mRNA for bcl-2 was detectable in chondrocytes of both healthy and osteoarthritic cartilage. bcl-2 protein was present in the chondrocytes of the middle layer of cartilage by immunohistochemical staining. In osteoarthritis (OA), chondrocytes adjacent to cartilage defects expressed a particularly high signal intensity. Flow cytometry analysis demonstrated the presence of bcl-2 protein in virtually all chondrocytes.
Our results show that bcl-2 is expressed in healthy adult and osteoarthritic human cartilage. The increased staining of chondrocytes adjacent to osteoarthritic defects indicates a differential regulation of programmed cell death during the degenerative process in OA.