Growth factor expression in the osteophytes of the human femoral head in osteoarthritis

Osteoarthritis is characterized by marked osteophyte formation consisting o f new cartilage and bone. Because several growth factors are known to be in volved in chondrogenesis and osteogenesis, the expression of transforming g rowth factor-beta 1 and basic fibroblast growth factor in the osteophytes o f the human femoral heads in osteoarthritis were examined. Transforming gro wth factor-beta 1 messenger ribonucleic acid was detected in the osteophyte s by reverse transcription-polymerase chain reaction. All of the nine exami ned osteophytes expressed transforming growth factor-beta 1 messenger ribon ucleic acid, whereas one of four osteoarthritic femoral heads and none of f our osteonecrotic femoral heads expressed transforming growth factor-beta 1 messenger ribonucleic acid. The extent of transforming growth factor-beta 1 messenger ribonucleic acid expression varied among the osteophytes. Trans forming growth factor-beta 1 or basic fibroblast growth factor was analyzed in osteophytes immunohistochemically. Transforming growth factor-beta 1 wa s localized in the superficial cells in the osteophyte cartilage, but it wa s scarcely detected in the superficial cells in the degenerative articular cartilage. Basic fibroblast growth factor was detected in the cells in the whole layer of osteophyte cartilage and in the articular cartilage. There w as a difference in the localization, which suggests the different roles of transforming growth factor-beta 1 and basic fibroblast growth factor in bon e and cartilage metabolism in osteophyte formation.