Porcine osteochondrosis: deficiencies in transforming growth factor-beta and insulin-like growth factor-I.

Osteochondrosis and dyschondroplasia are common multifocal disturbances of endochondral ossification in many species of domestic animals, and are characterized by the retention of avascular cartilage. These cartilage disorders are characterized by a failure of chondrocyte differentiation, matrix mineralisation and its replacement by bone. Rabbit polyclonal antibodies to transforming growth factor-beta (TGF-beta) and to insulin-like growth factor-I (IGF-I) were used to detect the two growth factors in normal and osteochondrotic porcine epiphyses. In the normal pig epiphyses IGF-I and TGF-beta were present in the chondrocytes of the epiphyseal hyaline cartilage and IGF-I was readily localised to the hypertrophic chondrocytes in the growth cartilage adjacent to the epiphyseal ossification centre. Both growth factors were found to be deficient in chondrocytes at sites of osteochondrosis. Both these growth factors are thought to be involved in the cascade of events associated with chondrocyte function during endochondral ossification. Deficiencies in TGF-beta and IGF-I demonstrated in porcine osteochondrosis and previously shown in avian dyschondroplasia suggest further similarities in the pathogenesis of these conditions.