To examine the repair collagens produced by cells in injured cartilage,
the femoral articular surfaces of three groups of New Zealand white rabbits
were injured by making both superficial and deep lacerations and drill
holes. Eight weeks after surgery, the rabbits were killed and slices of
injured articular cartilage were harvested. The types of collagen being
synthesized at the site of these lesions were identified by labeling the
recovered specimens in vitro with 3H-proline and by characterizing the
collagen using sodium dodecyl sulphate electrophoresis, carboxymethyl
cellulose chromatography, and cyanogen bromide peptide analysis. In all
cases, tissue-specific type II ([alpha1 (II)]3) cartilage collagen was
synthesized. Histological examination using toluidine blue showed that the
chondrocytes bordering the cartilage defect produced by deep lacerations
and drill holes responded by increased cellular activity, as shown by cell
cloning and increased matrix staining. The drilled holes were completely
filled by tissue with staining and morphological characteristics similar to
those of hyaline cartilage.