Collagen metabolism in iso- and homografts of tendons

Abstract

Summary Composite flexor tendon tissue grafts of rats were transplanted as iso- and homografts to the subcutaneous tissue on the back of recipient rats of histocompatible strains. The grafts were labelled with tritiated proline and removed for examination at monthly intervals for 6 months and finally at 10 months. After 6 months the tendon isografts were morphologically intact whereas the homografts showed some structural weakness. There were no adhesions between the tendon sheath and the tendons. Early revascularisation of the grafts by the host was demonstrated by intracardiac injection of Kiton Fast Green. The radioactivity studies showed metabolism of the collagen of the grafts within the recipient. The radioactivity of the iso- and homografts declined except for a transitory increase after 1 month. There were only slight differences between the activity of iso- and homografts. The zero level of radioactivity had not been reached by the end of the experimental period and there was still residual activity in the grafts at 10 months; this was higher in homografts than in isografts. The morphological changes in the homografts after 4 months are explained by changes in the collagen molecule. The increasing activity after 1 month in iso- and homografts could be explained either by an exchange of the isotope or shift of the labelled proline between the grafts and a hypothetical metabolic pool in the recipient.