TENASCIN EXPRESSION IN ENDOMYOCARDIAL BIOPSY SPECIMENS IN PATIENTS WITH DILATED CARDIOMYOPATHY - DISTRIBUTION ALONG MARGIN OF FIBROTIC LESIONS

Objective-To examine the hypothesis that tenascin, an extracellular ma trix glycoprotein, contributes to fibrotic changes in dilated cardiomy opathy. Methods-The localisation of tenascin in biopsy specimens of th e hearts obtained from eight patients with dilated cardiomyopathy was examined using staining by the avidin-biotin-peroxidase complex method . Results-(1) Perimysium and endomysium. Although positive staining fo r tenascin was observed in the enlarged perimysium and endomysium in a ll patients, moderately intense staining was characteristically observ ed near the replacement fibrotic lesions. In the narrow perimysium and endomysium of the myocardium not containing replacement fibrotic lesi ons, tenascin was not present, as in the control specimens. (2) Replac ement fibrotic lesions. Non-homogeneous positive staining for tenascin was detected in all replacement fibrotic lesions examined. Intense te nascin deposition was observed in the peripheral portion of the replac ement fibrotic lesions. The tenascin staining observed in the small re placement fibrotic lesions was more intense than that in the large les ions. Conclusions-Tenascin contributes to the development of the fibro tic changes seen in the dilated cardiomyopathic heart. Its characteris tic location, specifically the distribution along the margin of the fi brosis, suggests that fibrotic change is a continuous process in heart s with dilated cardiomyopathy.