RAPID VISUALIZATION OF VIABLE AND NONVIABLE ENDOTHELIUM ON CARDIOVASCULAR PROSTHETIC SURFACES BY MEANS OF FLUORESCENT DYES

Increasing interest in endothelialization of synthetic and tissue card iovascular prostheses in vitro emphasizes the need for simple and rapi d methods to evaluate presence of endothelium on surfaces. Scanning el ectron microscopy is a commonly used method for this purpose. In this study we investigated alternative and more rapid staining methods. Hum an saphenous vein endothelial cells in culture and on cardiovascular p rosthetic materials (pyrolytic carbon, cusps of bioprosthetic heart va lves, pig aorta, and expanded polytetrafluoroethylene) were labeled by exposing them to medium containing 5-chloromethylfluorescein diacetat e or 1,1-dioctadecyl-3,3,3',3'-tetramethylindo carbocyanine perchlorat e. For comparison, specimens were also fixed acid processed for scanni ng electron microscopy. A bright fluorescence of endothelial cells lab eled with 5-chlormethylfluorescein diacetate or 1,1-deoctadecyl-3,3,3' ,3'-tetramethylindo carbocyanine perchlorate were clearly visualized i n culture, on pyrolytic carbon, and on expanded polytetrafluoroethylen e. Unfixed, prelabeled cells could be visualized immediately and unlab eled cells could be investigated for viability within 1 hour. Cells se eded on biologic tissue specimens could be visualized within 15 minute s with a modified hematoxylin-eosin staining. We suggest the use of th ese methods for rapid visualization of endothelium present on surfaces of cardiovascular prosthetic materials where they can partly replace the use of scanning electron microscopy.