EARLY PRESENCE OF ENDOTHELIAL-LIKE CELLS ON THE FLOW SURFACE OF POROUS ARTERIAL PROSTHESES IMPLANTED IN THE DESCENDING THORACIC AORTA OF THE DOG

The purpose of this study was to investigate early arterial graft heal ing and its sources in porous Dacron prostheses after very short impla ntation periods in the dog, using extensive histologic examination of serial sections. Preclotted Dacron prostheses 6 cm long and 8 mm in di ameter were implanted in the descending thoracic aorta (DTA) of 14 dog s, and retrieved at 7 days (n = 6), 10 days (n = 4), and 14 days (n = 4). The flow surface was assessed for thrombus coverage, endothelial-l ike cell (ELC) coverage, and the number of microvessel ostia. Where an ELC island was identified under the stereomicroscope, full-wall longi tudinal tissue samples were taken, and embedded in resin for light mic roscopy study of 6-mu m, H&E-stained serial sections to determine gene ral healing and interstitial tissue presence. If there was more than o ne ELC island, another full-wall sample was taken and embedded in para ffin for staining with laminin, collagen IV, and smooth muscle alpha-a ctin antibodies, and PTAH. All grafts were patent with very little thr ombus. Islands of endothelial-like cells were found for each time peri od, and on all 14-day grafts. Endothelial-like cell coverage was highe st at 14 days. On 7- and IO-day grafts, cells proved to be endothelium were found in the middle of the flow surface, unconnected to either p annus or perigraft tissue ingrowth. Healing occurs as early as 7 days in porous knitted Dacron grafts. The source at periods earlier than 10 days appears to be cells from the blood stream.