Early normalization of platelet survival by endothelial seeding of Dacron arterial prostheses in dogs

Current synthetic vascular prostheses do not acquire a complete lining of vascular endothelium in humans or dogs. Seeding of autogenous venous endothelium has been reported to remedy this defect, but previous studies have been primarily morphologic. To see if venous endothelial seeding caused a measurable decrease in platelet-prosthetic interaction in vivo, serial ¹¹¹In-labeled platelet survival studies were done in dogs with seeded (n = 8) and unseeded (n = 9) thoracoabdominal Dacron bypass prostheses. Changes in platelet survival time (PST) were compared with endothelial coverage scores, which were determined by blinded survey of removed prostheses by scanning electron microscopy (SEM). The PSPs before surgery (± SD) were 5.02 ± 0.79 days (seeded) and 5.31 ± 0.99 days (control) (P = 0.51). Seven weeks after surgery the PSTs were 4.01 ± 1.10 days (seeded) and 2.67 ± 0.88 days (control) (P = 0.013). The subgroup of four dogs with seeded prostheses that had complete endothelial coverage showed restoration of the platelet survival pattern to that of the linear decay seen before surgery. SEM studies showed that this normalization of PST occurred despite the presence of small nidi of platelet adhesion on exposed Dacron fibers and irregularities of the endothelial pattern consistent with flow disturbances and venous jet lesions near anastomoses. Endothelial seeding, when technically successful, appears to sharply curtail the degree of platelet interaction with vascular prostheses and restore a normal platelet survival pattern. Longer studies of seeded prostheses are needed to determine if seeding protects against the late complications of intimal hyperplasia and thrombotic occlusion.