Evidence that thrombus organizing blood derived cells produce prostaglandin I2-

An artificial vessel replacement, which is athrombogenic and impermeable for a migration from the adjacent tissue, was implanted end to end into the thoracic aorta of 10 sheep. The center of this tube has a Dacron surface, which is known to trap blood elements. We examined the tissue samples built up by blood derived cells between 2 and 84 days morphologically by means of light microscopy as well as by SEM and TEM. We checked the thrombus fragments of 7 cases for their PGI2-generation using MONCADA's bioassay. In our specimens we found an average activity of 4, 7 pg PGI2 mg/min. The morphological examination revealed different stages of thrombosis and organization consisting of a large number of cells. Macrophages, fibroblast like cells, myofibroblasts as well as endothelial cells and foreign body giant cells around the Dacron fibers could be found. Our experimental design excludes the ingrowth of mesenchymal elements, which suggests that blood derived cells are able to produce PGI2.