Lack of intimal hyperplasia response in an experimental model of non-endothelial vascular wall damage

The endothelial and media1 layers are generally presumed to play an important role in the appearance and development of intimal hyperplasia. We have carried out a short-, media- and long-term study of the morphological changes taking place in the comrnon iliac artery of rats after surgical removal of the adventitial layer. Our aim has been to assess the likely role played by this layer in the development of intimal hyperplasia. Our results show recurrent periods of cellular desquamation and almost complete absence of hyperplastic response during the first two months. After three months three is a slow process of endothelialization which is completed by the 6th month and persists one year after adventitial resection. Thus, adventitial resection seems to cause instability at the subendothelial bed level, not allowing the junction and embedding of endothelial cells nor the development of intimal hyperplasia. This lack of hyperplasia might also result from the fact that the endothelial desquamation process does not involve cellular rupture, which would prevent mitogenic-factor release. After morphological repair of the endothelium, a slow morphofunctional recovery of the artery takes plac

Seeding of expanded polytetrafluoroethylene (ePTFE) vascular grafts. A morphological study of porcine endothelial and fibroblast cells

The need to improve clinical results with small and medium calibre grafts has led to extensive research on cell seeding of prosthetic materials. Numerous problems remain regarding identification, seeding, adhesion and survival of the cells attached. We have studied the behaviour of seedings of endothelial and fibroblast cells on ePTFE grafts. Scanning electron microscopy allows us to observe the morphological characteristics and their interaction with the biopolymers. It has been possible to differentiate both cellular types by their characteristics and interactions with the ePTFE. At the same time, from this ~ i vni t ro~st udy it can be concluded that the time needed to obtain a stable and confluent monolayer on ePTFE pretreated with fibronectin is between 18 hours to 4 days for endothelial cells, and 24 hours for fibroblasts. These would be the optimal time periods for ain vivo. grafting of the seeded prostheses