Characterisation of a Vascular Prosthetic Material (Silcrothane)

Introduction. Vessel replacement is a major concern for surgeons, since autologous vessels are not always available and the use of prosthetic materials generally leads to complications such as thrombosis and restenosis. The aim of this study was to evaluate a new prosthetic material (silcrothane) for use as a vascular substitute. Materials and Methods. First, we analysed the prosthesis structure by light (LM) and scanning electron microscopy (SEM). Compatibility was tested (3 and 6 months) by implanting segments of prosthesis (1 cm in length) into the dorsal muscle of white New Zealand rabbits. These fragments were retrieved and processed for subsequent LM examination, to detect signs indicative of biological reaction provoked by the grafts in the host. A small prosthetic fragment was fixed in 10% formaldehyde for LM, and in 3% glutaraldehyde for SEM. Cuts were histologically examined after basic staining procedures and immunohistochemical methods (RAM-II, alfa-actin and MMP-12). Results. No signs of rejection were detected 3 and 6 months after implant in the experimental animals. On microscopy, concentric parallel layers running perpendicularly to the long axis of the silcrothane prosdlesis were observed. The composition of the prosthesis is fibrillar with the presence of numerous pores of different size and shape, with differences between the prosthetic surfaces. The silcrothane was embedded in neoformed tissue that was highly vascularised and rich in white blood cells and foreign body reaction cells. These cells were absent in the 6 month specimens. At 3 months, a thick cell barrier, showing the characteristics of white blood cells and many neovessels, could be seen between the prosthesis and host tissue. In areas where the cell barrier was most extensive, cones of cell infiltration similar to those observed at the inner surface - but larger - were detected. Conclusions. a) Silcrothane is highly stable and of a suitable structure for use as a vascular substitute. b) Its porous nature makes it ideal for cell colonisation. c) Biocompatibility and foreign body reaction trials showed the presence of neovessels around the prosthetic graft and a cell infiltrate penetrating the inner third of the transplanted prosthesis.