What Is the Optimum Cover Factor?

When fabricating a small diameter arterial prosthesis, the performance requirements include controlling dimensions, maintaining a uniform structure, ensuring superior mechanical properties as well as excellent biocompatibility. Material selection and fabricating methods can influence these factors. In this study, three 100% polyester prostheses, three bicomponent polyester/silk prostheses and three 100% silk prostheses were woven into seamless tubular prototype prostheses with three different basic weaves. After degumming/scouring they met the target inner diameter of 3.83 ± 0.30 mm which demonstrates that weaving is a precise and accurate way to manufacture small caliber arterial prostheses. In conclusion, the woven samples had a uniform wall structure along their strength and a range of low water permeability values and probe bursting strengths depending on their cover factor.

Micropatterning Polymer Materials to Improve Endothelialization

Several studies have shown that 65 % of expanded poly (tetrafluoroethylene) (ePTFE) vascular prostheses had to be explanted within 10 years of implantation in humans. The reasons for these explantations relied on thrombosis formation and poor hemocompatibility of synthetic polymers. It has been shown that surface modification of ePTFE arterial prostheses could enable their endothelialization therefore improving their biocompatibility and hemocompatibility. Indeed, endothelial cells naturally cover the biological blood vessel wall and consequently, an endothelial layer constitutes the best achievable hemocompatible surface. In this context, our strategy consisted in micropatterning cell adhesion (RGD) and proliferation (WQPPRARI) peptides on the surface of plasma-functionalized PTFE, therefore enabling covalent conjugation of the peptides. Basically, the technology consisted in spraying a solution of the adhesion peptide, therefore leading to 10 µm-diameter RGD spots semi-randomly distributed over the sample and covering 20 % of the whole polymer surface. In a second step, proliferation peptide was applied to the remaining surface by soaking, therefore covering the unreacted surface. The 20 % coverage was obtained by using an x-y table, programmed to move from side to side of the surface on x value, with an increment on y value that has been calibrated.