Tissue engineered vascular grafts based on poly-lactic acid blends

Abstract

A great deal of research has been pursued in the last decade with the goal of developing blood vessel substitutes. Tissue engineering has emerged as a promising approach to address the shortcomings of current options. One of the major tasks in this research field is the possibility to tune the biodegradability of the implantable devices (scaffolds). After implantation, the scaffold has to be replaced by extra cellular matrix; with this respect, it is crucial that this replacement takes place with appropriate dynamics and a well-defined timescale. In this work tissue-engineered vascular graft were produced, utilizing several PLLA/PLA blends (100/0, 90/10, 75/25 wt/wt) in order to tune their biodegradability. The tubular-shape scaffolds were obtained by performing a dip-coating around a nylon fibre, followed by a diffusion induced phase separation process. A porous open structure was detected across the thickness of the walls of the scaffold. Moreover, the internal surface is homogeneous with micropores 1–2 microns large. The results have shown that it is possible to obtain the required morphology of the scaffold, in term of wall thickness, for each PLA/PLLA ratio, by varying simple experimental parameters. Moreover a decrease of crystallinity was observed, when raising the amorphous polymer content. Cell cultures were carried out into the scaffold and the non-cytotoxicity of scaffolds, adhesion and cell proliferation inside them were evaluated. The results have shown that the scaffold do not induce cell toxicity; cells are able to grow into the scaffold covering its internal surface, so they can be considered suitable for the application for the designed aimed.