טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentMaya Livnat
SubjectA Novel Tissue Engineering Approach to Preventing Blood
Vessel Restenosis using Drug-Eluting Endoluminal
Coatings
DepartmentDepartment of Biomedical Engineering
Supervisor Professor Seliktar Dror


Abstract

Drug-eluting stents signify a major achievement in reducing the incidence of coronary restenosis following percutaneous transluminal coronary angioplasty. However, where drug-eluting stents have been unsuccessful, endoluminal gel paving strategies offer renewed optimism; mainly, in a variety of vascular procedures requiring catherter-based sustained, localized delivery of therapeutic drugs and biological factors. However, endoluminal paving has met with very limited clinical success because of the technical difficulties and stringent safety demands.  The current study presents an alternative to gel paving using a 40-µm thick biodegradable polymeric film for deployment onto the artery wall during balloon angioplasty and stenting. The film is made from a yet compliant network of alginate and polyethylene glycol (PEG) which is securely held affixed to the vessel wall by the expanded stent sturts. The alginate-based films are characterized by measuring their strength, elasticity, degree of swelling, degradability in water and saline, and drug release properties. The alginate-based films were implanted into the subcutis of rats in order to assess the in-vivo degradation of the material. The combination of alginate and PEG afforded the films sufficient strength and compliance for endoluminal deployment using an in vitro organ culture system. In characterizing the films’ degradability, it was determined that the ionic concentration of the buffered saline was the main determinant in regulating the degradation kinetics and the release kinetics of the drug molecule Paclitaxel. Subcutaneous implantation of the films reveals that the material was completely degraded after 5 weeks. These results suggest that the use of alginate-based, PEG-containing polymeric films for endoluminal coverage offers an alternative solution to conventional drug-eluting stents, with the added advantage of uniform endoluminal coverage of the treated segment, and homogenous endoluminal application of the active substance.