Multilayer Stents

Thierry B, Winnik FM, Merhi Y et al, Bioactive coatings of endovascular stents based on polyelectrolyte multilayers. Biomacromolecules 2003 4 1564-1571. 

Finally, there are devices that are completely different, such as the Multilayer Flow Modulator (M.F.M) from Cardiatis, that does not incorporate any fabric, or membrane at all, but relies on thrombosis of the sac due to disturbed flow through the stents. In theory, this would allow an extremely low profile, as well as the ability to cover branched portions of the aorta without concern for disrupting flow to essential organs such as the intestines or kidneys. However, while the theoretical concept has merit, the cUnical performance has yet to be demonstrated. 

New technology opens up completely new possibilities to design 3D structures for medical applications. The hexagonal braiding technique developed by Schreiber et al. (2009) allows various shapes such as bifurcations or stent into the stent to be produced. Such braided multilayer structures create mechanically separated layers on the outside and an inner structure that facilitates, for example, a functional respiratory epithelium to be established and make it possible to maintain the mucociliary function of the stented area in treatment of lung cancer (PulmoStent, 2014). 

Lin, Q. K., Ding, X., Qiu, F. Y, Song, X. X., Fu, G. S. and Ji, J. (2010). In situ endotheU-ahzation of intravascular stents coated with an anti-CD34 antibody functionalized heparin-coUagen multilayer. Biomaterials, 31,4017-4025. 

The possibility of an ease tuning of the composition of the multilayers allows the building of materials with good bio-compatibility with cells and tissues. This allows the preparation of different coating for biomedical devices, such as stents, tracheal prostheses, artificial vessels and many other applications [232]. 

To determine whether the CS/HA multilayers may be exploited as in situ drug delivery system, sodium nitroprusside (SNP) was incorporated in the multilayers. SNP, a nitrous oxide dmior that spraitaneously decomposes in biological environments [153], is extensively used clinically to reduce blood pressure and has emerged as a promising modality in the treatment of restenosis [154]. SNP-loaded multilayers have been shown to reduce platelet adhesion below that associated with multilayers devoid of the drug. The enhanced thromboresistance of the self-assem-bled multilayer, together with the anti-inflammatory and wound healing properties of HA and chitosan, are expected to reduce neointimal hyperplasia that is associated with stent implantation. 

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