et Systèmes Complexes"
31 mai 2010
Bâtiment Condorcet, 4ème
étage, salle 454 A.
(Inserm U 698)
Polymeric 3D Scaffolds for Cardiovascular Tissue Engineering
diseases are the first cause of mortality in the developed countries.
Among these diseases, those related to the vessel wall thickening might
require heavy surgery techniques such as multiple bypasses. Current
synthetic vascular grafts used in cardiovascular surgery with less than
6 mm diameter grafts have a low patency rate, mostly due to acute
thrombus formation and intimal hyperplasia.
We have developed new small-diameter materials as an alternative for
arterial replacement. In one approach, we have used tubular
pulullan/dextranbased grafts of 2 mm internal diameter, prepared and
molded by a cross-linking technique using sodium trimetaphosphate.
Using microsurgical techniques with Wistar adult rats in infrarenal
aortic bypass, grafts withstood aortic blood pressure and exhibited
physiological blood flow, as evaluated with ultrasound techniques and
angiographies at 4 and 8 weeks post-surgery. Harvested grafts evaluated
by light microscopy and immunohistochemistry evidenced a neointima
formation at 8 weeks with collagen deposition and smooth muscle-like
cells circumferential growth on the luminal surface without intimal
hyperplasia or aneurysm formation.
In a second approach, polyvinyl alcohol (PVA), a water-soluble
synthetic polymer with excellent film forming, emulsifying, and
adhesive properties, was cross-link with STMP to form hydrogels and
membrane devices suitable for biomedical applications. This procedure
requires no organic solvent, nor melting process to obtain films with
high mechanical strength. The resulting membrane was successful to be
used for replacement of an arterial vessel in rat during without
mechanical or thrombotic complication. This cross-linking method
confers to polyvinyl alcohol particular mechanical properties such as
compliance, elasticity and resistance to mechanical stress, compatible
with the circulatory blood flow. Lastly, new 3D hydrogels were prepared
by copolymerization of acrylate and polysaccharides. These polymers
coated on surfaces were demonstrated to promote endothelial cell
In conclusion, the ability of these biocompatible polymer-based grafts
to support vascular tissue synthesis proved to be quite successful.
Applications of these materials also included 3D scaffolds for cell
culture, hybrid scaffolds to enhance tissue integration, and new
biocompatible materials for drug and gene delivery by chemical
functionalization of the materials.
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