Marion Maire

Low Thrombogenicity Coating of Nonwoven PET Fiber Structures for Vascular Grafts

Vascular PET grafts (Dacron) have shown good performance in large vessels (≥ 6 mm) applications. To address the urgent unmet need for small-diameter (2-6 mm) vascular grafts, proprietary high-compliance nonwoven PET fiber structures were modified with various PEG concentrations using PVA as a cross-linking agent, to fabricate non-thrombogenic mechanically compliant vascular grafts. The blood compatibility assays measured through platelet adhesion (SEM and mepacrine dye) and platelet activation (morphological changes, P-selectin secretion, and TXB2 production) demonstrate that functionalization using a 10% PEG solution was sufficient to significantly reduce platelet adhesion/activation close to optimal literature-reported levels observed on carbon-coated ePTFE.

Combining Electrospun Fiber Mats and Bioactive Coatings for Vascular Graft Prostheses

The patency of small-diameter (<6 mm) synthetic vascular grafts (VGs) is still limited by the absence of a confluent, blood flow-resistant monolayer of endothelial cells (ECs) on the lumen and of vascular smooth muscle cell (VSMC) growth into the media layer. In this research, electrospinning has been combined with bioactive coatings based on chondroitin sulfate (CS) to create scaffolds that possess optimal morphological and bioactive properties for subsequent cell seeding. We fabricated random and aligned electrospun poly(ethylene terephthalate), ePET, mats with small pores (3.2 ± 0.5 or 3.9 ± 0.3 μm) and then investigated the effects of topography and bioactive coatings on EC adhesion, growth, and resistance to shear stress. Bioactive coatings were found to dominate the cell behavior, which enabled creation of a near-confluent EC monolayer that resisted physiological shear-flow conditions. CS is particularly interesting since it prevents platelet adhesion, a key issue to avoid blood clot formation in case of an incomplete EC monolayer or partial cell detachment. Regarding the media layer, circumferentially oriented nanofibers with larger pores (6.3 ± 0.5 μm) allowed growth, survival, and inward penetration of VSMCs, especially when the CS was further coated with tethered, oriented epithelial growth factor (EGF). In summary, the techniques developed here can lead to adequate scaffolds for the luminal and media layers of small-diameter synthetic VGs.

3D Printing of Microstructured and Stretchable Chitosan Hydrogel for Guided Cell Growth

The ability to produce complex micro‐ or nanostructures from naturally derived hydrogels is significant for biomedical applications. However, precisely controlled architectures of soft hydrogels are difficult to be achieved due to their limited mechanical properties. Despite intensive research, significant challenges persist to fabricate hydrogels with ordered structures and adequate mechanical and biological properties for mimicking native tissues. In this work, a 3D printing technique is proposed to fabricate chitosan hydrogel with highly flexible and organized microfiber networks. The microstructured hydrogel scaffolds are obtained through a neutralization step. The strain at failure of hydrogel filaments can reach up to ≈400% and maximum strength is ≈7.5 MPa. The hydrogel scaffolds feature surface textures that can guide and align cell growth. This approach of tailoring hydrogels opens doors to design and produce 3D tissue constructs with topographical, biological, and mechanical compatibility.