Arterial bypass surgery with synthetic vascular prostheses achieves poor patency rates compared to autogenous natural materials, and this is a challenge for tissue engineering research concerning small caliber vascular grafts. Modifications of the prosthetic surface followed by endothelial cell seeding may reduce thrombogenicity and intimal hyperplasia. Planar polyethylene terephthalate (PET) vascular prosthetic samples were impregnated with the copolymer poly(glycolide-L-lactide) (PGL) or with the terpolymer poly(glycolide-L-lactide-(e)caprolactone) (PGLCap) in order to lower the permeability of the knitted fabrics and ensure a less adhesive background. Subsequent modification with adhesive protein assemblies composed of collagen type I (Co) in conjunction with laminin (LM), fibronectin (FN) or fibrin (Fb) gel was performed to enhance cell adhesion. Bovine pulmonary artery endothelial cells (EC) of the CPAE line were seeded on to the coatings and subjected to static tissue culture conditions for 7 days. Impregnation of the PET prostheses decreased the initial adhesion and proliferation of the EC. After coating with the protein assemblies, the impregnated PET provided better substrates for cell culture than the protein-coated PET, on which the EC population started decreasing after 4 days of culture. The cells proliferated better on the CoFN, CoFb and CoFbFN coatings than on the Co and CoLM coatings. Impregnation type and adhesive matrix protein deposition may play an important role in successful endothelialization, healing and clinical performance of vascular grafts.
Artificial vascular prostheses are used for bypass surgery. Thrombogenicity often cause graft occlusion. Targeted surface alterations including cell seeding may improve the haemocompatibility. Knitted commercial tubular PET (polyethylene terephtalate) vascular prostheses with collagen impregnation were modified by adsorption of laminin (LM) or coating with fibrin network (FB) on the luminal surface. Human endothelial cells were harvested, cultured and seeded at the density of 150x10\3 cells/cm square on all grafts. The cell lining was continuously visualized and quantified. The retention was 21%, 37% and only 2% of the seeding density on the unmodified (UM), LM- and FB-coated grafts, respectively. These seeded prostheses were exposed to a laminar shear stress (SS) 15 dynes/cm square for 40 minutes (UM, LM, FB) and 120 min (UM, LM) in a chamber simulating blood circulation. The SS was excluded in static (ST) control grafts. After 40 min-SS the cell numbers were78%, 27% and 72% for the UM, LM and FB prosthesis compared to the ST. The cell densities were 61% and 57% on the UM and LM after 120 min-SS. To conclude, the endothelium formed a confluent layer whereas laminin immobilization improved endothelial adhesion but not the flow resistance. Reverse effect was observed on fibrin coating.
We investigated adhesion and growth of vascular smooth muscle cells (VSMC) on proteins assemblies prepared by coating of thin fibrin net with ultrathin layer of collagen I, fibronectin or laminin. The assemblies were deposited on polystyrene (PS) non-modified with plasma discharge, i.e. a treatment commonly used for creation of surfaces suitable for cell cultivation. All samples with the fibrin assemblies improved initial attachment and spreading of VSMC as well as their subsequent growth in comparison with the pristine PS. The adhesion area of VSMC increased on fibrin coated with collagen I and fibronectin, while on laminin it remained similar as that on the pure fibrin. Thin 3D fibrin net markedly changed the morphology of VSMC from polygonal to star-like shape with protrusions. Cells all tested samples formed vinculin-containing focal adhesion plaques and α-actin cytoskeleton, an important marker of VSMC differentiation. The protein assemblies can be used for improvement of cell adhesion and growth on various artificial materials used in tissue engineering, e.g. for construction of bioartificial vascular prostheses.
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