ICAM-1 and VCAM-1 expression by endothelial cells grown on fibronectin-coated TCPS and PS
Ype J T van der Zijpp1, Andre A Poot, Jan Feijen
1Institute for Biomedical Technology (BMTI), Department. of Chemical Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.
Insights
Endothelial cell activation on vascular graft polymers is influenced by seeding density, not surface hydrophilicity. Fibronectin coating minimizes differences in leukocyte adhesion molecule expression.
Area of Science:
- Biomaterials Science
- Vascular Biology
- Cellular Engineering
Background:
- Small-diameter vascular grafts often fail due to blood coagulation and platelet adhesion.
- Endothelial cells can create an antithrombogenic surface, but cell detachment remains a challenge.
- Endothelial cell activation, potentially triggered by polymer surface characteristics, can lead to leukocyte infiltration.
Purpose of the Study:
- To investigate the impact of polymer surface characteristics (hydrophilic vs. hydrophobic) on endothelial cell activation.
- To determine how seeding density and fibronectin coating affect endothelial cell behavior and inflammatory marker expression.
- To understand the relationship between surface properties and endothelial cell adhesion molecule expression.
Main Methods:
- Human umbilical vein endothelial cells (HUVECs) were seeded at various densities on tissue culture polystyrene (TCPS; hydrophilic) and polystyrene (PS; hydrophobic) surfaces.
- Surfaces were coated with fibronectin to enhance cell adhesion prior to seeding.
- Expression of leukocyte adhesion molecules (ICAM-1 and VCAM-1) was measured during cell proliferation.
Main Results:
- ICAM-1 expression was not significantly affected by polymer surface type but was influenced by seeding density and proliferation time.
- VCAM-1 expression was slightly higher on the hydrophilic TCPS surface and also dependent on seeding density and proliferation time.
- Low seeding densities resulted in lower expression of both ICAM-1 and VCAM-1 in the initial stages of proliferation.
- Fibronectin coating appeared to minimize differences in leukocyte adhesion molecule expression between the two surfaces.
- Endothelial cell proliferation was slower on the hydrophobic PS surface compared to the hydrophilic TCPS surface.
Conclusions:
- Polymer surface hydrophilicity has a limited direct impact on endothelial cell expression of ICAM-1 and VCAM-1, likely due to fibronectin coating.
- Endothelial cell activation markers are more sensitive to seeding density and proliferation time than to surface type.
- While surface type minimally affected inflammatory marker expression, it did impact endothelial cell proliferation rates, with slower growth on hydrophobic surfaces.
Abstract:
Small-diameter vascular grafts rapidly fail as a result of blood coagulation and platelet deposition. Endothelial cells lining the inner side of blood vessels can provide the graft lumen with an antithrombogenic surface. One of the remaining problems is cell detachment after restoration of blood flow, because of infiltration of leukocytes that respond to an inflammatory-like activation of the endothelial cells. This endothelial activation is possibly caused by the surface characteristics of the underlying polymer. To get more insight into the effects of the polymer surface on endothelial cell activation, we seeded human umbilical vein endothelial cells (HUVECs) in various densities and subsequently grew them on tissue culture polystyrene (TCPS; hydrophilic) and polystyrene (PS; hydrophobic) surfaces. To improve cell adhesion, surfaces were coated with purified fibronectin prior to cell seeding. During proliferation, the expressions of the leukocyte adhesion molecules ICAM-1 and VCAM-1 were determined. Results indicate that ICAM-1 expression is not influenced by the character of the polymer surface, and that VCAM-1 expression is slightly higher on the TCPS surface. Expressions of both adhesion molecules are influenced by the seeding density and time of proliferation. At low seeding densities (< or = 10,000 cells/cm(2)), a relatively low percentage of nonexogenously activated cells expressed ICAM-1 during the first 3 days of proliferation compared to higher seeding densities. Although less pronounced, this was also observed for the percentage of cells expressing VCAM-1. During proliferation, the amount of ICAM-1 per endothelial cell increased, whereas the expression of VCAM-1 remained low. The absence of large differences in leukocyte adhesion molecule expression by endothelial cells grown on TCPS or PS is possibly caused by coating of the surfaces with fibronectin. It is known that surface hydrophilicity influences protein adsorption. Although this had no or little effect on leukocyte adhesion molecule expression, endothelial cell growth was affected, because proliferation was slower on the hydrophobic PS.
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