Abstract
Protein-repulsive surfaces modified with ligands for cell adhesion receptors have been widely developed for controlling the cell adhesion and growth in tissue engineering. However, the question of matrix production and deposition by cells on these surfaces has rarely been addressed. In this study, protein-repulsive polydopamine–poly(ethylene oxide) (PDA–PEO) surfaces were functionalized with an RGD-containing peptide (RGD), with a collagen-derived peptide binding fibronectin (Col), or by a combination of these peptides (RGD + Col, ratio 1:1) in concentrations of 90 fmol/cm2 and 700 fmol/cm2 for each peptide type. When seeded with vascular endothelial CPAE cells, the PDA–PEO surfaces proved to be completely non-adhesive for cells. On surfaces with lower peptide concentrations and from days 1 to 3 after seeding, cell adhesion and growth was restored practically only on the RGD-modified surface. However, from days 3 to 7, cell adhesion and growth was improved on surfaces modified with Col and with RGD + Col. At higher peptide concentrations, the cell adhesion and growth was markedly improved on all peptide-modified surfaces in both culture intervals. However, the collagen-derived peptide did not increase the expression of fibronectin in the cells. The deposition of fibronectin on the material surface was generally very low and similar on all peptide-modified surfaces. Nevertheless, the RGD + Col surfaces exhibited the highest cell adhesion stability under a dynamic load, which correlated with the highest expression of talin and vinculin in the cells on these surfaces. A combination of RGD + Col therefore seems to be the most promising for surface modification of biomaterials, e.g. vascular prostheses.Electronic supplementary materialThe online version of this article (doi:10.1007/s10856-015-5583-3) contains supplementary material, which is available to authorized users.
Highlights
Cell adhesion and proliferation are crucial steps in cell cultivation and in various tissue engineering applications
The cell numbers on surfaces with RGD-containing peptide (RGD) or collagen-derived peptide binding fibronectin (Col) were significantly higher than the cell numbers on poly(ethylene oxide) (PEO)-PDA
The novelty of this study lies in the modification of the material surface with RGD as a ligand for cell adhesion receptors, and with ligands allowing a specific interaction with fibronectin in order to facilitate the deposition of extracellular matrix (ECM) on the scaffolds
Summary
Cell adhesion and proliferation are crucial steps in cell cultivation and in various tissue engineering applications. On most conventionally used biomaterials, such as synthetic polymers, ceramics or metals, the cell adhesion is mediated by proteins adsorbed on the material surface from biological fluids, including serum-supplemented cell culture media, blood or interstitial fluid. An alternative approach, which can circumvent these problems, is based on surface material coatings that completely suppress the non-specific protein adsorption and cancel out the non-specific cell/material interactions. Surface adherent non-fouling layers can be achieved by a reaction of the polymer-functionalized terminal group with the material surface (‘‘grafting to’’), or by surface initiated polymerization from a surface-bound reactive species (‘‘grafting from’’). Protein-repulsive surfaces carrying reactive functional groups can be modified with various biomimetic groups (for example, the well-known fibronectin-derived RGD peptide ligand) [7]. Used bioconjugative reactions are exemplified by the thiolene reaction of thioles with an activated double bond [8], the alkyne-azide cycloaddition reaction [9] (click chemistry) and native chemical ligation [10]
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