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End date: 2022 × Start date: 2022 × End date: 2019 × Start date: 2011 × DDC: 570 × Has files: Yes × Version: publishedVersion × Subject: cell adhesion × WGL Institute: DWI ×

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    Quantifying ligand-cell interactions and determination of the surface concentrations of ligands on hydrogel films: The measurement challenge
    (Melville, NY : AIP Publishing, 2015) Beer, Meike V.; Hahn, Kathrin; Diederichs, Sylvia; Fabry, Marlies; Singh, Smriti; Spencer, Steve J.; Salber, Jochen; Möller, Martin; Shard, Alexander G.; Groll, Jürgen
    Hydrogels are extensively studied for biomaterials application as they provide water swollen noninteracting matrices in which specific binding motifs and enzyme-sensitive degradation sites can be incorporated to tailor cell adhesion, proliferation, and migration. Hydrogels also serve as excellent basis for surface modification of biomaterials where interfacial characteristics are decisive for implant success or failure. However, the three-dimensional nature of hydrogels makes it hard to distinguish between the bioactive ligand density at the hydrogel-cell interface that is able to interact with cells and the ligands that are immobilized inside the hydrogel and not accessible for cells. Here, the authors compare x-ray photoelectron spectrometry (XPS), time-of-flight secondary ion mass spectroscopy (ToF-SIMS), enzyme linked immunosorbent assay (ELISA), and the correlation with quantitative cell adhesion using primary human dermal fibroblasts (HDF) to gain insight into ligand distribution. The authors show that although XPS provides the most useful quantitative analysis, it lacks the sensitivity to measure biologically meaningful concentrations of ligands. However, ToF-SIMS is able to access this range provided that there are clearly distinguishable secondary ions and a calibration method is found. Detection by ELISA appears to be sensitive to the ligand density on the surface that is necessary to mediate cell adhesion, but the upper limit of detection coincides closely with the minimal ligand spacing required to support cell proliferation. Radioactive measurements and ELISAs were performed on amine reactive well plates as true 2D surfaces to estimate the ligand density necessary to allow cell adhesion onto hydrogel films. Optimal ligand spacing for HDF adhesion and proliferation on ultrathin hydrogel films was determined as 6.5 ± 1.5 nm.
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    Synthetic 3D PEG-Anisogel Tailored with Fibronectin Fragments Induce Aligned Nerve Extension
    (Columbus, Ohio : American Chemical Society, 2019) Licht, Christopher; Rose, Jonas C.; Anarkoli, Abdolrahman Omidinia; Blondel, Delphine; Roccio, Marta; Haraszti, Tamás; Gehlen, David B.; Hubbell, Jeffrey A.; Lutolf, Matthias P.; De Laporte, Laura
    An enzymatically cross-linked polyethylene glycol (PEG)-based hydrogel was engineered to promote and align nerve cells in a three-dimensional manner. To render the injectable, otherwise bioinert, PEG-based material supportive for cell growth, its mechanical and biochemical properties were optimized. A recombinant fibronectin fragment (FNIII9*-10/12-14) was coupled to the PEG backbone during gelation to provide cell adhesive and growth factor binding domains in close vicinity. Compared to full-length fibronectin, FNIII9*-10/12-14 supports nerve growth at similar concentrations. In a 3D environment, only the ultrasoft 1 w/v% PEG hydrogels with a storage modulus of ∼10 Pa promoted neuronal growth. This gel was used to establish the first fully synthetic, injectable Anisogel by the addition of magnetically aligned microelements, such as rod-shaped microgels or short fibers. The Anisogel led to linear neurite extension and represents a large step in the direction of clinical translation with the opportunity to treat acute spinal cord injuries.