Thomas Groth

Bio: Thomas Groth is an academic researcher from Martin Luther University of Halle-Wittenberg. The author has contributed to research in topics: Membrane & Adhesion. The author has an hindex of 38, co-authored 186 publications receiving 5191 citations. Previous affiliations of Thomas Groth include Wittenberg University & Polytechnic University of Catalonia.

Studies on the biocompatibility of materials: fibroblast reorganization of substratum-bound fibronectin on surfaces varying in wettability.

Abstract: The ability of human fibroblasts to remove and reorganize fibronectin (FN) bound on material surfaces was studied as a novel feature of material surface biocompatibility. Other traditional parameters of biocompatibility analyzed included cell spreading, clustering of fibronectin receptors into focal adhesions, development of stress fibers, and cell growth. Five different materials with surface wettability ranging from hydrophilic (underwater contact angle 25 degrees) to hydrophobic (underwater contact angle 111 degrees) were used, i.e., clean glass (GLASS), aminopropylsilane (APS), octadecylsilane (ODS), polylactate (PL), and silicone (SI). When cells were cultured on these materials in serum-containing medium, formation of FN receptor-rich focal adhesions and actin stress fibers were more evident on the hydrophilic surfaces (GLASS and APS) compared to the hydrophobic ones (PL, ODS, and SI). Cell growth showed a similar pattern, that is, increased cell proliferation with increasing material surface wettability. Preadsorption of FN on the material surfaces increased subsequent cell spreading and cytoskeletal reorganization on hydrophobic surfaces except SI. Removal and reorganization of FN from the material surfaces into extracellular matrixlike structures occurred on GLASS but not on less wettable surfaces, suggesting that this removal/reorganization process may be more sensitive to changes in surface wettability than other parameters of biocompatibility.

Thermoresponsive polymers and their biomedical application in tissue engineering – a review

Abstract: Thermoresponsive polymers hold great potential in the biomedical field, since they enable the fabrication of cell sheets, in situ drug delivery and 3D-printing under physiological conditions. In this review we provide an overview of several thermoresponsive polymers and their application, with focus on poly(N-isopropylacrylamide)-surfaces for cell sheet engineering. Basic knowledge of important processes like protein adsorption on surfaces and cell adhesion is provided. For different thermoresponsive polymers, namely PNIPAm, Pluronics, elastin-like polypeptides (ELP) and poly(N-vinylcaprolactam) (PNVCL), synthesis and basic chemical and physical properties have been described and the mechanism of their thermoresponsive behavior highlighted. Fabrication methods of thermoresponsive surfaces have been discussed, focusing on PNIPAm, and describing several methods in detail. The latter part of this review is dedicated to the application of the thermoresponsive polymers and with regard to cell sheet engineering, the process of temperature-dependent cell sheet detachment is explained. We provide insight into several applications of PNIPAm surfaces in cell sheet engineering. For Pluronics, ELP and PNVCL we show their application in the field of drug delivery and tissue engineering. We conclude, that research of thermoresponsive polymers has made big progress in recent years, especially for PNIPAm since the 1990s. However, manifold research possibilities, e.g. in surface fabrication and 3D-printing and further translational applications are conceivable in near future.

Engineering the extracellular environment: Strategies for building 2D and 3D cellular structures.

Abstract: Cell fate is regulated by extracellular environmental signals. Receptor specific interaction of the cell with proteins, glycans, soluble factors as well as neighboring cells can steer cells towards proliferation, differentiation, apoptosis or migration. In this review, approaches to build cellular structures by engineering aspects of the extracellular environment are described. These methods include non-specific modifications to control the wettability and stiffness of surfaces using self-assembled monolayers (SAMs) and polyelectrolyte multilayers (PEMs) as well as methods where the temporal activation and spatial distribution of adhesion ligands is controlled. Building on these techniques, construction of two-dimensional cell sheets using temperature sensitive polymers or electrochemical dissolution is described together with current applications of these grafts in the clinical arena. Finally, methods to pattern cells in three-dimensions as well as to functionalize the 3D environment with biologic motifs take us one step closer to being able to engineer multicellular tissues and organs.

Mediation of Biomaterial–Cell Interactions by Adsorbed Proteins: A Review

Abstract: An appropriate cellular response to implanted surfaces is essential for tissue regeneration and integration. It is well described that implanted materials are immediately coated with proteins from blood and interstitial fluids, and it is through this adsorbed layer that cells sense foreign surfaces. Hence, it is the adsorbed proteins, rather than the surface itself, to which cells initially respond. Diverse studies using a range of materials have demonstrated the pivotal role of extracellular adhesion proteins--fibronectin and vitronectin in particular--in cell adhesion, morphology, and migration. These events underlie the subsequent responses required for tissue repair, with the nature of cell surface interactions contributing to survival, growth, and differentiation. The pattern in which adhesion proteins and other bioactive molecules adsorb thus elicits cellular reactions specific to the underlying physicochemical properties of the material. Accordingly, in vitro studies generally demonstrate favorable cell responses to charged, hydrophilic surfaces, corresponding to superior adsorption and bioactivity of adhesion proteins. This review illustrates the mediation of cell responses to biomaterials by adsorbed proteins, in the context of osteoblasts and selected materials used in orthopedic implants and bone tissue engineering. It is recognized, however, that the periimplant environment in vivo will differ substantially from the cell-biomaterial interface in vitro. Hence, one of the key issues yet to be resolved is that of the interface composition actually encountered by osteoblasts within the sequence of inflammation and bone regeneration.

Biomedical Applications of Layer‐by‐Layer Assembly: From Biomimetics to Tissue Engineering

Abstract: The design of advanced, nanostructured materials at the molecular level is of tremendous interest for the scientific and engineering communities because of the broad application of these materials in the biomedical field. Among the available techniques, the layer-by-layer assembly method introduced by Decher and co-workers in 1992 has attracted extensive attention because it possesses extraordinary advantages for biomedical applications: ease of preparation, versatility, capability of incorporating high loadings of different types of biomolecules in the films, fine control over the materials’ structure, and robustness of the products under ambient and physiological conditions. In this context, a systematic review of current research on biomedical applications of layer-by-layer assembly is presented. The structure and bioactivity of biomolecules in thin films fabricated by layer-by-layer assembly are introduced. The applications of layer-bylayer assembly in biomimetics, biosensors, drug delivery, protein and cell adhesion, mediation of cellular functions, and implantable materials are addressed. Future developments in the field of biomedical applications of layer-by-layer assembly are also discussed.