Nanoengineering approaches for guiding cellular behavior
- Autores: Dencho Milkov Gugutkov
- Directores de la Tesis: George Altankov (dir. tes.), Maria Pau Ginebra i Molins (tut. tes.)
- Lectura: En la Universitat Politècnica de Catalunya (UPC) ( España ) en 2017
- Idioma: español
- Tribunal Calificador de la Tesis: Roumen Pankov (presid.), Marta Pegueroles Neyra (secret.), Yannis F. Missirlis (voc.)
- Programa de doctorado: Programa de Doctorado en Ingeniería Biomédica por la Universidad Politécnica de Catalunya y la Universidad de Zaragoza
- Materias:
- Enlaces
- Tesis en acceso abierto en: TDX
- Resumen
Tissue engineering aims to replace restore or help regeneration of injured tissue or organ with scaffolds that mimic the natural extracellular matrix (ECM). The design of such scaffolds requires deeper understanding of the factors that determine the cellular behavior. This thesis is focused on the cell-biomaterials interaction, but it strives to go beyond the classical material science, looking for new options to obtain control over the cell behavior.
Cellular interaction with artificial substrata is a well-described paradigm usually attributed to the adsorption of adhesive proteins from the surrounding medium. The recognition of these proteins triggers an order of specific signaling events, reminiscent of the natural interaction of cells with ECM, affecting strongly their behavior. One important aspect of such interaction, however, is the organization of the matrix proteins - a hallmark for the ordinary ECM.
Recent studies in our group showed that also in-vitro the cells tend to create organization. They remodel the adsorbed matrix proteins (in a fibril-like pattern) as an attempt to make their own provisional ECM. This phenomenon, described basically for fibronectin (FN), appears to involve also other matrix proteins, such as fibrinogen (FBG), and even collagen IV and vitronectin, which, being non fibrillar proteins by their nature, also undergo linear reorganization. Thus, cells somehow ¿prefer¿ fibrillar assemblies trying to imprint such patterns in their microenvironment. Other types of protein arrangements, however, for example network-like assemblies, which are also typical for the ECM, are insufficiently studied and this comprises an essential part of this work.
In the first part of the thesis particular attention is devoted on the peculiar behavior of adsorbed FN and FBG in the nanoscale observed by atomic force microscopy (AFM). Joint work with the group of Prof Salmeron-Sanches from the Polytechnic University in Valencia revealed that apart from the classical view for rather stochastic adsorption of matrix proteins, the lateral protein-protein interactions prevail on some surfaces giving rise to self-assembly in a network-like structures with significant consequences on the cell behavior. The thesis focuses particularly on the biological activity of these networks. The performed studies clearly suggested that the modulation of the network formation (using model surfaces with varying density of -OH groups) has evident impact on cell adhesion and functionality ¿ a fact, confirmed with two different cell systems: fibroblasts and endothelial cells. Another line of performed research lie on the fact that matrix proteins can sequestrate from the surrounding liquid phase to form structures of various shapes, including fibers with a diameter of only few nanometers and lengths up to centimeters; thus resembling the natural ECM components. A fascinating possibility to mimic similar structures is to engineer nanofibers, based on matrix proteins, via electrospinning technology - an approach extensively explored in the second part of the thesis. It was evidently shown that the cells readily recognize such fibrils and attach to them much faster than on planar substrata. Thus, one can anticipate that mimicking the organization of ECM with nanofibers will help to understand how cells respond to such an environment, an issue that is fundamental for biology.
Besides, this approach represents an additional tool for controlling the cell behavior as proposed in this thesis. Therefore nanofibers based on natural matrix proteins (e.g., fibrinogen, fibronectin) and synthetic polymers (e.g. polylactic acid, (PLA); poly(ethylacrilate), (PEA)) were systemically elaborated. Their implication as a model system revealed that by varying with the composition, the organization and the mechanical properties of these fibers a tight control over the cellular response may be obtained.
