Biogenic thermoresponsive polyelectrolyte multilayers as potential substrata for the generation of cell sheets for tissue engineering

• Applicants: Professor Dr. Thomas Groth; Professor Dr. Kai Zhang
• Subject Area: Biomaterials
• Term: from 2017 to 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 369505795

A novel approach for the formation of thermoresponsive surface coatings based on derivatives from cellulose and chitosan as biogenic, biocompatible and environmentally-friendly biopolymers from renewable resources will be explored for making culture substrata for mammalian cells to permit non-enzymatic release of cells and cell sheets by temperature change. Three different thermoresponsive elements together with sulfate as anionic groups will be introduced into the backbone of these biopolymers. The resulting polyelectrolytes will be systematically characterized regarding their chemical structures, molecular weights, zeta potentials and lower critical solution temperatures (LCST), in order to achieve thermoresponsive compounds with a sufficient charge density as well as a transition temperature around 37°C. After the selection of candidate derivatives with suitable LCST and charge density, these polyelectrolytes will be used for the formation of multilayers via the layer-by-layer (LbL) technique, which will be studied by surface plasmon resonance, quartz micro balance, ellipsometry and contact angle measurements. The thermoresponsive effects shall be analyzed by changes of water content and wetting properties of the multilayer coatings in the temperature range from 5°C-37°C. Protein adsorption is a prerequisite for the adhesion of cells and has been shown to be a determinant of cell adhesion on thermoresponsive surface coatings, which will be studied in this project regarding the binding of fibronectin and serum proteins. Multilayers with thermoresponsive properties that permit reversible adsorption of proteins will be further used to study the adhesion and growth of cells from three different germ layers. The thermoresponsive effect will be studied by changes in cell shape and detachment of single cells during decrease of temperature from 37°C to 5°C as well as by the release of complete cell sheet in response to temperature changes. Altogether, the development of the new system provides essential advantages over existing fully synthetic thermoresponsive polymers like poly(N-isopropylacrylamide) because of the inherent bioactivity of sulfated cellulose/chitosan towards mitogenic and morphogenic growth factors, the excellent biocompatibility as well as the potential long-term degradability. These advantages allow these systems not only to be feasible for in vitro applications to generate cell sheets for engineering various tissues for transplantation including skin, cornea, myocardium, etc., but also to be potentially useful for diverse in vivo applications, where the thermoresponsive release of proteins and/or cells is desirable.

• DFG Programme: Research Grants