Markierung immortalisierter Zelllinien und Stammzellen mit funktionalisierten Partikeln für biomedizinische Anwendungen

Abstract

Magnetic cell labeling has emerged as a potentially powerful tool for studying in vivo trafficking of transplanted cells, e.g. in studies for tissue repair by magnetic resonance tomography. The objective of this study was to evaluate the feasibility and efficiency of labeling of cells with functionalized superparamagnetic nanoparticles without the use of transfection agents. Fluorescent polymer particles were synthesized by the miniemulsion process. The surface charge was varied by adjusting the amount of copolymerized monomers with amino and carboxy groups thus enabling to study the cellular uptake in correlation to the surface charge. The iron in the cell was detected histochemically by the Prussian blue reaction or by transmission electron microscopy. Quantification of the iron content in the cell was performed with the ferrozine assay. Fluorescent activated cell sorter measurements were performed for detecting the uptake of the particles in mesenchymal stem cells, and the three cell lines HeLa, Jurkat, and KG1a. These cell lines were chosen as they can serve as models for clinically interesting cellular targets. Confocal laser scanning microscopy and transmission electron microscopy were performed for subcellular localization of the nanoparticles. Concerning surface functionalization of the particles for these cell lines a clear correlation of surface charge and fluorescence intensity could be shown. For an efficient uptake of the nanoparticles, no transfection agents were needed. Aminogroups on the surface of the particles resulted in higher intracellular uptake compared to carboxygroups. For sustained release application, (bio)degradable polymers like poly(alkylcyanacrylate) or polyesters are the first choice. Fluorescent poly(D,L-lactide) and poly(butylcyanacrylate) nanoparticles were synthetized using the miniemulsion process and cell uptake was determined. Considerable intracellular uptake was found in all examined cell lines.