Preparative agarose gel electrophoresis for reducing matrix interferences of organoid cell medium prior to LC-MS analysis of insulin.

Organoids are 3D cell cultures with microanatomies mimicking aspects of real organs, useful for e.g. animal-free studies of development, disease, and drug discovery. The cell medium of organoid models of Langerhans islets, regulating blood glucose levels by insulin secretion, can be analyzed by liquid chromatography-mass spectrometry (LC-MS). However, organoid medium complexity is a major challenge, as matrix interferences can reduce sensitivity and selectivity, even with optimized LC-MS conditions. By applying preparative agarose gel electrophoresis-electrodialysis (PGE-ED), we were able to decrease the cell medium background signal, allowing for reduced interferences affecting LC-MS analysis of human insulin.

Preparative protein concentration from biofluids by epitachophoresis.

With increasing demands on protein analyses in complex biological matrices, the insistence on developing new sample preparation techniques is rising. Recently, we introduced a new displacement electrophoresis technique (epitachophoresis) and instrumentation for preparative concentration and cleaning of DNA samples. This work describes the possibility of applying this device to protein samples. We have developed a method for the epitachophoretic concentration of proteins in a cationic mode and tested it by concentrating and collecting the protein zones from complex biological matrices (urine and growth medium). Under optimized conditions, we have obtained recoveries up to 99%. Furthermore, the applicability of the developed method was proven by concentrating and collecting the cytochrome c zone from a HeLa cell line growth medium, where the protein cytochrome c was released during cell apoptosis.