Cell Separation with Counter-Current Chromatography and Thin-Layer Countercurrent Distribution in Aqueous Two-Phase System

Abstract

When mixed in aqueous solution at low concentrations the neutral polymers dextran and poly(ethylene glycol) (PEG) form a two-phase system consisting of a PEG-rich phase floating on a dextran-rich phase. These polymer phase systems have previously been shown to selectively partition cells and other particles between the phases and their interface on the basis of various surface properties of the particles. In combination with automated countercurrent techniques, partitioning in polymer phase systems gives rapid and sensitive fractionation of particle mixtures. This article contrasts separations obtained with mixtures of erythrocytes in polymer phase systems, using a nonsynchronous coil planet centrifuge (NSCPC - a version of Ito's countercurrent chromatograph) and in three different thin-layer countercurrent distribution (CCD) instruments. The result from CCD are shown to be in accord with simple theory and thus provide assistance in interpreting the theoretically complex results from the NSCPC. For polymer phase systems, the NSCPC was found to have a fractionation capacity similar to a CCD device providing twenty to thirty transfers.