Fractionation of cells and subcellular particles with Percoll

At present, centrifugation is the most common method fur separation and iso lation of cells and subcellular particles. The technique can be used for a wide range of applications. During latter years it has become obvious what a powerful method density gradient centrifugation is, especially when used in conjunction with sensitive assays or clinical treatments. The most activ e areas for use of density gradient centrifugation include purification for in vitro fertilization of sperm of both human and bovine origin, isolation of cells for cell therapy of patients receiving chemo- and radiation thera py and basic research both on cellular and subcellular levels. These treatm ents and investigations require homogeneous populations of cells and cell o rganelles, which are undamaged after the separation procedure. Percoll, onc e introduced to reduce convection during centrifugation, has proved to be t he density gradient medium of choice since it fulfills almost all criteria of an ideal density gradient medium. Recently good results have also been o btained after silanization of colloidal silica particles, e.g, BactXtractor (TM). The latter medium has proved to be useful in recovery of microorganis ms from food samples free of inhibitors to the Polymer Chain Reaction (PCR) . The separation procedures described for Percoll in this review seem to be applicable to any cells or organelles in suspension for which differences in size or bouyant density exist. Furthermore, since Percoll media are iner t, they are well suited for the separation of fragile elements like envelop ed viruses. (C) 2000 Elsevier Science B.V. All rights reserved.