Usefulness of Ficoll in electric field-mediated cell fusion

Electrofusion is a technique that enables the production of new cell types with desired properties to be done. Ehrlich ascites tumor cells are fused by means of an electric field. Under too harsh external field strength or pulse length conditions, however, membrane breakdown leads to a loss of cellular cytoplasm. Addition of the high polymer Ficoll to the fusion medium increases its density and osmotic pressure, thus preventing cytoplasm from running out and, therefore, maintaining cell viability. Fusion between cells of different sizes is made possible or facilitated by means of Ficoll, as big cells do not lose their cytoplasm under conditions required for enhancing membrane permeability of the small cells. In presence of the proteolytic enzyme pronase, addition of Ficoll to the fusion medium further raises the fusion percentage compared to the exclusive addition of pronase. The fusion of cells of different densities is also greatly facilitated and its percentage increased by addition of Ficoll, thus obviating the necessity to perform electrofusion under conditions of microgravity.