The invention provides in one aspect a method of producing a fused cell, comprising the steps of providing a porous filter, allowing parent cells to attach to either side of the porous filter, and causing fusion of the cell membranes through the pores of the porous filter so that the cytoplasms of the cells are contiguous through the porous filter whilst the chromosomes or nuclei of the parent cells remain separated by the porous filter. The invention also provides cells derived from fused cells, and compositions and tissues comprising cells derived from fused cells.
