The Use of Dimethyl Sulfoxide in Mammalian Cell Fusion

Abstract

Since Pontecorvo (1975) first demonstrated that polyethylene glycol (PEG) is an efficient fusogen of mammalian cells, its usefulness for this purpose has been demonstrated in a wide variety of cell types and organisms, including bacterial L forms (Yoshiyuki et al., 1979) and fungal protoplasts (Anné and Peberdy, 1976). There have been a number of publications describing refinements of the basic fusion protocol outlined in the earlier reports (Pontecorvo, 1975; Davidson and Gerald, 1976). Methods to fuse cells in suspension with PEG have been perfected (O’Malley and Davidson, 1977; Hales, 1977). Schneiderman et al. (1979) reported that decreasing the Ca++ concentration during and immediately following fusion diminished the toxicity of PEG, resulting in a higher recovery of proliferating hybrids. Another laboratory reported that the treatment of cultures with the lectin phytohemagglutinin prior to fusion enhanced the effectiveness of PEG at lower concentrations, thus decreasing the cytotoxicity of the procedure (Mercer and Schlegel, 1979). Norwood et al. (1976) reported that dimethyl sulfoxide (DMSO) enhanced fusion of human diploid cells over a range of concentrations of PEG. All of these refinements provide the investigator with greater maneuverability in developing chemically induced cell fusion systems suitable for his or her needs. In this chapter the role of DMSO in the optimization of mammalian cell fusion will be discussed. However, as will be discussed below, the mechanism of cell fusion remains to be elucidated. Therefore, it should be emphasized that the utility of DMSO or any other additive in facilitating mammalian cell fusion must be experimentally determined for any given experimental situation. We do not propose that DMSO is a panacea which will solve all problems encountered in cell fusion, but rather that it is one of a number of additives (Klebe and Mancuso, 1981) available to the investigator which enhance mammalian cell fusion.