Human tumour and dendritic cell hybrids generated by electrofusion: potential for cancer vaccines

Hybrid cells created by fusion of antigen presenting and tumour cells have been shown to induce potent protective and curative anti-tumour immunity in rodent cancer models. The application of hybrid cell vaccines for human tu mour therapy and the timely intervention in disease control are limited by the requirement to derive sufficient autologous cells to preserve homologou s tumour antigen presentation. In this study, the efficiency of various met hods of electrofusion in generating hybrid human cells have been investigat ed with a variety of human haemopoietic, breast and prostate cell lines. Ce ll fusion using an electrical pulse is enhanced by a variety of stimuli to align cells electrically or bring cells into contact. Centrifugation of cel ls after an exponential pulse from a Gene Pulser electroporation apparatus provided the highest yield of mixed cell hybrids by FAGS analysis. An exten sive fusogenic condition generated in human cells after an electrical pulse contradicts the presumption that prior cell contact is necessary for cell fusion. Alignment of cells in a concurrent direct current charge and osmoti c expansion of cells in polyethylene glycol also generated high levels of c ell fusion, Waxing of one electrode of the electroporation cuvette served t o polarise the fusion chamber and increase cell fusion 5-fold. Optimisation of a direct current charge in combination with a fusogenic pulse in which fusion of a range of human cells approached or exceeded 30% of the total pu lsed cells. The yield of hybrid prostate and breast cancer cells with dendr itic cells was similar to the homologous cell fusion efficiencies indicatin g that dendritic cells were highly amenable to fusion with human tumour cel ls under similar electrical parameters. Elimination of unfused cells by den sity gradient and culture is possible to further increase the quantity of h ybrid cells, The generation and purification of quantities of hybrid cells sufficient for human vaccination raises the possibility of rapid, autologou s tumour antigen presenting vaccines for trial with common human tumours, ( C) 2000 Elsevier Science B.V. All rights reserved.