Cellular immunotherapy of cancer is a hot topic ever since the discovery that the immune system is capable of recognising tumour cells. Dendritic cells (DCs) are the professional antigen presenting cells that are best suited for cell-based immunotherapy and therefore ex vivo generated DC cancer vaccines are currently applied in clinical trials. Several methods have been devised for the loading of DCs with tumour information. Instead of identifying, characterising and targeting only a single tumour-associated antigen (TAA), dendritic cells can also be loaded with whole-cell tumour information. In the majority of cases, identifying a TAA is a tedious process and targeting only a single antigen is not likely to succeed unless that antigen is necessary for the function and survival of cancer cells. For this reason, a whole tumour cell approach has several advantages.

The fusion of dendritic cells with tumour cells is used as such a whole tumour cell loading strategy and the application of the fusion outcomes, e.g. possible hybrids cells, have been shown to induce anti-tumour immunity in several cancer models and clinical studies (Orentas et al. 2001, Hayashi et al. 2002, Rosenblatt et al. 2005). Nevertheless, the absence of a reliable and reproducible fusion method, the poor fusion efficacies and the limitation of autologous tumour material for some tumour types were thought to prevent a broad application as cancer vaccine.

This study aimed for the development of new fusion devices to overcome these limitations. Cluster formation, which typically takes place in commercially available electrofusion chambers during cell alignment owing to similar electrophysical parameters (such as cell size, shape and transmembrane potential), was found to be a major limitation of heterologous mammalian cell fusion. The formation of cell clusters and homologous fusions can be avoided by a so-called arranged electrofusion process, where two fusion partners are subjected to an alternating arrangement inside the fusion chamber. This alternating arrangement was realised in two newly developed electrofusion chambers by means of micropatterning and microfluidics, whereas clinical requirements have been considered throughout the whole process development. Both electrofusion chambers were also dimensioned to produce a sufficient amount of hybrid cells at once, thus satisfying the requirement for high-throughput cell fusion.