New ways to print living cells promise breakthroughs for engineering complex tissues in vitro.

The ability to control the placement of cells and the assembly of networks in vitro has tremendous potential for understanding the regulation of development as well as for generating artificial tissues. To date, most engineering tools that can place materials with precision are not compatible with the requirements of living cells, and so approaches to tissue engineering have focused on patterning substrates as a way of controlling cell growth rather than patterning cells directly. In this issue of Biochemical Journal, however, Eagles et al. adapt electrohydrodynamic printing technology to 'print' living cells from a neuronal cell line on to a substrate. The importance of this approach is that it has the potential for unprecedented control over the position of cells in culture by directly placing them, thus allowing for the systematic assembly of cell networks.