Melissa Krebs and Randall Erb are graduate students working on different subjects at different universities in different cities. They are also brother and sister — and recently their wish to work together sparked a collaboration on tissue engineering that means they are now co-authors as well (Nano Lett. 9, 1812–1817; 2009).

Krebs is a student of Eben Alsberg, an expert on tissue engineering at Case Western Reserve University in Cleveland, Ohio, whereas Erb works on magnetic nanosystems in Benjamin Yellen's group at Duke University in Durham, North Carolina. Together with their advisers, the brother and sister devised a project that would draw on the expertise of each group: the use of a magnetic fluid to tie mammalian cells together.

The goal of the experiments, which also involved researchers from the University of Massachusetts, was to regenerate tissue by controlling the spatial arrangement of cells within a biomaterial matrix. Although a variety of approaches exist, they are often compromised by being slow, expensive or damaging to the cells.

Krebs, Erb and co-workers used inert, biocompatible ferrofluids to drive cells into linear structures under an applied magnetic field. The technique does not require special surfaces, the cells are not modified and no toxic chemicals are needed. The nanoparticles making up the ferrofluid can be removed after the assembly, allowing the structure to be transferred to a cell culture surface.

Such collaborations can be indispensable in some areas of medicine according to Alsberg. “It is often difficult to advance complex fields such as regenerative medicine without the contributions of researchers with often disparate backgrounds,” he explains, adding that this particular multidisciplinary project had another advantage: “The collaboration arose through fortuitous circumstances since Mrs Krebs and Mr Erb are siblings. Dr Yellen was not aware of the work my lab was doing, and the opposite was true as well”.