The magnetically driven formation of three-dimensional (3D) aggregates of embryonic stem cells (ESCs) that can become heart cells is described in Nature Communications this week. Creating 3D tissue structures from individual cells and stimulating them to form more specialised cell types is an important goal for regenerative medicine.

A number of studies have demonstrated that mechanical factors can influence stem cell differentiation, but much of the previous work has focussed on 2D structures. Claire Wilhelm and colleagues describe 3D magnetic assembly of ESC structures along with remote mechanical stimulation for stem cell differentiation. They show that such structures can be produced by incorporating iron oxide nanoparticles into ESCs. Once magnetised, these cells can be remotely manipulated with magnetic fields to form 3D aggregates and mechanically stimulated to differentiate into heart cells. The authors find that internalising magnetic iron oxide particles in ESCs does not affect their viability and ability to differentiate into different cell types.

This process allows for the whole ESC differentiation profile to be investigated without any biochemical triggers, and may represent an alternative approach to conventional techniques for producing 3D tissue structures.