Metre-long gel microfibres that encapsulate cells and extracellular-matrix proteins can replicate intrinsic functionalities of tissues, reports a study published online in Nature Materials this week. These fibres, which can be weaved and reeled into tissue-like shapes, could be used as templates for the reconstruction of muscle fibres, blood vessels or neural networks.

Fibre-shaped gels with embedded cells can be readily made in standard microfluidic chips. However, these require the rapid gelation provided by synthetic polymers, which do not stimulate the formation of the cell-cell connections that are typical of living tissues. Using a double-coaxial microfluidic device, Shoji Takeuchi and colleagues embedded cells in natural extracellular-matrix proteins - such as collagen and fibrin, which allow for the necessary cell-cell interactions - and protected them with a rapidly gelating hydrogel shell, which is later removed by a specific enzyme. The researchers report that the resulting fibres beat spontaneously when they contained cardiomyocytes, and that tubular structures or neural networks formed in the fibres when they encapsulated endothelial cells or cerebral cortical cells.

The researchers also show that microfibres of pancreatic islet cells transplanted underneath the kidney of diabetic mice normalize the concentration of glucose in their blood for about two weeks. These fibres could later be removed.