Laser photoablation of guidance microchannels into hydrogels directs cell growth in three dimensions.

Recent years have seen rapid progress in the engineering and application of biomaterials with controlled biological, physical, and chemical properties, and the development of associated methods for micropatterning of three-dimensional tissue-engineering scaffolds. A remaining challenge is the development of robust, flexible methods that can be used to create physical guidance structures in cell-seeded scaffolds independently of environmental constraints. Here we demonstrate that focal photoablation caused by pulsed lasers can generate guidance structures in transparent hydrogels, with feature control down to the micron scale. These photopatterned microchannels guide the directional growth of neurites from dorsal root ganglia. We characterize the effect of laser properties and biomaterial properties on microchannel formation in PEGylated fibrinogen hydrogels, and the effect of photoablation on neural outgrowth. This strategy could lead to the development of a new generation of guidance channels for treating nerve injuries, and the engineering of structured three-dimensional neuronal or nonneuronal networks.