Three-dimensional guidance of DRG neurite outgrowth using multi-photon photo-ablation

'Brain on Chip' technologies based on two-dimensional in-vitro neural cultures have attracted much interest in both basic and applied Neuroscience over the past two decades. Extending this technology towards more brain-like three-dimensional geometries while maintaining the ability to record and/or control the neural activity is an important neural engineering challenge. We have developed a versatile new optical strategy for generating complex 3-D patterns having micron scale resolution that can be practically applied for guiding cellular outgrowth in semi-transparent bio-synthetic hydrogels. This method is based on multi-photon photoablation of the solid phase of a hydrogel material, which creates a highly localized imperfection in the amorphous hydrogel matrix. When applied to a highly crosslinked biocompatible matrix, the micro-ablations provide a conductive niche for preferential guidance of neurites and support cells. Moreover, the optical transparency of the materials make them ideal for experimental studies involving cellular optical imaging and/or optical control of neural activity and could potentially enable the future development of a 'Brain in Chip' technology.