Angioneural crosstalk in scaffolds with oriented microchannels for regenerative spinal cord injury repair

The aim of our work is to utilize the crosstalk between the vascular and the neuronal system to enhance directed neuritogenesis in uniaxial guidance scaffolds for the repair of spinal cord injury. In this study, we describe a method for angioneural regenerative engineering, i.e., for generating biodegradable scaffolds, produced by a combination of controlled freezing (freeze-casting) and lyophilization, which contain longitudinally oriented channels, and provide uniaxial directionality to support and guide neuritogenesis from neuronal cells in the presence of endothelial cells. The optimized scaffolds, composed of 2.5 % gelatin and 1 % genipin crosslinked, were characterized by an elastic modulus of ∼51 kPa and longitudinal channels of ∼50 μm diameter. The scaffolds support the growth of endothelial cells, undifferentiated or NGF-differentiated PC12 cells, and primary cultures of fetal chick forebrain neurons. The angioneural crosstalk, as generated by first forming endothelial cell monolayers in the scaffolds followed by injection of neuronal cells, leads to the outgrowth of long aligned neurites in the PC12/endothelial cell co-cultures also in the absence of exogenously added nerve growth factor. Neuritogenesis was not observed in the scaffolds in the absence of the endothelial cells. This methodology is a promising approach for neural tissue engineering and may be applicable for regenerative spinal cord injury repair.