The control of polarized human neurite/axon development at the single neuron level is critical in geographically directing signal propagation in engineered neural networks, for both in vitro and in vivo applications. While there is an increasing need to exert control over axonal growth for the successful development and establishment of integrative and functional in vitro systems, controlled, polarized distribution of either human-derived neurons or motoneurons in vitro has yet to be reported. In this study, we established the polarized distribution of stem cell derived human motoneurons, using a patterned surface, and maintained the cells in a serum-free system. A surface pattern with defined polarity was developed using self-assembled monolayers (SAMs). A cell permissive SAM, DETA (trimethoxysilyl propyldiethylenetri-amine), combined with photolithography and a nonpermissive fluorinated silane, 13F (tridecafluoro-1,1,2,2-tetrahydroctyl-1-dimethylchloro-silane), generated a surface where neurons only adhered to the designed attachment sites and did so with preferred orientation. In addition, 75% of the cells attached to the patterns were motoneurons compared to their percentage in the standard unpatterned surface which was used as a control condition (20%), demonstrating the preference of these human motoneurons in adhering to the patterns. The ability to dictate the distribution and polarity of human motoneurons will be essential to the engineering of human-based functional in vitro systems in which the control of signal propagation is necessary but more importantly for cell implantation studies. Such systems will greatly benefit the study of motor function as well as aid the development of high-throughput systems for drug screening and test beds for use in preclinical studies related to conditions such as spinal cord injury, ALS, and muscular dystrophy.
Keywords: Motoneurons; human; polarity; surface chemistry.