Three Dimensional Conjugation of Recombinant N-Cadherin to a Hydrogel for In Vitro Anisotropic Neural Growth.

Living cells are extensively being studied to build functional tissues that are useful for both fundamental and applied bioscience studies. Increasing evidence suggests that cell-cell adhesion controlled by intercellular cadherin junction plays important roles in the quality of the resulting engineered tissue. These findings prompted efforts to interrogate biological effects of cadherin at a molecular scale; however, few efforts were made to harness the effects of cadherin on cells cultured in an in vivo-like three dimensional matrix. To this end, this study reports a hydrogel matrix three dimensionally functionalized with a controlled number of Fc-tagged recombinant N-cadherins (N-Cad-Fc). To retain the desired conformation of N-Cad, these cadherins were immobilized and oriented to the gel by anti-Fc-antibodies chemically coupled to gels. The gels were processed to present N-Cad-Fc in uniaxially aligned microchannels or randomly oriented micropores. Culturing cortical cells in the functionalized gels generated a large fraction of neurons that are functional as indicated by increased intracellular calcium ion concentrations with the microchanneled gel. In contrast, direct N-Cad-Fc immobilization to microchannel or micropore walls of the gel limited the growth of neurons and increased the glial to neuron ratio. The results of this study will be highly useful to organize a wide array of cadherin molecules in a series of biomaterials used for three-dimensional cell culture and to regulate phenotypic activities of tissue-forming cells in an elaborate manner.