Optimized Topological and Topographical Expansion of Epithelia.

Autologous epidermis grafts generated in vitro represent a promising option for the treatment of burn wounds. The procedure relies on of a sufficient number of cells harvested from healthy tissue, which are then sparsely seeded on a target surface. The time required to reconstitute a fully confluent and mature monolayer and the limited availability of cell seeds hinder the broad clinical application of this procedure. Here, a novel engineering approach to enhance the in vitro expansion of epithelial tissues is designed and experimentally validated. The method combines three independent elements supporting fast epithelialization. First, the tactical seeding of epithelial cells at high density in confined channels generated by means of magnetic silicon stencils. Second, the implementation of a curved interface along the channels, increasing the edge interface length. Third, a rationally developed and oriented anisotropic topography, in the form of gratings, aligned perpendicularly to the channels. Upon removal of the stencil, unconfined cell monolayers are free to expand and invade the open space, in a process of epithelialization that fully exploits the directional migration of epithelial collectives. As compared to sparse seeding, this approach attains an almost three times faster full epithelialization of a target surface with the same number of cells. Molecular signals triggered by cell-cell and cell-substrate contacts supported this enhanced response. In summary, we introduce a facile and scalable approach yielding fast in vitro epithelial tissue expansion with optimized yield.