Micropatterning of living cells by laser-guided direct writing: application to fabrication of hepatic-endothelial sinusoid-like structures.

Here, we describe a simple protocol for the design and construction of a laser-guided direct writing (LGDW) system able to micropattern the self-assembly of liver sinusoid-like structures with micrometer resolution in vitro. To the best of our knowledge, LGDW is the only technique able to pattern cells "on the fly" with micrometer precision on arbitrary matrices, including soft gels such as Matrigel. By micropatterning endothelial cells on Matrigel, one can control the self-assembly of vascular structures and associated liver tissue. LGDW is therefore uniquely suited for studying the role of tissue architecture and mechanical properties at the single-cell resolution, and for studying the effects of heterotypic cell-cell interactions underlying processes such as liver morphogenesis, differentiation and angiogenesis. The total time required to carry out this protocol is typically 7 h.