Directed assembly of cell-laden microgels for building porous three-dimensional tissue constructs.

The organization of cells within a well-defined microenvironment is important in generating the resulting tissue function. However, the cellular organization within biodegradable scaffolds often does not resemble those of native tissues. In this study, we present directed assembly of microgels to organize cells for building porous 3D tissue constructs. Cell-laden microgels were generated by molding photocrosslinkable polyethylene glycol diacrylate within a poly(dimethyl siloxane) stencil. The resulting microgels were subsequently packed as individual layers (1 mm in height) on a glass substrate by removing the excess prepolymer solution around the microgels. These clusters were crosslinked and stacked on one another to fabricate thick 3D constructs that were greater than 1 cm in width and 3 mm in thickness. To generate pores within the engineered structures, sodium alginate microgels were integrated in the engineered constructs and used as a sacrificial template. These pores may be potentially useful for fabricating a vascular network to supply oxygen and nutrients to the engineered tissue constructs. This simple and versatile building approach may be a useful tool for various 3D tissue culture and engineering applications.