UCSF

Purified populations of cells can be reconstituted into organoids that recapitulate aspects of their in vivo structure and function. These organoids are useful as models of healthy and diseased tissue in the basic sciences, in vitro screens, and regenerative medicine. Existing strategies to reconstitute organoids from purified cells face obstacles with respect to cell-viability, multicellular connectivity, scalability, and compatibility with subsequent experimental or analytical techniques. To address these challenges, we developed a strategy for rapidly casting populations of cells into microtissues of prescribed size and shape. This approach begins by chemically remodeling the adhesive properties of living cells with membrane-anchored ssDNA with modest annealing kinetics. Populations of complementary labeled cells are then combined into microwells that rapidly mold the DNA-adhesive cell populations into 3D aggregates of uniform size and shape. Once formed, aggregates are removed from the molds in the presence of "capping" oligonucleotides that block hybridization of residual surface DNA between aggregates in suspension. Finally, transfer of aggregates to biomimetic gels for 3D culture completes the process of reconstitution. This strategy of chemical micromolding allows for control over aggregate internal topology and does not perturb the natural process of self-organization in primary human mammary epithelial cells.