Bioassembly of three-dimensional embryonic stem cell-scaffold complexes using compressed gases.

Tissues are composed of multiple cell types in a well-organized three-dimensional (3D) microenvironment. To faithfully mimic the tissue in vivo, tissue-engineered constructs should have well-defined 3D chemical and spatial control over cell behavior to recapitulate developmental processes in tissue- and organ-specific differentiation and morphogenesis. It is a challenge to build a 3D complex from two-dimensional (2D) patterned structures with the presence of cells. In this study, embryonic stem (ES) cells grown on polymeric scaffolds with well-defined microstructure were constructed into a multilayer cell-scaffold complex using low pressure carbon dioxide (CO(2)) and nitrogen (N(2)). The mouse ES cells in the assembled constructs were viable, retained the ES cell-specific gene expression of Oct-4, and maintained the formation of embryoid bodies (EBs). In particular, cell viability was increased from 80% to 90% when CO(2) was replaced with N(2). The compressed gas-assisted bioassembly of stem cell-polymer constructs opens up a new avenue for tissue engineering and cell therapy.