In-vitro development of highly organized three dimensional (3D) -engineered tissues consisting of multiple types of human cells and extracellular matrix (ECM), which possesses a similar structure and function as natural tissues, is the key challenge for tissue engineering and pharmaceutical assay as modulation of 3D-cell to cell interaction inside the 3D-artificial tissues is one of the significant issues. Nearly all tissue cells in the body reside in the micrometer-sized fibrous meshwork of the ECM. The ECM is typically composed of fibronectin (FN), collagen, and laminin and provides complex biochemical and physical signals. Therefore, control of cellular microenvironment using artificial ECM and growth factors will be important in-vitro technique to control 3D-cell assembly. We have developed a simple and unique "bottom-up" approach, of "hierarchical cell manipulation" and "cell-accumulation" technique, using nanometer-sized Layer-by-Layer films consisting of fibronectin and gelatin (FN-G) as a Nano-ECM. This approach easily provides more than 100-200μm thick 3D tissues with a blood capillary analogous. We have also reported inkjet cell protein printing to fabricate 3D-hepatcite tissue chips with 440 arrays for drug toxicity assay. 3D-cell printing is expected to be the next tissue engineering technology for construction of 3D tissues with precisely controlled structure.
