3D Printed Tissue Models: Present and Future.

Three-dimensional (3D) tissue modeling is an emerging field of investigation for disease mechanisms, drug testing, and therapeutic effects for human survival. Various methods have been developed to recapitulate tissue mimetic microenvironments; however, they could mimic only the fragmentary phase of disease. Cells should be tested under two-dimensional (2D) substrate or encapsulated into hydrogels, and thus, they cannot mimic natural tissue behaviors or arrangements in the body. 3D printing technology allows us to create precisely controlled 3D tissue or organ models through localization of cells, biomolecules, and materials precisely similar to tissue specific microenvironments. In this article, we review the recent advances of 3D printed in vitro tissue models that can support normal or diseased tissue differentiation, integration, and spatiotemporal reaction by drug treatment or cancer metastasis. With the development of fabrication methods, the 3D printed in vitro tissue model can be utilized to study the complex human physiology in tissue and organ contexts, which could potentially be used as a substitute for animals and applied in drug development and toxicology testing.