5D Printing and its Application in Tissue Engineering

Abstract

Tissue engineering offers a promising approach to treat difficult problems in human body tissue repair. It involves using live cells to form implantable devices for body tissue regeneration. In scaffold-based tissue engineering, a porous scaffold provides a microenvironment for cells to adhere, proliferate and differentiate and a structural framework for new tissue formation. Most human body tissues are complex and their regeneration requires structurally complex scaffolds that resemble tissue structures and can provide biochemical cues such as growth factors (GFs). Incorporating GFs and even live cells in scaffolds can greatly facilitate tissue regeneration. 3D printing has many advantages in scaffold fabrication, such as control of pore shape, size, porosity, etc. Furthermore, 3D printing can make complex tissue engineering scaffolds, including multilayered scaffolds with different layer characteristics for regenerating body tissues that exhibit multilayered structures such as osteochondral tissue. Therefore, like in other industries, 3D printing has already made a high impact in the tissue engineering field, with numerous researchers around the world using 3D printing technologies to produce various tissue engineering products. 4D printing emerged in 2013 and immediately attracted world’s attention. 4D printing uses 3D printing technologies to produce shape-morphing objects. Such objects can meet the demanding requirements in particular applications. The concept of 4D printing has been evolving and one current popular definition of 4D printing is that the shape, property and functionality of a 3D printed object can change with time in a predefined design. 4D printing relies on advances in 3D printing technologies, smart materials, and smart designs. It has become an actively pursued subject in both academia of different disciplines and industry, including tissue engineering. We have conceptualized 5D printing and are applying it in tissue engineering. 5D printing produces shape-morphing and information-embedded structures, and the information, which is the 5th dimension in 5D printed structures, is delivered in situ during applications of these structures. More importantly, with 5D printed structures, the delivered information affects the surrounding environment (or 5D printed structures) and guide changes in the environment (or 5D printed structures). For 5D printing in tissue engineering, the embedded information can be biomolecules such as GFs. Using 5D printing, shape-morphing, mesenchymal stem cell (MSC)-containing and GF-delivering multilayered complex scaffolds may be constructed for gastrointestinal (GI) tissue engineering. Under GFs’ guidance, MSCs will differentiate into different types of cells in the cell-scaffold constructs for GI tissue regeneration. This talk will present our work in 3D/4D/5D printing of scaffolds for body tissue regeneration. It will focus on the design and construction of complex tissue engineering scaffolds.