Session: 03-13-01: Conference-Wide Symposium on Biomedical Manufacturing & Materials

Paper Number: 114989

114989 - 3d Bioprinting of Engineered Full-Scale Human Tissues and Organs 

Three-dimensional (3D) bioprinting is driving major innovations in tissue engineering and regenerative medicine, in which bioinks composed of cells and extracellular matrix (ECM) materials are stacked into complex 3D functional constructs to mimic living tissues and organs using various additive manufacturing approaches. Such engineered tissues and organs are envisioned to be used for the replacement of damaged or injured human tissues and organs, providing a promising solution to the challenge of tissue and organ donor shortage. Due to the complexity of human tissues and organs, it is still technically challenging to duplicate their architectures, which makes the following cell printing or seeding work even more difficult.

Among diverse 3D bioprinting strategies, support bath-assisted 3D printing is of great popularity and has been widely used to fabricate 3D constructs with complex architectures. However, current yield-stress support bath materials cannot be on-demand added and/or removed during printing, severely constraining the application scope of this additive manufacturing approach, especially for creating full-scale human tissues and organs. In this presentation, we proposed a new concept of stimuli-responsive yield-stress fluid and demonstrated a nanoclay-Pluronic F127 nanocomposite that can serve as a thermosensitive support bath material with an interactive dual microstructure. The key material properties were characterized to unveil the interactions in the dual microstructure and microstructure evolutions under stressed and un-stressed conditions as well as at different temperatures. Some key scientific issues, including filament formation principle, surface roughness control, and thermal effects of newly added nanocomposite, during printing were comprehensively investigated.

To demonstrate the functionality and merits of this support bath material for biofabrication applications, various full-scale human tissues and organs were printed. First, cornea was 3D printed using a new strategy for controlling the step distances during printing, which enabled the surface roughness of an engineered cornea to reach the order of tens of microns. Then, human eyeball with two different materials was fabricated. Since the support bath materials was able to be liquefied at lower temperatures (e.g., 4 ℃), it was technically feasible to clean the residual materials entrapped in the closed chamber and re-fill it with desired liquids. Thus, the engineered eyeball was promising to mimic real human eyeball for surgery training purpose. To validate the capability of proposed method for printing overhanging architectures, a human heart valve was designed and successfully printed, which possessed a well-defined shape. Finally, a derived fabrication strategy, called inverse 3D printing, was proposed to duplicate the complex geometries of a full-scale human brain. These cases well demonstrated the printing capability space of stimuli-responsive yield-stress support bath-assisted 3D printing, providing a viable, reliable, and versatile engineering solution for the biofabrication of human tissues and organs in the future.

Presenting Author: Yifei Jin University of Nevada

Presenting Author Biography: Dr. Yifei Jin joined the Department of Mechanical Engineering at the University of Nevada, ‎Reno in July 2019. His primary research interests mainly involve 3D bioprinting of living tissue constructs, 3D printing of hydrophobic functional materials, yield-stress fluids for 3D printing applications, stimuli-responsive materials for 4D printing applications, and fabrication of multi-layered capsules. His research emphasizes the coupling of materials and fabrication approaches to develop novel 3D printing techniques and understand the underlying physics during printing.

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