Engineering of tissue constructs using coaxial bioprinting

Bioprinting is a rapidly developing technology for the precise design and manufacture of tissues in various biological systems or organs.Coaxial extrusion bioprinting,an emergent branch,has demonstrated a strong potential to enhance bioprinting's engineering versatility.Coaxial bioprinting assists in the fabrication of complex tissue constructs,by enabling concentric deposition of biomaterials.The fabricated tissue constructs started with simple,tubular vasculature but have been substantially developed to integrate complex cell composition and self-assembly,ECM patterning,controlled release,and multi-material gradient profiles.This review article begins with a brief overview of coaxial printing history,followed by an introduction of crucial engineering components.Afterward,we review the recent progress and untapped potential in each specific organ or biological system,and demonstrate how coaxial bioprinting facilitates the creation of tissue constructs.Ultimately,we conclude that this growing technology will contribute significantly to capabilities in the fields of in vitro modeling,pharmaceutical development,and clinical regenerative medicine.

A matrigel-free method to generate matured human cerebral organoids using 3D-Printed microwell arrays

The current methods of generating human cerebral organoids rely excessively on the use of Matrigel or other external extracellular matrices(ECM)for cell micro-environmental modulation.Matrigel embedding is problematic for long-term culture and clinical applications due to high inconsistency and other limitations.In this study,we developed a novel microwell culture platform based on 3D printing.This platform,without using Matrigel or external signaling molecules(i.e.,SMAD and Wnt inhibitors),successfully generated matured human cerebral organoids with robust formation of high-level features(i.e.,wrinkling/folding,lumens,neuronal layers).The formation and timing were comparable or superior to the current Matrigel methods,yet with improved consistency.The effect of microwell geometries(curvature and resolution)and coating materials(i.e.,mPEG,Lipidure,BSA)was studied,showing that mPEG outperformed all other coating materials,while curved-bottom microwells outperformed flat-bottom ones.In addition,high-resolution printing outperformed low-resolution printing by creating faithful,isotropically-shaped microwells.The trend of these effects was consistent across all developmental characteristics,including EB formation efficiency and sphericity,organoid size,wrinkling index,lumen size and thickness,and neuronal layer thickness.Overall,the microwell device that was mPEG-coated,high-resolution printed,and bottom curved demonstrated the highest efficacy in promoting organoid development.This platform provided a promising strategy for generating uniform and mature human cerebral organoids as an alternative to Matrigel/ECM-embedding methods.