Rapid continuous 3D printing of customizable peripheral nerve guidance conduits

Abstract

Engineered nerve guidance conduits (NGCs) have been demonstrated for repairing peripheral nerve injuries. However, there remains a need for an advanced biofabrication system to build NGCs with complex architectures, tunable material properties, and customizable geometrical control. Here, a rapid continuous 3D-printing platform was developed to print customizable NGCs with unprecedented resolution, speed, flexibility, and scalability. A variety of NGC designs varying in complexity and size were created including a life-size biomimetic branched human facial NGC. In vivo implantation of NGCs with microchannels into complete sciatic nerve transections of mouse models demonstrated the effective directional guidance of regenerating sciatic nerves via branching into the microchannels and extending toward the distal end of the injury site. Histological staining and immunostaining further confirmed the progressive directional nerve regeneration and branching behavior across the entire NGC length. Observational and functional tests, including the von Frey threshold test and thermal test, showed promising recovery of motor function and sensation in the ipsilateral limbs grafted with the 3D-printed NGCs.

Bionic 3D printed corals

“…Key characteristics to achieve in material design were 1) high microalgal cell viability and growth, 2) microscale printing resolution, and 3) optimization of light scattering and biomechanical parameters including material stiffness, porosity and molecular diffusion. The photo-induced, free radical polymerization mechanism underlying our 3D printing technique allowed us to precisely control the mechanical properties via modulating the crosslinking density of the polymerized parts 27 . Any material and fabrication parameters (e.g., light intensity, exposure time, photoinitiator concentration, material composition) that affect the crosslinking density can be employed to tune the mechanical properties of the printed parts.…”

“…The yellow food dye (Wilton ® Candy Colors) was added to limit the penetration of polymerization-inducing light into the bio-ink. This leads to higher light absorption relative to scattering and enhanced the spatial resolution of the printing 27 . The food dye is non-toxic and diffuses out after 24 hr (data not shown).…”

“…A 405-nm visible LED light panel was used for photopolymerization. A digital micromirror device (DMD) consisting of 4 million micromirrors modulated the digital mask projected onto the prepolymer solution for microscale photopolymerization 27 . The continuous movement of the DMD was synchronized with the projected digital mask to create smooth 3D constructs that are rapidly fabricated without interfacial artifacts.…”

“…Cylindrical constructs were 3D printed using the same bio-ink as used to print bionic coral tissue. The Young’s modulus was calculated from the linear region of the stress–strain curve 27 . Three samples were tested, and each sample was compressed three times.…”

Kinetics of Enhancement for Corneal Cross-linking: Proposed Model for a Two-initiator System

“…Greater details of the roles of oxygen in CXL [12][13][14][15][16], anticancer [17][18] and 3D bioprinting [19][20] have been reported. Numerical results of this study to investigate the role of oxygen, comparing to the clinical data of Wertheimer et al [7] will be published elsewhere.…”