Page 289 - IJB-9-6

International Journal of Bioprinting Progress in bioprinted ear reconstruction

Table 2. Overview of reviewed studies on 3D bioprinting for auricular reconstruction
Study Aim of study Study Animal Study focus 3D printing Components Printed Printed Cell nature/type Notable post- Assessment Findings Limitations and suggested
setting model (if technique shape material printing of success/ improvements
any) modifications integration
Chung et al. To assess the feasibility of In vitro N/A Direct printing Extrusion Cells in bioink + Resembling PCL GelMA-HAMA Photocuring of the Histopathology • The design of a print affects its stiffness and • Further improvements
(2020) [9] using a hybrid printing scaffold printed pinna; other cell-supportive printed bioink was flexibility significantly. could be developed
approach to fabricate a together shape bioink using a 400 nm UV • Scaffolds printed with a 400 μm nozzle tip to generate smoother
scaffold for the outer ear source at a focal had the lowest compressive modulus but were intersections for each
of clinically relevant size. distance of 5.0 cm similar in stiffness to native auricular cartilage region
Attempted to address and an intensity of and had the fastest printing time. • Incorporate a gradual
the distinct regions in 15–30% • Increasing the nozzle diameter decreases decrease or increase of
the auricular cartilage by the compressive modulus of PCL scaffolds, the strand spacing of
varying the pattern design while increasing strand spacing and using each part at the junction
(as opposed to hybrid orientations of 0/45° leads to more flexible
scaffolds printed with structures.
one specific mechanical • Scaffolds can serve as a temporary support
modulus across the entire for host tissue integration and chondrocyte
construct). differentiation. A scaffold with similar
properties before implantation could improve
its handling and shape retention after
implantation.
• Cells remained viable for up to 7 days after
printing.
• The presence of a surrounding hydrogel
during the printing process helps protect cells
from shear forces at the nozzle tip, leading to
good cell viability during the printing process.
Lee et al. To develop a non-toxic In vitro N/A Direct printing Multi-head tissue/ Scaffold printed Resembling PCL & PEG Human ASCs The cell-printed Mechanical • The sacrificial layer technique allowed for the A system for incubating
(2014) [27] method for producing organ building first and then pinna; other exposed to structures were testing; electron construction of complex structures of any printed cells will need to
inverse pyramidal and system seeded with cells shape chondrogenic incubated a microscopy shape. be developed and attached
bowl-shaped structures induction medium week at 37℃ • The PEG sacrificial component did not to the printer in order to
that are optimized for and adipogenic in a humidified impact cell viability or proliferation and could keep the cells alive during
auricle printing. induction medium atmosphere be easily dissolved in water or cell culture the printing of large
containing 5% CO . media within 40 minutes. structures such as an ear, as
2
The sacrificial PEG • Hydrogels may provide a better environment the viability of the printed
layer was dissolved. for chondrocyte proliferation, but printed cells may be compromised
adipocytes had a lower proliferation rate. during this process.
• Chondrocytes and adipocytes had similar
proliferation rates when printed separately,
and chondrogenesis and adipogenesis
occurred effectively when the two cell types
were co-printed and co-cultured.
• An ear-shaped structure containing both
chondrocytes and adipocytes not only
maintained its shape, but also regenerated
both auricular cartilage and earlobe fat.
Otto et al. To investigate the usability In vitro N/A Direct printing Fused deposition Cells in bioink + Resembling PCL Novel human Cultured in vitro Histopathology; • Extrusion printing does not negatively Short-term study; no in vivo
(2021) [29] of human AuCPCs in modeling scaffold printed pinna; other AuCPCs in chondrogenic micro-CT scan; impact cell viability, metabolic activity, or the testing of this method yet
auricle 3D printing. (extrusion) together shape media for 30 days mechanical production of GAGs.
testing • The extrusion of AuCPCs through a
microvalve system did not harm cell viability
(which remained at 8% over 10 days),
metabolic activity (which was not different
between cast and printed cells), or GAG
production (which occurred over 28 days in
vitro).
• PCL scaffolds with various strand spacings
support GAG production.

(Continued)

Volume 9 Issue 6 (2023) 281 https://doi.org/10.36922/ijb.0898