Page 288 - IJB-9-6

International Journal of Bioprinting
Table 2. Overview of reviewed studies on 3D bioprinting for auricular reconstruction
Study Aim of study Study Animal
setting model (if
any)
Chung et al. To assess the feasibility of
(2020) [9] using a hybrid printing
approach to fabricate a
scaffold for the outer ear
of clinically relevant size.
Attempted to address
the distinct regions in
the auricular cartilage by
varying the pattern design
(as opposed to hybrid
scaffolds printed with
one specific mechanical
modulus across the entire
construct).
Lee et al. To develop a non-toxic In vitro N/A Direct printing Multi-head tissue/ Scaffold printed
(2014) [27] method for producing
inverse pyramidal and
bowl-shaped structures
that are optimized for
auricle printing.
Otto et al. To investigate the usability
(2021) [29] of human AuCPCs in
auricle 3D printing.
Volume 9 Issue 6 (2023)
Progress in bioprinted ear reconstruction
Study focus 3D printing Components Printed Printed Cell nature/type Notable post- Assessment Findings Limitations and suggested
technique shape material printing of success/ improvements
modifications integration
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
scaffold printed pinna; other cell-supportive printed bioink was flexibility significantly. could be developed
together shape bioink using a 400 nm UV • Scaffolds printed with a 400 μm nozzle tip to generate smoother
source at a focal had the lowest compressive modulus but were intersections for each
distance of 5.0 cm similar in stiffness to native auricular cartilage region
and an intensity of and had the fastest printing time. • Incorporate a gradual
15–30% • Increasing the nozzle diameter decreases decrease or increase of
the compressive modulus of PCL scaffolds, the strand spacing of
while increasing strand spacing and using each part at the junction
orientations of 0/45° leads to more flexible
structures.
• Scaffolds can serve as a temporary support
for host tissue integration and chondrocyte
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.
Resembling PCL & PEG Human ASCs The cell-printed Mechanical • The sacrificial layer technique allowed for the A system for incubating
organ building first and then pinna; other exposed to structures were testing; electron construction of complex structures of any printed cells will need to
system seeded with cells shape chondrogenic incubated a microscopy shape. be developed and attached
induction medium week at 37℃ • The PEG sacrificial component did not to the printer in order to
and adipogenic in a humidified impact cell viability or proliferation and could keep the cells alive during
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.
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
modeling scaffold printed pinna; other AuCPCs in chondrogenic micro-CT scan; impact cell viability, metabolic activity, or the testing of this method yet
(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.
280 https://doi.org/10.36922/ijb.0898