Page 303 - IJB-9-6

International Journal of Bioprinting Progress in bioprinted ear 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
Brennan et al. To evaluate the design In vivo Rats Direct printing Laser sintering Scaffold only Resembling PCL N/A Sterilized by Histopathology; • A 3D-printed bioscaffold was developed H&E was used to assess
(2021) [4] and initial performance of animal PCL with a pinna low-temperature micro-CT scan; for auricular reconstruction with a realistic for vascularization.
the auricular scaffold in a mixture of 4% ethylene oxide gas mechanical anatomic appearance that meets or exceeds Quantification of
preclinical animal model hydroxyapatite sterilization prior to testing the best outcomes of rib cartilage grafting angiogenesis has inherent
study. Our hypothesis was (Plasma Biotal) implantation • The shape of the construct was durable and challenges based off how
that the two-stage approach where the HA did not experience contraction or distortion the histology captures the
would limit the overlying serves primarily as over the course of the experiment. blood vessels and the lack
soft tissue strain and thus a flowing agent for • The scaffold demonstrated robust tissue of specificity of H&E to
result in lower rates of soft powder spreading ingrowth and angiogenesis, suggesting it could stain vessels. So other stains
tissue ulceration, necrosis, during the laser support the growth of cartilaginous tissue. should be used.
and related complications sintering process • The technique resulted in unparalleled ear Additional work is
compared to the single- appearance in vivo. necessary to assess the
stage reconstruction. • Ulceration was a problem in all the rats, potential to cellularize the
regardless of single or two staging. scaffold with the ultimate
• Minor superficial ulcers occurred most goal of gradual replacement
commonly at the lateral (86% of animals) with a native cartilage
and superior (29% of animals) helix of the matrix.
scaffold.
• Promisingly, there were high rates of
improvement in ulceration over time with
only a quarter of models demonstrating
worsening in ulceration over the course of
experimentation. Bolstered by findings of
robust angiogenesis, the authors speculated
that the improvement in wound healing
was secondary to the angiogenesis and
transformation of a bare PCL scaffold to an
integrated, vascularized tissue implant.
• The porous architecture design may improve
outcomes by reducing skin complications
and allowing increased tissue and vascular
ingrowth to enhance reconstruction and
accelerate healing of skin ulceration.
Chang et al. To analyze the use of highly In vivo Rat Direct printing Extrusion Scaffold printed Resembling PCL Porcine punch All scaffolds were Histopathology; • Vascularization was observed in both No statistically significant
(2020) [47] translatable 3D–printed animal first and then pinna biopsies inserted sterilized with micro-CT scan unseeded and seeded scaffolds, indicating that difference was observed
auricular scaffolds with seeded with cells into scaffolds ethylene oxide non-autologous tissue implants do not inhibit between cartilage-seeded
and without novel cartilage to facilitate Prior to vessel formation. and unseeded scaffolds
tissue inserts in a rodent chondrocyte implantation. Half • This technique is readily clinically translatable in any category of
model. seeding of the sample was as it eliminates in vitro requirements and ulceration. This may be
cartilage-seeded, accompanying regulatory burden. due to the small sample
with the other • The 3D-printed auricles with and without size or the methods used
unseeded. cartilage inserts were structurally similar to to measure ulceration.
human ears and measurements remained The use of additional
consistent. immunohistochemistry
• There was no significant retraction or might clarify whether
degradation of scaffolds during the chondrocytes are present
experiment, suggesting resistance to beyond the limits of the
contractile forces and sustained feasibility of cartilage punch biopsy and
such implants. from which tissue they
• Micro-CT imaging showed infiltration of soft arise.
tissue into the pores of hybrid scaffolds.
• Healing of ulceration was seen in both
conditions, with smaller rates of scaffold-
induced ulceration in cartilage-seeded
scaffolds.
(Continued)

Volume 9 Issue 6 (2023) 295 https://doi.org/10.36922/ijb.0898