Page 112 - IJB-9-1

International Journal of Bioprinting Robotic in situ bioprinting

4.2. Bone former, which covers the excised total thickness wound

Bone fracture healing and the realization of the function with autologous skin graft, has been considered the gold
of bones to withstand and adapt to mechanical stresses standard treatment. However, the applicability of grafts
are results of the synergic effect of bone cells, extracellular is limited by the supply of available donor sites; thus, it
matrix, and bioactive molecules. Vascularized bone graft is difficult to repair skin damage covering a large area.
has been recognized as the gold standard in the field of 3D bioprinting is able to deliver bio-inks to specific sites
bone healing for four decades. Approximately a couple for the reconstruction of damaged skin with biomimetic
of million bone grafts are performed yearly across the functions and activities. Recently, there has been
globe to treat bone lesions. These traditional technologies remarkable progress in the field of skin bioprinting, which
for repairing defects based on autogenous or allogeneic shows great potential in revolutionizing the paradigm of
bone grafts have several limitations, including donor- treatment in injury and surgery. By vividly mimicking
site availability and morbidity, graft incorporation and the layered architecture, consisting of epidermis and
remodeling, low biological properties, and high cost. 3D dermis, damaged skins have been repaired successfully
bioprinting provides novel solutions to these enormous through bioprinting. Lee et al. revealed the potential of
clinical challenges. In particular, repairing bone damage 3D bioprinting for tissue engineering using human skin
by direct in situ 3D bioprinting has been viewed as as a prototypical example. The fabricated constructs were
a promising entrance for applying 3D bioprinting in cultured and exposed to the air-liquid interface to promote
clinical settings. Some reports have evaluated in situ 3D maturation and stratification. The fabricated skin can be
bioprinting for clinical use or injury repair, demonstrating viewed as morphologically and biologically representative
the employability of this technology in healing damaged of in vivo human skin tissue, as indicated by histology
[52]
bones. According to Keriquel et al., automatic robotic and immunofluorescence characterization results .
bioprinting can be employed by surgeons to achieve Cubo et al. performed 3D bioprinting of human bilayered
precise cellular implantation at a micron or millimeter skin using bio-inks containing human plasma, primary
scale. Mesenchymal stromal cells with collagen and human fibroblasts, and keratinocytes. Long-term in vivo
nano-hydroxyapatite were successfully printed for in vivo analysis of the structure and function of the printed skin
bone regeneration in a calvaria defect model in mice . using an immunodeficient mice model verified that the
[50]
After hematoxylin-eosin-safran staining, the histologic bioengineered skin obtained by the Cartesian printer was
[53]
evaluation of in vivo bone repair in a calvaria defect in very similar to human skin . Albanna et al. conducted
mice at 1 and 2 months is shown in Figure 4B. Li et al. validation testing of a mobile skin bioprinting system that
developed an in situ 3D bioprinting technology based offers rapid on-site management of extensive wounds.
on a robotic manipulator to repair long segmental bone Through printing layered autologous dermal fibroblasts
defects in a living swine model. By robotic-assisted means, and epidermal keratinocytes in a hydrogel carrier,
the operation time was significantly reduced, which may the excisional wounds showed rapid closure, reduced
[54]
be beneficial to patients . Lipskas et al. combined 3D contraction, and accelerated re-epithelialization .
[40]
bioprinting and robotic-assisted minimally invasive 4.4. Other tissues or organs
surgery techniques to improve regenerative medicine. They
investigated the remote center of motion, which is critical Repair and regeneration of other tissues or organs,
to minimally invasive surgery, followed by biomaterial including muscle, vascular, neural structures, and liver,
development. The repair of knee defects was used as an through 3D bioprinting have also been successfully
example of the application of in vivo 3D printing . developed, thus providing potential clinical applications.
[51]
Chen et al. used a combination of 3D printing with digital
4.3. Skin near-infrared photopolymerization to perform proof-of-
Skin, which consists of epidermis, dermis, and subcutaneous concept in vivo noninvasive bioprinting. The bio-ink was
tissue, is the largest organ in the human body. It serves printed in situ into a customized ear-like construct, with
as a protective barrier against mechanical, thermal, and chondrification and a muscle tissue, layer-by-layer without
physical injuries as well as hazardous substances. The skin surgical implantation . Lee et al. constructed vascular
[55]
performs physiological functions, including physiological channels and created adjacent capillary networks through
metabolism and nerve conduction. Its self-regeneration a natural maturation process based on 3D bioprinting.
process is slow, in which wounds beyond 4 cm in diameter The connection of capillary networks to the large perfused
[56]
do not repair well without intervention. Conventional vascular channels was realized by the presented means .
methods for repairing skin wounds include autologous Owens et al. fabricated fully biological grafts, composed of
skin transplantation and artificial skin substitutes. The cells and cell-secreted material, with reliable reproducibility

Volume 9 Issue 1 (2023) 104 https://doi.org/10.18063/ijb.v9i1.629