Page 70 - IJB-9-2

International Journal of Bioprinting Bioprinting in wound dressing and healing

the university and research institutions from the USA technology. There are several challenges of reducing
and Singapore. these disadvantages.
(vi) The cells are the ultimate source to ensure the (iv) The main disadvantage of extrusion printing is the
durability and function of the patient’s regenerated low speed and resolution, while the presence of shear
skin tissue. Currently, the most commonly used stress affects the viability of the cells. Improving the
cell types in the manufacturing process of wound resolution and cell viability is an important direction
healing and skin regenerations are keratinocytes and in this technique.
fibroblasts. However, using only these two types of (v) It is still a challenge for the current bioprinting
cells is not able to fully develop the various functions technology to fabricate complex skin structures, such
of the skin, so other cells and appendages are needed. as hair follicles and other skin attachments, although
Among them, stem cells are unique cell populations it is now able to fabricate microscopic structures
that are able to self-renew and differentiate. Stem cells such as papillae. Applying advanced micro- and
can release specific growth factors and cytokines. nano-manufacturing technology to skin printing can
These growth factors induce the skin to produce improve precise and uniform pigment, hair follicle
proteins, elastic fibers, and new proteins.
deposition, and printing efficiency.
(vii) The leading technologies currently used for In situ and non-invasive in vivo printing requires more
bioprinting of skin are inkjet printing, laser-assisted dexterous and convenient devices for the rapid closure of
printing, and extrusion printing. In addition, in situ wounds in specific body parts. To reduce the impact of
printing and non-invasive in vivo printing are new respiratory amplitude on scanning and printing accuracy
modalities developed. in in situ printing, a more advanced real-time feedback

Meanwhile, based on the review of this topic, we system can obtain more accurate scanning data and
believe that the following issues regarding the bioprinting monitor the patient’s physiology in real time during the
in wound dressing and healing need to be investigated: printing process to optimize the printing path at any time.

(i) Although inkjet printing allows for high-precision Acknowledgments
deposition of bioinks, it may expose cells and materials
to thermal and mechanical stress environments. None.
High-frequency sound waves can affect the viability
of cells. Inkjet printing is also limited by the viscosity Funding
of the bioink used. Therefore, inkjet printing is used This work was supported by the National Natural Science
as a printing technology limited to low-viscosity Foundation of China (22004026).
biological inks. Inkjet printing is often used with
extrusion printing to achieve vascularized skin Conflict of interest
printing. Further exploration of the coupling of this
technology is necessary. The authors declare no conflicts of interest.
(ii) Light-cured printing does not use nozzles, so high cell Author contributions
density printing is possible. However, the irradiation
and curing process of UV light will inevitably cause Conceptualization: Li Fu, Hassan Karimi-Maleh
damage to the cells in the bioink. Bioinks need to be Investigation: Shuduan Mao, Junjie Man, Jialei Wang,
mixed with photoinitiators to achieve curing, and the Chengliang Yin
presence of photoinitiators may make bioinks toxic. Methodology: Li Fu
In addition, it is necessary to develop non-UV light Formal analysis: Shuduan Mao, Junjie Man, Jialei Wang,
as a curing light source and biological photoinitiator. Chengliang Yin
Writing – original draft: Shuduan Mao, Junjie Man, Jialei
(iii) Laser-assisted printing is also a nozzle-free Wang, Chengliang Yin
technology that offers similar benefits to light-cured Writing – review & editing: Li Fu, Hassan Karimi-Maleh
printing. However, metal particles can contaminate
cells when they absorb high-energy laser beams. References
The high air pressure generated by local evaporation
affects cellular activity. The high cost of laser- 1. Singh M, Nuutila K, Kruse C, et al., 2015, Challenging the
assisted printing and the low cell survival rate have conventional therapy: Emerging skin graft techniques for
led to limited research on the application of this wound healing. Plast Reconstr Surg, 136(4): 524e–530e.

Volume 9 Issue 2 (2023) 62 http://doi.org/10.18063/ijb.v9i2.653