Page 149 - IJB-9-3

International Journal of Bioprinting Bioprinting tissue-engineered bone-periosteum biphasic complex.

directly affect the scaffold conductivity. As a superior to further explore the above parameters and adjust the
polymer–ceramic composite, PLLA/HA has been widely mechanical properties of GelMA accordingly.
studied and applied in various aspects of biomedicine [6,36] . To sum up, by forming a co-culture layer between the
Although the degradation products of PLLA may cause bone phase and periosteum phase, the new co-culture
inflammatory reaction, the subclinical inflammation of the bioprinting strategy could not only simulate the normal
host could effectively promote collagen synthesis . When bone-periosteum tissue in structure, but also significantly
[7]
the ceramic is combined with PLLA matrix composites, improve the repair effect compared with other monophasic
its biocompatibility can also be improved. Besides, PLLA/ scaffolds, thereby illustrating the advantages and prospects
HA composites could effectively solve the problems caused of this bioprinting strategy in constructing complex living
by metal implants, such as stress shielding and the need tissues and organs. Thus, the technology of 3D bioprinting
for a second operation . Our study found that 5.4 W could meet the requirements for establishing an integrated
[37]
PLLA+20% HA scaffold was not only superior to other co-culture system, and the combination of co-culture
material groups in maximum force and elastic modulus, but concept and engineering tissue construction could be
also had good biocompatibility. For the critical-sized bone considered a promising strategy for repairing critical-
defect, the ideal tissue engineering structure should provide sized bone defects. However, there are some limitations
an appropriate environment similar to the natural healing. in this study. First, it is difficult to control the osteogenic
The mechanical strength and bone conduction properties differentiation direction of stem cells in vivo. Second, the
of the scaffolds are required to be higher for the long and degradation and absorption of materials and the rate of
irregular bone defects at the stressed sites. Such a graft bone reconstruction in vivo also need to be matched. In
should have sufficient strength to promote not only the addition, the structural design and construction of the
integration with the host tissue, but also the load transfer complex rely on the advances of bioprinting technology.
under load-bearing conditions. In our study, a rabbit skull
defect model was used to validate the co-culture bioprinting 5. Conclusion
mode in vivo. The bone defect at the weight-bearing site
should also be investigated, and it is necessary to select In this study, the strategy of co-culture was introduced into
alternative materials with better mechanical strength. After the 3D bioprinting system to manufacture tissue-engineered
optimizing the printing structure and design, we could bone-periosteum complex and improve bone defect repair
repair the segmental defect of long bone in other larger ability. The structure of natural bone tissue consisting of
animals. In addition to animal species, appropriate age and periosteum phase and bone tissue phase was physiologically
size of bone defect should also be considered . imitated, and a co-culture layer was formed between these
[38]
two different phases. To the best of our knowledge, this is
GelMA-based hydrogels have suitable biological and the first study describing the application of bioprinting to
adjustable physical properties . From the processing construct bone-periosteum complex. Through optimizing
[20]
point of view, GelMA can be crosslinked under UV light the parameters of material ratio of bone scaffold and
to achieve adjustable mechanical properties. It can also be crosslinking time of GelMA, an integrated bionic structure
micromanufactured using different methods to generate was constructed and a good repair effect was achieved. The
personalized structures . GelMA applied in bioprinting results showed that the 3D bioprinting tissue engineering
[20]
is a tissue repair strategy based on cell-laden GelMA structure based on co-culture system might solve the
transplantation. The combination of GelMA and cells play problem of critical-sized bone defect, and was expected to
a key role in this process . GelMA-based hydrogels are construct other complex tissues and organs.
[39]
very similar to ECM in some basic characteristics, there
are cell attachment that allow cells to proliferate and Acknowledgments
diffuse in them . In our study, GelMA showed good
[20]
wrapping and biological activity. By exploring the effect of We would like to sincerely thank the support and help
different crosslinking durations on cell activity, we found from the School of Mechanical and Power Engineering,
that rabBMSCs and rabPDSCs in GelMA still showed high East China University of Science and Technology in the
cell viability and proliferation activity after crosslinking work of bioprinting.
(Figure 4B–E). Importantly, after crosslinking, the 3D co- Funding
culture mode of rabBMSCs and rabPDSCs was successfully
realized within GelMA (Figure 4F). In fact, the physical The study was financially supported by the Natural
properties of GelMA hydrogels could be adjusted by a series Science Foundation of Shanghai Science Commission
of parameters, such as material and initiator concentration, (No. 21ZR1437000), Innovative Research Team of High-
as well as the UV exposure time . Therefore, we need level Local Universities in Shanghai (No. SHSMU-
[40]

Volume 9 Issue 3 (2023) 141 https://doi.org/10.18063/ijb.698