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International Journal of Bioprinting Proteins-loaded 3D-printed PEEK cage

However, some of the PEEK substrates were damaged due 5. Conclusion
to surgical forces applied during the procedure.
In this study, we designed and fabricated a 3D-printed
4. Discussion PEEK intervertebral fusion device via FDM. To improve
its fusion effect, we sequentially sulfonated the structure,
Intervertebral disc degeneration (IDD) refers to a group loaded it with BMP2, and grafted SP on the structure.
of conditions that involve the gradual breakdown or After the fusion device is implanted, SP is initially released,
deterioration of structures in the lumbar spine. It is recruiting MSCs to the implant surface from surrounding
32
often associated with aging and wear and tear on the tissues. As the Gel/Chi multilayer films degrade, BMP2
spine. 1,2,33 IDD can affect various components of the is gradually released, further promoting osteogenic
spine, leading to symptoms such as pain, stiffness, and differentiation of MSCs. The in vivo results revealed that
limited mobility. In severe cases, surgical interventions, S-P-BMP2/LBL and S-P-BMP2/LBL-SP exhibited superior
34
such as discectomy, spinal fusion, and artificial disc fusion effects, particularly attributable to the strategy
replacement, may be considered. 6,35 Spinal fusion with of recruiting MSCs before osteogenic differentiation.
an interbody cage is a commonly adopted clinical This work presents a novel approach for designing and
procedure. Currently, most interbody cages are made of preparing PEEK intervertebral fusion devices with
Ti alloy or PEEK. excellent fusion effects.
Polyetheretherketone (PEEK) is known for its excellent
mechanical, thermal, and chemical properties, making Acknowledgments
it suitable for various applications across medical and None.
other industries. 36,37 However, PEEK interbody cages
face limitations in processability, bioinertness, and Funding
radiolucency. Hence, FDM 3D printing is a feasible
38
method for fabricating PEEK interbody cages with This work was supported by the Sichuan Provincial
complex geometries. Department of Science and Technology (grant number:
39
2023ZYD0072).
As displayed in Figure 3B, 3D-printed PEEK cages
exhibit a prominent rough striped surface structure Conflict of interest
attributed to the melting and cooling time. The rough
surface of PEEK is beneficial for the stability of implanted The authors declare no conflicts of interest.
cages. To accelerate the fusion of PEEK cages, BMP2
and SP were incorporated into the structure. BMP2 was Author contributions
loaded into the porous network structures formed from Conceptualization: Feng Zheng, Haibin Lin
sulfonation, and the structure was then sealed with Gel/Chi Methodology: Feng Zheng, Haibin Lin
multilayer films. SP is a peptide with a chain of 11 amino Formal analysis: Xiaoqiang Gao, Sheng Chai
acid residues, serving as a chemoattractant and activator Investigation: Xiaoqiang Gao, Sheng Chai
for macrophages, lymphocytes, and stem cells. 26,40 SP is Project administration: Feng Zheng, Haibin Lin
capable of restoring the cellular potential of senescent stem Supervision: Huan Liu
cells by possibly modulating the expression of paracrine Visualization: Feng Zheng, Huan Liu
factors from MSCs, which could accelerate MSC‐mediated Writing - Original Draft: Feng Zheng, Xiaoqiang Gao,
tissue repair. 41,42
Sheng Chai
To retain the bioactivity of SP, we grafted SP on the Writing - Review & Editing: Huan Liu
outermost Chi layer via Schiff base reaction. All groups All authors read and approved the final manuscript.
reported good cytoactivity, except for the sulfonation
group. When the modified PEEK cage is implanted Ethics approval and consent to participate
into the body, SP would be released first to recruit All animal experiments were approved by the Experimental
MSCs to the implant (Figure 4). Subsequently, BMP2 Animal Ethics Committee of Southwest Medical University
is released slowly (Figure 4A) to promote osteogenic (20230228-013).
differentiation of MSCs (Figures 5 and 6). Results from
micro-CT and the push-out test validated the fusion Consent for publication
effects of BMP2-loaded PEEK cages, particularly in the
S-P-BMP2/LBL-SP group. Not applicable.

Volume 10 Issue 5 (2024) 304 doi: 10.36922/ijb.3574