3D bioprinting has long been heralded as having the potential to revolutionize tissue engineering and regenerative medicine. The possibility of printing and growing organs and bones is not beyond reach but there still remains a number of significant challenges, particularly relating to the “bioinks” used in the printing process [1].
These bioinks, which may be natural (e.g. collagen, gelatin etc.) or synthetic, incorporate cells with the aim of replicating complex human tissue but there are challenges with these bioinks. Natural bioinks often need to be treated with UV light or chemicals to support crosslinking so that the printed structure holds it shape. But these processes often affect cell viability.
New 3D bioprinting tech
However, researchers at KAUST (King Abdullah University of Science and Technology) employed Cellix’s ExiGo syringe pump to print ultrashort peptide bioinks which supported large-scale constructs that could hold their shape while stimulating cell growth [2]. The secret sauce was not just the ultrashort peptides used as the bioink but also the printing process using the ExiGo syringe pump.
KAUST researchers led by Prof. Charlotte Hauser, used ultrashort peptides composed of 3-7 natural amino acids, which unlike the more classical natural gelatin-based bioinks, don’t require UV light or chemicals to solidify the structure. Peptide bioinks have rapid gelation; in other words, they solidify quickly. Because of this, peptide bioink formation requires precise instantaneous mixing and printing with the cells that are selected for printing. This is where the ExiGo syringe pump comes into play. KAUST researchers combined 3 ExiGo syringe pumps with a custom-designed nozzle and robotic arm which facilitated the controlled mixing region for bioink extrusion.
Experimental set-up
The researchers experimented with different waveforms (constant flow, ramp, sine and square wave) before they successfully achieved a consistent flow of bioink throughout the printing process via automated time-dependent pulsing with the square waveform. They further optimized their process resulting in printing of more accurate, complex and long-lasting constructs with improved mechanical properties.
Next steps
The possibilities for this peptide-based bioink are hugeofciting. As it solidifies into a cartilage-like hydrogel, it resembles the natural matrix that underlies and supports bone formation in the human body [3]. However, many other applications exist in tissue engineering and KAUST researchers are now investigating other applications beyond bone regeneration.of
According to Salwa Alshehri, Ph.D. Student, [4]:
“Our system is a simple, efficient and robust model that closely resembles the complex architecture of native bone tissue. Using these peptide-based hydrogels, we can now build 3D disease models for tissue engineering, biomedical research and drug testing.”
Planning your own 3D printer experiments?
Consider the advantages of ExiGo syringe pump for 3D bioprinting
Time-varied pulsing provided better continuous flow avoiding material buildup within the extruder unit
Clogging is avoided as the gelation rate is periodically reduced which avoids gel clumps in the printed constructs.
Standardization of the 3D bioprinting process reducing clogging and clumping during printing. This allows for more accurate and complex constructs for applications in tissue engineering.
Why choose an ExiGo syringe pump vs. Harvard Apparatus syringe pump?
For many years, syringe pumps were the only option for microfluidic applications and most papers cited use of Harvard Apparatus syringe pumps. However, there are a number of limitations of these pumps compared with Cellix’s ExiGo syringe pump:
1. Switching response time of ExiGo syringe pump is extremely fast (down to 50ms) vs. Harvard Apparatus pumps where it is comparatively slow (~30s). The technique employed by KAUST researchers for 3D printing of their bioinks involves time-dependent pulsing via square waveforms is only possible with the ExiGo syringe pump as it requires an extremely fast response time.
2. Cellix’s ExiGo syringe pump uses an open-source GUI-based interface: SmartFlo software. This was one of the key reasons KAUST researchers chose the ExiGo syringe pump “as the Labview-based GUI interface allows pumping with a combination of various flow profiles and automation by programming pumps in advance.”
3. Flow stability of the ExiGo syringe pump is higher than Harvard Apparatus syringe pumps.
Click here to learn more about Cellix’s ExiGo syringe pumps. If you have any questions or if you’d like a quote, contact us now.
[1] Hongli Mao et al. Recent advances and challenges in materials for 3D bioprinting. Progress in Natural Science: Materials International, Volume 30, Issue 5, 2020, Pages 618-634, ISSN 1002-0071. doi.org/10.1016/j.pnsc.2020.09.015.
[2] Zainab Khan et al. Time-dependent pulsing of microfluidic pumps to enhance 3D bioprinting of peptide bioinks. Proc. SPIE 11637, Microfluidics, BioMEMS, and Medical Microsystems XIX, 1163709 (5 March 2021). doi.org/10.1117/12.2578830
[3] Hepi H. Susapto et al. Ultrashort peptide bioinks support automated printing of large-scale constructs assuring long-term survival of printed tissue constructs. Nano Letters. 2021. doi.org/10.1021/acs.nanolett.0c04426
[4] Emily Henderson. Novel peptide-based hydrogels hold great promise for tissue engineering applications. News Medical Life Sciences. 17 Jun 2021.