Researchers from the US and the UK have been working together on complex and unique bioprinting techniques, outlining their findings in the recently published ‘3D Printing in Suspension Baths: Keeping the Promises of Bioprinting Afloat.’ Focusing on the use of suspension in extrusion-based 3D printing, the researchers develop a strategy for creating ‘water-rich’ and self-supporting parts; however, one of their main goals is to disrupt the current status quo of bioprinting.
While bioprinting continues to progress at an impressive pace with many incredible results, the researchers point out that there are still ongoing questions regarding the ability to fabricate truly functional tissue—leading to the pinnacle of success in 3D printing organs for viable transplant. Because 3D printing puts such minor strain on cells during production processes, the technology is viewed as ‘an attractive candidate’ for taking tissue and organ engineering to the next level. Here though, the authors suspect that greater change is necessary within bioprinting to reach that goal of 3D printing entirely functional organs.
Researchers around the world today tend to be involved either in 3D printing that involves extrusion of filament, creating parts and prototypes that are self-supporting (medical devices are a good example), while others, however, are heavily involved in fabrication related to biomimicry, focusing on tissue engineering—usually with the use of bioinks:
“Such structures are more permissive to tissue maturation than is the printing of the previously mentioned polymer-rich constructs. However, bioinks are less suited for use as fabrication materials, due to their innate weak mechanical properties, and thus they are generally avoided for printing structures that are greater than several millimeters in size or require a high structural fidelity,” explain the researchers.
As 3D printing in suspension media has become more viable as a platform, so has the idea of using it as a combination of the two avenues—using extrusion-based 3D printing that deposits materials into a bath. Because objects are suspended within the security of liquid, there is less chance of collapse. Microstructures also quickly recover their shape, transforming back to a solid state. 3D printing of soft materials is possible including those with a high water content, meaning that many more materials become available for use.
Potential benefits of 3D printing with in suspension media include:
- Prevention of collapse of structures
- Improved continuous extrusion
- Rapid material deposition
- Elimination of dehydrated materials and cells
- Availability of omnidirectional printing
- Printing in arbitrary locations
Suspension media can be retained after the printing process also:
“The inclusion of cells throughout a suspension medium conjures up the idea of the medium acting as a platform to position cells in 3D space, as well as providing a bulk matrix fulfilling some of the functions of a native ECM. The noticeable advantage of suspension media being leveraged in this manner is linked to the opportunity to fabricate larger 3D tissue constructs in a shorter time, increasing the throughput of 3D bioprinting.”
Bioprinting could receive a real boost also as suspension media can act as a support system for low-viscosity bio-inks—assisting in achieving greater viability and sustainability of cells as well as fabricating shapes that are not in need of ‘persistent scaffolding material.’
“We foresee the exploitation of suspension media to double as a bulk matrix providing an enabling technology to engineer large functional tissues. Additionally, we believe there is the potential to embed organoids and print surrounding vascular channels within the suspension medium,” concluded the researchers. “Work by the Lutolf research group in Switzerland showed that separate stages in organoid formation require different mechanical environments. The opportunity to alter the mechanical properties of the suspension medium over time, such as by either the addition of crosslinking chemistries or dilution of a microparticle medium, may be permissive to mimicking the dynamic character of the organoid microenvironment.
“Analogous to the upsurge of research in the biofabrication field within the introduction of the various 3D-printing platforms, we believe suspension media can provide the required technological platform that will support the next level of 3D-bioprinting research.”
Bioprinting continues to encompass a vast area of study as researchers continue to transform the cell culture, innovate with hydrogel microenvironments, create composites for bone regeneration, and so much more.