Skip to 0 minutes and 12 seconds So now we’ll pick up on a real challenge– the ability to create, to print 3D structures containing living cells. Now we must match the actual properties of the material with the living cell to provide protection during the printing process and to provide the mechanical robustness after the printing process. Coupled with that, the fact we will need to deliver biologically active molecules to sustain those living cells in the structure during the printing process. And we have quite a complex, multi-dimensional challenge for 3D printing. Steve, how do we confront a challenge like this where we need to have materials that can actually protect the cells during printing and then create the mechanical robustness we need after printing?
Skip to 0 minutes and 59 seconds So in this case we need to develop a new form of printing technique. We need to take the benefits of extrusion printing and couple that with materials developments in how we protect the cells during the actual extrusion process. One approach that we’ve taken in doing this is coaxial extrusion. Using coaxial printing, we can build complex structures containing two materials. A special nozzle is used to feed one type of material inside another. The core may contain sensitive components, such as living cells. The shell material is designed to hold the structure together and protect those delicate entities contained within. The ability to distribute biologically active molecules within these 3D printed structures also means that we can control their accessibility.
Skip to 1 minute and 48 seconds We can control when cells can access those molecules during the development process. In biological terms, we are engineering controlled delivery system, controlled delivery systems for biologically active molecules. This is also the basis of other applications in releasing anti-inflammatories, immunosuppressant agents as required for medical implants. Would materials like gelatin still be appropriate for printing, but printing with living cells? Absolutely. So we can formulate the materials so that it is tailored to maintain the cell viability. So now our choice of materials takes on an extra challenge. The material has at least three roles to play. It must keep the cells suspended in the ink reservoir during the printing process. It must protect the cell during the printing.
Skip to 2 minutes and 41 seconds And afterwards, it must provide enough mechanical robustness so that we can create 3D structures with these cells strategically distributed throughout the structure that we want to create.
Printing with a 'living ink'
The need to innovate the printing hardware
Printing the printers: In the lab
In 2014/2015 the process for printing with cells was revolutionised.
Before this time, commercially available 3D bioprinters were not able to print living cells in a way that preserved those cells. The Biofabrication team at the University of Wollongong were able to use 3D printers, to print the necessary parts needed to customise cell printers to make co-axial, extrusion printing possible.
This technological development allowed cells to be protected during the printing process. The main advantage of co-axial printing is the ability to make structures out of multiple materials, i.e. one material printed within another material.
Printing the printers: The surgical context
Significant thought was needed to translate the necessary technology into the operating theatre. The handheld BioPen was developed for this purpose. This device allows free-form bioprinting to be applied in a surgical context. The BioPen, fitted with the same Co-axial tip enables the deposition of living cells and biomaterials in a manual, direct-write fashion. The device has a number of advantages over robotically manipulated surgical bioprinters:
- A manually operated tool allows for surgical sculpting
- Allows for increased surgical dexterity
- Smaller, less cumbersome device
- BioPen is easier to sterilise and to keep sterile
- The flexibility of in-situ biofabrication allows for free-form construction of substitute tissue
© University of Wollongong, 2020