Skip to 0 minutes and 21 seconds We have heard from Professor Peter Choong the need for 3D fabricated structures to facilitate cartilage regeneration. He has also pointed out the advantages that 3D printing would bring to a challenge like this. Let’s consider the materials properties that we might require for cartilage regeneration. Here we need to look at materials that will have very specific properties. They need to match with the modulus of the stiffness of cartilage they need to be compatible with living cells, and must have enough mechanical robustness so as we can actually implant the structure into the defect. Steve, what types of materials are we going to use in order to facilitate cartilage generation? A very good example material would be gelatin.
Skip to 1 minute and 5 seconds We use gelatin to extrusion print open lattus-type structures that can then be pulsated with cells and then implanted into the body. So gelatin is basically a jelly-like material. So if we print that, how do we actually get a solid structure on the other side of the printing process? So what we have to do is modify that gelatin material so that we can add groups to it to post-cure. And usually we use UV light to post-cure the structure and give it mechanical robustness. So we’re actually curing, with light, the gelatin material after the printing process or during the printing process? You can take both approaches.
Skip to 1 minute and 42 seconds You can cure during the actual printing, or you can produce a layer and cure layer, produce a second layer and cure sequential layers. And so Professor Choong has taken these 3D printed structures, based on gelatin, and injected stem cells within that structure. Preliminary experiments in animal show that this is quite capable of regenerating or facilitating the regeneration of cartilage. Our next step and our next challenge will involve actually printing those cells within that cartilage regeneration structure.
Skip to 2 minutes and 21 seconds Let he returned to the BioPen. Here we have an example where there’s a need to create customised hardware for a particular clinical challenge. Steve, tell me a little bit more about the BioPen. Well, the BioPen is a device that we’ve put together to allow us to have greater control over the extrusion of multiple materials simultaneously. There are many examples of multiple materials being extruded from separate dispensing units. What we’ve done is developed a coaxial extrusion head, that’s been manufactured out of the fabrication, that allows us to deposit an outer sheathing that protects an inner core of our cell-laden material.
Skip to 2 minutes and 58 seconds It’s a manually operated device used by the clinician in a surgical environment, where they’re then able to accurately deposit the material at the defect site. So this is really the first example we’ve encountered where it’s been necessary to customise the hardware for a particular clinical challenge? Yes. And in the case of this example, we’re using our UV curable gelatin material. And for that reason, we’ve coupled the UV curing capability into this BioPen device so that we can coaxially extrude two materials and cure it in situ as we’re depositing it.
Skip to 3 minutes and 34 seconds I understand that the development of the BioPen really occurred very quickly, from an regional idea coming from the clinicians, for our ability to design it, and then our ability to create the first protocol. And it happened so quickly because of 3D printing. The first iteration was actually a coaxial tape that was produced for a custom 3D printer. We then decided, on the advice of a clinician, to make that a mobile device. Very simply, we printed up each of the components using our in-house technologies and have continuously refine those design. So that now, we’re at iteration 5 of the actual device.
Skip to 4 minutes and 13 seconds So this is the first example of a project wherein we’ve had to develop the machinery in tandem with the development of the materials. This effective integration of two apparently different disciplines is necessary for rapid acceleration in the clinical area. Steve also mentioned that the ability to create this hardware has been facilitative because we were able to use existing 3D printers. We are, in fact, in the era of printers printing printers.
Cartilage: Material selection
How do you engineer cartilage?
Many different strategies are being adopted, and our answers to the cartilage problem are now more directed than ever, by defining our structures with bioprinting and capitalising on decades of biomaterials research in polymers, ceramics and cell biology.
Using these technologies, researchers like Professor Jos Malda at the University of Utrecht, and his colleagues are able to create UV curable biopolymers which increase scaffold strength 5-fold. They can place this material atop of ceramic scaffolds that support the underlying bone and give the artificial cartilage a fighting chance by preventing crushing in the early phases of implantation.
Extensive research is also focusing on reducing the movement of these scaffolds, by fixing the scaffolds to the surrounding tissue with various biological ‘glues’. With a continued push to translating these materials from animal trials (currently these scaffolds are extensively used in repairing cartilage damage in equine models, typically race horses) to clinical outcomes, cartilage could quite easily become the first mass printed engineered tissue in the coming years.
© University of Wollongong, 2020