3D printing, the Oxford way

Materials World magazine
,
1 Mar 2018

Gary Peters talks to Sam Olof* about a method to 3D print laboratory-grown cells to form living structures.

Can you tell me more about your work and background?

For the last 18 months, I have been working at OxSyBio as Chief Technical Officer. I previously worked at the University of Oxford with Professor Hagan Bayley exploring 3D printing of living cells. Before this, I was at University of Bristol and worked on biophysics overlapping with building artificial cells. 

When I started working with Professor Bayley, we thought it would be interesting to explore the printing of hybrid systems, or living tissues using a droplet printing method. Dr Alexander Graham, 3D bioprinting scientist at OxSyBio, and I have worked side by side to develop the first iteration of a technique that could print cells. We used that as a launchpad for translating the technology out to the wider company.

What’s an average day for you?

In theory, I coordinate our research into the 3D printing tissue space with our growing scientific team within OxSyBio. But in practice, as we are a small company, this has covered a range of activities – scientific planning, fundraising, managing our IP estate with the university and our IP lawyers, working with Dr Hadrian Green, our CEO, to establish our external partnerships with academic labs and other companies. This is part of what makes working in a small company really interesting. 

How did this research into 3D printing laboratory-grown cells to form living structures first come about?

Research started back in 2011 in the Bayley lab at the University of Oxford. This lead to a paper released in 2013 (Villar et al., A tissue-like printed material, Science) about 3D-printing synthetic tissues with no living component in them. That was a combination of engineering – building the printer – and the biophysics of how you would build a model tissue from simple biological constituents. That’s really how the interest in printing started in the Oxford lab. 

In 2014, we began to explore whether or not what was being done in the 3D printing of living tissues could be complemented or improved upon. We noticed that in the early 2000s there had been a push to attempt 3D-printed cells from desktop ink jet printers, which was promising but had seemingly stalled, partly because of the problems of using commercial systems. 

We thought that if we had a bespoke printer, perhaps we had a better chance of getting an ink-jet like technology, as a drop-on-demand system, to print cells.

How does your process work?

Typically, 3D printing will take one of two forms - top-down approach, or bottom-up. For example, printing in metals or ceramics, often you have a powder bed of a precursor material that you can trigger a reaction from. Alternatively, and particularly in the bio-printing space, it will be more top-down. You have a print head with pre-loaded bio-ink. We were particularly focused on bio-inks that contained living cells and a scaffold matrix. Our technique allowed us to dispense the cells spatially at high resolution, in a layer-by-layer fashion, based on a digital 3D model.   

What materials are you using?

The bio-ink will mainly consist of cells from humans and/or animal sources and other necessary components for functional tissue development, specifically, a hydrogel-based scaffold material, usually in it’s pre-gel state with cell nutrients, such as amino-acids, sugars and proteins, blended in an osmotically balanced solution. 

What makes your research different from other work on 3D-printing tissues?

For us, it was about coming up with a something that had high-resolution, relatively high-cell density, and on an apparatus that was relatively inexpensive – the hardware we have costs under £10,000. When we started the research, the nearest alternative cost hundreds of thousands of pounds.

Is this the only research of its kind?

The tissue engineering and bioprinting space is very active. However, our work flow would be the first of its kind, in that it incorporates these synthetic and biomimicry elements in a single system.

What’s exciting from our point of view is that you can print these non-cellular tissues, but also cellular tissues next to one another or as part of the same structure. In that respect, it is very distinct.

What are the real-world applications?

A great question. In-vitro, complex tissue models as an alternative to animal testing has been floated for quite some time. It’s an opportunity to bring patients into the laboratory by sourcing human cells and printing them into a complex model without needing to test on an animal. That’s one of the low-hanging goals of this type of method.

We’ve also been looking at how we use 3D printing to create tissue models that can be used for either diagnostic or therapeutic applications. I think it is a complex problem. How far does validation need to go before these types of tissues are adopted? That’s going to be an ongoing challenge, to push it to a standard where you can say we don’t need to use a mouse as part of this validation process.

So, there is strong demand for this type of work?

There is definitely interest in this area, and has been for a while. One of the challenges is that these things are costly and do take a long time to validate. Even if you are in a position that we are, where you show that you can print tissues, keep them alive and have quite complex behaviours, there is another round of testing and validation that needs to happen before they can be integrated into industrial scale workflows.

Scale is another thing, in terms of taking techniques that are relatively small and bespoke and producing things on a larger scale. 

However, it does look promising. There are lots of talented people working on this and some of the issues of where to source cells are being tackled with gene-edited lines. That will help with the inputs.

You mention validation - what needs to happen for that challenge to be overcome?

In the USA, there are guidelines being discussed, in terms of what a non-animal-derived method would need to do in order for it to be accepted.

There’s also a whole raft of companies working in this space, but it is costly. We need some of the big companies to really start driving these technologies and putting them up against the current gold standards and looking at what quality of data can be generated.

What were the challenges during your research?

Technically it’s very difficult to keep active matter in the form of cells, bacteria, or whatever you are trying to print, alive while you are trying to bulk process it.

Harvesting cells, diluting them into different bio-polymers and getting good consistency in those materials, and then printing a product that is still living after it has been put through a mechanical process, is innately difficult. Also, getting the right material properties designed into bio-inks – and the resulting structure you make – is a challenge. That’s why it took us more than three years to get this paper done – even with a large team of scientists split across multiple departments at Oxford and Bristol Universities – as it required optimisation of the chemistry, biology, and hardware in parallel. Validation is the step beyond that. The challenge for us in the chemistry department was, fundamentally, about material consistency.

How did you overcome these? 

Lots of hard work from a group of scientists in the lab – our most recent paper has 10 authors. Having a background in materials chemistry was not a bad place to start. Even so, it was a bit like trying to thread the eye of the needle. We worked a lot on bio-ink formulation to produce specific gel properties.

What’s next for this research? And, overall, how will this market/research area change?

I think the field is moving towards non-animal tissue for toxicology – there has been a big push for that. At OxSyBio, we want to use what we can do with the technology we currently have. We are aiming to get diagnostic products as soon as we are able. We believe it could be two to five years to get products to market in a way that is not particularly disruptive to existing workflows in industry but has benefits from having been 3D printed.

We could get better consistency into life sciences projects, which could benefit patients – that’s something we think is achievable.

Longer term, we think there is huge potential in the therapeutic benefits of being able to make bespoke tissues on demand. Previously people have suggested they could be printed and surgically implanted, but there also might be options for utilising printed tissues for repair and preventative measures.

*Dr Sam Olof is the Chief Technical Officer at OxSyBio and formerly a Visiting Scientist in Chemical Biology at the University of Oxford. He received a Masters Degree in Chemistry from the University of Bristol in 2009.