Bioprinting algae to grow human organs

Using algal cells to provide oxygen to human tissue in a dish
23 November 2020

Interview with 

Shrike Zhang, Harvard University


Algae on a rock


Over the past few years, medical scientists have been using 3D printing to create artificial human tissues with the goal of, one day, replacing their natural diseased counterparts. But cells need oxygen, and it’s tough to engineer these ‘bioprinted’ body parts so - that while they’re growing - they don’t die of oxygen starvation or a toxic build up of carbon dioxide before blood vessels can plumb themselves in. So a team in the US are trying to solve the problem using algae. Yes, it does sound strange, but algae are plants: they use light to drive the process of capturing carbon dioxide and releasing oxygen, so by laying down algal cells alongside human cells, one can feed the other and keep both healthy in the process, while an organ develops. Eva Higginbotham heard how it works from Shrike Zhang...

Shrike - We combined our algae and human cells where the oxygen produced by the algae cells can promote the growth of the human cells. After removing the algae we can have a better engineered human tissue.

Eva - What is the problem that you were trying to solve by creating this?

Shrike - Oxygen supply. So providing sufficient oxygen from within engineered tissues has been a major problem or challenge over the years. And if you engineer thicker tissue, it's very hard to get oxygen into the middle of the tissue because oxygen doesn't really go through the thick tissues or dense cells 10. This way that we have devised is to really provide long-term oxygen release from within the engineered tissue. So that's perfectly solving this long-term dilemma that's faced by this whole community.

Eva - What sorts of tissue are people growing in a lab that they need to be able to get oxygen all the way in?

Shrike - This basically applies to pretty much every single type of tissue that people engineer. All the way from, for example, the brain, to the heart, to the liver - there's almost no tissue in the human system that does not have an interconnected network of blood vessels.

Eva - So how have you solved the problem?

Shrike - We use bioprinting to deposit these algae containing structures. If you shine a light across this construct then the algae can actually produce oxygen.

Eva - How on earth do you actually print algae?

Shrike - We use a Jello-like structure containing algae, which are called Bioink. And then if you control how this Bioink is extruded you can start to deposit these algae structures in three dimensions.

Eva - You know what I'm thinking of is whipped cream that comes in a can! You know, where you squeeze things out, either that or like a glue gun?

Shrike - Yeah, sort of yeah.

Eva - And you've actually sent me some pictures that show these algae and it almost looks like you've printed them to look like a honeycomb. Why did you print them in that shape?

Shrike - We printed them in this honeycomb shape just because we were trying to model or mimic human liver structures. But again, using bioprinting, you can essentially deposit any shape or structure that you want.

Eva - And so within these honeycomb circles I can see lots of bubbles, is that bubbles of oxygen?

Shrike - Yes, exactly.

Eva - And so taking this sort of structure that you've made you then throw on some liver cells, is that right?

Shrike - Yeah, basically. So you can throw your liver cells onto the structures. So then these oxygen bubbles that are created by this algae are going to be used to supply the oxygen to the cells.

Eva - Would you then be implanting algae as a part of someone's regrown heart?

Shrike - No. Once the liver tissue is sufficiently oxygenated, you can actually selectively remove these algae patterns from the liver tissue that you can then directly implant into human systems.


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