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Making living ink

Seaweed can be used to make a living ink suitable for 3D bioprinting.
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Many of the materials we use for 3D bio-printing actually come from natural sources. We have examples like allogeneic from seaweed that we’re 3D printing for muscle regeneration. 3D printing cardozan from crab shells for cartilage regeneration, and now starting to 3D print ulvan, which is a polysaccharide from green seaweed for wound healing. As we move towards clinical applications, it’s important that we start to think about controlling the source of those materials, ensuring the reproducibility and reliability of that source so that we can tackle the regulatory issues and make sure that those materials are translated effectively and efficiently into the 3D bio-printing process.
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I’m now going to talk the Pia Winberg from Venus Shell Systems about some of the issues around ensuring the reproducibility and reliability of those materials for 3D bio-printing. So, Pia, as you know, we’re doing a lot of work on 3D bio-printing, which requires as a major component of those inks bio-materials, many of them naturally occurring bio-materials. And one of the things we’re starting to think about, or everyone needs to think about, is the actual source of those materials and how we control that. So can you tell me a little bit about how you do that in the seaweed area? Yeah, well, the oceans are a great source for new bio-materials that we really haven’t explored yet.
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I mean, people are looking on land and in rain forests and places, but the ocean is full of gels that are compatible with the human body because it’s got osmotic environment that you have to cope with. And so the molecules there could be, in many cases, very suitable to the human body. But the traditional sourcing of materials from the ocean has been around fishing and even collecting of seaweeds, and so people aren’t too concerned about the actual identity of species necessarily always. So you get misidentification of things sitting even on the food shelf.
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You can imagine then when the molecules change, even within closely related species, how difficult it is to get a molecule that’s always consistent from a crab, for example, because the crab species might keep changing, the sources might keep changing. So what’s happened in the recent half a century is aquaculture has come online and it’s the cultivation of these materials and fish and crabs and seaweeds. And that means that if we start to put the genetic control on what it is we’re growing, have traceable and quality control procedures in place, we can then actually maintain that source, those genes that create that molecule in production.
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And therefore, we can start to get consistent, natural marine molecules that can be put into the human body. So naturally occurring materials are obviously forming the backbone of the major components we’re finding in bio-inks. We know we’re using materials from trees, nanocellulose, for example, we’re using animal derived materials like collagen, but it seems like the sea, and seaweed in particular, is just an amazing source of materials for 3D bio-printing, and a source that we can carefully control and regulate that process to get reproducible molecules. Well, what the oceans are offering us, I guess, is distinct from the land plants is a similarity to the molecules that we’re getting from animals on land.
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And so they offer us a non-animal source of some of these molecules, and that can be important if we’re starting to put it into human bodies. For example, a lot of the molecules now like heparin, for example, comes from pig mucosa. So there will be limitations in how we can use those things in medical devices. But not only a non-animal source, a prolific, abundant, and a sustainable source. And so I would regard the oceans as the next frontier of molecules because we haven’t even identified all of the species that we can work with there yet.
Cells don’t make good building blocks

Working with cells

Hydrogels are jelly-like materials widely used for tissue engineering due to their compatibility with cells. Many types of living cells can grow happily inside these hydrogels. However, hydrogels lack the viscosity and strength to hold their shape after printing.
Recently, multiple-component composite hydrogels, such as alginate (from-seaweed) blended with gelatin (the foodstuff used in marshmallows), have been developed to improve the gel-like characteristics and enable high resolution printing of free-standing hydrogel constructs. These structures were created using extrusion printing, the ‘tooth-paste squeezing’ technique.
In most current research, the living cells are not incorporated into the hydrogel inks during printing. The cells, such as chondrocytes for cartilage regeneration, can be seeded onto the printed structures in a Petri dish or bioreactor. The goal here is to create a ‘cartilage patch’ suitable for implantation to help heal a defect or injury. Integrating cells at precise locations during printing would have huge advantages over the post-seeding approach. Achieving this will require some clever ways to help the cells survive the printing process.

Conversation starter

  • What other materials can hydrogels be made out of?
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Bioprinting: 3D Printing Body Parts

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