On December 9, 2019, Whakaari/White Island erupted as three tour groups explored the volcano.
Of the 47 people on the island at the time of eruption, only 25 survived. Most of these survivors experienced severe, complex burns that covered large areas of their bodies, and so required skin grafts to treat their wounds.
When a patient needs a skin graft, doctors prefer to use tissue taken from the patient’s own body so the graft is a perfect match for that particular person.
However, in situations like the Whakaari eruption, victims can sustain wounds so large it becomes impossible to find enough healthy skin to transplant. In these situations, doctors turn to tissue banks instead.
Tissue banks, which contain tissue taken from both living and deceased donors, are always limited by the number of donations they receive.
The supply of donor skin in New Zealand was quickly exhausted following the eruption, so doctors had to turn to other nations for aid. At the height of the emergency, doctors requested 120sq m of donor skin from tissue banks in the United States, an astonishing number given the average human body contains only 2sq m
Disasters at the scale of the Whakaari eruption highlight the need for alternative sources of tissue that do not depend on donors. But how can we grow skin outside of the body?
At its most simple, a tissue is made up of cells embedded in a jelly-like substance called the extracellular matrix. These matrices have a certain texture, or "stiffness", which is unique for each type of tissue.
The brain, for example, feels similar to soft tofu, whereas bone and tendon are extremely strong. Skin falls somewhere in between these two, with a flexibility that allows us to move our bodies with ease, but a toughness that protects us from injury in day-to-day life.
In order to engineer artificial skin, we must first replicate this jelly-like extracellular matrix. In scientific terms, a jelly is called a “hydrogel” because it is a solid that contains a high volume of water.
There are many different skin-like hydrogels available, however they are often very soft and unstable. If skin cells are placed into a hydrogel matrix that feels like soft tofu, they will probably survive (as long as the matrix is not toxic to them).
However, they will not grow into any structures that resemble normal human skin. If they are instead placed into a matrix that has the same structure and stiffness as native skin, they are much more likely to replicate, migrate, and eventually grow into a structure that would be functional and transplantable.
So how can we take a soft, fragile hydrogel and turn it into something with the strength and flexibility of skin?
To solve this problem, scientists frequently turn to composite materials. A composite is simply any material that is a mixture of two or more components.
Ideally, this mixture will function better than any of the individual components alone. A good example of this is the addition of rebar to concrete, which greatly improves the strength of the resulting composite.
In a similar fashion, adding a network of strong fibres to a soft hydrogel will create a composite gel with better stiffness and strength.
When it comes to natural fibres, few are as strong as cellulose. Cellulose is the structural component of plant cell walls that gives them their strength and durability.
Cellulose is also non-toxic to human cells, and so can be used in materials that are transplanted into the body.
Though we know a lot about the structure of cellulose produced by land-dwelling plants, seaweed cellulose has received much less attention.
Anyone who has swum through a kelp forest will know seaweed is very flexible, bending and flowing as the current moves past it. Kelp is also extremely strong, because it has evolved to withstand the immense forces of crashing waves.
When cellulose is isolated from kelp, it forms a unique, nest-like bundle of incredibly long fibres that are only a few nanometres wide. It is likely these cellulose properties help give kelp its impressive strength and flexibility.
Is it possible, therefore, to combine these strong, flexible kelp fibres with a hydrogel to create skin-like materials for tissue engineering? This is the question my PhD aims to answer.
With the world’s first seaweed cellulose biorefinery nearing completion in Paeroa, this becomes a question not only of scientific curiosity, but also one of commercial opportunity.
It is my hope this research could help to move tissue engineering out of the realm of science fiction and into reality, all with the help of a unique and under-utilised New Zealand resource.
• Janet Reid is a Phd candidate with the University of Otago, School of Pharmacology and Toxicology). This article was the winner of the 2024 Otago Medical School Research Society science writing competition. Submissions were independently judged by Dr Rosie Jackson, Dr Ruth Warren, and Jennifer Gale: the winner was chosen by Dr Blair Hesp, managing director of Kainic, who also sponsored the runner-up prize. The prize for the winners was sponsored by the Otago Postgraduate Medical Society. As it has in previous years, the Otago Daily Times has agreed to run the winning submission.
