Biomaterials
populations around the lesion. However, scaffolds can also incorporate growth-promoting molecules in order to encourage regeneration: here, the cells are transplanted onto the injury site. Some materials also have innate properties that can support repair by preventing further damage. For instance, chitosan can inhibit the secretion of chemical messengers that bring on inflammation while PEG may help suppress production of free radicals, unstable atoms that can damage cells.
A long road ahead
Strategies for spinal cord repair will develop and mature over the next few decades.
between neurons – in the central nervous system (CNS) and that will mount a wound response when there’s an injury.
When we’re very young, our astrocytes have a natural ability to bring on repair after CNS injury, O’Shea explains. However, this capability drops off as we get older: in adults, they instead form a protective border around the lesion. “Our goal is: how can we mobilise astrocytes to engage in these wound repair responses more broadly, and for longer periods of time, to kind of mimic what happens in these more immature systems?” His lab’s answer is to engineer materials that provide astrocytes with different types of information: the right kind of growth cues that encourage mounting of the wound response, the metabolic fuel they need to carry out these activities, and information that gives them an idea of where to position themselves within the lesion environment – for instance, by sensing the concentration of molecules around them. These materials can be injected right into the injury site, O’Shea adds.
Research is at preclinical stage and so far, the team have investigated the effects of their materials in mouse studies. “We’ve seen some interesting biological effects in terms of wound repair outcomes by augmenting the astrocyte response,” O’Shea shares. “We’re now at the present stage of seeing how those interventions confer functional outcomes.”
This means that, as it stands, we can say that this strategy has the potential to bring on wound repair – but we don’t yet know what degree of tissue regeneration it could lead to, and to what extent it could restore functionality. O’Shea’s approach aims to incite the wound response from inside the body, by modulating cell
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These advances are certainly exciting – but it’s still very early days. There’s a long way to go before we’ll see regenerative treatments in human trials, let alone in clinics. It’s a journey that Serafin thinks will consist of many little steps over a number of years, until researchers eventually reach their ‘aha’ moment. At present, the main form of therapy being investigated in clinical trials is rehabilitation strategies, says O’Shea. And in that space, our most advanced option is electrical stimulation – such as peripheral nerve, epidural and deep brain stimulation – to restore locomotor functions, like walking. It aims to recover, or rewire, damaged circuits rather than regenerate injured tissue. Some electrical stimulation treatments are available in clinics that may restore muscle strength and help with some movements, like a hand-gripping motion. Yet because this requires some viable nerve fibres to work with, it won’t be of much help to people with complete injuries where there are none to stimulate, O’Shea adds. “There is definitely going to be a need to continue to work on these regenerative type strategies, where we’re focused on actually dealing with repairing and regenerating tissue, to be able to augment outcomes in people that have really severe injuries.”
But whatever the approach, materials are set to play a key role. For instance, we could develop scaffolds that have the optimal amount of conductivity for promoting repair – something that Serafin says is currently being looked into. Or design those that interface better with neural tissue so they can stay implanted safely for a long time, adds O’Shea.
Over the next few decades, we’ll hopefully see strategies for spinal cord repair develop and mature. Though in the meantime, there’s plenty for us to still discover about the injury itself. “I think we understand a lot, but we don’t understand everything,” says Serafin. “It’s such a complex tissue… your spinal cord is basically the width of your pinky finger. It’s [amazing to] think that something like that has so much power.” ●
Medical Device Developments /
www.medicaldevice-developments.com
KOTOIMAGES/
Shutterstock.com
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