Medical illustration of brain stroke symptoms xray 3D rendering

Tiny transporters could deliver treatment to stroke patients

Image credit: Peter Schreiber - Dreamstime

Swarms of nanoparticles around 15,000 times smaller than a pinhead have the potential to deliver vital drugs to the brain, offering new hope to patients in the early stages of a stroke.

The research, conducted by a team from the University of Manchester, shows that tiny vesicles called liposomes – just 100nm in diameter – can translocate through the damaged blood-brain barrier following a stroke.

These liposomes may offer a way to get vital drugs to the lesions (a region in an organ or tissue which has suffered) to stop further damage.

The brain is the only organ in a mammals body to have its own “security system”: a tightly packed network of blood vessels and barriers that allow the entry of essential nutrients while blocking other potentially harmful substances. However, this barrier also blocks lifesaving drugs, rendering it difficult to treat a range of conditions, including strokes.

The study, which the team carried out on mice, shows that that liposomes can potentially transport life-saving drugs across the barrier. The team were also able to generate microscopic pictures of the brain tissue using state-of-the-art imaging techniques, showing the nanomaterial is a viable transporter.

“The discovery that nanomaterials may be able to facilitate the treatment of stroke is exciting: scientists have long been grappling with the difficulties of treating brain injuries and diseases,” said Stuart Allan, a professor of Neuroscience from the University of Manchester. “The brain-blood barrier is a major frontier in neurology, so the prospect of being able to cross it may have applications to other conditions as well – though clearly, much more work needs to be done.”

A blood clot forming in the carotid artery

A blood clot forming in the carotid artery

Image credit: American Heart Association

Until now, scientist and experts in the field haven’t yet devised a reliable way to deliver drugs to the damaged brain efficiently. According to the experts, this is one of the last frontiers in medical science.

But now the team show that following a stroke event, liposomes are able to penetrate the brain by being transported across the tightly packed endothelial cells by using pouch-like structures known as caveolae.

That means doctors might one day be able to protect tissue in the acute phases of a stroke, by delivering drugs – which are currently still being developed – that can protect brain’s neurons from further injury.

“Liposomes are a tried and tested method of delivering drugs to the body – and are currently used to treat patients, for example, to target cancer drugs into the tumour at high doses which increase their concentration relative to other parts of the body,” said Dr Zahraa Al-Ahmady, an honorary research fellow at the university. “They are easy to manufacture and used across the NHS. But our research shows that Liposomes have important implications for neurologists too.”

In the days following a stroke, when brain cells – or neurons – have died, the researchers showed that liposomes (made from lipids which are long chains of oily or waxy organic molecules found in all living things) also able to penetrate the brain to help promote the repair of neurons.

“This discovery is an important milestone on the use of liposomes for yet another debilitating disease, such as stroke,” summarised Professor Kostas Kostarelos, a nanomedicine expert at the University of Manchester. “Liposomes have had a tremendous impact on offering treatment options in oncology, vaccination, lung and skin disease since they were first discovered by British haematologist Alec Bangham in 1965.”

In July 2018, researchers based at the University of Illinois at Chicago delivered chemotherapy drugs to the spinal cord of an animal model to treat hard-to-reach tumours with magnetic nanoparticles.

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