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Microbubbles are almost unimaginably small – you could fit ten thousand of them into a single full stop. But now a team of researchers at Leeds is hoping to use them as a drug delivery device to treat cancer and other serious diseases.

Microbubbles are already used in medicine to improve ultrasound imaging – they can be injected into a patient’s bloodstream to improve the images produced from an ultrasound scan, giving doctors a clear picture of how blood is flowing around tumours and through heart defects. But now Leeds researchers believe these bubbles offer the possibility of a new method of fighting cancer.

Currently, a patient receiving chemotherapy has drugs injected into their bloodstream to fight the tumour. But these drugs – designed to attack and kill cancer cells – also spread around the patient’s entire body, causing damage to healthy cells and causing the well-known side effects of fatigue, hair loss and nausea.

“These drugs go everywhere, and they are very toxic,” says Professor Stephen Evans who heads the Leeds Microbubble Consortium, a team of researchers exploring how microbubbles could make this process less unpleasant for the patient. “We have people based in physics, which is my group, people in engineering and then people in medicine, and we came together to develop a project to aid the therapeutic delivery of drugs to tumours.”

They believe microbubbles could carry these harmful drugs around the body, with the shell of the bubble stopping the drugs from harming the healthy cells. The bubbles could then be burst remotely by ultrasound to release the drug right at the site of the tumour.

Microbubbles have the added advantage that as they burst they can temporarily break down cell tissue in the tumour, delivering the medicine directly to where it is needed.

And now the Leeds team believes these amazing bubbles have the potential to treat a host of different conditions.

There are huge benefits opened up through the use of microbubbles: “We could use a lot less of a drug,” says Prof Evans, “and we might also be able to use more toxic drugs which already exist but can’t be used because of the potential side-effects if they were delivered to the whole body.”

Leeds researchers have designed and built the HORIZON machine which can produce up to a billion of the bubbles in just three minutes.  The machine is designed to produce the bubbles with the desired drugs and targeting agents – which makes the bubble more likely to concentrate in a particular area of the body – already included. In 2019, the team announced a major development of the technology which allowed a 16-fold increase in production, enabling them to create samples in much larger quantities more quickly. They have also successfully freeze-dried drug-loaded bubbles to give them a longer shelf life.

Leeds researchers are also pioneering the way the treatment is released when the microbubbles reach the tumour. As the bubbles travel through the patient’s bloodstream, researchers will use an ultrasound scanner to track them, with the advanced technology used at Leeds producing much more detailed imaging allowing doctors to see tumours in more detail than previously possible.

And when the ultrasound scan shows that the bubbles have reached the site of a tumour, the ultrasound can be switched to a different frequency which allows researchers to burst them at exactly the right spot. “A bit like how an opera singer can crack a wine glass by hitting a certain note with their voice, we can use a specific ultrasound frequency to pop the bubbles as they reach the right place in the body,” Professor Evans explains.

Donors’ support for this work has allowed the team to grow and new projects to begin.

The potential of microbubbles in medicine goes beyond cancer and Leeds researchers are excited about the potential for this type of treatment for a number of different conditions. “We’re working hard to extend the application of microbubbles beyond what even we thought was possible,” says Prof Evans. “Proof-of-concept studies are underway to look at how they can be used to combat infection, deliver oxygen to babies in the womb, as well as help fight cancers.”

One idea is that the bubbles could be filled with antibiotics and used to treat an infection in a specific area of the body. This could be particularly useful for infections in people who have been fitted with pacemakers: “If somebody has a pacemaker then these can get infected and we believe that we can burst these bubbles in a way that can break up the biofilms that are growing,” says Professor Evans.

“When antibiotics fail, they fail because they can’t get to the bacteria that they need to get to, whereas we believe bursting the bubble actually releases a lot of energy and it not only breaks up those bacterial films but it actually penetrates the drug much deeper. We see that from the cancer work and we want to extend that into other areas.”

Other researchers are also watching the results of the research closely to see whether the process could be used in their area of medicine. Professor Evans explains that the procedure might be able to be used to treat conditions which restrict blood flow to an unborn baby during pregnancy: “One of our clinical colleagues saw the work on the treatment of cancer and asked whether it would be possible to put oxygen inside the bubbles to deliver it directly to the foetus prevent these problems.”

The team is working towards being able to start clinical trials and although they are a still some time away from treating patients, they are very optimistic about the direction of the project.

Including the generous support of Footsteps Fund donors, the total raised for Microbubbles through the Making a World of Difference Campaign is now £172,000. 

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Media Coverage:

Yorkshire Evening Post (1)

Yorkshire Evening Post (2)

EPM Magazine

Pharmi Web

Tomorrow’s Laboratories

The Pharma Letter


Innovation and Impact


Steve Evans

Sally Peyman

Footsteps Fund support

Scientific poster

Professor Steve Evans

Professor Steve Evans discusses University of Leeds research into Microbubbles - and explains how they hold the potential for a future revolution in the treatment of cancer.

Microbubbles animation

An animation to explain how microbubbles could be used to carry chemotherapy agents to attack cancer.

How you can help

With your support we can strengthen the microbubbles research team at Leeds, by bringing in the PhD students and Postdoctoral Researchers whose work will help us to tackle the technical and regulatory hurdles which must be overcome before this potentially revolutionary treatment can be taken forward into clinical trials

And because the University is a charity, UK taxpayers can make their gifts go further. Gift Aid enables the University to reclaim the basic rate of tax on the value of the donation, while higher rate (40%) and additional rate (45%) taxpayers can reclaim the difference between their rate of tax and the basic rate.

Gift will support PhD studentPostdoc Fellow (one year)Postdoc Fellow (three years)
You give£64,000£104,000£312,000
The University claims Gift Aid (1)£16,000£26,000£78,000
Full value of gift£80,000£130,000£390,000

If you are a Higher Rate (40%) taxpayer:

You claim tax relief (2)£16,000£26,000£78,000
Net cost to you£48,000£88,000£234,000

If you are an Additional Rate (45%) taxpayer:

You claim tax relief (3)£20,000£32,500£97,500
Net cost to you£44,000£71,500£214,500

1. Added at the basic rate of tax.
2. Higher rate relief is the difference between basic rate and higher rate tax.
3. Additional rate relief is the difference between basic rate and additional rate tax.

For further information on tax-effective giving and eligibility click here

You may also choose to make your gift in instalments.