You could fit ten thousand microbubbles into a single full stop. But now a team of researchers at Leeds is hoping to use these tiny bubbles as a drug delivery device to treat cancer and other serious diseases.
Microbubbles, as the name suggests, are very small bubbles - just one-thousandth of a millimetre across. Researchers at Leeds think that they could have a big impact on the way we treat some of our most serious illnesses.
Microbubbles are already used in medicine to improve the use of ultrasound imaging - they reflect soundwaves better than human tissue and can be injected into a patients bloodstream to improve the images produced from an ultrasound scan.
The bubbles move around the body and eventually burst without causing any damage. This has led a team at Leeds to look at whether these bubbles could be filled with more than just harmless gas. Researchers at the University believe that if these bubbles carry medication they could deliver drugs directly to cancerous tumours.
Currently, if a patient is receiving chemotherapy they will have drugs injected into their bloodstream to fight the tumour. But these drugs designed to attack and kill cancer cells spread around the patients body, causing damage to healthy cells and causing the well-known side effects of chemotherapy fatigue, hair loss and nausea.
Traditionally, when you inject chemotherapies you get a lot of toxicity because the drug is effectively going everywhere, and these are very toxic drugs
says Professor Stephen Evans who is leading a team of researchers from across the University to look at how microbubbles could help to 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.
The idea that Leeds researchers are working on is to use microbubbles as a vehicle to carry these harmful drugs around the body, contained in even smaller packages called liposomes, which stop the drugs from harming the healthy cells.
The bubbles can then be burst remotely using ultrasound to release the drug in precisely the right place. Microbubbles have the added advantage that as they burst they can temporarily break down the cell tissue in the tumour, delivering the medicine directly into the tumour cells.
The microbubbles currently used in medicine are made of a lipid shell a naturally occurring fatty substance which doesnt dissolve easily in liquid and filled with different gases depending on what they are being used for.
To use them to treat cancer, a single dose of medicine would require 10 million of these individual bubbles and its important that they are of similar size, with similar amounts of the drug contained in them.
To make this process as efficient as possible, researchers within physics have created the HORIZON machine which produces the microbubbles. The machine is appropriately small and portable and can produce up to a billion of the bubbles in just a few minutes, more than enough for the researchers purposes.
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. The idea is that the whole process could be made as easy as slotting in the materials a patient needs and letting the machine produce the treatment. Professor Evans explains:
We have this idea - rather like one of these coffee machines where you put a sachet in and you get your different flavours out. What we want is to be able to put a sachet in depending on the drug type that you want or depending on whether you want your bubbles to target a particular type of cancer.
New ways to test treatments
Finally, Leeds has innovative tools which enable us to test these processes. Researchers are using organoids to test the microbubble treatment. These are miniature versions of human organs which are created on plastic chips with cancerous cells in them, Professor Evans explains:
Researchers can test the use of microbubbles on these organoids and see whether it has an effect on the tumour but also if it has any unwanted side-effects.
You could have a chip for almost every organ and then start to link these chips together so if we made an organ which was mimicking our colon we might then, behind that, have a liver organoid.
Then as we introduce the drugs into the tumour with our microbubbles we can see the effects of whether we destroy or kill that tumour, but actually we can also then follow that drug around into the liver organ or see if it's having any detrimental effects that we might not want on the liver.
The team are 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.
Researchers are enjoying working with colleagues across the University - its not often that such a diverse team of researchers work together on one project like this, right from the basic science through to treating patients. Professor Evans says:
The post-doctoral researchers and PhD students in the team love this project because of the diversity of the people that are required to deliver the goal. I think we're very proud of the project and we're keen to move it on towards real treatments for patients. To be doing that at Leeds is great.