Bubbles ? what ? fighting cancer ? No way ?!!!!!!

Yes way! scientists have been studying methods of transporting drugs around the body to reach regions that are hard to release drugs.

The institute of biomedical engineering at the University of Oxford have been making advancements with tiny BUBBLES. These tiny bubbles work to produce an effective outcome with higher dosages to target areas with little side affects. The drugs would be encapsulated within these tiny nano-particles which provides advantages: we would be able to control when the drug gets activated within the blood stream, it also allows us to attach protein receptors to the surface of the particle to allow it to 'stick' to the target cell, what is even more interesting is that we will be able to release such drugs using a physical stimulus, such as ULTRASOUND to which they are very responsive.

You may be thinking, bubbles in the blood stream ? Are you crazy ? what happens if it blocks the coronary arteries causing a heart attack and death ? Or arteries to the brain causing an ischaemic* stroke ? Well we have to make these bubbles absolutely tiny (micro bubble). 50 times smaller than a human hair. However, these bubbles being so small will be exposed to an abundance of surface tension, so what they coated them in a shell (bio-polymer). This shell allows us to fit a layer of a drug between the shell and the gas core.

Popping the bubbles is a piece of cake using Ultrasound. It sends sound waves that expand and contract the shape of the bubble back and forth - eventually creating enough surface tension to the bubble thus popping it and releasing the drug. We can send ultrasound waves in a very localised fashion which can only target certain areas of the subject. Other than releasing the drug, Ultrasound can be used as imaging to see where the bubbles are and where the drug has been active. Because this drug is much more accurate to the target zone there will be less side affects. Side affects normally occur when the drug is taken up by healthy cells in the neighbouring tissue.

They used cancer as a study to see the effectiveness off the bubble transport. Cancer cells arise from various mutations in normal cells within the body. It is normally multiple mutations of genes, such as deletions of tumour suppressor genes or over expression of oncogenes which allow cancer cells to avoid cell programmed death. They then divide at a much faster rate than normal human cells and will grow into a large tumour made up of a mass of deformed cells. This tumour will need a larger supply of blood, thus going through angiogenesis* to form more blood vessels around the cells. But even though more blood cells are made there is still little availability of oxygen in the area for any drug to work at good effectiveness. Here is an experiment to see the area of drug that worked in a cancer tumour without the use of bubbles and ultrasound :

RED is the blood vessels

BLUE is the cancer cells

GREEN is the treated cells

As we can see there is a little treated area related to the entire area of cancer cells. The drug looks like it can only reach areas of cancer cells around the blood vessels and cannot reach that further out, but is not very powerful in those areas.

The bubbles have a couple tricks up their sleeve: when the ultrasound sends out waves that expand and contracts the bubbles - it acts like a pump which forces the drug further away from the initial area of popping and reaches areas much further away. On top of this, bubbles carry an extra supply of oxygen with them which further increases the effectiveness of the drug that we may use. Here is the experiment using bubbles and ultrasound to transport drugs to tumour cell areas:

RED is the blood vessels

BLUE is the cancer cells

GREEN is the treated cells

Here we can see the drug has reached a much larger distance from the area which it was popped and we can see a much more abundant area of treated cells showing the effectiveness of bubbles and ultrasound within cancer treatment.

One may think they may be injecting a whole lot of toxic chemicals that will be harmful to normal cells in the body and will cause horrible side affects. But working alongside an institution in Northern Ireland they have come up with a new drug that can become active when exposed to ultrasound. So whilst moving through the blood stream the drug will be inactive until the bubble is popped which also allows for more efficient drug targeting.

OMDs ! The way in which these drugs work is fascinating. So when the ultrasound is emitted onto the tiny bubbles, it will contract and when it contracts it will heat up. When this bubble contracts enough at the certain frequency it will heat up enough to emit light. This light can actually change the chemical properties of the chemical used and therefore activating it for use in cancer cells.

Oof !!!

  • *ischaemic - reduction of blood supply to tissues causing a shortage of oxygen - literally in greek meaning 'stopping of blood'

  • *angiogenesis - development of new blood cells in this case due to a growth of a tumour to bring more oxygen to the cancer cells



oxford at home: Eleanor stride on biomedically-engineered bubbles - university of oxford - youtube