AUS tries to hit cancer where it lives
Every year about 14 million people worldwide have cancer diagnosed, the US Centres for Disease Control and Prevention says, and that number is likely to increase.
As people live longer with the risk of death from illness such as heart disease reduced, forecasts indicate that as many as one in two people in certain countries will ultimately develop some form of cancer.
It is a frightening statistic that makes it all the more crucial for scientists to come up with better ways of treating the condition.
Scientists at the American University of Sharjah are among those studying microscopic particles that could deliver drugs to cancer cells.
Chemotherapy drugs, which typically target fast-growing cells, can exert their effects throughout the patient’s body and can have a range of unwelcome side effects.
As well as harming the cancerous cells they can also damage other cells that grow quickly, such as hair follicles, leading to hair loss, or cells that line the mouth, causing painful ulcers.
But if chemotherapy drugs can be delivered using tiny particles such as liposomes and micelles – tiny spherical particles in which a water-loving (hydrophilic) layer or layers surrounds a water-hating (hydrophobic) substance – the side effects could be reduced.
This is because the particles can be programmed so that they migrate to the cancer cells specifically, meaning the drug does not attack other, healthy cells.
At AUS, a team led by Prof Ghaleb Husseini is interested in how ultrasound could be used to activate drug-carrying liposomes and micelles. Ultrasound consists of pressure waves that travel at a frequency too high for humans to hear.
The researchers, made up of seven faculty members, two visiting academics and 12 postgraduate and undergraduate students, have been synthesising liposomes and micelles in the laboratory and assessing their structure.
Studies using substances that glow have helped them to assess how much of the chemotherapeutic agents or a model drug has been released by the tiny particles, providing an understanding of how the particles can be induced to deliver a drug.
Prof Husseini’s group’s research is a long way from being used in patients. But the aim of such studies is to reach a situation where an anti-cancer drug held within particles could be given to people with certain forms of cancer, probably intravenously, much like current chemotherapy methods.
Ultrasound would then be applied to cause the particles to release the drug. Ultrasound can lead to the release of drugs from particles through several processes, one of which is called transient cavitation. This involves the ultrasound causing bubbles near the nanocarriers to oscillate in size dramatically, which severely disrupts the particles’ structure.
“Transient cavitation causes the production of microjets that shear these structures open or pierce a hole in their membrane, thus causing the drug to diffuse out,” said Prof Husseini, who works in the university’s department of chemical engineering.
There are many advantages to using ultrasound in this way, said Prof Husseini.
Ultrasound waves are non-invasive and, when applied at the right frequency and dosage, do not harm the patient. Using certain types of ultrasound is well established in hospitals. They allow, for example, parents to see images of their unborn child.
If being used in cancer treatment, ultrasound waves can be carefully controlled and focused on a particular area of the body.
Other benefits include their ability to strengthen the effect of the drugs and the way they can help transport the drugs through tissues and membranes. The heat ultrasound creates – again, localised to the site of illness – can help to kill off cancerous cells.
A paper co-authored by Prof Husseini said ultrasound had also been investigated as a way of improving the effectiveness of chemotherapy when the drugs used are not in carrier particles.
Ultrasound has also been used separately from chemotherapy to treat types of cancer, including pancreatic, liver and prostate, although these techniques are at an early stage of development.
Research into ultrasound to activate drug-containing liposomes or micelles is part of a wider research effort by scientists across the globe, using nanoparticles to deliver anti-cancer drugs, often without ultrasound.
Typically, nanoparticles migrate to cancer cells because they have specific antibodies attached. The antibodies might home in on a particular protein that is attached to the surface of the cancer cells.
One study this year showed the potential such methods have for treating cancer. Published in the journal ACS Nano, the research carried out in the Netherlands found that mice were less likely to develop early-stage tumours if injected with nanoparticles that held a drug to block enzymes useful to cancer cells.
Mice injected with nanoparticles without the drug developed larger numbers of these tumour nodules, on average.
An antibody that targeted tumour cells was attached to the external surface of the nanoparticles to make them hunt out cancer cells. As noted by Science, which also reported the research, earlier tests by other scientists found that the same drug, when not packaged safely in nanoparticles, killed mice.
While his work involving ultrasound is at an earlier stage, Prof Husseini is looking ahead to the time when his methods could also be assessed in vivo.
“We need two to three more years to start in-vivo studies. This will give us the chance to synthesise and examine the feasibility of four to five different carriers and their susceptibility to ultrasound,” he said.
But more funding is needed. Prof Husseini said his group, set up in 2012 with an AUS grant, was looking for external financing. “We hope that research and government institutions would consider funding the next stages of our project,” he said.
Updated: May 2, 2015 04:00 AM