Light at the end of the tunnel
For the 3.5 million Australians who live with persistent pain, new research into using light to turn pain on and off could literally be the light at the end of the tunnel.
With increasingly more and more medical professionals, consumer organisations and healthcare policymakers acknowledging that persistent pain is one of the biggest healthcare crises in Australia today – with wide- reaching financial and ethical burdens – comes additional pressure for sustainable pain- management solutions.
A large burden
Many of the one in five Australians – and one in three aged 65 years and older – who have persistent pain rely on medication, such as opioids, simply to be able to get out of bed each day. This is an inadequate solution for the individual sufferers, not to mention a huge cost to the country: persistent pain places a great financial burden on Australia, with the overall costs in the same range as cancer and cardiovascular disease. In fact, persistent pain is Australia's third-most- expensive health problem, costing the country $34 billion each year.
This is why so many people in Australia – from pain sufferers to pain-management specialists to politicians – have taken notice of the groundbreaking discovery of a small team of scientists at a university in the United States.
Researchers from Stanford University in California recently discovered a way to turn pain on and off, using light.
The team of scientists from Stanford Bio-X, an innovative laboratory dedicated to breakthroughs in biological research, have used the burgeoning field of optogenetics – a way of manipulating nerves by using light – to control pain.
Under a set of controlled but replicable conditions, the researchers modified the genes of laboratory mice by injecting light- sensitive proteins (called opsins) into the nerves in their paws. After a couple of weeks, the scientists shone light on the paws of the mice through the glass bottom of the cage and discovered that the nerves had become sensitive to light.
The team of scientists continued their trials and discovered that one colour of light (blue) caused the mice to flinch and lick their paws, indicating a pain response, while another colour of light (yellow) made the mice less sensitive to both thermal and mechanical stimulation of pain. In fact, the range of different colours within the light colour spectrum achieved different degrees of either pain-activating or pain- inhibiting sensation when shone on the paws of the mice. Notably, the mice developed an aversion to all shades of blue light and, when given a choice,would avoid entering areas of the cage which were illuminated with blue light.
So groundbreaking is this new discovery that these mice are even helping scientists to rewrite the book on pain: exactly what pain is, how and why pain occurs, and why millions of people worldwide continue to experience pain for up to decades after their original accident or injury has healed.
It is still early days, but so encouraging is this new discovery that scientists who have questioned whether persistent pain changes the biological structure of nerves, are asking whether they can now be changed back to their pre-injury state.
Professor of bioengineering and mechanical engineering, Scott Delp, heads up the Stanford Bio-X laboratory which made the discovery. Even as his laboratory team continues to fathom the full extent of what they have discovered, Professor Delp already has one goal in mind: that one day his team's discovery will help to improve the lives of people who have persistent pain.
'This is an entirely new approach to study a huge public health issue,' Professor Delp said shortly after his team publicly released the details of their discovery. The research which resulted in the light- sensitivity discovery was led by two graduate students, Shrivats Iyer and Kate Montgomery.
Linda Porter, the pain-policy advisor at the National Institute of Neurological Disorders and Stroke in the United States also recognises the enormous potential of the new discovery.
'This powerful approach shows great potential for helping the millions who suffer pain from nerve damage,' Ms Porter said. 'Now, with a flick of a switch, scientists may be able to rapidly test new pain- relieving medications and, one day, doctors may be able to use light to relieve pain.'
A central element which led to the team's initial discovery was a new approach which enabled them to rapidly incorporate opsins into the nerves of the mice.
'The fact that we can give a mouse an injection and two weeks later shine a light on its paw to change the way it senses pain is very powerful,' Mr Iyer said.
This speed will greatly assist the research team as they continue to explore all of the possibilities which are connected with optogenetics being used to treat pain. But, because pain is largely misunderstood and under-researched, the field of pain is a vast one to explore, document and control.
Also, the new technique does have some limitations. One drawback is that the genetic modification in the mice started to lose effectiveness after four to five weeks following the initial injection. Another issue is that the technique is invasive: requiring surgery and injection into the nerves – which is not a pleasant prospect for the many millions of people worldwide who suffer from neuropathic pain.
Professor Delp has confirmed that his team have many challenges ahead and much still to learn before their findings can be used to improve the lives of people with persistent pain. But, so great is the need for a practical solution to the global epidemic of persistent pain, that he is adamant that this be the focal point of his team's ongoing research.
While, along with the Stanford Bio-X scientists, there is a lot that we still do not understand about persistent pain, what we do understand is that this new discovery has the potential to transform the lives of millions of persistent-pain sufferers around the world.