Light at the end of the tunnel for persistent pain sufferers

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, writes Karyn Markwell from the Australian Pain Management Association (APMA).
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.
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 ground-breaking discovery of a small team of scientists at a university in the United States.
The discovery
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.

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“So ground breaking 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.”
KATHRYN MARKWELL

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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 ground breaking 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.
The team
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.
But Professor Delp, who has a special interest in muscles and movement in the human body, has already recognised the potential of using optogenetics to study the nerves that control not only pain, but also movement, touch and other sensations throughout our body. In fact, it was a few years ago when Professor Delp’s team was exploring the use of optogenetics to control muscle movement that they discovered – by accident – that the opsins were also affecting the nerves that signal pain.
“We thought ‘wow, we’re getting pain neurons, that could be really important’,” recalled Professor Delp.
Consumer review: MedicineList+ smartphone app
MedicineList+ is a free app for Android and iPhone produced in Australia by NPS MedicineWise (www.nps.org.au). It was designed to help consumers to remember when to take their medication, but its benefits are much further reaching. MedicineList+ allows users to scan barcodes directly from medication packaging, to create a personal and interactive medication list. The app’s alert feature reminds users when to take each medication.
The app enables users to keep all of their health and medical information together, by recording their health (height and weight, allergies/reactions, medical conditions, etc) and results from medical tests. The portability of the smartphone technology means that this information can easily be shared with a GP or pharmacist, who can then make the most informed decisions possible regarding future medication and care.
In case of accident or injury, MedicineList+ allows users to enter emergency contact information, treating doctors’ contact details and even details of their Medicare and private-health information and government-issued benefit cards.
One handy aspect of the MedicineList+ app is the ability to record all of this information for multiple people on the one app.
Those who are accustomed to smartphones would find MedicineList+ easy to use. But those who aren’t comfortable with this technology might prefer either the paper or online versions available from NPS MedicineWise.
The MedicineList+ app was independently trialled by a member of the Australian Pain Management Association, who has lived with persistent pain for more than 20 years.
The encouraging discovery of the light-sensitivity research provides Professor Delp with hope that the nerves which are affected by chronic conditions, such as motor neurone disease, may also receive significant improvement from optogenetics. It is not overstating the fact to say that this discovery has the potential to have far-reaching effects in the fields of bioengineering, neuroscience and even psychiatry, with experts claiming that optogenetics could, in future, play a role in managing everything from brain disease to alcoholism. Professor Delp’s team is eager to share their findings with other scientists who want to improve on the technology.
“It’s a completely new tool that is now available to neuroscientists everywhere,” said Professor Delp.
The research which resulted in the light-sensitivity discovery was led by two graduate students, Shrivats Iyer and Kate Montgomery. Like Professor Delp, the pair are already recognising that their research will likely be the foundation of ongoing medical and scientific discoveries; but for now, they are focusing on what they know for certain: that they have been able to use light to control pain.
“One of the first ways we see this technique being used is chronically stimulating different neuron populations and seeing how chronic stimulation (or inhibition) of these fibers changes the development of different pain models,” said Ms 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.”
The future
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 team started with a virus that had been engineered to contain the DNA that produces the opsin, which they then injected directly into the nerves of the mice. It was only a fortnight later – a short time in the world of clinical research – that the nerves that control pain had incorporated the opsin proteins and the team discovered the effect of the light upon those nerves.
Mr Iyer said that the virus’s quick response is a huge advantage.
“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 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.
Developing a new therapy from the ground up would be incredibly rewarding,’ Professor Delp said. “Most people don’t get to do that in their careers.’’
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.
“This powerful approach shows great potential for helping the millions who suffer pain from nerve damage. 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.”
Karyn Markwell,
Media Manager
Karyn Markwell is the media manager for the Australian Pain Management Association (APMA), a non-profit, evidence-based community organisation which assists people with persistent (chronic) pain. APMA gives people hope that with the right treatment and life skills, their pain will improve and they can start to enjoy life again.