EDUK feature: let there be light

Cutting edge equipment is revolutionising the way we tackle some of our most serious health issues. Light amplification by stimulated emission of radiation (laser) technology doesn’t simply provide convenience in our homes and offices. Lasers are now used to diagnose, cut and heal our bodies.

 

Professor Stephen Bown, director of the National Medical Laser Centre at University College London, has been researching photodynamic therapy (PDT) to treat skin lesions and tumours. PDT is now offered in 150 centres in the UK. ‘PDT kills the living cells in skin tumours but doesn’t damage the underlying scaffolding that holds the tissue together and regenerates with remarkably little scarring,’ Bown explains.

 

The ability to administer PDT anywhere in the body using a fibre optic laser is a ‘massive breakthrough,’ says Bown. Oesophageal cancer, for example, can be treated with an injection of a photosynthesising drug that is activated by endoscopic laser treatment. Not only are such treatments cost-effective and easy to use but they also save precious surgical resources.

 

According to Harry Moseley, head of scientific services at the University of Dundee’s National Photobiology Unit, laser light can also be used to guide the surgeon’s hand. ‘We can diagnose and detect cancer using fluorescent drugs that accumulate in the tumour and photosensitise under laser light,’ he explains. ‘It gives better results than surgery alone.’

 

 

Moreover, emerging fields such as biophotonics – the study of biology, light and electronics – are rapidly fuelling cross-fertilisation between physics and medicine.

 

Deep tissue imaging using optical coherence tomography (OCT) – a light-based version of ultrasound, is currently being tested at the University of Sheffield. ‘OCT uses rapid pulses of light, perhaps the fastest 3D medical imaging method we have,’ explains Steven Matcher senior lecturer in Biomedical Engineering. ‘Compared to other optical techniques, it has a much higher resolution. (One day) we could attach an OCT probe directly onto a scalpel to give surgeons real-time guidance.'

 

Pushing the boundaries of science has been a feature of laser technology since its first demonstration in 1960 by Theodore Maiman at the Hughes Research Laboratories in California. Described as a ‘solution looking for a problem’, it has shown its versatility at every turn.

 

LASIK eye surgery was adapted from a procedure called keratomileusis, first conducted by José Barraquer in 1963. Technological improvements in the late-1980s saw ophthalmologists adopt this laser-assisted surgery to improve eyesight worldwide. More than 100,000 procedures are completed every year and complications are rare.

 

The eye was an obvious place for the pioneers of laser treatments to begin, as it is a natural light receptor. Since then, laser use has expanded into cosmetic surgery, dentistry and beyond. Port-wine birthmarks and tattoos can be removed using laser techniques and permanent hair removal is now a simple matter of super heating and destroying hair follicles.

 

PDT, meanwhile, has become a speedy out-patient procedure. Photosensitive drugs are spread on to a lesion and covered with gauze, then laser light is applied – the whole procedure takes less than an hour.

 

 

By using a needle with a laser light source, difficult-to-reach internal cancers can also be removed, as Bown explains. ‘Conventional treatment, for tongue cancer as an example, is a 10-hour operation, three days in intensive care and two weeks in hospital - there is no comparison.’

 

There are photobiology units at Dundee, Manchester and King’s College London, and the range of applications for PDT keeps growing as components become cheaper and more portable.

 

Recently, fibre laser PDT has inspired dramatic developments in treatments for pancreas and prostate cancer at the National Medical Laser Centre. Other research also suggests that linking photosynthesising drugs to antibodies can achieve greater selectivity between tumour and normal tissue.

 

This selectivity includes a technique called photochemical internalisation which breaks up cellular consuming lysosomes in tumour cells, allowing chemotherapy drugs to work more effectively. ‘If you can reduce the dose by 10 or even 100 times, then you avoid side effects, reduce costs and target it where it is needed,’ says Bown. ‘The first work on patients started last summer and the results are remarkable.’

 

 

At the University of St Andrews, neurobiologist Frank Gunn-Moore is celebrating a £1 million award to develop optical transfection devices – effectively laser syringes to inject materials such as DNA or drugs into cells. ‘It is really difficult to get compounds into nerve cells,’ he explains. ‘Using a laser our team can create permeability and reach the growth cone. It allows you to target a genetic message where it is needed.’

 

By examining cellular-level events, the team hopes to rapidly focus drug delivery and gene therapy on debilitating diseases such as Alzheimer’s.

 

Next on the St Andrews agenda is tissue engineering. Preliminary work on stem cells has shown that by inserting a gene, cells can be made to differentiate into primitive tissue. This fits nicely with work under way at the University of Sheffield where Matcher sees OCT imaging as the perfect way to monitor how tissues grow in a bioreactor. ‘When you exercise, your bone is like a sponge – it is full of pores that contain fluid. We would like to replicate those conditions in an artificial environment – a bioreactor – and then characterise that fluid flow using OCT, so we can turn tissue engineering from an art into a science.’

 

It is a distinction everyone working in medicine understands: lasers provide precision and the opportunity to drive technological breakthroughs that can fundamentally change healthcare delivery at all levels. Physics is being made to adapt to biology in ways that were unimaginable 50 years ago. In the process it is making light work of solving a number of previously incurable problems.