Research into a new treatment for nerve damage caused by diabetes could bring relief to millions of diabetic patients, say experts.
The treatment might also reduce the number of amputations of toes and feet if early effects on nerve protection and regeneration are borne out long-term. Nerve disease in diabetes is the major cause of non-traumatic lower limb amputations in Europe and North America.
Scientists at The University of Manchester, working with colleagues at American biotech firm Sangamo BioSciences Inc, have discovered a way of stimulating genes that prevent nerve damage caused by the disease.
Professor David Tomlinson, who is leading the research in Manchester, says the study has massive potential for the management of diabetic neuropathies or nerve disorders.
"Diabetic neuropathy is a major problem in insulin-dependent diabetes, particularly in patients who have had the disease for a period of time," said Professor Tomlinson, who is based in the University's Faculty of Life Sciences.
"This approach to gene therapy is quite different to previous attempts at treatment as we do not inject a gene that produces a 'foreign' copy of a therapeutic protein. This is the normal approach and has problems from immunological side-effects.
"Instead, we turn on the patient's own gene to produce a natural version of this therapeutically beneficial protein. The most significant advantage of this is that the protein is made as if the patient's body had made it naturally.
"Our study has shown that a single treatment with a DNA-binding protein protected against nerve damage that in humans can lead to limb loss."
The results of the pre-clinical studies were recently presented to the American Diabetes Association in California and the first phase of clinical trials has now begun.
An estimated 50 per cent of patients with long-term diabetes develop some form of neuropathy that can cause numbness and sometimes pain and weakness in the hands, arms, feet and legs.
Currently, patients are treated with painkillers and antidepressants that do not treat the underlying nerve damage. Progression to amputation is not inevitable but is always a threat.
Problems may also occur in other organs, including the heart, kidneys, sex organs, eyes and digestive tract.
The incidence of diabetes, a condition in which the amount of glucose in the blood is too high, is increasing dramatically, with the World Health Organisation estimating that some 300 million people worldwide could be affected by 2025.
The causes of diabetic neuropathy are not fully understood but researchers investigating the effect of glucose on nerves believe it is likely to be a combination of factors.
Sangamo's Chief Medical Officer, Dr Dale Ando, said: "We have been greatly encouraged by Professor Tomlinson's data and have moved the programme into the clinic.
"The first phase of human trials will assess safety and examine the effects of a single treatment in one leg compared with a placebo treatment in the other leg."
The Diabetes and Glandular Disease Clinic in San Antonio, Texas, is involved in the clinical trials.
Dr Mark Kipnes, a clinical investigator for Sangamo and endocrinologist at the clinic, said: "Currently, there are no effective therapies available to treat this debilitating and frequent complication of diabetes and patients are generally prescribed painkillers to alleviate symptoms.
"We are excited to be involved in testing this novel approach that may potentially have a dramatic therapeutic effect in populations of patients already suffering from neuropathy and those that are at risk of developing it."