Neurotrophic factors in the treatment of peripheral neuropathy.

Peripheral neuropathies are common and frequently debilitating disorders which may include various subpopulations of motor, sensory or autonomic neurons depending on the underlying aetiology. They are likely to be the first group of neurological disorders to be successfully treated with growth factors since peripheral nerves are accessible to proteins given systemically. Preclinical and ongoing clinical trials of nerve growth factor (NGF) suggest that it will be useful for the treatment of diabetic, toxic and compressive sensory neuropathies. At appropriate doses NGF has no significant side effects in humans. Since NGF administration to mature animals stimulates synthesis of brain-derived neurotrophic factor and perhaps other neurotrophins in peripheral nerves, the spectrum of neuropathies treatable with NGF is wider than might be predicted. Preclinical studies suggest that insulin-like growth factor 1 (IGF-1) will be useful for the treatment of mixed motor and sensory neuropathies. For example, IGF-1 treatment can prevent the experimental motor and sensory neuropathies caused by the antitumour drugs, vincristine and cisplatin. Other neurotrophic factors have also shown promise in preclinical trials. The successful use of growth factors in the treatment of peripheral neuropathies may provide the first true therapy for this previously untreatable and devastating group of neurological disorders.