Gene therapy for diabetic neuropathy

Blisters to the feet, a mere annoyance for most people, are a grim and sometimes life threatening danger for diabetics, whose ulcerations can be so serious that they require amputation of the lower leg. These injuries occur because of nerve degeneration, which reduces pain perception the lower leg. Although the biochemical link between hyperglycemia and this peripheral neuropathy remains a matter of debate, the same symptom occurs in patients with type I and type II diabetes and can be observed in animal models of both conditions. Isner and his colleagues recently showed that a similar neuropathy, this one arising from ischemia in the hindlimbs, results from loss of blood flow within the vessels that support the nerves, and they found that this response can be blocked using VEGF therapy to increase the growth of these vessels. Here, the same group shows that diabetic neuropathy causes a dramatic loss of vessels in the sciatic nerve in rat and rabbit models of diabetes. Systemic injections of naked DNA encoding VEGF restore vascular function and blood flow within this nerve and can maintain or even restore nerve function. Based on some tests of VEGF gene therapy on humans, including some diabetics, the authors suggest that this treatment may not led to complications that result from uncontrolled vascular growth in other tissues.