Walking barefoot on sand "felt like walking on glass" for Keith Wenckowski, who has lived with type-one diabetes for more than two decades.

One of the participants in a new Northwestern Medicine study who suffered from painful diabetic neuropathy (PDN), Wenckowski finally found relief from the constant foot pain that required him to wear shoes at all times, even to the beach.

The study found that those with PDN who received two low dose rounds of a non-viral gene therapy called VM202 had significant improvement of their pain that lasted for months.

"I can now go to a beach and walk on the sand without feeling like I am walking on glass," Wenckowski said.

The results of this phase two, double-blind, placebo-controlled study will be published March 5 in the journal Annals of Clinical and Translation Neurology.

Right now there is no treatment for this disease of the peripheral nerves that affects 20 to 25 percent of diabetics. Patients with the most extreme form of the disease feel intense pain with a slight graze or touch. The pain can interfere with daily activities, sleep, mood and can diminish quality of life.

"Those who received the therapy reported more than a 50 percent reduction in their symptoms and virtually no side effects," said Dr. Jack Kessler, lead author of the study. "Not only did it improve their pain, it also improved their ability to perceive a very, very light touch."

Kessler is the Ken and Ruth Davee Professor of Stem Cell Biology in the department of neurology and a professor in the department of pharmacology at Northwestern University Feinberg School of Medicine. He also is an attending physician at Northwestern Memorial Hospital.

VM202 contains human hepatocyte growth factor (HGF) gene. Growth factor is a naturally occurring protein in the body that acts on cells -- in this case nerve cells -- to keep them alive, healthy and functioning. Future study is needed to investigate if the therapy can actually regenerate damaged nerves, reversing the neuropathy.

Wenckowski had continuous numbness, but now, more than a year since he received the therapy, his symptoms have not returned. "I am hoping the effects I am feeling do not cease," he said.

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Neuropathy: Relief for diabetics with painful condition