First Stem Cell-Based Therapy Trial for Peripheral Arterial Disease
DURHAM, N.C. – Shortly before Christmas, James Wilkerson should learn whether a novel cell therapy treatment he received at Duke University Medical Center using his own bone marrow cells will save him from having his foot amputated.
A multidisciplinary team of researchers at Duke plans to enroll at least ten patients like Wilkerson in a pilot Phase I trial to test this novel approach, which involves removing bone marrow cells from patients, isolating specialized stem cells involved in arterial formation and repair, and then injecting these cells into tissue starved of blood supply.
Wilkerson, a 72-year-old retiree from Clarksville, Va., is believed to be the first person in the U.S. to receive such a cell-based therapy to restore blood flow-starved tissues in his leg.
He suffers from critical limb ischemia, the most severe form of peripheral arterial obstructive disease. The condition is characterized by blocked or destroyed arteries in the leg. Over time, the lack of nutrients and oxygen carried by the blood can cause tissue death and gangrene. In Wilkerson's case, a wound on his left foot will not heal and if left untreated, will necessitate amputation.
"The Duke doctors tried everything they could think of to save my foot, so this new stem cell procedure is my last resort," said Wilkerson, who received the treatment Sept. 27. "I'm hoping and praying that this is going to work – it could be a big breakthrough for me and people like me. Even if it doesn't work for me, I'm sure that what they learn will help someone else in the future."
"Mr. Wilkerson has undergone numerous procedures to try to restore blood flow, but they haven't worked," said Duke vascular surgeon Jeffrey Lawson, M.D., Ph.D, who along with Nelson Chao, M.D., and Michael Murphy, M.D., are principal investigators of the trial. "We are hopeful that ultimately this approach will stimulate the growth of new blood vessels to restore circulation to these starved muscles. This is his last option short of amputation."
The researchers said that by 12 weeks after Wilkerson's procedure, they will be able to determine whether or not the injection of his own cells helped restore enough blood flow to his foot to forestall amputation. Based on the results of a recent clinical trial in Japan, in which 39 out of 45 patients saw improvements in limb perfusion (Hiroaki Matsubara, Kansai Medical University, Osaka, Lancet, Aug. 10, 2002), the Duke team is encouraged that this cellular-based therapy could be effective.
In the clinical trial, researchers will first remove bone marrow from the hip by means of long needle, just as they do during bone marrow transplant procedures for other conditions. The bone marrow is then sent to Chao's laboratory.
"From these bone marrow cells we can isolate a specific type of cell known as vascular progenitor cells," Chao said. "These cells are responsible for the development of blood vessels in early life as well as vascular repair in adulthood. These progenitor cells are capable of secreting angiogenic factors that can stimulate the growth of new blood vessels."
Chao, who leads Duke's Division of Cellular Therapy, said that while the process of isolating these specialized cells from bone marrow is common in his laboratory, this is the first time such cells have been directly injected into damaged tissue in the hope of restoring blood flow.
Wilkerson received a total of 41 injections of his vascular progenitor cells at different points between his right knee and ankle. The researchers hope at a minimum to be able to restore enough blood flow to allow the wound to heal or to be able to perform a skin graft.
The Duke team said this pilot trial's main goal is to prove that this approach is safe, and they plan to use the results to gain support from the National Institutes of Health for a much larger clinical trial.
If this pilot trial proves safe, the team plans to expand their research to study additional approaches, ranging from injecting the cells into different locations to growing the cells with other agents, such as vascular endothelial growth factor (VEGF), to improve the potency of the progenitor cells.
"What we learn from this trial could possibly apply to other areas of the body, such as the heart," Murphy said. "While leg muscle is different than cardiac muscle, the leg can be a safe place to be doing such promising work.