LONDON — Injecting patients' own stem cells into their leg muscles could create new blood vessels, eliminating pain from poor circulation and helping to prevent gangrene or amputations, new research indicates.
The study, described in the medical journal the Lancet, is the first demonstration that implanting stem cells into humans can result in new blood vessel networks, a process called angiogenesis.
Experts say the findings offer hope to millions of people who suffer pain in their limbs because of clogged arteries but can't undergo surgery for the condition.
Controlling blood vessel growth is an emerging field of medicine. In the case of cancer, which spreads by sprouting its own blood vessel network, scientists are testing drugs to thwart angiogenesis.
But when parts of the body are starved of oxygen because blood vessels supplying them are blocked, doctors want to boost blood vessel growth.
The main focus of research is on the heart and limbs, and study of the brain is being planned. Heart attacks, limb amputations and strokes can result from severe circulation problems, as can sores that fail to heal.
"This is truly a landmark paper because of its use of stem cells to induce angiogenesis," said Dr. William W. Li, president and medical director of the Boston-based Angiogenesis Foundation, who was not involved in the research.
"It's a brand-new approach to treating limbs starved of blood supply," Li said.
One question that remains is whether the stem cells actually became blood vessel cells or whether they released growth factors that prompted other cells to construct new vessels.
The study was done by scientists at three Japanese universities: Kansai Medical University in Osaka, Kurume University School of Medicine in Kurume and Jichi Medical School in Tochigi.
It involved 45 people with severe blood circulation problems in their legs. About half had already had a bypass operation in their legs, nearly half had gangrene, and 69% had diabetes. Many had sores that wouldn't heal, suffered pain in their legs even when sitting and were not candidates for surgery or other artery-widening techniques.
The legs that received the stem cells had more improvement than the others on a test comparing blood pressure. Similar results were seen in a second circulation test that measured differences in oxygen inside and outside tissues.
After their legs were injected with stem cells, 16 of the 20 people in the main study no longer experienced pain while sitting down.
X-rays before and after the implantation showed increased blood vessel networks in 27 of the 45 stem cell recipients.