Study Investigates Use of Stem Cells to Treat Severe Coronary Artery Blockage
MADISON - Steve Myrah has traveled to Costa Rica and Belize to admire exotic birds. He's journeyed to South Africa on an animal-watching excursion. And this summer, the 68-year-old retired university administrator and his wife are planning to sail the Aegean Sea.
He's traveled the world, but Steve Myrah can't walk a block down his own street without having chest pains.
Having suffered from severe coronary artery disease since his mid-40s, Myrah is participating in a trailblazing clinical trial investigating whether a person's own stem cells can stimulate the growth of new blood vessels in the heart.
"I used to walk home four miles from work. I mean, I used to cross-country ski and go hiking, and now I can't do any of that without getting angina," says Myrah, a Middleton man who is the first patient to be enrolled in the University of Wisconsin School of Medicine and Public Health portion of the national study, sponsored by the Cellular Therapies business unit of Baxter Healthcare Corporation.
UW is one of 14 sites in the phase II clinical trial, investigating the use of adult stem cells to treat patients with a severe type of coronary artery blockage called chronic myocardial ischemia (CMI). Myocardial ischemia is a serious heart condition that results in limited blood flow to the heart, affecting hundreds of thousands of new individuals each year.
Promising Treatment Offers New Hope
Like Myrah, patients eligible for the study have exhausted other conventional "revascularization" treatments to restore blood flow in the heart, such as surgical coronary artery bypass or angioplasty.
"In patients without conventional revascularization options who have failed medical therapy, this treatment strategy offers the potential of new hope for improved quality of life," says Amish N. Raval, MD, head of cardiovascular regenerative medicine at the UW School of Medicine and Public Health. Raval is the principal investigator for UW's portion of the study.
After several treatments failed for Myrah, he says he's optimistic about the innovative new treatment - though he recognizes that he might have received a placebo rather than his stem cells.
"I'd settle for half as much chest pain as I have now," says Myrah, who daily wears time-release nitroglycerin patches to help ease the pain. The patches must be removed for eight hours a day, so he also takes four to seven under-the-tongue nitroglycerin pills a day.
"Sometimes I have to take one when I'm just sitting there. Sitting and watching the Badgers play basketball is always good for a couple," jokes Myrah, who enjoyed a long career at UW-Madison, retiring in 2001 from his position as Secretary of the Academic Staff.
When his chest pains first surfaced in the 1980s, Myrah underwent his first angioplasty, a procedure to restore blood flow through several narrowed arteries in his heart.
"I felt wonderful for a few weeks," Myrah recalls.
But the chest pains soon returned. Doctors performed angioplasty a second time, with the same short-lived benefits. During his third angioplasty, Myrah's cardiologist used a more aggressive approach that helped relieve his chest pain for nearly a decade.
By 1993, when Myrah was in his mid-50s, the pain returned once again. After having five-vessel coronary artery bypass surgery, Myrah enjoyed another decade of relief from his chest pain. But in 2003, the angina started yet again.
His cardiologist explained that small vessels in the back of his heart were causing the problems, but they couldn't be reached for further surgical treatment.
"So they've been treating it with medication ever since, but what I can do is limited," said Myrah.
Using Stem Cells to Stimulate Vessel Growth
As the first patient in UW's portion of the clinical trial, Myrah was injected last week with a protein that helps to release adult stem cells called CD34+ from his bone marrow into his bloodstream. Next, Myrah was connected to a special cell separation system to collect the CD34+ stem cells from his bloodstream - a process called apheresis.
"I wouldn't go through all of this if I didn't think it was worth it," Myrah said with a smile, about halfway through the all-day apheresis process (pictured, above left).
The next day, Baxter's cell selection system removed the CD34+ cells from the other cells also collected during apheresis. That afternoon, Raval used data from electrical and mechanical mapping of Myrah's left ventricle to target the area of his heart with poor blood flow.
Raval then injected the stem cells, or a placebo, directly into Myrah's heart muscle using a special cardiac catheter.
This innovative new area of research is called regenerative medicine - treating disease by using growth factors, genes or stem cells to promote blood vessel or tissue growth. Raval says he and his UW research associates have focused on adult stem cells for several reasons.
"Adult stem cells are 'precursor' cells that dwell in almost all organs in the body and have the potential to turn into a limited number of cell types," Raval explains. "Current research is aimed at removing a person's own adult stem cells from the bone marrow and placing them into other body organs to repair damaged tissue."
With chronic myocardial ischemia (CMI), this approach has shown promise in a previous study. In a phase I trial investigating the CD34+ stem cell injections into the hearts of CMI patients, 15 of the 18 total subjects who received the cells reported feeling better - with reductions in chest pain and/or improved exercise capacity. These results prompted Baxter Healthcare Corporation to sponsor the larger, phase II trial to investigate the safety, tolerability and effectiveness of the new stem cell treatment.
Approximately 10 volunteers are being recruited for the UW arm of the study.
For Steve Myrah, much of the motivation for participating in the study could be found at the Pheasant Branch nature conservancy near his Middleton home. There, his wife Dagny enjoys going on walks to enjoy the lush prairies and wooded hills along the nature trails.
"She misses me," Myrah says. "That's something I'd really like to be able to do with her someday."
Study Enrollment Details
Subjects in the current phase II study are randomly selected to receive either one of two dosing levels of CD34+ stem cells, or placebo. Researchers will conduct follow-up examinations for 12 months following the investigative procedure.
To be included in the study, patients must:
- Be at least 21 years old
- Experience chronic chest discomfort at rest and with minimal exertion
- Have found inadequate relief from medications
- And be unsuitable candidates for conventional revascularization techniques, such as surgical bypass, angioplasty or stents
For more information, contact study coordinator Soni Vander Ark, RN, at (608) 265-0612.
Date Published: 06/06/2007