Growing New Blood Vessels and
Providing Options
Exciting new developments are occurring in angiogenesis research - the study
of growth factors used to increase the blood supply to areas in need of more
blood. “In other words,” says Timothy Henry, M.D., “angiogenesis is our attempt
to enhance the body’s natural process of blood vessel development."
Collateral blood vessel growth
enhanced by angiogenesis. Dr. Henry, who joined the Minneapolis Heart Institute Foundation in October
as the new director of research, is a leading international expert in the field.
“Therapeutic angiogenesis is an exciting new approach to the treatment of
patients with coronary artery disease. It offers hope to the growing patient
population with coronary and peripheral artery disease not amenable to the
traditional therapies of bypass surgery or angioplasty," explains Dr. Henry.
"Our long-term goal is that it might eventually become an alternative to high
risk bypass surgery and angioplasty, and as such, may represent the next major
advancement in the treatment of heart disease."
The growth factors Fibroblast Growth Factor (FGF) and Vascular Endothelial
Growth Factor (VEGF) are naturally produced in our bodies to trigger the growth
of tiny arteries (collateral vessels or collateral arteries) in areas where
blood flow is limited. For example, when the coronary arteries that deliver
blood to your heart muscle are narrowed or blocked because of fatty deposits,
your body will secrete FGF and VEGF to grow new collateral vessels. These new
arteries will deliver blood flow to the areas that are compromised.
James Letexier, the first
person to receive gene therapy in Minnesota, with his cardiologist, Timothy
Henry, M.D. However, collateral arteries are much smaller than the major arteries in your
heart and deliver smaller amounts of blood flow to the heart muscle. Sometimes
patients do not grow enough collateral vessels to prevent angina (chest pain)
from occurring. This is where angiogenesis research may help. By giving more of
what your body produces naturally – i.e., growth factors specific to blood
vessels, such as VEGF and FGF - new blood vessels may be grown which will
improve the blood supply to the heart and decrease angina.
Different approaches are being studied to provide the best blood vessel
growth. First, in early clinical trials, the proteins FGF and VEGF were given to
promote angiogenesis. Results have been encouraging and further research is
planned. Second, in gene therapy, the genetic code (DNA) for the growth factor
is given directly into the heart. This gene is absorbed into the heart muscle
cells which then produce the growth factor which will help develop new blood
vessels. Either the protein or the gene can be given by injection into the
coronary artery (like an angiogram) or directly into the muscle (during surgery
or a procedure similar to an angiogram). Dr. Henry and his colleagues continue
to investigate both the ideal method in which to deliver the growth factor as
well as the best growth factor or combination of growth factors to use.
All these approaches are still investigational and are available only in
clinical trials that are under the supervision of the U.S. Food and Drug
Administration (FDA). Angiogenesis research trials require an extensive
screening process to evaluate whether a patient is qualified for the study.
Related areas of research include growth factors for severe peripheral artery
disease (for patients with leg pain and/or ulcers) and myogenesis, which will
utilize muscle cells from the leg to replace heart muscle cells damaged after a
heart attack.
"We're very optimistic about this new frontier in the treatment of heart
disease," concludes Dr. Henry. "It's tremendously exciting to be a part of
it."
Patients who are interested in learning more about the clinical trials
underway should contact Mari Jordan at 612/863-3976 or email at mari.jordan@allina.com.
