I often cover orthopedic stem cell studies and breakthroughs, but given that heart disease is still the nation’s number one cause of death, I thought we’d take a detour this morning. Most of the stem cell therapy studies focused in this area have either focused on bone marrow mesenchymal stem cells or cells derived from the heart muscle. However, new research shows that there may another stem cell type we should be using, those derived from blood vessels.
What Happens During a Heart Attack?
A myocardial infarction (commonly known as a heart attack) occurs when there is a blockage in a coronary artery and oxygenated blood can no longer get to the part of the heart that it supplies. A blockage can result from a slow buildup of plaque in the artery over time, and while this buildup can eventually block off blood supply to the heart, the smaller vessel can also become blocked when a piece of plaque breaks off a blood vessel, travels through the vascular system, and forms a clot in a coronary vessel, cutting off blood and oxygen supply to any heart tissue beyond it.
During a heart attack, the ischemic heart muscle tissue made up of cardiomyocytes (heart muscle cells) becomes damaged and dies. Scar tissue forms in its place. In much of our other body tissues, local stem cells would rush to the damaged tissue and begin the repair and regeneration process; however, self-repair is extremely limited in the heart muscle. So a heart attack typically damages the heart beyond our body’s natural ability to repair the tissue.
Most of the research in this field of cardiac muscle regeneration has focused on either stem cells derived from bone marrow or the heart muscle itself. However, recently, researchers have discovered that stem cells in the walls of the coronary blood vessels may be the key to regenerating heart muscle tissue. Let’s take a look at the study.
In Culture, Stem Cells in the Blood Vessel Walls Can Differentiate into Beating Cardiomyocytes
In a new study, researchers set out to investigate if stem cells that live in the vascular walls had the potential to differentiate into heart muscle cells (cardiomyocytes), which would allow these cells to repair and regenerate damaged heart muscle tissue. In cultured vascular-wall stem cells, researchers discovered that these stem cells can indeed differentiate into beating cardiomyocytes (heart muscle cells). But there’s a problem. In mice, a heart attack stimulates the vascular-wall stem cells to action, which then migrate to the damaged tissue; however, the cells at that point are hung up in the scar tissue and cannot differentiate into the specialized cardiomyocytes. The researchers’ hope is to be able to find therapeutic avenues that will enable these coronary blood-vessel-wall stem cells to regenerate the heart muscle to repair damage after a heart attack.
More on Cell Differentiation
I recently discussed the difference between stem cells (e.g., the stem cells in the coronary vessel walls we are discussing here today) and specialized cells (e.g., the cardiomyocytes in this case). As mentioned, in culture, these vascular-wall stem cells can differentiate and become specialized heart muscle cells. So what is differentiation exactly? When a cell is dying, a chemical reaction simulates local stem cells (meaning stem cells in the area), which move into the damaged area and then divide. This creates both a progenitor cell and a reserve stem cell. The progenitor cell transforms into the specialized cell it is replacing. Learn more below.
While this differentiation process occurs naturally in many tissues throughout our body, this repair and regeneration process, as mentioned before, is very limited in heart muscle tissue that is damaged and dying. Perhaps this newest study will lead to ways to repair the heart following a heart attack in the future.
The upshot? This most recent study is a good thing for those of us with a history of heart disease in the family. Why? If a patient survives his or her first heart attack, he or she is often never the same because of this scarred down and dead heart muscle. In those patients, having many cellular tools to inject directly into that scar that will break it up and regenerate new heart muscle could mean the difference between a very limited and a normal life.