What is the number one killer of Americans? Heart disease. Yes, heart disease affects millions of adults in the United States. According to the Centers for Disease Control and Prevention, one in every four deaths is caused by heart disease, which accounts for about 600,000 deaths annually. Every 60 seconds someone is killed by a heart attack. Also, about 935,000 people have a heart attack every year. Among these 935,000 people, 610,000 have their first heart attack, and 325,000 heart attacks happen in people that have had a heart attack before sometime in their life. These staggering facts and statistics have led scientists and researchers to try to develop prevention for this deadly disease.
The heart is an organ about the size of your fist. Its function is quite intricate. The heart is responsible for pumping blood throughout the rest of the body, and it has a complex network of vessels, chambers, and pathways that the blood goes through. First, the blood that is unoxygenated enters the right atrium. It then passes through the tricuspid valve, which leads the blood to the right ventricle. After reaching the right ventricle, the blood goes through another valve and comes into the pulmonary artery. The pulmonary artery takes the blood to the lungs where is receives oxygen, therefore becoming oxygenated. Oxygenated blood returns to the heart by pulmonary veins and enters the left atrium. It then passes the bicuspid valve and gets to the left ventricle. Blood passes through another valve and comes to the aorta, or the largest artery in the body. Lastly, the aorta moves the blood throughout the rest of the body.
Sometimes when the heart does not function in the correct manner, many complications can occur. People can develop different forms of heart disease and suffer from heart attacks. Some causes and predispositions to heart disease include hypertension, or high blood pressure. An individual with hypertension puts extra pressure on the heart and makes the heart work harder than it normally would. Heart disease can also be congenital, meaning that it is present from birth. Often times children can inherit the disease if it runs in the family. Other risk factors include obesity, poor diets, and physical inactivity. All of these three risk factors contribute to the development of fatty deposits, or plaque, in the artery walls. If the walls of the arteries are blocked by plaque, the heart may not receive an adequate amount of blood, or blood flow may obstruct completely. This can cause angina pectoris, or chest pain, and can also cause a heart attack.
It is extremely important to know the warning signs of a heart attack, especially if an individual is at a risk for developing the disease. Some common warning signs include shortness of breath, dizziness, squeezing pressure in the chest, and spreading pain to the neck and shoulders. Less common warning signs include pain in the abdomen, anxiety, difficulty breathing, and paleness. If an individual is having any of these symptoms, he or she needs to go to the hospital and receive medical care as soon as possible.
There are a few different ways to protect the heart so that someone is less likely to develop heart disease. For example, it is important to follow doctor’s instructions and take medications as prescribed. Most of the time doctors will prescribe medications if an individual has predisposing risk factors, such as hypertension. By treating the hypertension, doctors hope to minimize the likelihood of an individual developing heart disease. Also, it is important to eat a healthy diet low in salt, fat, and cholesterol so that plaques are not formed in the arteries. Exercising is also important because it contributes to a healthier heart.
Because heart disease remains a prominent health challenge, researchers wanted to come see if they could come up with a way to repair a damaged heart. They concluded that adult stem cells can help replace damaged heart muscle and establish new blood vessels to supply them. They based their conclusions on an experiment conducted by Orlic and colleagues. In the experiment, researchers induced a heart attack in mice by tying off a major blood vessel, the left main coronary artery. They then selected a group of adult primitive bone marrow cells that have the capacity to transform into different cell types. When these cells were injected into the damaged wall of a ventricle, the cells led to formation of new smooth muscle cells, vascular endothelium, and cardiomyocytes, thus generating new myocardium, including coronary arteries, arterioles, and capillaries. Researchers also found out that mice that received the transplanted cells survived in greater numbers than mice that did not receive the transplantation.
Another study by Jackson et al showed that heart tissue can be regenerated in the mouse heart attack model through the process of introducing adult stem cells from mouse bone marrow. Investigators purified a group of hematopoietic stem cells from a genetically altered mouse strain. The cells were then transplanted into the marrow ten weeks before the mice were subjected to a heart attack by tying off a different major blood vessel, the left anterior descending coronary artery. The survival rate for the mice that received the transplantation was 26 percent. The analysis of the experiment revealed that the region surrounding the damaged heart tissue showed the presence of donor derived cardiomyocytes and endothelial cells. Thus, the hematopoietic cells injected into the mouse marrow responded to signals of the injured heart, migrated to the region of the damaged area, and differentiated into several different types of cardiac tissue that are needed to repair the heart. This study suggests that the hematopoietic stem cells can be delivered to the heart through bone marrow transplantation as well as through direct injection into the heart tissue, thus providing another possible therapeutic strategy for regenerating injured cardiac tissue.
For more information about this research study, click here.