Stem cells are found throughout the cellular makeup of humans and animals. There are at least two major types of stem cells, called embryonic and adult stem cells. Unlike embryonic cells, which are harvested from fertilized eggs, adult stem cells exist in mature tissue throughout the body. Many researchers consider adult stem cells from humans to be vital to the improvement of medical technology, yet a portion of the public feels it is an ethical violation to experiment on human tissue.
Adult stem cells are found in many areas of the body, including the brain, heart, stomach, skin, bone marrow, and muscles. Like a blank disk, stem cells are essentially identical, but can be imprinted with a variety of different genetic signals as needed. Most of the time, adult stem cells lie dormant in the body. When an injury or disease causes tissue damage, adult stem cells begin to divide and take on the characteristics of the attacked tissue cells, in order to heal the body and allow it to function normally.
Many scientists believe that adult stem cells can play a vital role in advancing treatment and cures for many diseases. In stem cell therapy, adult cells can be harvested and genetically modified by doctors to create the type of cell a patient needs. The cells can then be put back into the patient to help control or cure his or her disease. Experts suggest that the ability to use a patient's own cellular material to cure him or her will lessen the chance of transplant or therapy rejection, as the body will be less likely to attack its own cells.
Since stem cell research began in the late 20th century, medical experts have made several early advances in the fight against cancer and blood disorders. Some believe adult stem cells may hold the cure to diabetes, as laboratory testing has shown that stem cells can be manipulated to start producing the insulin a diabetic patient lacks. Many experts also suggest that, using stem cells, organs can be grown from a patient's own genetic material, allowing for better and more successful transplants and organ replacements.
There is considerable debate about whether using embryonic stem cells from humans is ethical. While many agree that the use of adult stem cells is more palatable, some critics argue that experimenting on any type of human tissue may lead to a slippery slope of less acceptable experiments. Nevertheless, adult stem cell research is often touted as a solution to the ethical problems posed by experimenting on fertilized human eggs. Influential establishments concerned with ethics, such as the Catholic Church, have come out in strong support of adult stem cell research.