Stem cells are cells that can differentiate from an undifferentiated state into a variety of tissue cells, including embryonic stem cells, adult stem cells, and induced pluripotent stem cells. These cells play an important role in regenerative medicine and the treatment of incurable diseases, and while ethical issues and technical challenges remain, continued research is expected to lead to revolutionary medical breakthroughs.
Stem cells are also called hepatocytes, stem cells, and mother cells. All names imply that they are cells that can develop into any tissue. Because of this potential, stem cells offer revolutionary possibilities in the medical field, especially in the treatment of incurable diseases and regenerative medicine. Stem cells are “undifferentiated” cells, meaning they have not yet differentiated. As such, they do not yet possess the characteristics of tissue, but can differentiate into various tissue cells under the right conditions. Stem cells are primarily harvested from embryos in the early stages of division and can be cultured into specific cell lines based on prior input.
The term stem cell was first proposed by Maximov of Russia at the Berlin Hematology Society in 1908, and it wasn’t until 1963 that the existence of stem cells was proven by a team of researchers at the University of Toronto in Canada. Since then, stem cell research has expanded into many areas of life sciences and medicine, and scientists have delved deeper into the endless possibilities of stem cells. Since then, test-tube babies, mouse cloning, and the creation of Dolly the cloned sheep through somatic cell cloning in the United Kingdom and the United States have been successful, and stem cell research has gained widespread attention. In 2004, in South Korea, Dr. Woo-Seok Hwang announced that he had successfully cloned embryonic stem cells from human eggs, but in 2005, an investigation revealed that his research data had been manipulated. The case sparked a global debate about bioethics and scientific responsibility, and has since led to increased discussion about transparency and ethical standards in scientific research. In 2013, a team of researchers from Oregon Health and Science University in the United States announced that they had successfully cloned human embryonic stem cells, marking the first scientifically verified case of human embryonic stem cell cloning. This success marked a turning point in stem cell research, and the field has continued to evolve since then, overcoming a variety of ethical and technical challenges.
There are different types of stem cells. There are three main types of stem cells: embryonic stem cells, adult stem cells, and pluripotent induced stem cells. First, embryonic stem cells originate from a fertilized egg, which is created by the fertilization of a sperm, a male reproductive cell, and an egg, a female reproductive cell. Embryonic stem cells have the strongest differentiation capacity, meaning they can develop into a variety of body tissues, from nerve cells to heart cells. Typically, stem cells are harvested and cultured from embryos on the fourth day after fertilization by an egg and sperm, but they can also be isolated through somatic cell transplantation. In somatic cell transplantation, the nucleus, which contains the cell’s genetic information, is removed from the body’s somatic cells, and the egg’s nucleus is removed and cultured with the isolated nucleus to obtain embryonic stem cells with the same genetic information. Embryonic stem cells are also called pluripotent stem cells because they have the ability to differentiate into various types of cells. This ability opens up the possibility of transplantation therapy, but it also carries the risk of tumor formation due to misdifferentiation. Stem cells are easy to transplant because they are non-immunoreactive, can proliferate in large numbers, and can differentiate into almost any cell in the body. However, they have the disadvantage of being difficult to control their differentiation, which can lead to cancerous cells, and they inevitably require egg donation and the destruction of fertilized eggs, which has raised significant ethical concerns.
Adult stem cells are found in very small amounts in each tissue of the body. Unlike embryonic stem cells, which can differentiate into many different types of cells, adult stem cells are predetermined to differentiate into cells that make up a specific tissue. This makes them more suitable for treatments aimed at regenerating a specific tissue or organ, as opposed to embryonic stem cells. For example, bone marrow cells are determined to differentiate into blood cells, and skin stem cells are determined to differentiate into skin only. In the case of adult stem cells, there is no destruction of the fertilized egg, which is ethically acceptable, and the differentiation is stable, so there is no potential for cancer cells. However, they have the major disadvantage that they can only differentiate into specific cells, are difficult to culture, and are difficult to donate due to immune rejection issues.
Induced pluripotent stem cells are often referred to as IPS stem cells. They are stem cells that have been reverse-differentiated into stem cells, such as embryonic stem cells, using somatic cells, and have the advantage of being able to come from any part of the human body. This technology has great potential not only for treating certain diseases, but also for genetic research and drug development. Dr. Shinya Yamanaka, a Japanese scientist, was the first to successfully reverse differentiate them, a feat that earned him the Nobel Prize in Physiology or Medicine, making them the most ethically acceptable and medically viable stem cells.
Because of their ability to differentiate into any cell, stem cells are among the most medically valuable. Especially in recent years, the promise of regenerative medicine and personalized treatments has made stem cell technology a key part of the future of healthcare. And with recent advances in stem cell research, stem cell therapy actually being used clinically in blood disorders and trials in neurology, stem cells are becoming closer to home, gaining not only medical but also popular interest. In addition, experimental studies on spinal cord injuries and various neurodegenerative diseases are being actively conducted in Korea and abroad.
Although stem cell therapy is currently underway, there is still a long way to go. There are still too many ethical and technical issues that need to be resolved before stem cell therapy can be used to treat incurable diseases. In addition, the discussion on the commercialization of stem cells is growing in importance, along with the establishment of social and legal systems. However, if stem cell research continues, it is expected to make a revolutionary leap in science and medicine.
