In this blog post, we will examine whether stem cells can be the solution to incurable diseases and explore the ethical issues and potential solutions associated with them.
The desire to live a long and healthy life is a desire that humans have held since ancient times. This desire has driven the continuous exploration and advancement of human life, and as a result, we now have today’s medical technology and various treatment methods. One of these is regenerative medicine. Regenerative medicine is a field of study that researches methods for damaged tissues or organs to repair or replace themselves, contributing to extending human life and improving quality of life.
The core concept of regenerative medicine is the use of stem cells. Treating various incurable diseases using stem cells is one of the main goals of this field. While the term “regenerative medicine” may sound unfamiliar at first, the concept itself is not that difficult. Simply put, it involves using stem cells to regenerate damaged tissue and thereby restore health. Recently, as the importance of stem cells has become increasingly recognized, related research has been actively underway.
Stem cells are cells capable of developing into any type of tissue within an organism. These cells possess the ability to differentiate into various tissues under specific conditions. New cells differentiated from stem cells can replace diseased cells, which is the fundamental principle of regenerative medicine. Since most incurable diseases result from damage to bodily tissues, the use of stem cells can treat many such conditions. For example, when stem cells are administered to an area damaged by a heart attack, they differentiate into new cells that form heart tissue, thereby healing the damaged area.
Furthermore, stem cells show great potential for treating degenerative diseases. Parkinson’s disease, a degenerative brain disorder, is caused by the death of dopamine-secreting neurons, and transplanting fetal brain tissue is currently the most effective treatment. However, since transplanting fetal brain tissue can raise ethical concerns, stem cell therapy is emerging as the best alternative. Furthermore, stem cells can be used as samples for new drug development research or chemical testing. Additionally, stem cells can be used to treat hair loss and prevent skin aging, thereby contributing to improving the quality of human life.
The driving force behind a stem cell’s ability to differentiate into various cell types is its differentiation potential. Differentiation potential can be classified into three categories based on its degree: totipotency, pluripotency, and multipotency. Totipotency refers to the ability to form a complete organism, with the zygote serving as an example. Pluripotency refers to the property of being able to differentiate into all types of cells that make up an organism, though it cannot form a complete organism on its own. Finally, multipotency refers to the property of being able to differentiate only into a limited number of cell types. Stem cells are present in small quantities in each of our body’s organs; these are multipotent stem cells—that is, stem cells with a somewhat lower differentiation potential that can differentiate only into a limited number of cell types.
Types of stem cells include embryonic stem cells, which use embryos, and adult stem cells found within the human body. Recently, induced pluripotent stem cells (iPSCs), created by inducing dedifferentiation in mature cells, have emerged as a new category. Since these stem cells possess distinct characteristics and potential applications, it is important to thoroughly understand their respective advantages and disadvantages and utilize them appropriately in relevant fields.
In the context of embryonic stem cells, an “embryo” refers to a zygote formed by the union of a sperm and an egg; embryonic stem cells are extracted from embryos after fertilization but before implantation. Because they are derived from dividing cells, embryonic stem cells possess excellent differentiation potential. However, this high differentiation potential also carries a risk of becoming cancerous cells, necessitating precise handling techniques. Furthermore, the fact that they are extracted from a fertilized egg raises ethical concerns, and there is also the risk of an immune rejection reaction when transplanted into a patient.
Cloned embryonic stem cells are currently being researched as a way to overcome the limitations of conventional embryonic stem cells. Cloned embryonic stem cells are not extracted from fertilized eggs but from cloned embryos created artificially using somatic cell nuclei and oocytes. Therefore, using the patient’s own somatic cell nucleus can resolve the issue of immune rejection. However, since cloned embryos can also be viewed as living organisms, ethical issues arise regarding the destruction of life and human cloning.
Unlike embryonic stem cells, adult stem cells are stem cells found within the human body, present in small quantities in each organ. Because they are cells found within the human body, they do not cause immune rejection and are the easiest type of stem cell to handle; however, as mentioned earlier, their limited differentiation potential is a major limitation of adult stem cells. Nevertheless, adult stem cells are attracting attention from many researchers for their practicality and safety, and their range of applications is continuously expanding.
New types of stem cells capable of overcoming the limitations of the two types introduced above are currently under investigation. Induced pluripotent stem cells (iPSCs), which are created by inducing the dedifferentiation of already differentiated cells, do not raise ethical concerns regarding the destruction of life because they are derived from a single cell. Furthermore, because they possess excellent differentiation potential, they can differentiate into all types of cells in the body. However, much research is still needed before they can be commercialized.
In addition to the limitations inherent in stem cell research itself, the field faces difficulties due to social opposition regarding its ethical implications and legal regulations. In fact, the United Kingdom is the only country that has legally permitted stem cell research. Under these circumstances, social consensus and legal frameworks are necessary for the advancement of stem cell research. If such social discussions proceed actively, stem cell research will be able to develop more rapidly and stably. Thus, while stem cells hold immense potential, the path to commercialization remains long. We look forward to the day when active research on stem cells leads to their direct application for the benefit of humanity.
