This blog post will look at the possibilities and innovations that stem cell research can bring to the field of disease treatment and regenerative medicine.
All organs and tissues in our body are made from the stem cell mass that is formed from the division of a fertilized egg. Stem cells are different from the hundreds of millions of cells in our body in that they can divide and produce more of the same stem cells and can differentiate into different types of cells, such as skin, muscle, and blood. Research into the differentiation potential of stem cells can lead to breakthroughs in the treatment of diseases. Therefore, stem cell research is being actively conducted around the world.
Stem cells that can be obtained from mammals can be divided into two main types: embryonic stem cells obtained from embryos and adult stem cells obtained from adult tissues.
Embryonic stem cells are obtained from embryos that have been fertilized for only a few days, i.e. from blastocysts, which are one of the early stages of development. The fertilized egg, which is formed when a sperm and an egg meet, undergoes successive divisions from one to two, four, eight, and sixteen, reaching the stage of a cell mass called a blastula after four to five days. This cell mass is divided into an inner and outer layer, with the outer layer becoming the placenta and the inner cells becoming the embryo. Embryonic stem cells refer to the cells located inside the blastocyst. Just as a newborn baby has infinite possibilities, these cells have the potential to differentiate into any cell or even an individual, which is referred to as totipotent or pluripotent.
In the adult body, there are progenitor cells that work to repair damaged tissues. These cells are in a resting phase and then move to the damaged area and differentiate into damaged tissues. Adult stem cells are obtained from these. So far, tissues that have been shown to be able to obtain adult stem cells include the brain, bone marrow, blood, blood vessels, skeletal muscles, skin, and liver. However, because only a small amount of liver cells exist in the body’s tissues, the number of stem cells that can be obtained is small. In addition, adult stem cells are already to some extent differentiated, so the range of differentiation into other types of cells is limited compared to embryonic stem cells.
Embryonic stem cells can be mass-produced and, when used in patients, do not cause immune rejection, so they can be transplanted into other people and other species. However, because it is difficult to control differentiation, it is necessary to conduct precise research because it may become cancerous if not managed properly.
Adult stem cells have a limited use compared to embryonic stem cells in that the number of stem cells that can be obtained is small and the range of differentiation into other types of cells is small. In addition, there is another problem because there is an immune rejection reaction when receiving stem cells from another person.
The greatest value of stem cells is that they can be used to obtain large quantities of cells or tissues that can replace damaged tissues and be used to treat incurable diseases. Parkinson’s disease, a degenerative brain disease, is caused by the death of dopamine-producing nerve cells, and the most effective treatment is to transplant fetal brain tissue. However, fetal brain tissue is very limited and raises many ethical and social issues. If a method of inducing the differentiation of dopaminergic neurons from stem cells can be developed, it will be possible to obtain large quantities of dopaminergic neurons for transplantation into patients with Parkinson’s disease. In addition, if a large number of β-cells secreting insulin are obtained, it will be possible to treat type 1 diabetes patients who depend on insulin injections. Moreover, the value of this dream regenerative medicine, which could reshape the entire global medical market, which currently amounts to around 120 trillion won, is increasing exponentially. According to the current cases, stem cells can be used to treat stroke and are also used to regenerate knee arthritis.
The ethical issue of destroying embryos arises because blastocysts must be used to study embryonic stem cells. Embryos are still in the stage before becoming fetuses, but there is a debate going on about whether or not using embryos that can be expressed as fetuses for research is taking away human life. Because of this, some countries ban or allow embryonic stem cell research. This is permitted in European countries such as Sweden, Finland, Greece, the UK, and the Netherlands, and in South Korea, Japan, India, and Iran. On the other hand, there is no such ethical controversy surrounding adult stem cells because they are obtained from adults.
One of the most surprising discoveries in the last decade is iPS cells. iPS cells are cells that have been differentiated into pluripotent cells through a special process of adult stem cells. This has opened up the possibility of creating cells with differentiation omnipotence from patients to cure incurable diseases such as Huntington’s disease and chronic diseases such as autoimmune diseases without immune rejection.
As Nancy Reagan said, “Stem cell research is the hope that we will finally be able to get answers that we have not seen or heard before,” and stem cells are an innovative topic in the treatment of human diseases. However, at present, it can be said that the research using stem cells is in its early stages. Many cancer patients are being treated with bone marrow stem cell transplantation, but it is safe to say that other disease areas have not even begun. Active research will help us understand stem cells much more deeply, and we should focus on alleviating or treating disease symptoms through clinical trials. Stem cell research is a much broader field than what has been discovered so far, and there is much more to be accomplished in the future.
