Stem Cells and Stem Cell Therapy

Stem cells play a crucial role in the human body because they control many important processes in the body. There is enormous potential in these cells for the treatment of a wide variety of diseases – this is referred to as stem cell therapy. In the context of stem cell research, scientists are always trying to further develop the possibilities of this form of therapy and a lot has happened in research in recent years. Below we give you an overview of the properties of stem cells and their applications in medicine. 

The egg cell as the first stem cell

Nerve cells, muscle cells or skin cells – as different as they are, their origin lies in a common cell: the stem cell, more precisely in the fertilized egg cell, the zygote. This cell forms each of our more than 200 different cell types. It is therefore referred to as a  totipotent (or omnipotent)  stem cell because it has the ability to develop into a completely separate organism.

So there is enormous power in this stem cell, and even if the ability of totipotency is lost after a very short time, this power remains with us in a weakened form even in adulthood, in the form of adult stem cells.

What are stem cells? 

Stem cells, as commonly defined, are any cell in the body that has the ability to develop into different cell types or forms of tissue.

A distinction must be made between two major  types of stem cells  , embryonic stem cells and adult stem cells:

  • Embryonic stem cells  are pluripotent, which means that they are not yet fixed in their differentiation and therefore can develop into all possible forms.
  • In contrast,  adult stem cells  can only specialize in a defined area, for example in blood formation. So they are multipotent. 

How are embryonic stem cells formed?

Strictly speaking, embryonic stem cells are only created in the laboratory and do not occur in the human body at all. Nevertheless, the early stage of development of an egg cell after fertilization is a prerequisite for obtaining these stem cells.

The fertilized egg cell divides several times in the first five days until the so-called blastocyst has developed – a small ball filled with fluid. Only then does the blastocyst nest in the uterus, where the unborn child develops from then on.

The blastocyst consists of two types of cells: the outer cells, trophoblasts, and the inner cells, the embryoblasts. Our entire organism develops from the inner cells, from the brain to the inner organs to our skin. These embryoblasts have the unique ability to transform into all types of tissue.

If you take these embryoblasts and culture them (that is, let them develop in the laboratory), you get embryonic stem cells. In 1981, researchers were able to obtain embryonic stem cells from a mouse for the first time. Since then, scientists have been trying to use stem cells for therapies.

What is the role of adult stem cells in the body?

But what do we need stem cells for anyway? What is their job in our body? To better understand the topic, it is worth taking a closer look at what we need stem cells for in adulthood and where to find them. The formation of our blood components is a suitable example.

The  red blood cells  (erythrocytes) transport the oxygen from the lungs to all areas of our body and also ensure that the carbon dioxide produced during breathing is transported back. This task is associated with a lot of oxidative  stress for the cell  (this is what the processes in  the cell’s metabolism  are called that are permanently harmful), which is why an erythrocyte survives an average of only 120 days. It gradually loses its elasticity and is broken down by the body. 

It is estimated that our body produces 2×10 11  new red blood cells per day. Stem cells play a decisive role here:  multipotent, adult stem cells are located in the red bone marrow.  In this case, they are also called  haematopoietic stem cells,  since they are responsible for blood formation (haematopoiesis). These stem cells divide in several steps and become more and more specialized with each division until a complete erythrocyte has formed after about eight days. In this way, our body ensures a constant supply of red blood cells.

In addition to the red blood cells, the  white blood cells  (leukocytes) and blood platelets ( thrombocytes ) must also be constantly renewed. These cell types can also arise from the adult stem cells in the bone marrow.

If you line up all the possibilities for the development of adult stem cells, the picture resembles a tree diagram, at the end of which are the differentiated cells. The ability to transform into different types of cells is characteristic of stem cells. They are used for renewal in the body and help us, for example, to replace injured tissue.

What is the difference between embryonic and adult stem cells?

The main difference between the two types of stem cells – the adult and the embryonic stem cells – is the possible differentiation, i.e. the versatility of the cells. While embryonic stem cells can still pluripotently transform into all kinds of tissue types, adult stem cells are limited.

A hematopoietic (blood-forming) stem cell in the bone marrow can transform into various forms of blood cells, but it cannot transform into a nerve cell or a liver cell. Doctors speak of potency, which means that adult stem cells decrease.

Stem cell research: Focus on embryonic stem cells

It is precisely the versatility of embryonic stem cells that makes them a central research topic in which there are no limits to the imagination. New brain cells after a  stroke  or heart muscle cells after a  heart attack ? The list of possibilities is long, but in reality, research has not progressed that far.

However, more than 350 companies worldwide are currently researching new methods of using embryonic stem cells in medicine. 1

Ethical debate in embryonic stem cells – where does life begin? 

Strictly speaking, embryonic stem cells only develop in the laboratory when the embryo blasts are artificially removed. The embryo is usually destroyed in the process. These stem cells are obtained from “supernumerary” embryos that are created, for example, as part of artificial insemination. In Germany, this procedure is prohibited under the Embryo Protection Act, while other regulations apply in other countries.

Since embryonic stem cells can still specialize in all types of tissue, they are of particular interest for research. However, the question must be asked whether it is ethical to collect embryoblasts for this purpose.

In order to avoid this ethical problem, scientists have been researching new ways to give adult stem cells back the ability of embryonic stem cells. In 2006, the Japanese doctor Shin’ya Yamanaka discovered that mice skin cells could be “reprogrammed” back into embryonic stem cells using viruses. These cells are called  induced pluripotent stem cells (iPS). A year later, the same process was also successful in human skin cells, which paved the way for new therapeutic options in medicine.

Stem cell therapy – where is it already being used? 

Since the 1970s, adult stem cells have been used to treat diseases affecting the blood system. Especially in the treatment of  leukemia  – a form of  cancer  – stem cell donations can often save lives. Between 40 and 70 percent of stem cell transplants are successful, which is still a great success for medicine today.

 However , adult stem cells are also used in therapy for other diseases such as lymphomas or  multiple myeloma .

Obtaining adult stem cells – where do the stem cells come from?

All forms of stem cell therapy have one thing in common: They require stem cells. There are now numerous ways of obtaining stem cells. The three most common forms of  stem cell donation  are: 

  • Obtaining from the blood:  Most of the stem cells are located in the bone marrow. With the help of a medicinal stimulator (G-CSF), the stem cells are stimulated to enter the blood and finally, similar to a  blood donation , extracted from the blood.
  • Bone marrow transplant:  This procedure is done under  anesthesia . A part of the bone marrow with the corresponding stem cells is removed, preferably from the iliac crest. The stem cells are then transferred directly to the recipient, similar to donating blood through a vein.
  • Cord blood stem cell  donation :  Cord blood donation is a relatively new procedure in which stem cells are harvested from cord blood at birth . These stem cells are also known as neonatal stem cells and are significantly more potent than adult stem cells in adults.

Foreign or own stem cells?

In addition to the forms of collection, a distinction is made as to whether the stem cells come from a foreign donor (allogeneic stem cell transplantation) or from the patient himself (autologous stem cell transplantation).

Allogeneic transplants  act like an immunotherapy. The new cells help the recipient’s body get rid of malignant cells and establish themselves in the bone marrow, where they make new, healthy blood cells. However, it is difficult to find the right donor. Each of our cells has its own surface characteristics and these must match when donating. The determination of these properties of the cells is called typing.

Stem cell transplantation can also have significant side effects. In the worst case, so-called Graft-versus-Host-Disease (GvHD) occurs, in which the donor’s immune cells attack the recipient organism.

Autologous  stem cell transplantation  is much less common. It can take place, for example, if the stem cells of an affected person were removed and stored at birth. Or they are taken from patients before  chemotherapy  and transfused back after treatment. This therapy is often used for lymphoma or multiple myeloma.

Stem cell therapy – where could we use stem cells in the future?

Advances in stem cell research in recent years have made it possible for newer therapeutic approaches to be tried out for a wide variety of diseases.  The researchers are hoping for new treatment options, especially with the help of  induced pluripotent stem cells, which are similar to embryonic stem cells.

Research is currently being carried out in almost all areas of disease therapy. A focus of stem cell research is certainly the brain and nerves. Many diseases that attack the nerve cells in our brain and body are difficult to treat with drugs. For this reason, in the following diseases, it is hoped to find ways to replace the damaged nerve cells with new ones:

There are also other areas in which the first successes have been recorded in recent years: 

  • Macular Degeneration :  Stem cells are used to regenerate the  cornea  of ​​the eye. The first studies have already been carried out and the results are very promising. 2
  • Osteoarthritis  in the knee:  First studies were able to prove that the cartilage has demonstrably grown after a stem cell injection in the knee. Patients have also reported less pain and better mobility. 3
  •  Type 1 diabetes :  Here, researchers have succeeded in producing insulin-producing cells from induced pluripotent stem cells. However, first in the test tube – further research is therefore still pending. 4

Stem cell research: An area with a future

There are still some obstacles to be overcome, but in the future we can hope for new treatment methods with stem cells in some areas of medicine. Some researchers even go so far as to use this technique to rejuvenate our bodies. At the moment, however, these are mostly still fantasies about the future.

Nowadays it is already possible to freeze and store stem cells from umbilical cord blood. The idea behind this is that these cells are not yet specialized and can therefore later be used in diseases such as leukemia. The procedure should therefore represent a kind of insurance for the child, because the goal is to be able to use personalized stem cells for the treatment of a wide variety of diseases at some point.

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