Stem cell therapy has a huge potential to cure various disorders and internal injuries that were previously considered incurable.
All organisms are made up of cells or collections of cells. It is the smallest functioning unit of life. If we specifically talk about humans, different organs have different types of specialized cells with structural and functional modifications for performing specific functions needed for that organ.
Usually, these specialized cells cannot perform their functions when placed in another organ, like brain cells (neurons) cannot perform a function taking place in the kidney, as they do not have the appropriate machinery to perform the function of kidney cells. These specific function-performing cells are collectively termed differentiated cells.
On the other hand, our body contains cells without a defined job. In other words, they are undifferentiated cells termed as stem cells. Particularly, stem cells are the raw material present in the body that, in the future, will be specialized into a specific type of cell when the need arises.
They are the backup cells, prone to being differentiated when the body is in need of adding or replacing existing specialized cells.
For instance, when the hand gets a cut, normally a blood clot is formed to stop bleeding, but after one week, the clot gets recovered as the new skin cells join together, functioning perfectly as the previous cells. Where do these new skin cells come from? The answer to the question is stem cells. The stem cells arrived at the damaged area and started differentiating into the new differentiated skin cells.
Types of stem cells:
There are three types of stem cells:
- Embryonic stem cells
- Adult stem cells
- Induced pluripotent stem cells
Embryonic stem cells:
These types of stem cells are found in the very early developmental stage, just a few days after the zygote’s (the first cell of a human) formation, and divide into multiple cells; this stage is known as the blastula stage.
The stem cells found in the blastula stage are considered to be the finest stem cells, as they have the capability to differentiate into any type of human cell (it can be either a neuron, a nephron, a skin cell, and so on) dependent upon the specific type of conditions we provide them. Moreover, this capability of a cell to become any type of cell is termed pluripotency, and embryonic stem cells are the most pluripotent cells.
Adult stem cells:
These are the tissue stem cells, a type of stem cells found in the adult body. These stem cells provide newly differentiated cells to the adult body when any damage to the previously existing cells occurs. They go and replace the injured cells.
However, adult stem cells are not pluripotent; instead, they are termed as multipotent cells, which means they have a limited range of cells in which they can differentiate. In other words, adult stem cells cannot differentiate into any type of body cell, whereas they have a limited range of cells in which they can differentiate.
Like blood stem cells (haematocytes) found in the bone marrow, they have the ability to differentiate only into the cells that exist in the human blood (red blood cells, white blood cells, and so on), but they cannot differentiate into heart muscle cells or neurons. This limited differentiation capability is termed multipotency.
Induced pluripotent stem cells (IPS):
Induced pluripotent stem cells are not present in the human body; nevertheless, they are produced by scientists outside the human body by using the differentiated cells already existing in the body. You can understand them as they are artificially created stem cells by scientists.
Scientists take normal differentiated cells from the body, like skin or muscle cells, and reprogram them to revert themselves into the form of stem cells by providing specific conditions (Yamanaka factors Oct3/4, Sox2, Klf4, c-Myc).
These specialized stem cells, just like embryonic stem cells, are pluripotent and can be used to create any type of body cell by providing a specific environment.
Thus, they provide an edge over the other two types, as we do not have to interfere in the early development process (as it is a very delicate process) and we do not need to extract stem cells from an adult. Therefore, we can use any working cell of the body that is easy to extract and can be converted into a pluripotent stem cell.
Application:
Now let’s find the answer to the question of why stem cells are important. First, they help in the research and study of various biological functions and the behaviour of different types of cells under the conditions of disease.
They help us understand how our body grows or develops with time. Also, they help us understand the conditions under which a cell undergoes differentiation and how it develops modifications in its structure and function.
Moreover, we can also grow a complete working organ using stem cells and study its various functions and behaviours under certain conditions, and these organs are further used for testing various drugs to find out the action and mechanism of that drug on a specific organ.
Furthermore, they are used to replace those damaged or lost cells that our body does not have the ability to restore naturally or has lost that ability due to some reason (injury, genetic disorder, disease). This is a type of treatment monitored by using stem cells known as stem cell therapy. Stem cell therapy has huge potential in the near future as a treatment for various diseases.
If we talk about the current use of stem cells in treating diseases, then we will come to know that stem cell therapy is already being used to treat diseases like leukaemia and thalassemia (blood-related diseases) using adult stem cells found in the bone marrow, which differentiate into all types of blood cells (haematocytes).
Along with that, skin stem cells are used to cure the skin of people with several skin burns. In addition, some eye retina-related diseases are also under treatment through stem cell therapy.
Besides, stem cell therapy has also proven to be a promising cure for spinal cord injuries. Spinal cord injury results in a disconnection between the brain and the affected muscle due to the breakage of the neurons in the spinal cord connecting them.
So the signals cannot reach the muscle. Although Stem cell therapy is proven to be very effective in order to recreate the connection between the brain and the muscles.
Thus, injecting stem cells at the site of injury will result in the differentiation of stem cells into neurons, and their nerves will rejoin the broken connections.
But there is a high possibility that a certain part of the brain gets connected to a different muscle of the body than the previous one, so therapy sessions would be needed to learn a new connection between the brain and certain muscle parts.
Thus, stem cell therapy has a huge potential to cure various disorders and internal injuries that were previously considered incurable. Further research on stem cells can lead to new methods for treating diseases like cancer, diabetes, and other cell-related dysfunctional disorders.
This article is jointly authored by M. Tahir Arshad and Dr. Muhammad Mustafa.