Stem cells are the body’s infinite cell source. They are constantly created and their main purpose is to transform into other types of cells ultimately serving every single role in the human’s body. Specialized human cells (such as muscle cells) cannot multiply so their numbers have to constantly be replenished. This is where various types of stem cells come into play. Inside you, there are a hundred thousand million new blood cells created every single day by bone marrow stem cells. That should give you a perspective of the amount of work those tiny cells undergo each day.
A unique ability which stem cells (SC) have compared to other regular human cells is that they always create a specialized cell and another copy of themselves. This is called self-renewal and is what keeps our SC count constant.
Stem cells can be found in three major places:
- Bone marrow
- Umbilical cord blood (baby cord blood)
The first two kinds are a bit more advanced so they aren’t as flexible as the baby cord ones when it comes to infusing them into another body (stem cell transplant). The umbilical stem cells are quite primitive in their nature so they can adapt easily to various conditions and different recipients.
Once the stem cells are transplanted they begin repairing damaged tissues and strengthening the immune system of the recipient. This is one of the many advantages of stem cells.
Types Of Stem Cells
There are four main kinds of stem cells:
- Embryonic Stem Cells
- Tissue-Specific Stem Cells
- Induced Pluripotent Stem Cells
- Mesenchymal Stem Cells
Now, let’s take a detailed look at each of those four kinds:
Embryonic Stem Cells
This type of cells can be found inside the human blastocyst. This is a ball of cells which is formed a few days after the female egg is fertilized by a sperm. It is about the size of the dot above this “i”.
In normal conditions, these cells will further develop inside the blastocyst to ultimately be the stem cell which creates every tissue of the human. However, scientists have found a way to isolate this type of stem cells from the blastocyst in laboratory conditions, retaining the embryonic properties of the cell.
In simpler words, this means that they can obtain a pluripotent (that can do everything) cell. From then onward, imagination is the only limitation. Those cells are used to study diseases and normal development since they are a sustainable tissue source (self-sustainment). Of course, we do not take those cells from live blastocysts in real women, but are taken from blastocysts developed via in vitro fertilization (IVF) from assisted reproductions which were cancelled or no longer needed.
Tissue-Specific Stem Cells
This kind of stem cells, also known as adult stem cells can be found in all the parts of an adult human body. They are specific to the different tissues in the body and are far more specialized than the embryonic stem cells. For example there can be liver stem cells which regenerate the liver tissues. There are muscle stem cells regenerating muscle fibres, and so on.
The downside of those stem cells is that they can only turn into cells of the same tissue kind. For instance, liver stem cells cannot become muscle fibres, and vice versa.
Organs in our bodies contain small caches of such stem cells which have the job of replacing anything that is damaged in this organ or renew the cells that are getting older.
These cells are harder to find in the human body and are way harder to be cultivated (compared to embryonic ones). Studies on tissue-specific stem cells have helped us understand basic human development and the mechanisms behind the ageing process.
To learn more about storing the various kind of stem cells, go to our main page.
Mesenchymal Stem Cells
They are called MSC and are most often isolated from the stroma (the tissue which surrounds other tissues and organs). Many doctors and scientists call these cells stromal cells. MSCs were first discovered in bone marrow and were proven to be able to create bones, cartilages and fat tissue. They are being tested for treatments for many disorders since they are thought to have immunomodulatory and stem cell properties.
Induced Pluripotent Stem Cells
IPS cells are specially engineered lab cells. Scientists create them by converting normal tissue-specific stem cells to a kind of cell that has the properties of an embryonic stem cell. IPS cells are crucial for our understanding for disease development and progression. We also use them vastly for drug testing and developing new therapies.
IPS cells share a lot of the embryonic stem cell qualities. The major one is the ability to create any other type of cell in the human body. Even then, they aren’t quite the same those two kinds.
The first IPS cells were produced by using viruses to insert extra DNA inside a tissue cell. Even since then researchers have been testing new ways of creating those stem cells in order to use them as a source of cell cultures for medical treatments.
Some Final Words
There are four major type of stem cells and they are all equally important to the medical breakthroughs. Even so, scientists believe that there are more cell types out there capable of things we can only dream of right now. Stem cells are slowly but surely cementing their place as the most potent biological research topic.
If we learn how to use them, and more importantly – how to store them properly over time, we will have an answer for most of the modern diseases.