Stem cell-based therapies have the potential to treat and/or eradicate many of the most debilitating diseases and injuries that we may face during our lives. They, stem cells, are under-appreciated and misrepresented, and certain types (like embryonic) can be ethically contentious. In this article we answer the question, what are stem cells, and we discuss the uses of both mesenchymal and embryonic stem cells.
Stem Cells
Did you know that as you are holding your computer or phone and scanning the pages you have endogenous stem cells, (stem cells from within your body), actively working away to maintain your body (homeostasis) and as a result your health? For example, stem cells in your hands are holding your phone and scrolling down while stem cells in your retina (where light is transferred into vision) are reading these words. Your body is made up of stem cells.
What is a Stem Cell?
Every cell has a specific job to do and is shaped and programmed to do that job and only that job perfectly. A muscle cell is a muscle cell and only a muscle cell. A nerve cell will only ever be a nerve cell and a red blood cell will only ever be a red blood cell—nothing more. The fate of each cell is determined during the embryonic stage (which we will elaborate more on shortly), and this cannot be changed. There are, however, these wonderful cells that exist called stem cells. These cells have the remarkable ability to become any type of cell in the body. They are undifferentiated and haven’t yet specialized in a particular function or domain.
Stem Cells for Research
Stem cells can be used to repair damaged organs, bones, cartilage, and also to treat (but not yet cure) various diseases such as Alzheimer’s by making new brain cells or even used to help repair damaged immune systems. While skin cells protect your body, muscle cells contract, and nerve cells send signals, stem cells do not have any specific structure or function: However, that lack of specificity, is what makes them unique. Their “stem-like” properties are what makes these cells so special.
When Does Your Body Use Stem Cells?
Your body uses stem cells to replace warn-out cells when they die. For example, you completely replace the lining of your intestine every 4 days. Stem cells beneath the lining of your intestines replace these cells as they wear out. Your taste buds are replaced every 10 days or so and your skin cells every couple of weeks. Amazingly, your body actually replaces itself with a largely new set of cells every 7-10 years and some of our most important body parts are revamped even more rapidly. The cells that are the replacing of the old and/or damaged cells are adult stem cells also called somatic stem cells.
The Stem Cell Process
If you think about it the body’s ability to heal itself, which is a stem cell-dependent process, is rather striking. We do not have to think about it. Our stem cells just automatically do it for us because that is what they are programmed to do.
Can Stem Cells Help Illnesses?
It is not just injuries that stem cells work to address, but also pathogen-based illnesses as well. Get sick with a virus? The only reason you get better is because of stem cells that supply your immune system. Without them, even something as benign as the common cold could prove fatal.
Where Do Stem Cells Come From?
Stem cells can be largely divided into two categories—Embryonic (ESC) and Adult. There is actually a third category of stem cells known as Induced Pluripotent Stem Cells (iPSCs), which will not be discussed in this article.
Embryonic Stem Cells
Embryonic stem cells (ESCs) are derived from embryos created through in vitro fertilization prior to their implantation in the womb and not from eggs fertilized in a woman’s body. The stem cells are taken from inside the blastocyst (an embryo that is 3-5 days old and contains only 150 or so cells). The main advantage of ESCs is that they are pluripotent stem cells meaning they have the capacity to self-renew and develop into all cells of the body. Furthermore, one embryonic stem cell line can potentially provide an endless supply of cells with defined characteristics.
Downsides of Embryonic Stem Cells
There are a number of detracting features associated with ESC's. ESC's from a random embryo donor are often rejected after transplantation in a patient (i.e., immunogenic) and are capable of forming tumors or promoting tumor formation (i.e., tumorigenic). Moreover, harvesting stem cells from embryos courts a great deal of controversy as the removal of ESC's invariably results in the destruction of the embryo, bringing into the forefront ethical questions. For these reasons, we do not use or support embryonic stem cell research
Adult Stem Cells
Adult stem cells (ASCs) are stem cells that can be retrieved from living adults (and children) and are extractable from most tissues in the body. Some adult stem cells are somewhat specialized in that they cannot be changed into tissues that differ from the ones from which they came—for example, neural stem cells can only differentiate into specialized brain cells, whereas blood stem cells (i.e., Hematopoietic), can only form specialized cells of the blood system.
Other adult stem cells are more flexible and have been shown to be multipotent, a differentiation capacity that is more limited than pluripotent cells, meaning they can differentiate into several different cell types other than the ones from where they are extracted.
Mesenchymal Stem Cells
A major category of these more flexible adult stem cells is called mesenchymal stem cells (MSCs), cells from stroma, the connective tissue that surrounds other tissues and organs. Among these connective tissues, the easiest to isolate and commonly used sources of MSCs are to be found in the umbilical cord (from which our partner Vitro Biopharma derives its stem cell culture)/placenta tissue, the bone marrow, and the adipose tissue (i.e., fat cells).
While bone marrow was the earliest source of MSCs, stem cells extracted from the umbilical cord/placenta tissue makeup ~85% of the global commercialized allogeneic (stem cells harvested from a donor) stem cell market as they are a richer source of MSCs (according to some estimates, umbilical cord tissue contains nearly 10 times the amount of stem cells found in bone marrow).
Advantages of Mesenchymal Stem Cells
MSCs (mesenchymal stem cells) do have distinct advantages over ESCs. First, there are no ethical issues associated with harvesting MSCs. Second, research has thus far shown that allogeneic MSCs are neither immunogenic nor tumorigenic allowing them to be immune evasive and not rejected by the recipient. Given these properties, the clinical use of allogeneic MSCs may be considered as one of the most promising tools in the regenerative medicine kit.
Summary
Stem cells have the remarkable ability to become any type of cell in the body. They are undifferentiated and haven’t yet specialized in a particular function or domain. Stem cells can be largely divided into two categories—Embryonic (ESCs) and Adult. There is actually a third category of stem cells known as Induced Pluripotent Stem Cells (IPSCs).
A major category of the more adaptable adult stem cells is called mesenchymal stem cells (MSCs). These cells are from the stroma, the connective tissue that surrounds other tissues and organs. Among these connective tissues, the easiest to isolate and commonly used sources of MSCs are to be found in the umbilical cord.