Stem cells are a type of biological cells that can create specialized cells and divide, through a process called mitosis, in order to produce more cells of their kind. One can find this type of cells in a wide range of organisms such as mammals.
Specialists have found two types of cells in mammals: embryonic stem cells, and adult ones. The first ones are living secluded from the central cell mass of the elements called blastocysts, while the second ones are found in a wider range of tissues.
In the adult organism, cell stems help the body repair itself, restoring various adult tissues. In a forming embryo, there are more than just one type of stem cells. Depending on the location they find themselves in, there are ectoderm cells, endoderm cells, and, last but not least, mesoderm cells.
Sources of Adult Stem Cells inside The Human Body
- Bone marrow. The stem cells found in the bone marrow are removed by the harvesting process. This means drilling into the bone.
- Lipid cells found in the adipose tissue of the body. These require removal through liposuction.
- Blood cells. In this case, the extraction is made through apheresis. In this procedure, a certain amount of blood is extracted from the donor, and inserted into a medical machine which removes and separates all the stem cells, while returning some of that blood’s quantity back to the donor.
Medical procedures also provide the possibility of extracting stem cells from the umbilical cord, after the woman has given birth.
Usually, stem cells are often used in medical treatments and procedures such as bone marrow transplant. Moreover, this beneficial cells can be now grown and helped to differentiate into customized cell types, for different categories of tissue such as muscular or nervous.
The Main Properties of Stem Cells
All stem cells, regardless of their source, have three general properties:
- Self-renewal. They are capable of dividing and renewing themselves for long periods. Unlike other types of cells, stem cells can replicate many times, or proliferate. A starting stem population can produce millions of new cells. In the case in which these secondary cells are uncategorized, like the parent stem cells, they can also be capable of long-term self-renewal.
- Stem cells are unspecialized. This is one of the main characteristics of these cells. This mean that it does not have any tissue-specific structures that could allow it to perform specialized functions. For example, a stem cell cannot carry oxygen molecules through bloodstreams.
- Stem cells can produce specialized cells. Even though they are not specialized, stem cells can provide and create specialized cells such as heart muscle, blood cells, or nervous system cells. This process is called differentiation. The cells become more specialized at each step.
Differences and Similarities Between Embryonic and Adult Stem Cells
One major difference between the two categories of stem cells is their different abilities in the number and type of differentiated cells they can become. Embryonic cells can become all cell types of the body because they are pluripotent. On the other hand, adult cells are limited when it comes to differentiating into different cell types.
Embryonic stem cells can grow easily in culture. Adult cells are rare in mature tissues. This is why isolating them can be a tricky process. However, adult cells are believed to behave better after transplantation, having a lower rate of body rejection. This is an important advantage.
Potency Categories of Stem Cells
Stem cells are categorized by their ability to differentiate into other types of cells, like previously stated above. The complete classification includes:
- Totipotent. This is the ability to differentiate into all possible cell types.
- Pluripotent. The ability to differentiate into almost all cell types. An example is embryonic stem cells.
- Multipotent. This means some cells have the ability to differentiate into a narrow range of specialized cells, only into those who are closely related to the parent cell.
- Oligopotent. The ability to differentiate into a few cells.
- Unipotent. This is the ability to produce only cells of their own type but also have the ability of self-renewal. Examples of these cells include adult cells found in the muscle tissues.
How Are Stem Cells Identified?
They are identified by their regeneration ability for the well-functioning of the tissue. This proves the fact that stem cells can provide new blood elements that last a long period of time. These cells’ abilities can be further proven in vitro conditions, using different procedures and methods. The main focus of these procedures is to determine whether these cells have the ability to differentiate or not.
However, in vitro, the conditions in which cells are put differ from those outside this protected and supervised environment. This can make it harder for specialists to make sure that these cells will have the same behavior once they are taken out of the vitro environment. There are still researches going on, in order to determine if some adult cell extractions really are stem cells.
To be useful for transplant purposes, stem cells must be made to:
- Extensively proliferate and generate enough quantities of cells for creating new tissue.
- Differentiate into the desired cell types.
- Survive in the recipient after the transplant.
- Integrate into the surrounding tissue after transplant.
- Function appropriately for the duration of the recipient’s life.
- Avoid harming the recipient in any way.
Treatments in Which Stem Cells Are Used
Stem cell therapy is the use of stem cells in order to treat or prevent a disease or a condition. These health issues in which stem cell treatment is being investigated are:
- Parkinson’s disease
- Alzheimer’s disease
- Rheumatoid arthritis
- Stroke and traumatic brain injury repair
- Learning disability due to congenital disorder
- Spinal cord injury repair
- Heart infarction
- Anti-cancer treatments
- Baldness reversal
- Replace missing teeth
- Repair hearing function
- Restore vision and repair damaged cornea
- Amyotrophic lateral sclerosis
- Crohn’s disease
- Wound healing
Organ and Tissue Regeneration
This is the most important applicability of stem cells. Organs must be donated and transplanted, but demand for healthy organs is exceeding the supply. This type of cells could be used to grow a specific kind of tissue or organ.
Cardiovascular Disease Treatment
Researches have been made in order to create blood vessel from stem cells. The newly obtained blood vessels that were formed onto the studied subjects were as good as the natural ones and lasted for 280 days.
Brain Disease Medical Treatment
Extracted stem cells that also have the ability to differentiate into brain cells can help cure neural disease and conditions such as Parkinson’s and Alzheimer’s. This can be done by removing the damaged tissue, and replacing it with the new stem cells.
Cell Deficiency Therapy
This has not been done yet, but someday properly made heart stem cells may be replacing damaged tissue for patients with heart conditions. Similar treatments could be done on patients with type I diabetes. They may benefit from a transplant of pancreatic cells to replace the damaged cells that used to create inefficient insulin. Nowadays there is only one available therapy: a pancreatic transplant.
Blood Conditions Therapies
Specialists have been long used blood stem cells in order to treat diseases like sickle cell anemia, leukemia, and other immunodeficiency conditions. Blood stem cells can produce healthy cells for all kind of blood types. The downside of this process is its extraction part. The procedure consists of extracting the cells from the bone marrow and transplanting them to the sick patient.
Stem Cells Disadvantages
Stem cells treatments may require immunosuppression because of radiation procedures before the transplant in order to remove the patient’s previous cells, or because the patient’s immune system may target the stem cells.
Pluripotency is some stem cells could make it difficult to obtain a specific cell type. Not all the cells in a specific population differentiate the same. This means that it could be harder to achieve the exact cell type needed.
There were cases in which some stem cells formed tumors, after the transplantations. This is especially the case of embryonic stem cells.
Tissue Stem Cells
- Blood and skin stem cells. Due to blood stem cells proprieties, bone marrow transplants are able to replace a patient’s diseased blood system. Many patients benefit from this treatment every year, although some of them suffer from complications such as a growing risk of infection because the immune system of the patient attacks the new tissues. Skin stem cells have been used since the 1980s. They are used for burned patient, in order to replace the damaged skin tissue.
- Cord blood stem cells. These cells can be extracted from the umbilical cord of a baby after birth. Then, the cells can be frozen in cell banks. Cord stem cells are currently used to treat children with cancerous blood disorders such as leukemia, as well as genetic blood diseases. An advantage of cord blood transplants is that they appear to be less likely to be rejected by the immune system compared to the conventional bone marrow transplant. However, cord blood stem cells must still be matched to the patient to be successful.
- Mesenchymal stem cells. These stem cells are found in the bone marrow and are responsible for bone and cartilage repair. They also produce fat cells. Stem cells researches have shown that these types of cells can differentiate into many cells categories. However, the studies are not yet finalized and there is not a clear view of their properties. Furthermore, no treatment using mesenchymal stem cells are yet proven. Some specialists stated that these cells can avoid detection by the immune system and they can be transplanted from a person to another, with little to no risk of rejection by the body.
- Stem cells in the eye. These cells are taken from an area in the eye called the limbus and can repair damaged corneas. The treatment has been proven to be safe and effective in early stage trials. More studies on a large number of patients will be carried in the future in order to further prove that this therapy is effective and it can be approved by regulatory authorities.
As you can see, there are a number of facts that everyone should know about stem cells:
- Until now, very few stem cell treatments have been proven safe and effective. The best defined and most used stem cell treatment is the blood stem cell transplantation. All other applications of stem cells are to be proven in clinical trials and should be considered only experimental.
- There are risks when you try an unproven treatment. When you are facing a deadly disease it is understandable why you would think to try anything that is possible, in order for you to be healthy. Unfortunately, most of the unproven stem cells treatments have a small rate of success. Furthermore, they also carry real risks. Complications can create long-term health problems and could make your symptoms more difficult to handle. Expenses could be gigantic. In addition to treatment costs, there can also be accommodation charges and other fees. Be careful when choosing a potential therapy to treat your disease. Consider all aspects of the treatment, potential risks and benefits.
- Different types of stem cells are good for different purposes in the body. They have different functions. Scientists are exploring the roles that tissue-specific cells might play in the healing process. What we all need to understand is that these stem cells have specific and limited capabilities. For example, the blood stem cells found in the bone marrow regenerate only the cells in blood, while neural stem cells make brain cells.
- The same stem cell therapy is not likely to treat different diseases. This is due to the fact that stem cells are specific to certain areas of the body and they cannot form cells found in other tissues. However, this could be possible with careful manipulation in the lab under certain restricted conditions. Specialists have learned to make certain specialized stem cells through a multi-step process using pluripotent stem cells. This newly created cells can form all different kinds of cells in the body and they offer an excellent opportunity to develop new treatment strategies.
- Cells from your own body are not necessarily safe when used in therapies. Even though you might think that your immune system would not attack your own cells, practice could prove you wrong. Every time cells are removed from your body, there is a risk they may be contaminated with viruses, bacteria or other elements that could cause disease when they are reintroduced in your body.
In conclusion, stem cells researchers are making significant advances in understanding the development of these cells. They are trying to figure out what goes wrong in diseases and develop as many trials and tests they can, in order for those diseases to be cured. Though, there are many things to be still discovered about stem cells and their capacity for healing.