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Stem cells are the type of cells that can form all other body cells and can show their specialized functions as well. Stem cells are divided into daughter cells to form all other body cells they can form brain cells, blood cells, bone cells, and heart cells.
These stem cells come from the inner cell mass of the blastocyst. The zygote which is known as the fertilized egg will form two cells, again these cells will divide, and the process continues. It will form a ball-like structure of 150 cells which is known as a blastocyst1.
There are two cell types present in the blastocyst one is trophoblast and the other is inner cell mass. The inner cell mass gives rise to the human embryonic stem cells
Some Stem Cell Basics
Stem cells are those cells that act as formation cells for all the organs of the body. The stem cells are like blank chips which are programmed to do a specific task (formation of tissues and organs).
These cells are undifferentiated cells that under optimum condition starts to differentiate and form the specialized tissue or organ. These cells have the ability to self-renew so they can also produce some more stem cells.
These are of two types embryonic stem cells and adult stem cells. The embryonic stem cells which are produced from the human embryos are known as human embryonic stem cells.
Where Do Stem Cells Come From?
There are many sources from which stem cells originated. They are as follows:
Embryonic Stem Cells
The embryonic stem cells come from human embryos which are 3 to 5 days old. The embryo which is in this stage is known as Blastocyst and it contains 150 cells.
The embryonic stem cells are able to divide into more stem cells and they will become any type of cell of the body. This is a versatile embryonic stem cell. They are pluripotent stem cells. Their function is to repair and regenerate diseased organs and tissues.
Adult Stem Cells
Adult stem cells are also known as Somatic Stem Cells. The adult stem cells come from bone marrow and fat. These cells are less in numbers in comparison to embryonic stem cells. These are human stem cells. These are taken from adult tissues. These cells have the capability to produce many cells of the body.
In previous research, it was thought that somatic stem cells can only produce only one type of cell. They thought only the blood cells can be formed from the bone marrow stem cells.
Now, there is much stem cell research to know whether these cells can produce various types of body cells. Like, the bone marrow stem cells are able to produce bone cells and heart muscle cells as well.
Many researchers are in early-stage clinical trials. The purpose of these trials is to test the safety and usefulness of these cells. The safety of people is also an important point that we have to take care of during the research.
In recent research, stem cells are being tested for heart and neurological disease. Nowadays several types of research are going on for adult stem cells.
Perinatal Stem Cells
These stem cells come from amniotic fluid. Amniotic fluid2 is the fluid that fills the sac which protects and surrounds the developing fetus in the uterus.
Researchers have found the stem cells from the amniotic fluid which was drawn from pregnant women. This fluid was collected for testing and treatment purposes. This process is known as amniocentesis.
These stem cells are able to change into specialized cells.
Types Of Stem Cells
These are the types of stem cells on the basis of cell differentiation. they are classified into five types. The five stem cell types are as follows:
Totipotent Stem Cells
These are those cells that are able to produce a fully functional living organism. These are the most powerful stem cells.
They are able to differentiate themselves into embryonic and extraembryonic tissue like yolk sac, and allantois.
In human beings as well as in other placental animals, the extraembryonic tissue is able to form the placenta.
After four days of the post-fertilization process, these cells start to convert into pluripotent stem cells.
Pluripotent Stem Cells
These are the second most powerful stem cells.
These stem cells are very important as they have the property of self-renew. They are also able to differentiate into three germ layers i.e. endoderm, mesoderm, and ectoderm3.
These germ layers are also differentiated in order to form tissues and organs of the human body. When all proper functioning is done in the human body it is known as human pluripotent stem cells.
There are two main types of these stem cells. The two stem cell types are:
Natural Pluripotent Stem Cells
These are those cells that are naturally produced which is why they are named natural pluripotent stem cells. They are embryonic stem cells that are found at the early stage of the human embryo.
Induced Pluripotent Stem Cells
These are the Human Made stem cells. These are also written as iPS cells. It was first researched and originated from mice in the year 2006. Then the research was continued with the human embryos to produce human pluripotent stem cells.
In the year 2007, human cells are also formed. The induced pluripotent stem cells are tissue-specific cells that can be reprogrammed so that they are able to function the same as the embryonic stem cells.
The induced pluripotent stem cells are widely used in regenerative medicine and cellular therapy. They have a non-controversial nature.
Multipotent Stem Cells
These are those cells that are in the middle range. They also have the ability of self renew but they can only differentiate into some specific types of cells.
An example of multipotent stem cells is Mesenchymal Stem Cells. These stem cells are able to differentiate into bone cells (osteoblasts), fat cells (adipocytes4), muscle cells (myocytes), and cartilage cells (chondrocytes).
Oligopotent Stem Cells
These are able to differentiate in cell types lesser than the multipotent stem cells. They also contain the ability of self renew. But they can differentiate their cells to a limited extent. It can only divide into closely related cells.
An example of these stem cells is Hematopoietic stem cells (HSC).
These Hematopoietic stem cells are derived from the germ layer, mesoderm. They have the ability to divide into blood cells(Red blood cells, white blood cells, and platelets). They can divide into both lymphoid and myeloid cells.
Neutrophils, eosinophils, basophils, monocytes, platelets, macrophages, dendritic cells, and megakaryocytes are all myeloid cells whereas natural killer cells (NK cells), T cells, and B cells are lymphoid cells. The process by which hematopoietic stem cells give rise to blood cells is known as hematopoiesis.
Unipotent Stem Cells
These cells have the least potency to differentiate into cells. They can produce only a single type of cells. As the name suggests “Uni” means “One”, so they can divide into only one type of cell.
An example of these cells is muscle stem cells. They have the to ability of self-renew. They have unidirectional differentiation capacity.
Many stem cells are of skin cells so they are able to form skin cells. Some are able to form brain cells.
Stem Cell Lines
These are the group of cells that are formed from a single original stem cell. We are able to grow the stem cell lines in a lab. The cells in the stem cell line can continue to grow. They are not able to differentiate into specialized cells. They are free from genetic disorders and they can only continue to produce more stem cells. The stem cell line will form a cluster of cells that are stored.
Embryonic Stem Cell Lines
The embryonic stem cell line is the pluripotent stem cell line which is derived from the early stage of the human embryo i.e. blastocyst.
These cell lines have the ability to do the prolonged undifferentiated proliferation in the culture in order to maintain the capacity to differentiate them into the three germ layers (endoderm, mesoderm, ectoderm).
During the process of in vitro differentiation, the embryo stem cell is able to develop specialized somatic cells, like cardiomyocytes.
The outcomes of these cell lines are in various cardiac research areas, pharmacological testing, functional genomics, tissue engineering, and cell therapy.
Embryonic Stem Cell Research
The research on stem cells is a very well-known area these days. As the stem cells have the ability to form the tissues as well as the organs. They are also able to self-renew themselves.
The embryos which we used in the embryonic stem cells research are obtained from the eggs that the researchers form by in vitro fertilization. There are also in vitro fertilization clinics for this purpose. But these in vitro fertilized eggs are not implanted in the uterus.
Then they will grow the stem cells in some special solutions in the Petri dishes or in the test tubes.
Why Are The Adult Stem Cells Not Used For Research?
The adult stem cells are derived from the adult tissue specifically adult bone marrow. The adult cells are less durable and versatile in comparison to the embryonic stem cells.
The adult stem cells can contain the abnormalities from environmental hazards like replication error and toxins.
Adult stem cells are not able to produce all types of stem cells. so that with the help of adult stem cells all diseases are not able to treat.
Stem Cell Therapy
These are also known as regenerative medicine. We can also call it to stem cell treatment. In this therapy, we will treat or prevent a disease or diseased condition with the help of stem cell lines.
It is the mechanism for repairing dysfunctional, diseased, and injured tissues with the help of stem cells and their derivatives.
The use of stem cell therapy is to prevent and treat diseases with the help of stem cells. In starting the therapy is done with hematopoietic stem cells.
Generally, it will be in the form of bone marrow transplantation. All the cells are taken from the umbilical cord blood. Many types of research are going on in this field to it will become the more effective and safe treatment of various diseases like many neurodegenerative diseases and the diseases like heart disease, and diabetes.
These are known as regenerative medicine because they will help to regenerate the specific cells for a particular disease, as they are able to produce the new blood cells.
Bone marrow transplants and stem cell transplants are also part of stem cell therapy. Stem cell therapy is successful for around 45% of patients. The success rate should need to be increased as the research is going on in the area of stem cell therapies
Uses Of Stem Cells Therapy
Stem cell therapy is used to treat diseases. For several years, people who are suffering from some diseases like leukemia, blood cancers, and lymphoma are treated with hematopoietic stem cell transplantation (HSCT). HSCT is the majorly practiced form of stem cell therapy.
The other type of stem cell therapy is Prochymal. It was approved in 2012 in Canada. It is used for the treatment of acute graft-vs-host disease which occurs in children who are not responsive to the steroids.
It is based on mesenchymal stem cells (MSCs) and it comes under the allogenic stem therapy. They are derived from the bone marrow of adult donors. MSCs are derived from the marrow, then they should be purified, and then it is cultured and then packaged.
A single donor can donate up to 10,000 doses. Those doses are then stored in frozen conditions until they are needed.
Should We Donate Stem Cells?
Yes, the healthy donor can easily donate the stem cells. Many donors have donated stem cells.
Before the procedure starts the donor will get an injection of some particular medicine which will enhance the number of stem cells in the donor’s body.
The medicine will show some side effects on the donor’s body like bone pain, headache, nausea, and muscle ache.
Stem Cell Transplantation
Stem cell transplantation is also known as Bone Marrow transplant. It is the technique by which the stem cells are transferred to a patient body. The stem cells are transferred to the patient’s body to repair and replace the damaged stem cells.
Before the stem cell transplants the patient has to go through a high dose of chemotherapy and in some cases, it might go to radiation therapy.
The only purpose of these therapies is to prepare the patient’s body for transplantation. This procedure is known as a conditioning treatment.
The stem cells are infused into the bloodstream of the patient. Then, from there the stem cells reach the bone marrow and start performing their function.
Their function is to generate healthy cells. They will form new blood cells i.e. RBC, WBC, and platelets. This process is known as Engraftment.
Sometimes the human body will show many complications after the stem cell transplant. sometimes the immune cells start to treat the cells as foreign cells and start destroying them.
Types Of Stem Cell Transplantation
There are four types of stem cell transplantation. They are:
- Autologous transplantation
- Allogeneic transplantation
- Reduced-intensity stem cell transplantation
- Syngeneic transplantation
Autologous Transplantation
The autologous transplant is the procedure where the patient’s own stem cells are used. These cells are taken out from the patient body and then they will go through a treatment process.
After treatment, they are transplanted back into the patient body. It will reduce the chances of immune system rejection.
Allogeneic Transplantation
In this type of transplantation, the stem cells are taken from the donor organs. The donor may be a family member or it could be someone else whose stem cells are transplanted to the patient without any difficulty.
Reduced Intensity Stem Cell Transplantation
It is more like allogeneic transplantation. Here also we will take the stem cells from a donor but the chemotherapies which are given to the patient are less intensive.
Syngeneic Transplantation
It is a very rare type of transplantation. It can only be used in the case of identical twins. The identical twins also same tissue type and the same genetic makeup.
Stem Cell Clinics
Stem cell clinics are the place where stem cell transplantation and stem cell therapy take place. It contains all the necessary machines which are used during the entire process and a well-experienced staff with all the medicines available.
Conclusion
The stem cells are those cells that can make any type of body cells. They are used to treat and prevent many types of diseases. There are various types of stem cells. All these cells have different origins and they will perform different functions as well.
These stem cells are also donated by a donor to a patient to treat some diseases. There are stem cell transplantation and there are stem therapies that are given to the patients in the stem cell clinics.
There are several types of research that are going on in the field of stem cells. These researches are done to make stem cell transplantation and therapies more successful.
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