Stem Cells – Introduction
Stem cells are unspecialized cells found in multi-cellular organisms with an ability to proliferate into any one of the body’s more than 200 cell types. In a simpler language, these cells can be transformed into other cell type, found in the body on being given the right stimuli. Thus, they can be recreated to form liver, skin, red blood cells etc. The ability of the stem cells to transform varies, as some are more adaptable to transformation than others.
These are characteristically of the same type. Scientists have developed a special technology through which they can mould these cells to become the precisely the same cell that is required.
These cells can grow into anyone of the body’s more than 200 cell types. These cells retain the ability to divide throughout their life. The advancement in research has helped create interest in exploring the possibilities of fully functional differentiated cells such as cardiomyocytes, neurons and bone and cartilage. Primarily, these stems cells are divided into
Each of these can give rise to only specific cell types such as neuronal stem cells. These neuronal stem cells can give rise to only nerve cells and not blood cells or liver cells. Thus, their function is limited
The scientific human embryonic cells (hES) have triggered many debates in the recent times. The impacts of these debates have been so deep that it has affected the progress of the researches and clinical trials that this therapy is undergoing. Despite all this, scientists are committed and further research is on. The scientists are attempting different ways of isolating these cells in improved cultural conditions, such that its does not provoke ethical and political conflicts.
Collection issues While extracting the cell it is important to ensure that the cells are free from microbiological contamination, can be identified easily and they are away from circumstances that can change their genotype (internal coding or blue print) and phenotype (physical appearance of the organism).
The contaminations in the cell culture can be identified through changes that can be identified with the naked eye (visible) and changes that cannot be seen with naked eyes (invisible).
The visible changes include
The above changes cannot be reversed due to which the culture cannot be used and has to be discarded.
Invisible changes mean that the mixture is contaminated, mostly due to mycoplasma. (Mycoplasmas are a genus of bacteria that lack a cell wall and are mostly resistant to beta-lactum antibiotics). These contaminations can spread rapidly to other cultures and are hard to eradicate. This form of contamination can cause.
To avoid this form of contamination, it’s mandatory to perform routine screening of all the organisms in cell cultures.
Properties of Stem Cells
Today, with advent of technologies, transplant of live, heart, kidney etc. has helped save millions to lives. But with time, the demand of the organs has surpassed that of the supply. Stem cells offer a solution where the patient can have organ transplant that are derived from the stem cells. As these organs are usually from the donors own body (fully grown stem cell) or from people who are genetically related, the chances of organ rejection are minimal.
This is possible because stem cells have distinct properties that make them more suitable for various therapies and organ regeneration. Stem cells can be derived from three sources
Embryonic cells and umbilical cord stem cells are well suited for therapy because
These forms of embryos have high plasticity and can be stimulated to form just about any organ.
Fully grown stem cells are multipotent , i.e they generate only the cell types of the tissue in which they reside. E.g. blood forming (hematopoietic) fully grown stem cell in the bone marrow gives rise to different types of blood cells. But these cells cannot give rise to nerve cells in the brain. Hence they are also called specialized stem cells.
The three main areas of stem cell production are-
Organ transplant through fully grown stem cells from the donors himself has high success rate as body accepts the organ, completely nullifying the effects of organ rejection. But it also has a drawback as stem cell numbers are few and rare in matured tissues and available in limited numbers in cell culture. This is poses a problem when the patient has to undergo stem cell replacement therapies.
Similarities and Differences
Developed Stem Cells
Embryonic stem cells
Collection and Storage of Stem Cells
These stem cells are extracted from the umbilical chord of a new born, without posing a threat to the mother or the new born.
These are characteristically of the same type. Scientists have developed a special technology through which they can mould these cells to become the precisely the same cell that is required. These cells can grow into anyone of the body’s more than 200 cell types. These cells retain the ability to divide throughout their life. The advancement in research has helped create interest in exploring the possibilities of fully functional differentiated cells such as cardiomyocytes, neurons and bone and cartilage. Primarily, these stems cells are divided into
Umbilical chord stem cells
Immediately after the release of the fetus from the womb, two sides of the umbilical cord are clamped. With the help of a needle, cord blood is extracted. Cord blood is rich in stem cells. This along with a sample of the mother’s blood cells is preserved in a bag. It is protected from coagulated and contamination from micro-organisms.
In the cord blood cell bank, it is checked for infection such as AIDS, hepatitis and malaria and cryopreserved using liquid nitrogen for future use.
Human embryonic stem cells
They can also be extracted from aborted embryos and blastocysts developed from surplus embryos in the IVF lab.
Fully grown stem cells
n adults, stem cells are extracted from the brain, bone marrow and skin. The extraction process is similar to that of the extracting blood. The average amount of blood extracted from the individual is around 500ml of blood which is sufficient for resting, processing, cryopreservation and storage.
Markers to differentiate stem cells
Though there are a wide variety of stem cells which have the property of self-renewal, indefinite growth and differentiation, but the populations of these are limited in the human body. Among 100,000 circulation blood cells, only 1 is a stem cell. To identify this one cell, scientists use stem cell “markers”.
What are stem cell “markers?”
The outer covering or coating of every cell in the body is made of specialized protein called as receptors. These receptors are capable of binding or getting attached to other signaling molecules. Each cell type has a certain pattern of receptors which are unique to them, e.g. liver cells have their own combination of receptors through which they communicate among themselves and carry out their functions. These receptors act as the stem cell marker. This biological and chemical uniqueness helps to mark the stem cell receptors.
Doctors use the combination of the chemical properties of fluorescence and unique receptor patterns on cell surfaces to identify stem cells. This is used in the following two approaches
Immediately after the extraction, the stem cells are store using cryopreservation. Cryopreservation is the process through which these cells are preserved by freezing them slowly to sub-zero temperatures (ideally it is 77 K or -196˚C) in liquid nitrogen. The temperature does not allow any biological activity to take place. The cells are also protected with cryoprotectant solutions. These solutions are used to preserve the cells against the damaging effects of freezing.
When required, the cryopreserved blood is defrosted, devoid of chemicals and injected through the vein of the patient.
Treatments of Diseases with the help of Stem Cells
Stem cells are a breakthrough in the medical field where they have shown some promising results, even in the most challenging cases like Parkinson’s. So far, they have shown good progress in various nervous, cardiovascular and orthopedic diseases.
1. Treatment of diabetes-– For years, diabetes has been a slow killer to many Americans. From the young to the old, many have fallen prey to this disease. Scientists have tried to find a permanent cure to this disease.
So far, there is no cure for this disease, though it can be controlled by administering insulin several times a day. This is continued for life and requires frequent monitoring and life long follow up, so as to keep the glucose level in check. If not controlled, it can lead to heart diseases, retinopathy (a complication that can cause blindness) and organ failures.
Stem cell cultivation
To develop a therapy for diabetes, stem cells should be able to multiply in culture and self-renew. But researchers are still debating on whether there should produce only beta cells (the islets cells that produce insulin) or other types of pancreatic islet cells which play a key role in manufacturing insulin.
Developed Stem Cells
The latest study has proved that producing only beta cells does produce responsive changes in glucose, but the response is unable to adjust to the level of glucose present in the blood. Under normal circumstance, the response of the insulin to an abnormally high level of glucose is in two phases, first by quickly releasing high concentration of insulin and then by releasing decreased concentration of insulin, slowly. But the isolated beta cells and islet clusters either release insulin or do not release them at all.
Bearing the above observation in mind, researchers are trying to develop a type of system in which the stem cells can be cultured to produce the islet cluster that can adjust the release of insulin, according to the requirement.
Embryonic stem sells
The human embryonic stem cells can be cultivated under controlled condition. Upon stimulation, they can develop into islet cells of the pancreas. This is still getting researched on and scientists believe that this could be the answer to a permanent cure for diabetes. These cells can be cultivated and used by patients who require a transplant. They also have the possibility of curing type I diabetes as they can be engineered to avoid getting rejected by the body’s very own immune system.
A US- Brazilian project conducted using 23 patients proved that those who underwent a transplant of stem cells could produce their own insulin. These were the stem cells extracted from their won bon marrow.
2. Treatment of Alzheimer’s– The exact cause of this disease is yet not known though scientist believe that it could be due to genetic make up, lifestyle and environmental factors. As of now, it is among the most severe afflictions because it slowly strips patients of their memory, slowly pushing them toward dementia. As of now, this disease has no known cure, except for a few drugs that suppress the symptoms.
Stem cell therapy – Preclinical studies done on rats have shown that a compound related to DNA helped get better results in stem cell treatment of Alzheimer’s. The team discovered that if the bone marrow cells were treated with this compound, fully developed stem cells had more chances to turn into brain cells in rats. This study also helped to overcome the ethical concerns regarding the use of embryonic stem cells as it uses the stem cells derived from the patients own stem cells. There were also no chances of immunological rejections.
3. Treatment of blindness– A compound called as bromodeoxyuridine has helped stimulate stem cells to turn into retinal cells. This discovery has given a ray of hope to patients who are suffering retinitis pigmentosa (RP). This disease is characterized by cutting out the eyes ability to pick up light leading to a condition that is termed as ‘tunnel vision’ where the peripheral vision is blocked. This disease is an irreversible and degenerative. In future, researchers plan to extract stem cells from the umbilical cord blood and inject them into retinal cells.
4. Treatment of muscular dystrophy– This disease is caused due to genetic defects and is characterized by increasing muscle weakness over time. This is also among those diseases that cannot be cured. Researchers have discovered that a particular type of stem cells called mesoangioblasts can reach the muscle tissue after crossing the blood stream. This can be done post collection of blood from patients and stimulated under controlled conditions. Once these start multiplying through ‘self renewing’ they can be injected back into the patient’s blood. These stimulated stem cells then reach the patients blood stream.
6. Treatment for prostrate cancer– This is a form of cancer that grows in the prostrate. In UK alone, it had claimed more than 10,000 lives. Researchers have successfully isolated the stem cells that cause prostate cancer. Theories suggest that even cancer cells have stem cells that help in the growth and progression of this disease. Researchers are trying to target and kill the stem cells which increase the chances of survival, respond better to chemotherapy and may even help cure the disease. But the efficacy of this form of treatment is yet to be discovered.
7. Treatment of hair loss– Alopecia has taken form of an epidemic, with trichologists all over the world are trying to come up with a permanent solution to this disorder. Injecting live stem cells that have been stimulated under lab conditions to replace dead cells is still being researched on. Moreover, the new hair resembles that of the owner and starts growing normally. If proven effective, this can help to curb hair loss and reverse baldness forever.
8. Treatment for hearing loss– The inner part of the ear is responsible for detecting sounds. It also contains tiny hair cells that deform on hearing loud sounds. Unlike the hair cells on the other part of the body, these hair cells do not grow back once they die. This can happen due to noise damage, toxic compounds or aging and usually the only solution is hearing aids. Researchers are working on the possibility of stem cell therapy which can regenerate these dead hair cells. There are also possibilities of discovering molecules that enable hearing.
9. Treatment for spinal cord injury– This form of injury can result in complete loss of sensation below the area of injury. Millions of people across the glob get confined to the wheel chair due to an injury of the spinal chord.Stem cell therapy– group of scientists conducted preclinical studies on rats to study the effect of stem cells in case of spinal injury. Researchers added neurogenin-2 to stem cells while they were undergoing self renewal in culture. These stem cells were then transplanted into the spinal cord. The result was encouraging with no adverse pain and enhanced motor function. Besides, the sensory functions (sensation below the injured area) also clearly improved.
10. Treatment of cerebral palsy– This is a disorder that is caused due to brain damage which took place during pregnancy, labor or after birth. The symptoms include seizure, hearing loss, difficulty in speaking, blindness, lack of coordination and in severe cases may also cause mental retardation.
Umbilical Cord-Derived Stem Cell Therapy– – in this disease, the brain cells get injured and are killed due to insufficient nutrients and oxygen. Using this therapy; the neural stem cell growth can replace dead and injured neurons.
11. Hematopoietic stem cell transplantation– This procedure involves administering the original stem cells that are capable of restarting the normal bone function in the patient. This procedure is useful in curing leukemia and to correct congenital immunodeficiency disorder. This has also helped patients endure higher doses of chemotherapy as the tolerance level of bone marrow increases. This allows normal functioning of bone marrow and the marrow can be replaced with harvested stem cells. Besides treating leukemia, this therapy can also treat aplastic anemia, lymphomas such as Hodgkin’s disease, multiple myeloma, immune deficiency disorders and some tumors such as breast and ovarian cancer.
This can be done via two means, by using the stem cells from a donor source. In this form of transplant, it is important to match the human leukocyte antigen (HLA) between the donor and the recipients. Compatibility between the match decreases the chances of graft rejection and graft versus host disease (GVHD).
Advantages of Stem Cells Research
Stem cell therapy has brought about a lot of excitement and hope in the medical field. Scientists and researchers believe that this therapy is the solution to many diseases that were thought to be incurable.
The disadvantages of stem cell therapy
Stem cell was discovered only a few decades ago and there are certain areas of this therapy that cannot be overlooked
This is a process that is used to preserve stem cell by cooling them at sub-zero temperatures for future use. This process is also used in infertility treatments to freeze sperms, embryos, and ova. The technique is still new and is yet to achieve perfection, though is highly popular among scientists to preserve samples of their research. It is used by hospitals and research institutes.
De-freezing or thawing is done rapidly using special techniques, so that the cells do not get damaged. Post this, the cells get coaxed into differentiating into a particular cell type and introduced into the patients body.
Human Embryonic Stem Cells
Scientists are still studying the scope of human embryonic stem cells as they have the potential to develop into almost any cell in the human body. Using blastocyst, the inner cell mass of the early human embryos, they developed the first human embryonic stem cell lines. The focus was on discovering the true potential of these cells in treating diseases and conditions and to regenerate tissues for disfunctioning cells or organs. They had focused on spinal cord injury, multiple sclerosis, Parkinson’s disease, Alzheimer’s disease and diabetes among others. The source of the stem cells included 7 day embryos which were left post an IVF infertility treatment and 5- 7 week old embryos obtained through abortions and developed tissues such as umbilical cord blood and bone marrow. Since 1998, there have been controversies surrounding extraction of stem cells from embryos as it involved destroying them. As these were far more useful than developed stem cells, researchers focused more on them.
Below given links to the accessible documents on stem cells and the lab procedure.
To avoid this form of contamination, it’s mandatory to perform routine screening of all the organisms in cell cultures.
Stem cells Ethical and moral issues
If stem cell therapy has given a ray of hope to many, it has also given birth to various debates. While stem cells from the umbilical cord blood or the patients own body has no big impact, the idea extracting and using stem cells from live embryos has raised many ethical questions. The possibility of using human embryonic stem cells questions the two fundamentals that are highly respected one; one principle supports the prevention and elevation of human suffering and the other beckons us to value and respect human life.
The stem cells derived from the human embryos are extracted from IVF embryos, with due consent of the donors. Harvesting embryonic stem cells causes destruction of blastocycts. Blastocysts are structures that are formed in the early stages of embryogenesis. Supporters of embryonic stem cell research state that since blastocysts are a cluster of 150 cells and don’s even have a nervous systems, they cannot be classified as “live” or human beings. This means that extracting stem cells from embryos does not qualify as killing. Also harvesting these stem cells promises to get rid of various diseases and unlike develped stem cells, these can be stimulated to form any part of the body tissue and generate organs for transplant (pluripotent). Develped cells have limited potential to differentiate into a limited number of cell types (multipotent). They believe the practical aspects of embryonic stem cells make it more suitable for therapy as they can be easily cultured and are found in large numbers. Comparatively, Develped stem cells are rare and their number cannot be easily increased in cultures.
This is argued by people who are firmly against the concept of using stem cells from embryos as they believe that life begins at the moment of conception. Once the stem cells are extracted, the embryo ‘dies’. According to them, destroying the embryo is equivalent to killing. Proponents of this believe that using embryonic stem cell is unnecessary as Develped stem cells from bone marrow, brain and skin have already treated diseases like diabetes, Parkinson’s, leukemia etc. Some patients who need compatible stem cells refuse to use embryonic stem cells to get cured as they believe that they do not want to take a ‘life’ to get a kidney or see better. Various religious organizations and political parties have also opposed the idea as they believe that science should only use umbilical cord blood and develped stem cells to cure diseases and embryonic stem cells are ‘live’.
The matter is very delicate with various schools of thought having their own point of view. Its important here to figure out which life is more valuable, the one that is still to exist or the one that is straining to live.
In 2005, scientists at Harvard University scientists announced a break-through discovery that combines “blank” embryonic stem cells with developed skin cells, rather than with fertilized embryos, to create all-purpose stem cells viable to treat diseases and disabilities.
This discovery doesn’t result in the death of fertilized human embryos, and thus would effectively respond to pro-life objections to embryonic stem cell research and therapy.
Harvard researchers warned that it could take up to ten years to perfect this highly promising process.
As South Korea, Great Britain, Japan, Germany, India and other countries rapidly pioneer this new technological frontier, the US is being left farther and farther behind in medical technology. The US is also losing out on billions in new economic opportunities at a time when our country sorely needs new sources of revenues.
One Type Of Stem Cell Creates A Niche For Another Type In Bone Marrow
Hematopoietic stem cells (HSCs) have the ability to self-renew and to develop into any kind of blood cell, which enables them to replenish the entire blood and immune system.
Scientists have traced these qualities to a distinct locale or niche within the bone marrow that HSCs home in on, but the identity and function of the niche-forming constituents have not been clearly defined.
Now, the precise source of HSC maintenance and regulation within the bone marrow has been discovered by Cold Spring Harbor Laboratory (Cold Spring Harbor, N.Y.) researchers and members of a multi-institutional team.
The researchers report in a published study that the HSCs retain their unique features in response to signals from another stem cell population, the mesenchymal stem cells (MSCs), which create a supportive bone marrow niche for the HSCs.
“This is the first demonstration that one type of stem cell can regulate another type of stem cells,” said.
What are stem cells?
Stem cells are unspecialized cells i.e. they do not have any specific function. On given the necessary stimulation they have the ability to undergo mitotic cell division and differentiate into various cell types. There cell are found in mammals and have been path breaking in terms of curing disorders. They promise to decrease the dependency on donor organs and also decrease the risk on organ rejection.
3. Will my child be at risk while extracting stem cells from the umbilical cord?
There is absolutely no risk for the mother or the child while extracting the stem cells. These stem cells also benefit those who are genetically related to the child as the transplant is more readily accepted within family.
4. Can these stem cells be donated?
Stem cells can be donated and they have a higher success rates in transplants, than organs taken from live donors.
5. What are embryonic stem cells?
These are the stem cells that are extracted from embryos. The embryos can be acquired from extra embryos in an IVF treatment. Scientists are also attempting to extract these embryos from the amniotic fluid. Embryonic stem cells are said to be the most “malleable” as they can be differentiate into unlimited cell types, unlike fully grown stem cells.
6. What are fully grown stem cells?
These are stem cells that can be extracted from a matured fully grown. Stem cells are found in the bone marrow, skin and brain. These are not as adaptable as embryonic stem cells as the stem cells derived from a given part can only be stimulate to become a particular cell type. E.g. stem cells derived from the skin cells can only form skin and nerve cells and not liver cells.
7. Have the stem cells successfully treated diseases?
Stem cells have given a new hope to many blood cancer afflicts. Stem cells, on stimulation, have replaced the bone marrow and helped the body endure higher doses of chemotherapy. This has helped many get rid of cancer for good. The stem cells have also successfully treated diabetes and advanced kidney cancer.
9. Why use embryonic stem cells when there is so much controversy surrounding it? Why not just stick to fully grown stem cell research?
Human embryonic stem cells (hES) are pluripotent. This means that they can be stimulated to various cell types and have the ability to form all the tissues found in the embryos. They display much greater development potential than fully grown stem cells which are multipotent, i.e. they can differentiate only into few particular cell types.
10. Do stem cells also help in nervous system diseases?
Research done on animals has shown positive results in case of Parkinson’s and spinal chord injuries. Further clinical trials are being human beings with good progress. The exact effect will be known only after sometime.
11. How is the fully grown stem cells extracted? Is there any risk?
The extraction procedure is simple and same as extracting blood from the body. The risk involved is as little as that during routine diagnostic procedures.