Stem Cells Research

HOUSTON — (March 5, 2010); Components of the blood or hematopoietic
system derive from stem cell subtypes rather than one single stem cell that
gives rise to all the different kinds of blood cells equally, said scientists
from Baylor College of Medicine (www.bcm.edu) in a report that appears in the
current issue of the journal Cell Stem Cell (www.cell.com/cell-stem-cell/)

“While previous reports in journals have hinted at the possibility of stem cell
subtypes, this study represents the clearest data to show that is true,” said
Dr. Margaret Goodell, director of the Stem Cells and Regenerative Medicine
(STaR) Center (www.bcm.edu/star/) at BCM. “From a scientific point of view, it’s
making us re-evaluate the view of the stem cells that come from adults. It
challenges the dogma that there is one type of stem cell.”

She and the report’s first author, Dr. Grant A. Challen, a postdoctoral
associate in the Center for Cell and Gene Therapy (www.bcm.edu/genetherapy/) at
BCM, said that the stem cell subtypes they identified meet the strictest
criteria.

To accomplish this, Challen, Goodell and their colleagues used a special dye
technique to discriminate the different hematopoietic stem cell subtypes –
myeloid, which have a preference for giving rise to red blood cells, macrophages
(non-specific immune cells that engulf foreign bodies) and similar cells; and
lymphoid, which similarly preferentially give rise to the body’s immune system
cells.

By transplanting single stem cells into individual mice, Challen was able to
confirm that these subtypes exist and act as the researchers had thought. The
subtypes also maintain a stable population of the stem cells over time, another
characteristic of these progenitor cells.

“We cannot rule out that there is a single progenitor cell to both sub-types,”
said Goodell. “We don’t know where to look for it. Maybe it does not exist or
maybe it exists only when the bone marrow begins to be made but does not persist
into adulthood.”

The finding has implications for treatment.

“People have been looking for purer and purer stem cell types,” Goodell said.
“In doing that, they may not be getting all the stem cell types they need. Maybe
in the clinic, it is better to have less pure types.”

“You may need a spectrum of stem cells to create a complete blood system,” said
Challen.

In bone marrow or peripheral blood stem cell transplants for cancers or blood
disorders, doctors often wipe out a patient’s own bone marrow and replace it
with stem cells that can repopulate the bone marrow. Scientists are constantly
improving that system.

As animals age, their proportions of stem cell subtypes change, Challen said.
“The myeloid cells have a slower rate of baseline turnover and a higher rate of
self renewal. They persist over time, such that the myeloid-biased stem cells
become more prevalent with time. This may have implications for how different
types of cancers become more prevalent with age.”

The two types react differently to the presence of transforming growth factor
beta, Challen said. One type increases and the other decreases.

Challen said it is also important to remember the big question.”Does this
translate to humans as well? Some markers may be different, but I think it
will.”

Goodell holds the Vivian Smith Chair of Regenerative Medicine at BCM.

Stem cell research has gained a lot of momentum in the past few years-due to the potential and controversies surrounding it! A lot of scientists and researchers claim that stem cells can help in curing grave diseases like type 1 diabetes, Alzheimer?s disease, multiple sclerosis, as well as spinal cord injuries where as other argue about the ethics of producing them. The debate is still continues but we have to reach a standpoint somewhere, and look at the positive side than harp about the negatives!

What are stem cells?

Stem cells are the undifferentiated cells present in an organism which have the potential to develop into specialized organs or tissues. The stem cells divide through mitotic division and after division, they can either remain as a stem cell or grow into another type of cell, having specialized functions such as a muscle cell, a red blood cell, or a brain cell.

Stem Cells are of two types- embryonic stem cells or adult stem cells. The embryonic stem cells are derived from human embryos or the inner mass of the blastocyst and are pluripotent- meaning that they are able to divide into any type of specialized cell whereas the adult stem cells are found among the differentiated tissues or organs and have the potential to yield the same type of cells of a specialized tissue or organ. They also have the capacity to renew or repair any damage to the tissue or organ.

There has been a great deal of controversy surrounding the stem cells. The stem cells have the ability to grow into specialized types of organs- which means that they can be used for organ transplants because they can be grown to yield specific types of organs. Moreover it has been found out that stem cells can be used for curing diseases like cancer, Alzheimer?s disease, Parkinson?s disease, multiple sclerosis, and so on. So, one can see the tremendous potential which these cells have!

However, the advocators of human life despise or do not support this research because the extraction of embryonic stem cell requires the destruction of embryos- which means the end of a human life! Hence, the opposers of stem cell research do not regard it as ethical. President Bush has also strongly rejected the research on embryonic stem cells because he feels that this research in fact, destroys a human embryo! Funds devoted to stem cell research are being taken away due to strong oppositions by various ethical communities.

Even though stem cell research holds a lot of potential, yet it is being criticized on moral and ethical grounds. In the mean while we can just sit back and hope that people realize the immense value of this research and start advocating it!

If you or any of your relative is suffering from deadly diseases such as Parkinson?s, cancer, multiple sclerosis, Alzheimer?s or any other, then these small cells-could be a matter of life and death for you! It has been shown that the stem cells are capable of differentiating into specialized cells or organs of the body as well renewing or repairing any damage which has occurred in the tissues or organs of the body! Hence, you can see for yourself that these stem cells have a life-saving potential.

Stem cells are of two types and both of them have enormous potential in their own. These are embryonic stem cells and adult stem cells. The embryonic stem cells are derived from the blastocyst or the inner mass of the embryos, after fertilization has occurred whereas the adult stem cells are already present within the specialized tissues/organs, and multiply by mitotic division for replenishing dying cells and regenerating damaged tissues. Adult stem cells have been found to have a much longer track record in treatments, in comparison to the embryonic stem cells and are not controversial as they do not result in the destruction of embryos.

Stem cells are derived from blastocyst and can give rise to specialized cells in the body- for example, a blank cell can become a specialized cell if it attaches to the blood stream or if you have an injury in your spinal cord, then it can become a nerve, cartilage or motor cell. So, a stem cell can take any shape or form, depending on the requirements of the body. Hence, they are of immense importance in carrying organ transplants or treating deadly diseases such as cancer, Parkinson?s or Alzheimer?s.

Generally, if an organ transplant is required for a person, then it is very difficult to obtain a fresh piece of organ. But if the stem cells are controlled and manipulated properly, then they will grow into a specialized organ and will serve as a potential supply for organ transplant. Moreover, as these cells are able to renew or repair the damaged tissues, so can be used for replacing the cells lost in injuries or accidents. For example in Parkinson?s disease, the brain cells are lost or damaged, and hence a person is not able to co-ordinate his/her muscle movements and looses memory. But if you can add new cells in place of the dead ones, then the person will be able to live normally. So, think of the potential that this small cell has!

Hence, stem cell research can really affect everybody?s life. If you support this research, then you may be able to save your friend or relative from having an untimely death!

In biology the genome of the organism is the whole hereditary information of an organism that is encoded in the DNA or of some RNA viruses. You must note that this include both the gene and the non-coding sequence. In other words one can say that the genome is the complete description of the DNA sequence. It is the Genome which really defines the DNA sequence.

With the admission of the bio technology I must say that the whole concepts in the medicinal world are really changing. This is just like the invention of the atomic number. You must remember how the domination of the atomic mass was over shadowed by the atomic number.

The genome is also quiet similar to it. I must really feel that the genome is one of the most important aspects ever since the biotechnology has been introduced. You must have heard about the human genome project.

I would definitely like to add the human genome project in the conversation. I do feel that you too must be feeling very eager to know about the human genome project. This project started in the year 1990 under the custody of James D. Watson. The main target was to really get the detail of the DNA sequence of the human body. But at first the experiments was carried on animals like fruit fly and the laboratory mouse.

Many experiments were carried out and many genomes or the gene sequence were registered. Ever since the time the genome project has started the genome project team has really come up with some of the great results and this has revolutionized the field of biotechnology.

It is being attempted to find out the proper gene sequence of the human being and what gene sequence from the particular organ. There is really an attempt to develop those gene sequences in the laboratory.

Almost all the goals of the human genome projects have really been fulfilled and I must say that the projects have finished much before the projected time. You should know that at first the project members really decided to find the sequence of the 95 % of the DNA in the human body. I must say that not only they were able to finish the project in less time but you should also note that they were able to find the sequence of almost 99 % of the gene sequence. This was really something which was really not thought of.

No body really had an idea that the genome project team will come up with such a great results. But it really happened and we are really on the verge to make a human clone quiet soon and I do feel that this will be a tremendous achievement in the field of medical science.

Mesochymal stem cells are the multi potent stem cells that can be differentiated into variety of cell types. The cell types into which the MSC has been differentiated are as follows: osteoblast, chondrocytes, myocytes, adipocytes, and as described lately as beta pancreatic islets cells. However in the vivo results are now thought of as the misinterpretation of the spontaneous cell fusion between the damaged neuron a mesochymal cell present in the brain.

While the terms Mesenchymal Stem Cell and Marrow Stromal Cell have been used interchangeably, neither term is sufficiently descriptive as discussed below:

1. Mesenchyme is embryonic connective tissue that is derived from the mesoderm and that differentiates into hematopoietic and connective tissue, whereas MSCs do not differentiate into hematopoietic cells.
2. Stromal cells are connective tissue cells that form the supportive structure in which the functional cells of the tissue reside. While this is an accurate description for one function of MSCs, the term fails to convey the relatively recently-discovered roles of MSCs in repair of tissue.
3. Because the cells, called MSCs by many labs today, can encompass multi potent cells derived from other non-marrow tissues, such as adult muscle or the dental pulp of deciduous baby teeth, yet do not have the capacity to reconstitute an entire organ, the term Multi potent Stromal Cell has been proposed as a better replacement.

History
The scientists first described the clonal nature of the marrow cells in the year 1960. Subsequent experimentation revealed the
plasticity of marrow cells and how their fate could be determined by environmental cues. Culturing marrow cells in the presence of the osteogenic stimuli such as ascorbic acid, inorganic phosphate, dexamethasone can promote the differentiation into osteoblast.

Characteristic
There are many characteristic of the mesenchymal cells. Some of them are as follows:

1. Morphology
Mesenchymal cells are really characterized morphologically by a small cell body with a few cell processes that are long and
thin. As far as the cell structure is concerned I must say that the cell contains large round nucleus with which is surrounded by the chromatin particles giving it a clear appearance. The remaining part of the cell contains the mitochondria, Golgi body, rough endoplastic reticulam. The cells are long and thin and are widely dispersed.

2. Detection
There is no test available for finding the MSC on a single cell. The MSC really cannot be detected up till now.

However I really feel that the mesenchymal cells are quiet important for the human body and if you will not have it in the right quantity then I must tell
you that you will definitely find yourself really caught by some disease or the other sooner or later.

The endothelium is the thin layer of the cells which lines the interior surface of the blood vessels. This forms the interface between the circulating blood in the lumen and the rest of the vessel wall. Endothelial cell line the entire circulatory system from the cell to the smallest capillary. These cells reduce the turbulence and hence lead to the pumping of the blood to much further distance.

The endothelial tissue is the specialized type of the epithelium tissue which is one of the four types of biological tissue in the animals. More specifically it is a simple squamous epithelium.

Terminology

The foundational model of the anatomy makes the distinction between the endothelial cells and the epithelial cells on the basis of which the tissues can develop from and states that the presence of the vimentin rather than the keratin filaments separate them from the epithelial cells.

Endotheliums of the interior surface of the heart chamber are called the Endocardium. Both blood and the lymphatic capillaries are composed of the single layer of the endothelial cells called the monolayer.

Functions

1. Endothelial cells may be involved in many aspects of the vascular biology. Some of the functions are as follows:
2. Vasoconstriction and vasodilation, and hence the control of blood pressure.
3. Blood clotting (thrombosis and fibrinolysis).
4. Atherosclerosis.
5. Formation of new blood vessels (angiogenesis).
6. Inflammation.
7. Barrier function – the endothelium acts as a selective barrier between the vessel lumen and surrounding tissue, controlling the passage of materials and the transit of white blood cells into and out of the bloodstream. Excessive or prolonged increases in permeability of the endothelial monolayer, as in cases of chronic inflammation, may lead to tissue oedema/swelling.

In some organs, there are highly differentiated endothelial cells to perform specialized ‘filtering’ functions. Examples of such unique endothelial structures include the renal glomerulus and the blood-brain barrier.

The role of Endothelium

I do feel that you must have an idea about the cholesterol. The cholesterol really leads to the blood pressure. There is a certain increase in the blood pressure if the cholesterol is increased in the blood vessel. I really feel that the endothelium can do a lot in controlling the heart disease. It is really a very important part of the blood vessel.

Scientists have recently discovered that when people digest fat then cholesterol is carried in the blood. This sometimes increases the blood pressure because the cholesterol forms a layer above the interior wall of the blood vessels. As a result the blood does not move smoothly through the blood vessels which may lead to heart diseases.

Dendritic cells (DCs) are a kind of the immune cells and as such it forms the part of the mammalian immune system. As far as the main process is concerned I must say that its main job is to process the antigen material and current it on the surface to other cells of the immune system, thus functioning as antigen-presenting cells.

The dendretic cells are present in the small quantities in the tissues that are in contact with the external environment which is mainly the skin and the inner lining of the stomach, lungs, nose and the intestine. We can also find them in the immature state of the blood.

As soon as they are activated they move to the lymphoid tissues where they react with the T cell and the B cells to initiate and shape the adaptive immune response. At definite expansion stages they grow branched projections, the dendrites that give the cell its name. However, these do not have any particular relation with neurons, which also have similar appendages. Undeveloped dendritic cells are also called veiled cells, in which case they possess large cytoplasmic ‘veils’ rather than dendrites.

History
Dendritic cells were first described by Paul Langerhans (Langerhans cells) in the late nineteenth century. It wasn’t until 1973, on the other hand, that the term “dendritic cells” was given by Ralph M. Steinman and Zanvil A. Cohn. In 2007 Steinman has been awarded the Albert Lasker Award for Basic Medical Research for his discovery.

Types of Dendritic cells
There are generally two kinds of the dendritic cells. I must say that the two kind of the dendritic cells are myeloid and plasmacytoid which is also called the lymphoid.

I would at first like to discuss the myeloid dendritic cells.

1. Myeloid dendritic cells
These are most similar to the monocytes. The MDC are made up of two subsets:

• The more common mDC-1, which is a major stimulator of T cells.
• The extremely rare mDC-2, which may have a function in fighting wound infection.

2. Plasmacytoid dendritic cells
These look like the plasma cells but have the certain characteristic of the myeloid dendritic cells.

• Characteristic of the immature dendritic cells
• High intracellular MHC II in the form of MIICs.
• Expression of CD1a.
• Active endocytosis for certain particulates and proteins; presence of FcgR and active phagocytosis.
• Deficient T cell sensitization in vitro.
• Low/absent adhesive and costimulatory molecules (CD40/54/58/80/86).
• Low/absent CD25, CD83, p55, DEC-205, 2A1antigen.
• Responsive to GM-CSF, but not M-CSF and G-CSF.
• Maturation inhibited by IL-10.

Similarly there are some characteristic of the mature dendritic cells and I must tell you that these cells are really of great importance.

Beta cells are a type of the cell which is present in the pancreas in the areas called the islets of the langerhans. They make 65 to 80 % of the cells in the islets. The beta cells make and release insulin which is a hormone which regulates the level of the glucose in the blood. There is a baseline level of the glucose in the blood which is maintained by the liver. It can really respond quickly to spikes in the blood glucose. The response time is purely quick taking only 10 minutes.

If we leave the insulin apart, beta cells also release C-peptide, a byproduct of insulin production, into the bloodstream in equimolar quantities. You must know that the C-peptide helps to prevent neuropathy, and also other symptoms of diabetes related to vascular deterioration. Measuring the levels of C-peptide can give a practitioner an idea of the viable beta cell mass. Hence the C-Peptide is really very important.

The beta cells also produce the amyline which is also known as the IAPP islet amyloid polypeptide. Amyline acts as the part of the endocrine pancreas and contributes to the glycemic controls. Amyline metabolic function is really now some what characterize as the inhibiter of the appearance of the nutrients in the plasma. You can also say that it functions as the syenergic partner of the insulin. The insulin regulates the food intake for the long time and the amyline decrease the food intake for the short time.

Research
Much research has been done in the field of the beta cell physiology and the pathology. One of the major topics of concern is the effect of the beta cell on the diabetes. Many research scholars are really trying to find the way to cure or even control the diabetes with the help of the beta cells.
One of the other major topics is the replication of the adult beta cell and also its application in diabetes. The Larry L. Hillblom Islet Research Center at UCLA is one of the leading research centers in the field, within the Diabetes and Endocrinology Research Center, directed by Dr. Peter Butler.

Pathology
The diabetes mellitus type I is really caused by the destruction of the insulin producing beta cell by the cells of the immune systems.

In the diabetes mellitus type II is caused by decline of the beta cells over the time and the insulin resistance really plays a large role in the disease.

I would really say one thing and that is the research are really on and it could be very soon that we will find the permanent cure of the diabetes. This will really be a major break through in the field of medical science.

Somatic cells are the body forming cells of any organism and as the meaning suggest it really forms the body of any cell. The somatic word has been taken from the Greek word soma which really means the body.  It is quiet different from the germline cells. Germline cells are found in the mammals and the example of the germline cells those which participate in reproduction. However here you will not have to worry about it. I really feel that we are here to talk about the somatic cells and hence we should talk about the somatic cells which are also called body cells.

A simple use of the somatic cells can be determined as the cells which forms the body. The somatic cell contains the 46 chromosomes as 23 pairs of chromosomes. Each cell of the chromosome contains one chromosome from the father and the mother. This is really very interesting to note that the somatic cells contain twice the times the somatic cells contain the chromosomes. You should know that the somatic cells contain 46 chromosomes in 23 pairs whereas the germilne cells contain only 23 chromosomes which is really half the number as contained by the somatic cells.

As far as the gender of the born child is concerned you should know that it depends upon the fusion of the gernline cells. It’s really also known that the zygote contains46 chromosomes.

As far as the other species are concerned I must tell you that they contain a much more complex structure. As far as the different species are concerned I must tell you that those species which contains chromosomes arranged in pairs are called the diploid organisms. Those species which contain single unpaired chromosomes are called the haploids. However as far as the somatic cells are concerned the chromosomes arrange themselves in four or the tetraploids or even the six or the haploids. This means that they can have the diploid or the triploid germline cells. As an example you can take the modern cultivated species of the wheat which is called the triticum aestivum L, a hexaploid species whose somatic cells contain six copy of every chromatid.

In recent times the technique of cloning has really become very important. I do feel that you must have the idea about the cloning but the question really arises that what is really the importance of the somatic cells in the cloning process. Any retention of existing mitochondrial DNA prevents the new cell being identical. One method of doing this is called “somatic cell nuclear transfer” and involves removing the nucleus from a somatic cell, usually a skin cell.

I really feel that now you must have got an idea that how important the somatic cells are for the human body and its comparison with the germline cells.

Stem cells differ from the other kinds of cells in the body. There are basically three unique properties of the stem cells which are really very important. They have the capability of dividing and renewing for a long period of times. They are unspecialized and the third one is that they can give rise to the formation of the specialized cells.

Scientists are really trying very hard to understand the two fundamental properties of the stem cells which are really related to the self renewal properties of the stem cells.  The two fundamental properties are as follows:

1. The first point is that how can the embryonic cells proliferate for so long and this also without differentiating where as the adult stem cells cannot.
2. The second point is of the fact that how the stem cells can proliferate for so long and renews itself without differentiating.

While trying to answer these questions the scientists may find the way to understand how the cell proliferation takes place during the embryonic development abnormal cell division that leads to the cancer. In fact all these studies will help the scientists grow the embryonic cells and the adult cell better in the laboratory.

I would like to explain the two plus points of the stem cells in detail. The details with the description are as below:

1. Stem cells are unspecialized and can develop specialized cells
One of the fundamental properties of a stem cell is that it does not have any tissue-specific structures that allow it to perform specialized functions. A stem cell cannot work with its neighbors to pump blood through the body (like a heart muscle cell); it cannot carry molecules of oxygen through the bloodstream (like a red blood cell); and it cannot fire electrochemical signals to other cells that allow the body to move or speak (like a nerve cell). However, unspecialized stem cells can give rise to specialized cells, including heart muscle cells, blood cells, or nerve cells.

2. Stem cells can divide and renew itself on it own
Unlike muscle cells, blood cells, or nerve cells-which do not normally replicate themselves-stem cells may replicate many times. When cells replicate themselves many times over it is called proliferation. A starting population of stem cells that proliferates for many months in the laboratory can yield millions of cells. If the resulting cells continue to be unspecialized, like the parent stem cells, the cells are said to be capable of long-term self-renewal.

I really feel that these are some points which just reveal one point and that is the research on the stem cells can come out to be a major milestone in the field of medicine. We all know that the bio technology has really been a milestone in the field of medicinal world. And the research topics can really be more than a milestone.