Stem Cells Research

An adult stem cell is an undifferentiated cell found among the differentiated cells in a tissue or organ can renew itself and can differentiate to yield the major specialized cell types of the tissue or organ. The primary roles of the adult stem cell in a living cell are to maintain and repair the tissues and organs in which they are found. There are now some scientists who spell the adult stem cells as the somatic stem cells. Unlike the embryonic stem cells the adult stem cells are a bit different. The embryonic stem cells are known by the organs in which it is found such as the inner cell mass and the blastocysts. The origin of the adult stem cell in the tissue is still unknown.

Research on the stem cell has really led to some of the very exciting results. The scientists have found many adult stem cells in many different tissues in which they have never thought of that it would be present. All this findings related to the adult stem cells have really prompted the scientists to think that they can be used for the transplant or not. In fact the adult blood forming stem cells from bone marrow have been used in transplant for more than 30 years.

Certain kinds of adult stem cells seem to have the ability to differentiate into a number of different cell types, given the right conditions. If this differentiation of adult stem cells can be controlled in the laboratory, these cells may become the basis of therapies for many serious common diseases.

The history of the research on the adult stem cell began about 40 years ago. In 1960, the scientists discovered that the bone marrow contain about two types of stem cells. One population which was called the hematopoietic stem cells and this formed the all types of the blood cells found in the body.

The second one which was called the bone marrow stromal cells was also discovered few years after. The stromal cells are the fixed cell populations that generate bones, cartilage, fats and fibrous connective tissues.

Where are they found?
The adult stem cells are found in almost all the tissues and organs. You must know one point and that is the stem cells are found in almost all the tissues and organs. Yes, you can say that they might be one or two but they are present in almost all the tissue and organs.

Scientists in many laboratories are trying to find the way to grow the adult stem cells in cell culture and manipulate them to generate specific cell type in order to cure various injuries and the diseases. We can thus hope only for the best.

In the Field of genetics and the developmental biology, the somatic cell nuclear transfer (SCNT) is a laboratory technique for creating the Clonal embryo, using an ovum with the donor nucleus. It can be used in the embryonic cell research or in regenerative medicine where it is sometimes referred to as “therapeutic cloning”. It can also be used as the first step for the reproductive cloning.

In SCNT the nucleus, which contain the organism’s DNA, of a somatic cell is removed and the rest of the cell discarded. At the same time, the nucleus of an egg cell is detached. The nucleus of the somatic cell is then inserted into the enucleated egg cell. After being inserted into the egg, the somatic cell nucleus is reprogrammed by the host cell. The egg, now containing the nucleus of a somatic cell, is stimulated with a shock and will begin to divide. After many mitotic divisions in culture, this single cell forms a blastocyst (an early stage embryo with about 100 cells) with almost identical DNA to the original organism.

I would like to present some of the fields where the concept of SCNT can be used. I am listing two of them. They are as follows:

1. SCNT in stem cell research
2. SCNT in reproductive cloning

I would like to discuss the first one in detail. The detail is as follows:

SCNT in stem cell research
Only a handful of the labs in the world are currently using SCNT techniques in human stem cell research. In the United States, scientists at the Harvard University Stem Cell Institute, the University of California San Francisco, Stemagen (La Jolla, CA) and possibly Advanced Cell Technology are currently researching a technique to use somatic cell nuclear transfer to produce embryonic stem cells. In the United Kingdom, the Human Fertilization and Embryology Authority has granted permission to
research groups at the Roslin Institute and the Newcastle Centre for Life. SCNT may also be occurring in China.

In 2005, a South Korean research team led by Professor Hwang Woo-suk, published claims to have derived stem cell lines via SCNT, but supported those claims with fabricated data. Recent evidence has proved that he in fact created a stem cell line from a parthenote.

I must say that this is really a great step which is definitely going to take us to the new era where the medicines will have completely new meaning. Who had
though 20 years before that we will be able to grow the cells on our own? However this is a truth now. We can really do it.

I would also like to say that the SCNT has really been a find and it has really created a mile stone in the field of stem cell research.

A Genetic screen is the procedure or step to identify and select the individuals who possess the phenotype of interest. A genetic screen for new genes is often referred as the forward genetics and not the reverse genetics which the term to identify the mutant alleles that are already known. The mutant alleles that are not tagged for the rapid cloning are mapped and cloned by the positional cloning.

How to create a mutant population?
Since unusual alleles and phenotypes are rare, geneticists expose the individuals that are to be screened to a mutagen, such as a chemical or radiation, which generates mutations in their chromosomes. The use of mutagens enables “saturation screens” one of the first of which was performed by Nobel laureates Christiane Nüsslein-Volhard and Eric Wieschaus. A saturation screen is performed to uncover every gene that is involved in a particular phenotype in a given species. This is done by screening and mapping genes until no new genes are found.

Type of screening
I would like to describe the three types of screens for you. They are as follows:

1. Basic screen
A basic screen involves the looking for a phenotype of interest in the mutated population. One can really screen for the obvious phenotypes such as the fruit flies with no wing or a flower with no petal.

2. Temperature sensitive screen
More subtle is the temperature sensitive screen that involves the temperature shift to enhance the mutant phenotype. A population growth at low temperature would have a normal phenotype. However the mutation in the particular gene at the higher temperature will definitely make it unstable. You must know that the mutant phenotype is conditional and can be activated by just raising the temperature. A null mutation in such a gene may be lethal for the embryo and such mutation will be missed in the basic screen.

3. An enhancer or the suppressor screens
This is the most sophisticated type of the genetic screen. This type of the screen has the two advantages. First, new genes identified in the screen are often involved in the same biological process as the weak allele in the genetic background, in this case wing formation. Second, due to genetic redundancy, the mutant genes discovered may not have a visible phenotype of their own. In a more basic screen these would not be discovered, however, in the sensitized genetic background a visible phenotype is clear.

I really feel that the biotechnology has given a lot to the field of medicine. We are now on the verge to discover and cure many diseases which were not been able to be cured until now. Genetic screening is really a one small part of this vast field of biotechnology.

Cell division is the process by which the cell divides and forms two or more daughter cells. It is usually a small segment of the larger cell cycle. The type of cell division in the eukaryotes is known as the Mitosis, and it leaves the daughter cell capable of dividing again. The corresponding sort of the cell division in the prokaryote is also known as the meiosis. There is one another type of cell division present in the eukaryotes, called the meiosis, a cell is permanently transformed into a gamete which cannot be divided further again until fertilization.

For simple unicellular organisms such as the amoeba, one cell division is equivalent to reproduction? an entire new organism is created. On a larger scale, mitotic cell division can create progeny from multi cellular organisms, such as plants that grow from cuttings. Cell division also enables the reproducing organisms to develop from the one-celled zygote, which itself was produced by cell division from gametes. And after growth, cell division allows for continual renewal and repair of the organism. A human being?s body experiences about 10,000 trillion cell divisions in a lifetime.

Mitosis
Mitosis is the process in which a eukaryotic cell separates the chromosomes in its cell nucleus, into two identical sets in two daughter nuclei. It is generally followed immediately by cytokinesis, which divides the nuclei, cytoplasm, organelles and cell membrane into two daughter cells containing roughly equal shares of these cellular components. Mitosis and cytokinesis together define the mitotic (M) phase of the cell cycle – the division of the mother cell into two daughter cells, genetically identical to each other and to their parent cell.

The process of mitosis is complex and highly regulated. The sequence of events is divided into phases, corresponding to the completion of one set of activities and the start of the next. These stages are prophase, prometaphase, metaphase, anaphase and telophase. During the process of mitosis the pairs of chromosomes condense and attach to fibers that pull the sister chromatids to opposite sides of the cell. The cell then divides in cytokinesis, to produce two identical daughter cells.

Meiosis
In biology or life science, meiosis (pronounced my-oh-sis) is a process of reductional division in which the number of chromosomes per cell is halved. In animals, meiosis always results in the formation of gametes, while in other organisms it can give rise to spores. Before meiosis begins, the DNA in the original cell is replicated. Thus, meiosis starts with homologous chromosomes.

These are the two kind of cell division which is really prominent in living organism. I really feel that these are the most important processes in which the cell takes part or are related with.

Embryonic cells as the name suggest are derived from the embryos. Specifically the embryonic cells are derived from the embryos that develop from egg that have been fertilized in vitro in a vitro fertilization clinic which is then donated for the research purpose of the informed consent of the donor. The embryos from which the human embryonic stem cells are derived are typically four to five days old and are hollow microscopic balls of cells called the blastocyst.

The blastocysts include the three structures. They are as follows:

1. The first one is the trophoblast which is the layer of the cells that surrounds the blastocysts.
2. The blastocoels which is the hollow cavity inside the blastocysts.
3. The third one is the inner cell mass which is generally a group of thirty cells at one end of the blastocoels.

The another question which is really very important in the field of stem cells and related to this type of cell is that how are the embryonic cells grown in the laboratory.

How are the embryonic stem cells grown?
The growing cells in the laboratory are called the cell cultures. The human embryonic cells are isolated by the transferring the inner cell mass into a plastic laboratory cultural dish that contains a nutrient broth known as the culture medium. The cells divide and spread over the surface of the dish. This coating layer of the cell is called the feeder layer.

The reason for having the mouse cells in the bottom of the culture dish is to give the inner cell mass cells a sticky surface to which they can attach. Also, the feeder cells release nutrients into the culture medium. Recently, scientists have begun to devise ways of growing embryonic stem cells without the mouse feeder cells. This is a significant scientific advancement because of the risk that viruses or other macromolecules in the mouse cells may be transmitted to the human cells.

What laboratory tests are used to identify the embryonic stem cells?
The most important process related to the tests related to the embryonic cells is the characterization. I must tell you what actually the characterization is? The scientists test the cells to exhibit the fundamental properties that make then embryonic stem cells. This process is also called the characterization.

I would like to describe one test for you. It is as follows:

• The test is the growing and sub culturing of the stem cells for many months. This ensures that the cells are capable of long-term self-renewal. Scientists inspect the cultures through a microscope to see that the cells look healthy and remain undifferentiated.
• It is not only me, in fact all the scientists believe that the study of stem cell is really going to throw light on many unsolved theories of biology.

Researches on the stem cell are being carried out and the scientists are very eager to know that how organism is able to develop into complex organism from a single cell. Researches are also being carried out that how the dead cells are being replaced by the healthy cells. This promising area of science is also leading scientists to investigate the possibility of cell-based therapies to treat disease, which is often referred to as regenerative or reparative medicine.

Stem cells are one of the most famous and popular field of research in the field of bio-technology in recent times. But like many growing fields of scientific query, research on stem cells raises scientific questions as rapidly as it generates new discoveries.

The articles which I am writing are meant to answer following questions of the readers. For example, what are stem cells? What different types of stem cells are there and where do they come from? What is the potential for new medical treatments using stem cells? What research is needed to make such treatments a reality?

What are stem cells?
Stem cells have two important characteristics that distinguish them from other type of cells, but they are unspecialized cells that renew themselves for a long period of time through cell division.

The second is that under certain physiologic or experimental conditions, they can be induced to become cells with special functions such as the beating cells of the heart muscle or the insulin-producing cells of the pancreas.

Scientist work with primarily two kinds of cells which are as follows:

Embryonic stem cells.
Adult stem cells.
These two really have different functioning and characteristics.

Importance of stem cells
The stem cells are important to the living organism for many reasons. In the three to five days the old embryo called the blastocyst, stem cells in the developing tissues gives rise to multiple rise cell types that make up the heart, lungs, skins and other tissues. In some adult tissues such as bone marrow, muscles, brains discrete population of stem cells generate the replacement of cells that are lost through normal wear and tear, injury or disease.

As scientists learn more about stem cells, it may become possible to use the cells not just in cell-based therapies, but also for screening new drugs and toxins and understanding birth defects. However, as mentioned above, human embryonic stem cells have only been studied since 1998. Therefore, in order to develop such treatments scientists are intensively studying the fundamental properties of stem cells, which include:

Determining precisely how stem cells remain unspecialized and self renewing for many years.
Identifying the signals that cause stem cells to become specialized cells.
All the cases really prove that the stem cells can really prove out to be really a milestone in the field of biotechnology.