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Stem Cells Research

Research about aging and health related issues


Archive for March, 2009

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 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.

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.