How Are Embryonic Stem Cells Grown In Labortary?
Embryonic stem cells,are derived from embryos that develop from eggs that have been fertilized in vitro—in an in vitro fertilization clinic—and then donated for research purposes with informed consent of the donors.
The embryos from which human embryonic stem cells are derived are typically four or five days old and are a hollow microscopic ball of cells called the blastocyst.
The blastocyst is formed by
- Trophoblast, which is the layer of cells that surrounds the blastocyst
- Blastocoel, which is the hollow cavity inside the blastocyst
- Inner cell mass, which is a group of approximately 30 cells.
What Are Adult Stem Cells and Where Are They Found?
An adult stem cell is an undifferentiated cell found among differentiated cells in a tissue or organ. These cells can renew themselves and can differentiate to yield the major specialized cell types of the tissue or organ.
The primary roles of adult stem cells in a living organism are to maintain and repair the tissue in which they are found.
They are also termed as somatic stem cell. The origin of adult stem cells in mature tissues is unknown.
Adult stem cells have been found in many more tissues than they once thought possible. In right environment, 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 is possible under lab conditions, these cells may become the basis of therapies for many serious common diseases.
About 40 years ago, researchers discovered that the bone marrow contains at least two kinds of stem cells. One population, called hematopoietic stem cells, forms all the types of blood cells in the body. A second population, called bone marrow stromal cells, generate bone, cartilage, fat, and fibrous connective tissue.
There are a very small number of stem cells in each tissue.They may remain non-dividing for many years until they are activated by disease or tissue injury.
The adult tissues reported to contain stem cells include brain, bone marrow, peripheral blood, blood vessels, skeletal muscle, skin and liver.
Struggle, however is to grow adult stem cells in cell culture and manipulate them to generate specific cell types so they can be used to treat injury or disease.
How To Identify Adult Stem Cells?
One or more of the following three methods are used to identify adult stem cells
- Labeling the cells in a living tissue with molecular markers and then determining the specialized cell types they generate
- Removing the cells from a living animal, labeling them in cell culture, and transplanting them back into another animal to determine whether the cells repopulate their tissue of origin
- Isolating the cells, growing them in cell culture, and manipulating them, often by adding growth factors or introducing new genes, to determine what differentiated cells types they can become.
Brain Tissue Created From Stem Cells
Japanese researchers claim to have created functioning human brain tissue from stem cells, a world first that has raised new hopes for the treatment of disease.
Stem cells taken from human embryos have been used to form tissues of the cerebral cortex, according to experts at the government backed research institute Riken. The tissues self-organised into four distinct zones very similar to the structure seen in human fetuses, and conducted neuro-activity such as transmitting electrical signals.
“Transplanting tissues could raise hopes for greater functional recovery,” the institute said.
But study of invitro cultivation of more mature cortex tissue, such as those with six zones like in the adult human brain, will be stepped up. The tissues could also serve as “a mini organ” for studying the causes of Alzheimer’s disease.
Embryonic stem cells are harvested by destroying a viable embryo, a process that some find unacceptable. Riken said cortex tissues were also obtained from “induced pluripotent stem cells,” which are similar to embryonic stem cells but artificially induced.
How Do Stem Cells Develop and Work?
I can across a very good video that explains basics of stem cells and their functioning very well. This video is about eight minutes long and carries a good explanation about stem cells. Here we go–
Stem Cell Research To Get A Boost – Obama To Reverse The Limits
Stem cell research is poised to become better. A boost to stem cell research is about to arrive when President of USA, Mr Barack Obama would announce the reversal of restriction imposed by Bush government.
The news has been reported by American Constitution Society Blog today.
President is likely to announce this on Monday. Today is Saturday. Two more days to go.
Earlier, Bush government had limited the lines of stem cells that scientists can study. This, while being hailed by religious groups was opposed by scientists.
Obama said the Bush order limiting stem cell research “handcuffed our scientists and hindered our ability to compete with other nations.”
This is a welcome news in science. Stem cell is the most promising research that medicine could ever take.
What Are Embryonic Stem Cells?
Embryonic stem cells, as their name suggests, are derived from embryos.
Specifically, embryonic stem cells are derived from embryos that develop from eggs that have been fertilized in vitro—in an in vitro fertilization clinic—and then donated for research purposes with informed consent of the donors.
They are not derived from eggs fertilized in a woman’s body. The embryos from which human embryonic stem cells are derived are typically four or five days old and are a hollow microscopic ball of cells called the blastocyst. Read more
What Are Essential Properties of Stem Cells?
The classical definition of a stem cell requires that it possess two properties
Self-renewal
The ability to go through numerous cycles of cell division while maintaining the undifferentiated state.
Potency
The capacity to differentiate into specialized cell types. This requires stem cells to be either totipotent or pluripotent - to be able to give rise to any mature cell type.
This is the strictest definition*.
*Multipotent or Unipotent progenitor cells are sometimes referred to as stem cells.
Understanding Stem Cells – The Concept of Potency
To understand stem cells better, we need to understand the concept of potency. Potency defines the potential to differentiate into different cell types. of the stem cell.
Totipotent or omnipotent stem cells
These cells can differentiate into embryonic and extraembryonic cell types. Such cells can construct a complete, viable, organism. These cells are produced from the fusion of an egg and sperm cell.
Pluripotent, embryonic stem cells giving rise to other specialised cells. Image Credit Wikipedia
Pluripotent stem cells
These are the descendants of totipotent cells and can differentiate into nearly all cells i.e. cells derived from any of the three germ layers.
Multipotent stem cells
These can differentiate into a number of cells, but only those of a closely related family of cells.
Oligopotent stem cells
These cells can differentiate into only a few cells, such as lymphoid or myeloid stem cells.
Unipotent cells
These cells can produce only one cell type, their own, but have the property of self-renewal.
What Are Stem Cells?
Stem cells are special types of cells which have the characteristic ability to renew themselves through mitotic cell division [ A kind of cell division in which two similar cells are produced from one cell] and differentiating into a diverse range of specialized cell types.
Stem cells are present in most multi-cellular organisms.
The two broad types of mammalian stem cells are
- Embryonic stem cells
These cells are isolated from the inner cell mass of blastocysts in embryo.In a developing embryo, stem cells can differentiate into all of the specialized embryonic tissues. - Adult stem cells
These are found in adult tissues and participate in repair system for the body, replenish specialized cells and maintain the normal turnover of regenerative organs, such as blood, skin or intestinal tissues.
Stem cells can now be grown and transformed into specialized cells with characteristics consistent with cells of various tissues such as muscles or nerves through cell culture.
Highly plastic adult stem cells from a variety of sources, including umbilical cord blood and bone marrow, are routinely used in medical therapies. Embryonic cell lines and autologous embryonic stem cells generated through therapeutic cloning are promising candidates for future therapies.