Stem Cells - Learn About Types and Definition
Definition of Stem Cells
Stem cells are cells that have the potential to develop into stout cell types are different or special. Stem cells can be thought of as the cells are primitive, "not special" that is able to divide and become specialized cells of the body such as liver cells, muscle cells, blood cells and other cells with special functions. Stem cells are referred to as cell-cell "undifferentiated" because they still do not require on site development will form a specific tissue or organ. The process of change into a specific cell type known as differentiation. In some areas of the body, stem cells divide regularly to update and improve the existing network. Bone marrow and gastrointestinal tract (gastrointestinal tract) are examples of areas where stem cells serve to renew and repair tissue.
Examples of the best and most readily understood from the stem cells in humans is that of a fertilized egg, or zygote. Single-cell zygote is formed by the union of sperm and ovum. Sperm and ova carrying each with half the genetic material necessary to form a new individual. Once a single cell or zygote starts to divide, he was known as an embryo. One cell becomes two, two become four, four become eight, eight to sixteen, and so on; multiply rapidly until it finally creates a sophisticated whole organism. Organism, a person, is a very intricate structure composed of many, many, billions of cells with functions diverse as your eyes, your heart, your immune system, the color of your skin, your brain, etc.. All of the specialized cells that form body systems are descendants of the original zygote, a stem cell with potential to eventually develop into all types of body cells. The cells of the zygote is totipotent, meaning that they have the capacity to develop into any type of cell in the body.
The process by which stem cells are obliged to be differentiated, or specialized cells is complex and involves regulation of gene expression. Research is underway to further understand the events and molecular controls are necessary for stem cells to become specific cell types.
Why are Stem Cells Important?
Stem cells present in the exciting area of medicine because of their potential to renew and repair damaged tissue. Some current therapies, such as bone marrow transplants, have been using stem cells and their potential for regeneration (renewal) of the damaged tissues. Other therapies are under investigation involving the transplantation of stem cells into the damaged parts of the body and direct them to grow and differentiate into healthy tissue.
The Different Types Of Stem Cells
Embryonic stem cells
During the initial circumstances of the development of embryonic cells remain relatively undifferentiated or not different (immature) and seems to have the ability to become, or differentiate, into almost every tissue in the body. For example, cells taken from one part of the embryo that may have been part of the eye can be moved into other parts of the embryo and may develop into blood cells, muscles, nerves, or heart.
Cells at early embryonic stages are totipotent (see above) and can differentiate (hold the difference) to be all types of body cells. After about seven days, zygote form a structure known as a blastocyst, which contains a mass of cells that eventually become the fetus, and trophoblastic tissue which eventually becomes the placenta. If the cells are taken from blastocystpada this stage, they are known as pluripotent, which means that they have the capacity to become many different types of human cells. The cells at this stage is often referred to as a blastocyst embryonic stem cells. If any type of embryonic stem cells grown in culture in the laboratory, they can divide and grow indefinitely. The cells were then known as embryonic stem cell lines.
Fetal stem cells
Embryo is referred to as a fetus after the eighth week of development. Containing fetal stem cells that are pluripotent and eventually evolved into the tissues of the body are different in the fetus.
Stem cells of the adult
Stem cells of the adult is present in all human beings in small amounts. The adult stem cell is one of a group of cells that we have been able to manipulate it quite effective in bone marrow transplant arena through 30 years ago. These are stem cells that are largely tissue specific in their location. Instead of typically give rise to all body cells, these cells are capable of giving rise only to the few types of cells that develop into specific tissues or organs. They are by caused known as multipotent stem cells. Stem cells of the adult is sometimes referred to as somatic stem cells.
The most well characterized example of the adult stem cells are blood stem cells (hematopoietic stem cells). When we refer to bone marrow transplantation (bone marrow) stem cell transplantation, or blood transplantation, the transplanted cells are hematopoietic stem cells, or stem cell blood. These cells are very rare cells that are found primarily in the bone marrow of adults.
One of the exciting discoveries of the past years is the reversal of long-held scientific belief that the adult stem cells are stem cells that are fully obligated. Previously believed that hematopoietic stem cells, or blood-forming, can only create other blood cells and can never be other types of stem cells. Now there is evidence that some of the adult stem cells seem to be able to change direction obliged to become stem cells in different organs. For example, there are several models of bone marrow transplantation in mice with damaged hearts in which the liver grows back partially with cells derived from bone marrow transplanted. Similar studies can be conducted which show that many cell types can be derived which differ from each other. It appears that heart cells can be grown from bone marrow stem cells, that bone marrow cells can be grown from stem cells derived from muscle, brain and that stem cells can change into many types of cells.
Peripheral blood stem cells
Most blood stem cells present in bone marrow, but there is little that is present in the bloodstream. This means that so-called peripheral blood stem cells (PBSCs) can be isolated from blood samples taken. Blood stem cells can give rise to large numbers of different cells that form blood and immune system, including red blood cells, platelets, granulocytes, and lymphocytes.
* Red blood cells carry oxygen throughout the body and gives blood its color.
* Platelets are cell fragments that stop bleeding person and helps the body to clot and heal when he was interrupted.
* Granulocytes are the types of white blood cells that help fight bacterial infections.
* Lymphocytes are a type of white blood cells that are part of the immune system, help fight other infections, and also may be involved in protection against cancer.
All of the cells with very different functions are very different from stem cells derived from a common ancestral, an obligation of blood-forming (hematopoietic).
Umbilical cord stem cells
Blood from the umbilical cord (umbilical cord) contain some stem cells that are genetically identical to the newborn. As the adult stem cells, multipotent stem cells are able to differentiate into specific cell types, but not all. For these reasons, umbilical cord blood is often stored for possible future use when it comes to individual need stem cell therapy.
Induced pluripotent stem cells
Induced pluripotent stem cells (iPSCs) was first created for human cells in 2007. These are cells that are genetically adults have been converted (changed) to a state such as embryonic stem cells. In animal studies, iPSCs have been shown to have characteristics of pluripotent stem cells. IPSCs and humans can differentiate into fetal cell types differ that much. IPSCs is a valuable aid to the study of disease progression and drug treatment, and they may have future uses in science medical transplantation. Further research is needed regarding the development and use of these cells.
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