Every organ and tissue in our body grew out of a cluster of stem cells early in development. A stem cell differs from every other cell in the body in its ability to renew itself. It can divide into many more just like it.
Stem cells can repair and replace tissue in the human body. In other words, stem cells have the power to heal.
Think of our skin. The tissue in our skin needs constant renewal that could not take place without stem cells. Or muscle — stem cells in our muscles are what repair damaged tissue when we are injured.
Early in life, stem cells have the extraordinary potential to develop into any type of cell in the human body.
They start in the embryo as unprogrammed cells, then become specialized to create bone, muscle, skin, the heart, the brain, and over 250 other types of specialized cells. These are called pluripotent stem cells.
Using Stem Cells to Save People
Researchers have found that stem cells can be used to treat disease and injury. They stimulate the body to repair itself.
For example, bone marrow transplants have been taking place for more than 40 years.
These procedures rely on transplanting stem cells derived from bone marrow and have dramatically altered the treatment of blood disorders and certain cancers such as leukemia.
In the past 20 years, significant new discoveries have emerged — breakthroughs that the original discoverers of stem cells never dreamed about. Researchers are finding new ways to use stem cells to rebuild tissue in many parts of the body where it has been damaged, such as the eye, the pancreas and the brain. Some revolutionary treatments for blindness, MS, stroke and spinal cord injury are already in early stage clinical trials. (progress)
Two main sources of stem cells
Stem cells are a class of undifferentiated cells that are able to differentiate into specialized cell types. Commonly, stem cells come from two main sources:
Embryos formed during the blastocyst phase of embryological development (embryonic stem cells) and
Adult tissue (adult stem cells).
Both types are generally characterized by their potency, or potential to differentiate into different cell types (such as skin, muscle, bone, etc.).
Adult stem cells
Adult or somatic stem cells exist throughout the body after embryonic development and are found inside of different types of tissue. These stem cells have been found in tissues such as the brain, bone marrow, blood, blood vessels, skeletal muscles, skin, and the liver. They remain in a quiescent or non-dividing state for years until activated by disease or tissue injury.
Adult stem cells can divide or self-renew indefinitely, enabling them to generate a range of cell types from the originating organ or even regenerate the entire original organ. It is generally thought that adult stem cells are limited in their ability to differentiate based on their tissue of origin, but there is some evidence to suggest that they can differentiate to become other cell types.
Embryonic stem cells
Embryonic stem cells are derived from a four- or five-day-old human embryo that is in the blastocyst phase of development. The embryos are usually extras that have been created in IVF (in vitro fertilization) clinics where several eggs are fertilized in a test tube, but only one is implanted into a woman.
Sexual reproduction begins when a male’s sperm fertilizes a female’s ovum (egg) to form a single cell called a zygote. The single zygote cell then begins a series of divisions, forming 2, 4, 8, 16 cells, etc. After four to six days – before implantation in the uterus – this mass of cells is called a blastocyst. The blastocyst consists of an inner cell mass (embryoblast) and an outer cell mass (trophoblast). The outer cell mass becomes part of the placenta, and the inner cell mass is the group of cells that will differentiate to become all the structures of an adult organism. This latter mass is the source of embryonic stem cells – totipotent cells (cells with total potential to develop into any cell in the body).
In a normal pregnancy, the blastocyst stage continues until implantation of the embryo in the uterus, at which point the embryo is referred to as a fetus. This usually occurs by the end of the 10th week of gestation after all major organs of the body have been created.
However, when extracting embryonic stem cells, the blastocyst stage signals when to isolate stem cells by placing the “inner cell mass” of the blastocyst into a culture dish containing a nutrient-rich broth. Lacking the necessary stimulation to differentiate, they begin to divide and replicate while maintaining their ability to become any cell type in the human body. Eventually, these undifferentiated cells can be stimulated to create specialized cells.
Stem cells are either extracted from adult tissue or from a dividing zygote in a culture dish. Once extracted, scientists place the cells in a controlled culture that prohibits them from further specializing or differentiating but usually allows them to divide and replicate. The process of growing large numbers of embryonic stem cells has been easier than growing large numbers of adult stem cells, but progress is being made for both cell types.
Stem cell lines
Once stem cells have been allowed to divide and propagate in a controlled culture, the collection of healthy, dividing, and undifferentiated cells is called a stem cell line. These stem cell lines are subsequently managed and shared among researchers. Once under control, the stem cells can be stimulated to specialize as directed by a researcher – a process known as directed differentiation. Embryonic stem cells are able to differentiate into more cell types than adult stem cells.
Stem cells are categorized by their potential to differentiate into other types of cells. Embryonic stem cells are the most potent since they must become every type of cell in the body. The full classification includes:
Totipotent – the ability to differentiate into all possible cell types. Examples are the zygote formed at egg fertilization and the first few cells that result from the division of the zygote.
Pluripotent – the ability to differentiate into almost all cell types. Examples include embryonic stem cells and cells that are derived from the mesoderm, endoderm, and ectoderm germ layers that are formed in the beginning stages of embryonic stem cell differentiation.
Multipotent – the ability to differentiate into a closely related family of cells. Examples include hematopoietic (adult) stem cells that can become red and white blood cells or platelets.
Oligopotent – the ability to differentiate into a few cells. Examples include (adult) lymphoid or myeloid stem cells.
Unipotent – the ability to only produce cells of their own type, but have the property of self-renewal required to be labeled a stem cell. Examples include (adult) muscle stem cells.
Embryonic stem cells are considered pluripotent instead of totipotent because they do not have the ability to become part of the extra-embryonic membranes or the placenta.
CelGen Resources is committed to educating and helping people achieve optimum health and better quality of life through the healing benefits with stem cells. We provide information on stem cell therapy options for individuals suffering with various medical conditions such as inflammatory, degenerative illnesses etc.