Definition :Stem cells are defined as undifferentiated cells that have the potential of self-renewal and differentiate into a variety of mature cell types.Stem cells are unspecialized cells that give rise to specialized cells. The specialized cells provide sufficient number cells for the body’s repair during disease or injury. Stem cell transplants can benefit people with a variety of both cancerous (malignant) and noncancerous (non-malignant) diseases. Regenerative medicine has the potential to provide a cure to failing or impaired tissues.
Properties of Stem cells1. they are specialized without specific physiological properties;2.they undergo long-term self-regeneration; 3.they are capable of differentiating into tissue specific cell types.
When a stem cell divides, each new cell has the potential to either remain as a stem cell or become another cell with a more specialized function (i.e. a muscle cell, a red blood cell, a brain cell, etc.). Stem cells are capable of undergo cell division, after long periods of inactivity.•Under certain physiologic or experimental conditions, they can be induced to become tissue- or organ-specific cells with special functions
Embryonic and adult Stem cellsIn embryos, stem cells function to generate new organs and tissues. In adults, stem cells function to replace cells during the natural course of cell turn over.Hence stem cells are either embryonic stem cells (ESCs) or adult stem cells (ASCs).
General Types of stem cells :1. Adult stem cells - they are undifferentiated cells found in various tissues within the adult human body. They are distributed in the skin,brain,liver,muscle and retina. They remain in a non-dividing state for years. They can differentiate to become other cell types. e.g.Bone marrow stem cells, Mesenchymal cells.
2.Fetal stem cells : they are taken from fetus.
3.Cord blood stem cells : they are obtained from the blood within umbilical cord and placenta after the birth of a baby.
4.Embryonic stem cells : they are derived from the inner cell mass (ICM) of the blastocyst.
5.Induced pleuripotent stem cells(iPS cells) : they are reprogrammed cells which behave as embryonic stem cells.
Stem cell therapyStem cell therapy is a treatment to replace or repair damaged tissues using stem cells.When a patient's bone marrow fails to produce new blood cells, for whatever reason, he or she will develop anemia, persistent infections and bleeding problems. In order to restore blood cell production a patient may be given Stem cell transplantation (SCT) for healthy stem cells.Stem cell transplants are used to treat malignant diseases, mainly leukemia, lymphoma or myeloma which involve the bone marrow.
Types of stem cell therapyA stem cell therapy is a treatment that uses stem cells, or cells that come from stem cells, to replace or to repair a patient’s cells or tissues that are damaged. The stem cells might be put into the blood, or transplanted into the damaged tissue directly, or even recruited from the patient’s own tissues for self-repair. Specific tissues can be grown from a patient’s or donar’s stem cells outside the body and then transplanted into damaged or injured site. Stem cells from a patient or donor can be introduced into the body and their activity is encouraged by some clinical methods. Stem cell transplants can use cells from your own body (autologous stem cell transplant), from a donor (allogeneic stem cell transplant) or from an identical twin (syngeneic transplant).
Cord Blood Banking :The concept of using umbilical cord stem cells was first proposed by Edward Boyse in 1983. Umbilical cord blood stem cells are defined by the National Institute of Health (NIH) as “Stem cells collected from the umbilical cord at birth that can produce all of the blood cells in the body (hematopoietic).” The NIH also defines stem cells as “Cells with the ability to divide for indefinite periods in culture and to give rise to specialized cells.”
Cord blood is collected at the time of delivery by one of 2 techniques: either in vivo (while the placenta still remains in utero or in vitro in a specialized apparatus.Public or Family cord blood banks collect and store the blood within the umbilical cord and placenta after a baby is born. The stem cells are separated from the rest of the blood and are stored frozen in liquid nitrogen. UCB is full of blood-producing cells, much like bone marrow.Umbilical cord blood (UCB) has been considered as an attractive source of hematopoietic stem cell, which offers an alternative approach to bone marrow transplantation in the treatment of both malignant and non-malignant hematologic diseases. UCB is used for treatment of blood cancers and blood disorders, genetic disorders, and many other conditions.