Yes. Umbilical cord blood stem cells are the "youngest," safely available stem cells and they are the product of another miracle - a live birth. Freezing these cells essentially stops the clock and prevents aging and damage that may occur to the cells later in life. Another source of stem cells, embryonic stem cells, has been at the heart of heated debate.
Currently, embryonic stem cells are not being used to treat humans. A third category of stem cells is adult stem cells, such as those found in bone marrow. Adult stem cells serve very specialized roles in children and adults and are not as proliferative as those found in cord blood.
What are stem cells and how are they used?
Stem cells are the body's "master" cells because they create all other tissues, organs, and systems in the body. The stem cells found in cord blood are the building blocks of your blood and immune system and most readily replicate into:
Red Blood Cells - which carry oxygen to all the cells in the body,
White Blood Cells - which fight infection, and
Platelets - which aid in clotting in the event of injury.
There are three sources where stem cells are commonly found, they are:
Bone Marrow,
Peripheral Blood (the blood that circulates through your body), and
Umbilical Cord Blood.
The ability of cord blood stem cells to differentiate, or change into other types of cells in the body is a new discovery that holds significant promise for improving the treatment of some of the most common diseases such as heart disease, stroke, and Alzheimer's.
Currently, stem cells are primarily used in transplant medicine to regenerate a patient's blood and immune system after they have been treated with chemotherapy and/or radiation to destroy cancer cells.
At the same time the chemotherapy and radiation destroys the cancer cells in a patient, they also destroy stem cells. Therefore, an infusion of stem cells or a stem cell transplant is performed after the chemotherapy and/or radiation treatment. The stem cells then migrate to the patient's bone marrow where they multiply and regenerate all of the cells to create a new blood and immune system for the patient.
The promise of using stem cells for medical treatments has been the focus of research projects that are showing encouraging results.
Cord blood stem cells have been "triggered" to differentiate into neural cells, which could lead to treatments for diseases such as Alzheimer's and Parkinson's.
They have also proven their ability to turn into blood vessel cells, which could some day benefit treatments for heart disease, allowing patients to essentially "grow their own bypass."
Monday, 7 May 2007
Friday, 4 May 2007
What is Cord Blood?
After a baby is born and the umbilical cord is cut, some blood remains in the blood vessels of the placenta and the portion of the umbilical cord that remains attached to it. After birth, the baby no longer needs this extra blood. This blood is called placental blood or umbilical cord blood: "cord blood" for short.Cord blood contains all the normal elements of blood - red blood cells, white blood cells, platelets and plasma. But it is also rich in hematopoietic (blood-forming) stem cells, similar to those found in bone marrow. This is why cord blood can be used for transplantation instead of bone marrow.
Cord blood is being used increasingly on an experimental basis as a source of stem cells, as an alternative to bone marrow. Most cord blood transplants have been done to treat diseases of the blood and immune system. It has also been used to restore the functional deficiencies of several genetic metabolic diseases. To date, more than 70 different diseases have been treated with cord blood transplants.
Scientists are investigating the possibility that stem cells in cord blood may be able to replace cells of other tissues such as nerve or heart cells. Whether cord blood can be used to treat other kinds of diseases will be learned from this research.
Source: http://www.nationalcordbloodprogram.org/qa/
Thursday, 3 May 2007
Cord Blood. Concept
Umbilical cord blood is human blood from the placenta and umbilical cord that is rich in hematopoietic stem cells. Cord blood is collected after the umbilical cord has been detached from the newborn, and utilized as a source of stem cells for transplantation.Cord blood is stored by both public and private cord blood banks. Public cord blood banks store cord blood for the benefit of the general public, and most U.S. banks coordinate matching cord blood to patients through the National Marrow Donor Program (NMDP). Private cord blood banks are for-profit organizations that store cord blood for the exclusive use of the donor or donor's relatives.
Public cord blood banking is strongly supported by the medical community. However, private cord blood banking is generally not recommended unless there is a family history of specific genetic diseases. Private banking is unlawful in France and Italy, and opposed by the European Group on Ethics in Science and New Technologies. See cord blood bank.
Properties
Cord blood stem cells are more proliferative and have a higher chance of matching family members than stem cells from bone marrow. Fathers have a 25% chance of matching their child's cord blood stem cells. Siblings have a 25% chance of being a perfect cord blood match.
Collection, storage and costs
Main article: cord blood bank
There are 2 main methods in cord blood collection from the umbilical vein; before the placenta is delivered (in utero) or after (ex utero.)
With ex utero collection method, the cord blood is collected after the placenta is delivered and the umbilical cord is clamped off from the newborn. The placenta is placed in a sterile supporting structure with the umbilical cord hanging through the support. The cord blood is collected by gravity drainage yielding between 40-150 mL.
A similar collection method is done for in utero except that the cord blood is collected after the baby has been delivered but before the delivery of the placenta.
After collection the cord blood units must be immediately shipped to a cord blood bank facility. At public cord blood banks, this blood is then analyzed for infectious agents and the tissue-type is determined. Cord blood is processed and depleted of red blood cells before being stored in liquid nitrogen for later use.
New parents have the option of storing their newborn's cord blood at a private cord blood bank or donating it to a public cord blood bank. The cost of private cord blood banking is approximately $2000 for collection and approximately $125 per year for storage as of 2006. The donation of cord blood may not be available in all areas, however the opportunity to donate is becoming more available. Several local cord blood banks across the United States are now accepting donations from within their own states. The cord blood bank will not charge the donor for the donation, but the OB/GYN may still charge a collection fee of $100-$250, which is usually not covered by insurance. However, many OB/GYNs choose to donate their time.
"According to research in the Journal of Pediatric Hematology/Oncology (1997, 19:3, 183-187), the odds that a child will need to use his or her own stem cells by age twenty-one for current treatments are about 1:2,700, and the odds that a family member would need to use those cells are about 1:1,400." [1]
In 2005, University of Toronto researcher Peter Zandstra developed a method to increase the yield of cord blood stem cells to enable their use in treating adults as well as children.[2]
Usage
When cryopreserved cord blood is needed, it is thawed, washed of the cryoprotectant, and injected through a vein of the patient. This kind of treatment, where the stem cells are collected from another donor, is called allogeneic treatment. When the cells are collected from the same patient on whom they will be used, it is called autologous and when collected from identical individuals, it is referred to as syngeneic. Xenogeneic transfer of cells (between different species) is very underdeveloped and is said to have little research potential.[citation needed]
Diseases treated with cord blood
Beginning in the late 1980s, cord blood stem cells have been used to treat a number of blood and immune-system related genetic diseases, cancers, and disorders. Because of medical issues around using one's own cells, in nearly every instance the treatments are done using cells from another donor, with the vast majority being unrelated donors.
The principal diseases and disorders currently treated are listed at the National Donor Marrow Program website.
Source: http://en.wikipedia.org/wiki/Cord_blood
Friday, 20 April 2007
Umbilical Cord Blood Stem Cell Transplant
Newborn infants no longer need their umbilical cords, so they have traditionally been discarded as a by-product of the birth process. In recent years, however, the multipotent-stem-cell-rich blood found in the umbilical cord has proven useful in treating the same types of health problems as those treated using bone marrow stem cells and PBSCs.Umbilical cord blood stem cell transplants are less prone to rejection than either bone marrow or peripheral blood stem cells. This is probably because the cells have not yet developed the features that can be recognized and attacked by the recipient's immune system. Also, because umbilical cord blood lacks well-developed immune cells, there is less chance that the transplanted cells will attack the recipient's body, a problem called graft versus host disease.
Both the versatility and availability of umbilical cord blood stem cells makes them a potent resource for transplant therapies.
Source: http://learn.genetics.utah.edu/units/stemcells/sctoday/
Stem Cell Therapies Today
Did you know that several stem cell therapies are routinely used to treat disease today?
These include:
Adult Stem Cell Transplant: Bone Marrow Stem Cells
Adult Stem Cell Transplant: Peripheral Blood Stem Cells
Umbilical Cord Blood Stem Cell Transplant
Adult Stem Cell Transplant: Bone Marrow Stem Cells
Perhaps the best-known stem cell therapy to date is the bone marrow transplant, which is used to treat leukemia and other types of cancer, as well as various blood disorders.
Why is this a stem cell therapy?
Leukemia is a cancer of white blood cells, or leukocytes. Like other blood cells, leukocytes are made in the bone marrow through a process that begins with multipotent adult stem cells. Mature leukocytes are released into the bloodstream, where they work to fight off infections in our bodies.
Leukemia results when leukocytes begin to grow and function abnormally, becoming cancerous. These abnormal cells cannot fight off infection, and they interfere with the functions of other organs.
Successful treatment for leukemia depends on getting rid of all the abnormal leukocytes in the patient, allowing healthy ones to grow in their place. One way to do this is through chemotherapy, which uses potent drugs to target and kill the abnormal cells. When chemotherapy alone can't eliminate them all, physicians sometimes turn to bone marrow transplants.
In a bone marrow transplant, the patient's bone marrow stem cells are replaced with those from a healthy, matching donor. To do this, all of the patient's existing bone marrow and abnormal leukocytes are first killed using a combination of chemotherapy and radiation. Next, a sample of donor bone marrow containing healthy stem cells is introduced into the patient's bloodstream.
If the transplant is successful, the stem cells will migrate into the patient's bone marrow and begin producing new, healthy leukocytes to replace the abnormal cells.
Source: http://learn.genetics.utah.edu/units/stemcells/sctoday/
These include:
Adult Stem Cell Transplant: Bone Marrow Stem Cells
Adult Stem Cell Transplant: Peripheral Blood Stem Cells
Umbilical Cord Blood Stem Cell Transplant
Adult Stem Cell Transplant: Bone Marrow Stem Cells
Perhaps the best-known stem cell therapy to date is the bone marrow transplant, which is used to treat leukemia and other types of cancer, as well as various blood disorders.
Why is this a stem cell therapy?
Leukemia is a cancer of white blood cells, or leukocytes. Like other blood cells, leukocytes are made in the bone marrow through a process that begins with multipotent adult stem cells. Mature leukocytes are released into the bloodstream, where they work to fight off infections in our bodies.
Leukemia results when leukocytes begin to grow and function abnormally, becoming cancerous. These abnormal cells cannot fight off infection, and they interfere with the functions of other organs.
Successful treatment for leukemia depends on getting rid of all the abnormal leukocytes in the patient, allowing healthy ones to grow in their place. One way to do this is through chemotherapy, which uses potent drugs to target and kill the abnormal cells. When chemotherapy alone can't eliminate them all, physicians sometimes turn to bone marrow transplants.
In a bone marrow transplant, the patient's bone marrow stem cells are replaced with those from a healthy, matching donor. To do this, all of the patient's existing bone marrow and abnormal leukocytes are first killed using a combination of chemotherapy and radiation. Next, a sample of donor bone marrow containing healthy stem cells is introduced into the patient's bloodstream.
If the transplant is successful, the stem cells will migrate into the patient's bone marrow and begin producing new, healthy leukocytes to replace the abnormal cells.
Source: http://learn.genetics.utah.edu/units/stemcells/sctoday/
Monday, 2 April 2007
What is Cord Blood?
"Cord Blood" is the blood that remains in the umbilical cord and placenta following birth. Cord blood stem cells have the ability to treat the same diseases as bone marrow with significantly less rejection. Cord blood is collected after the baby is born and the umbilical cord has been clamped and cut. It is painless and safe. When cord blood is collected and stored, the stem cells are immediately available for transplantation. Children make up a large portion of the 10,000 individuals each year who are unable to find a transplant in time.
Years of medical research have led to an amazing discovery: the blood in a baby's umbilical cord. First used in transplant in 1988, umbilical cord blood is a plentiful and rich source of stem cells -the building blocks of the immune system- that can be used to treat a variety of life-threatening diseases including leukemia, other cancers, and blood and immune disorders. In just the last few years, hundreds of acutely ill patients have received treatment because of this tremendous medical advance.
Approximately 25% of these transplants have come from siblings, with the rest coming from donated cord blood samples. As more and more families save their cord blood, whether through donation or private storage, these numbers should increase dramatically. According to The Journal of the American Medical Association, "10,000 to 15,000 Americans each year who need a (bone marrow) transplant are unable to find suitable donors". Cord blood is an alternative transplant resource. As of the year 2000, more than 2,000 cord blood transplants have been performed worldwide.
CBDF Mission Statement
The Cord Blood Donor Foundation (CBDF) is a Not-For-Profit, 501 (c)3 human health and welfare organization dedicated to providing educational and public awareness and promoting further research using umbilical cord blood stem cells from live birth for the treatment of disease.
Source: http://www.cordblooddonor.org
Years of medical research have led to an amazing discovery: the blood in a baby's umbilical cord. First used in transplant in 1988, umbilical cord blood is a plentiful and rich source of stem cells -the building blocks of the immune system- that can be used to treat a variety of life-threatening diseases including leukemia, other cancers, and blood and immune disorders. In just the last few years, hundreds of acutely ill patients have received treatment because of this tremendous medical advance.
Approximately 25% of these transplants have come from siblings, with the rest coming from donated cord blood samples. As more and more families save their cord blood, whether through donation or private storage, these numbers should increase dramatically. According to The Journal of the American Medical Association, "10,000 to 15,000 Americans each year who need a (bone marrow) transplant are unable to find suitable donors". Cord blood is an alternative transplant resource. As of the year 2000, more than 2,000 cord blood transplants have been performed worldwide.
CBDF Mission Statement
The Cord Blood Donor Foundation (CBDF) is a Not-For-Profit, 501 (c)3 human health and welfare organization dedicated to providing educational and public awareness and promoting further research using umbilical cord blood stem cells from live birth for the treatment of disease.
Source: http://www.cordblooddonor.org
Thursday, 22 March 2007
Stem Cells and Cord Blood
Cells that have the ability to self-replicate and give rise to specialized cells. Stem cells can be found at different stages of fetal development and are present in a wide range of adult tissues. Many of the terms used to distinguish stem cells are based on their origins and the cell types of their progeny.
There are three basic types of stem cells. Totipotent stem cells, meaning their potential is total, have the capacity to give rise to every cell type of the body and to form an entire organism. Pluripotent stem cells, such as embryonic stem cells, are capable of generating virtually all cell types of the body but are unable to form a functioning organism. Multipotent stem cells can give rise only to a limited number of cell types. For example, adult stem cells, also called organ- or tissue-specific stem cells, are multipotent stem cells found in specialized organs and tissues after birth. Their primary function is to replenish cells lost from normal turnover or disease in the specific organs and tissues in which they are found.
Totipotent stem cells occur at the earliest stage of embryonic development. The union of sperm and egg creates a single totipotent cell. This cell divides into identical cells in the first hours after fertilization. All these cells have the potential to develop into a fetus when they are placed into the uterus. The first differentiation of totipotent cells forms a hollow sphere of cells called the blastocyst, which has an outer layer of cells and an inner cell mass inside the sphere. The outer layer of cells will form the placenta and other supporting tissues during fetal development, whereas cells of the inner cell mass go on to form all three primary germ layers: ectoderm, mesoderm, and endoderm. The three germ layers are the embryonic source of all types of cells and tissues of the body. Embryonic stem cells are derived from the inner cell mass of the blastocyst. They retain the capacity to give rise to cells of all three germ layers. However, embryonic stem cells cannot form a complete organism because they are unable to generate the entire spectrum of cells and structures required for fetal development. Thus, embryonic stem cells are pluripotent, not totipotent, stem cells.
Embryonic germ (EG) cells differ from embryonic stem cells in the tissue sources from which they are derived, but appear to be similar to embryonic stem cells in their pluripotency. Human embryonic germ cell lines are established from the cultures of the primordial germ cells obtained from the gonadal ridge of late-stage embryos, a specific part that normally develops into the testes or the ovaries. Embryonic germ cells in culture, like cultured embryonic stem cells, form embryoid bodies, which are dense, multilayered cell aggregates consisting of partially differentiated cells. The embryoid body-derived cells have high growth potential. The cell lines generated from cultures of the embryoid body cells can give rise to cells of all three embryonic germ layers, indicating that embryonic germ cells may represent another source of pluripotent stem cells.
Much of the knowledge about embryonic development and stem cells has been accumulated from basic research on mouse embryonic stem cells. Since 1998, however, research teams have succeeded in growing human embryonic stem cells in culture. Human embryonic stem cell lines have been established from the inner cell mass of human blastocysts that were produced through in vitro fertilization procedures. The techniques for growing human embryonic stem cells are similar to those used for growth of mouse embryonic stem cells. However, human embryonic stem cells must be grown on a mouse embryonic fibroblast feeder layer or in media conditioned by mouse embryonic fibroblasts. Human embryonic stem cell lines can be maintained in culture to generate indefinite numbers of identical stem cells for research. As with mouse embryonic stem cells, culture conditions have been designed to direct differentiation into specific cell types (for example, neural and hematopoietic cells).
Adult stem cells occur in mature tissues. Like all stem cells, adult stem cells can self-replicate. Their ability to self-renew can last throughout the lifetime of individual organisms. But unlike embryonic stem cells, it is usually difficult to expand adult stem cells in culture. Adult stem cells reside in specific organs and tissues, but account for a very small number of the cells in tissues. They are responsible for maintaining a stable state of the specialized tissues. To replace lost cells, stem cells typically generate intermediate cells called precursor or progenitor cells, which are no longer capable of self-renewal. However, they continue undergoing cell divisions, coupled with maturation, to yield fully specialized cells. Such stem cells have been identified in many types of adult tissues, including bone marrow, blood, skin, gastrointestinal tract, dental pulp, retina of the eye, skeletal muscle, liver, pancreas, and brain. Adult stem cells are usually designated according to their source and their potential. Adult stem cells are multipotent because their potential is normally limited according to their source and their potential. Adult stem cells are multipotent because their potential is normally limited to one or more lineages of specialized cells. However, a special multipotent stem cell that can be found in bone marrow, called the mesenchymal stem cell, can produce all cell types of bone, cartilage, fat, blood, and connective tissues.
Blood stem cells, or hematopoietic stem cells, are the most studied type of adult stem cells. The concept of hematopoietic stem cells is not new, since it has been long realized that mature blood cells are constantly lost and destroyed. Billions of new blood cells are produced each day to make up the loss. This process of blood cell generation called hematopoiesis, occurs largely in the bone marrow. Another emerging source of blood stem cells is human umbilical cord blood. Similar to bone marrow, umbilical cord blood can be used as a source material of stem cells for transplant therapy. However, because of the limited number of stem cells in umbilical cord blood, most of the procedures are performed for young children of relatively low body weight.
Neural stem cells, the multipotent stem cells that generate nerve cells, are a new focus in stem cell research. Active cellular turnover does not occur in the adult nervous system as it does in renewing tissues such as blood or skin. Because of this observation, it had been a dogma that the adult brain and spinal cord were unable to regenerate new nerve cells. However, since the early 1990s, neural stem cells have been isolated from the adult brain as well as fetal brain tissues. Stem cells in the adult brain are found in the areas called the subventricular zone and the ventricle zone. Another location of brain stem cells occurs in the hippocampus, a special structure of the cerebral cortex related to memory function. Stem cells isolated from these areas are able to divide and to give rise to nerve cells (neurons) and neuron-supporting cell types in culture.
Stem cell plasticity refers to the phenomenon of adult stem cells from one tissue generating the specialized cells of another tissue. The long-standing concept of adult organ-specific stem cells is that they are restricted to producing the cell types of their specific tissues. However, a series of studies have challenged the concept of tissue restriction of adult stem cells. Although the stem cells appear able to cross their tissue-specific boundaries, crossing occurs generally at a low frequency and mostly only under conditions of host organ damage. The finding of stem cell plasticity carries significant implications for potential cell therapy. For example, if differentiation can be redirected, stem cells of abundant source and easy access, such as blood stem cells in bone marrow or umbilical cord blood, could be used to substitute stem cells in tissues that are difficult to isolate, such as heart and nervous system tissue.
Source:
There are three basic types of stem cells. Totipotent stem cells, meaning their potential is total, have the capacity to give rise to every cell type of the body and to form an entire organism. Pluripotent stem cells, such as embryonic stem cells, are capable of generating virtually all cell types of the body but are unable to form a functioning organism. Multipotent stem cells can give rise only to a limited number of cell types. For example, adult stem cells, also called organ- or tissue-specific stem cells, are multipotent stem cells found in specialized organs and tissues after birth. Their primary function is to replenish cells lost from normal turnover or disease in the specific organs and tissues in which they are found.
Totipotent stem cells occur at the earliest stage of embryonic development. The union of sperm and egg creates a single totipotent cell. This cell divides into identical cells in the first hours after fertilization. All these cells have the potential to develop into a fetus when they are placed into the uterus. The first differentiation of totipotent cells forms a hollow sphere of cells called the blastocyst, which has an outer layer of cells and an inner cell mass inside the sphere. The outer layer of cells will form the placenta and other supporting tissues during fetal development, whereas cells of the inner cell mass go on to form all three primary germ layers: ectoderm, mesoderm, and endoderm. The three germ layers are the embryonic source of all types of cells and tissues of the body. Embryonic stem cells are derived from the inner cell mass of the blastocyst. They retain the capacity to give rise to cells of all three germ layers. However, embryonic stem cells cannot form a complete organism because they are unable to generate the entire spectrum of cells and structures required for fetal development. Thus, embryonic stem cells are pluripotent, not totipotent, stem cells.
Embryonic germ (EG) cells differ from embryonic stem cells in the tissue sources from which they are derived, but appear to be similar to embryonic stem cells in their pluripotency. Human embryonic germ cell lines are established from the cultures of the primordial germ cells obtained from the gonadal ridge of late-stage embryos, a specific part that normally develops into the testes or the ovaries. Embryonic germ cells in culture, like cultured embryonic stem cells, form embryoid bodies, which are dense, multilayered cell aggregates consisting of partially differentiated cells. The embryoid body-derived cells have high growth potential. The cell lines generated from cultures of the embryoid body cells can give rise to cells of all three embryonic germ layers, indicating that embryonic germ cells may represent another source of pluripotent stem cells.
Much of the knowledge about embryonic development and stem cells has been accumulated from basic research on mouse embryonic stem cells. Since 1998, however, research teams have succeeded in growing human embryonic stem cells in culture. Human embryonic stem cell lines have been established from the inner cell mass of human blastocysts that were produced through in vitro fertilization procedures. The techniques for growing human embryonic stem cells are similar to those used for growth of mouse embryonic stem cells. However, human embryonic stem cells must be grown on a mouse embryonic fibroblast feeder layer or in media conditioned by mouse embryonic fibroblasts. Human embryonic stem cell lines can be maintained in culture to generate indefinite numbers of identical stem cells for research. As with mouse embryonic stem cells, culture conditions have been designed to direct differentiation into specific cell types (for example, neural and hematopoietic cells).
Adult stem cells occur in mature tissues. Like all stem cells, adult stem cells can self-replicate. Their ability to self-renew can last throughout the lifetime of individual organisms. But unlike embryonic stem cells, it is usually difficult to expand adult stem cells in culture. Adult stem cells reside in specific organs and tissues, but account for a very small number of the cells in tissues. They are responsible for maintaining a stable state of the specialized tissues. To replace lost cells, stem cells typically generate intermediate cells called precursor or progenitor cells, which are no longer capable of self-renewal. However, they continue undergoing cell divisions, coupled with maturation, to yield fully specialized cells. Such stem cells have been identified in many types of adult tissues, including bone marrow, blood, skin, gastrointestinal tract, dental pulp, retina of the eye, skeletal muscle, liver, pancreas, and brain. Adult stem cells are usually designated according to their source and their potential. Adult stem cells are multipotent because their potential is normally limited according to their source and their potential. Adult stem cells are multipotent because their potential is normally limited to one or more lineages of specialized cells. However, a special multipotent stem cell that can be found in bone marrow, called the mesenchymal stem cell, can produce all cell types of bone, cartilage, fat, blood, and connective tissues.
Blood stem cells, or hematopoietic stem cells, are the most studied type of adult stem cells. The concept of hematopoietic stem cells is not new, since it has been long realized that mature blood cells are constantly lost and destroyed. Billions of new blood cells are produced each day to make up the loss. This process of blood cell generation called hematopoiesis, occurs largely in the bone marrow. Another emerging source of blood stem cells is human umbilical cord blood. Similar to bone marrow, umbilical cord blood can be used as a source material of stem cells for transplant therapy. However, because of the limited number of stem cells in umbilical cord blood, most of the procedures are performed for young children of relatively low body weight.
Neural stem cells, the multipotent stem cells that generate nerve cells, are a new focus in stem cell research. Active cellular turnover does not occur in the adult nervous system as it does in renewing tissues such as blood or skin. Because of this observation, it had been a dogma that the adult brain and spinal cord were unable to regenerate new nerve cells. However, since the early 1990s, neural stem cells have been isolated from the adult brain as well as fetal brain tissues. Stem cells in the adult brain are found in the areas called the subventricular zone and the ventricle zone. Another location of brain stem cells occurs in the hippocampus, a special structure of the cerebral cortex related to memory function. Stem cells isolated from these areas are able to divide and to give rise to nerve cells (neurons) and neuron-supporting cell types in culture.
Stem cell plasticity refers to the phenomenon of adult stem cells from one tissue generating the specialized cells of another tissue. The long-standing concept of adult organ-specific stem cells is that they are restricted to producing the cell types of their specific tissues. However, a series of studies have challenged the concept of tissue restriction of adult stem cells. Although the stem cells appear able to cross their tissue-specific boundaries, crossing occurs generally at a low frequency and mostly only under conditions of host organ damage. The finding of stem cell plasticity carries significant implications for potential cell therapy. For example, if differentiation can be redirected, stem cells of abundant source and easy access, such as blood stem cells in bone marrow or umbilical cord blood, could be used to substitute stem cells in tissues that are difficult to isolate, such as heart and nervous system tissue.
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