Blood cells grow in the same way as other human cells. They are developed in the bone marrow from a parent cell known as a “stem cell.” These stem cells begin to divide and mature until they are fully developed, forming all the different types of blood cells: white blood cells, platelets and red blood cells. Stem cells are usually found inside the bone marrow spaces of large bones, however, they can also travel from one bone to the other by way of the blood system.

bull; Other than embryonic stem cells, stem cells can be found in the fetal liver, bone marrow and yolk sac, among other areas of the body. (Put link to yolk sac diagram here and also in next question) Umbilical cord blood is taken from the cord attached to the placenta. This source of blood is a major source of hematopoietic stem cells, but also consists of other types of stem cells.

There are several stem cells found after the development process of embryonic stem cells begins. The most studied of these cells are those that migrate to the bone marrow. These are the hematopoietic stem cells first detected in the yolk sac and the embryo from a stem cell referred to as the hemangioblast. The blood vessels needed by the hematopoietic stem cells are also formed from the hemangioblasts and are referred as the angioblast.

Stem cells are present within various organs of the adult body and are called ‘adult stem cells’. The prototypical adult stem cell, the hematopoietic stem cell, is found in the bone marrow. The hematopoietic stem cells have the genetic 'blueprint' for forming all of the blood and immune cells. Thus, their main function is to be available to respond to infection and blood loss, while replacing cells on a day-to-day basis.

Stem cells have been reported in the: brain, termed neural stem cells, gut, root of teeth, skin, heart, kidney and teeth. Scientists are still finding different stem cells.

Some researchers believe that cancer is maintained by a few cancer stem cells, while others believe that it could be a normal stem cell “gone wrong”. Research on any type of stem cells is likely to lead to a better understanding of cancer stem cells. Once this information is fully understood, drugs can be developed to kill the cancer stem cells and thereby improve cancer treatment. Pardal R et al. Nature Reviews 2003;3: 895-902; Reya T et al.

Embryonic stem cells are undifferentiated, meaning that they don't belong to one specific organ. They have the potential to generate any type of tissue in the body. The potential that embryonic stem cells present to scientists is immeasurable. There have already been promising findings in the field of Parkinson's research using embryonic stem cells in mice and monkeys.

Embryonic stem cells are derived at a very early stage of development called a blastocyst. This is a simple ball of about 100 cells that is similar in all species of animals at this stage of development. Embryonic stem cells are derived from the cells in the center of this blastocyst. Blastocysts are obtained from in vitro fertilization clinics. These clinics have produced an estimated 500,000 healthy, much-loved children over the two decades of their existence.

Stem cells are cells that have the remarkable potential to develop into many different cell types in the body. Serving as a sort of repair system for the body, they can theoretically divide without limit to replenish other cells for as long as the person or animal is still alive. When a stem cell divides, each "daughter" cell has the potential to either remain a stem cell or become another type of cell with a more specialized function, such as a muscle cell, a red blood cell, or a brain cell.

Pluripotent stem cells are isolated from human embryos that are a few days old. Cells from these embryos can be used to create pluripotent stem cell "lines" —cell cultures that can be grown indefinitely in the laboratory. Pluripotent stem cell lines have also been developed from fetal tissue obtained from fetal tissue (older than 8 weeks of development).

Bone marrow is the soft, sponge-like material found inside bones. It contains immature cells called stem cells that produce blood cells. There are three types of blood cells: white blood cells, which fight infection; red blood cells, which carry oxygen to and remove waste products from organs and tissues; and platelets, which enable the blood to clot. Most stem cells are found in the bone marrow, but some stem cells called peripheral blood stem cells (PBSCs) can be found in the bloodstream.

Embryonic stem cells are different from other types of stem cells in that their main function is to make all of the different tissues of the body. Most other stem cells, such as the above-mentioned hematopoietic stem cell, function in the body to make at least cells of one tissue. All stem cells are termed pluripotent, meaning one stem cell could form multiples types of cells.

Cancer stem cells share many characteristics with normal stem cells. For example, a normal stem cell can self-renew, which means the daughter cells retain their numbers and properties/functions as the mother cells. Cancer stem cells also maintain the ability to self-renew. A few cancer stem cells could evade treatment and later give rise to a tumor, referred to as cancer relapse. The tumors formed are really the progenies of the cancer stem cells.

This is a controversial topic. While some scientists have reported evidence that hematopoietic stem cells can repair cardiac tissue, others have proven otherwise. Another research group reported that the bone marrow contained cells that could repair the liver. Later studies showed that the bone marrow cells did not form liver cells, but rather fused with those cells. Despite these negative results, interesting new information has been gained.

A:Stem Cell Researchers only point to embryo stem cells for research. Stem Cell Research Stem Cells are very unique cells. Stem Cells have the amazing ability to develop into several distinct cell types in the body. Thus Stem Cells can be used as a repair system for the body. Stem Cells can theoretically divide without limit in a living human or animal in order to replenish various types of cells.

Human embryonic stem cells are thought to have much greater developmental potential than adult stem cells. This means that embryonic stem cells may be pluripotent—that is, able to give rise to cells found in all tissues of the embryo except for germ cells rather than being merely multipotent—restricted to specific subpopulations of cell types, as adult stem cells are thought to be.

No, umbilical cord blood cells are taken from the baby's umbilical cord and placenta after the baby is born, and not from an embryo.

Bone marrow stem cells are collected through a procedure called "harvesting." Usually, several small cuts (not requiring stitches) are made in the skin over the hip (pelvic) bone. A harvesting needle is inserted through the cuts and into the bone to draw the marrow out of the bone. The donor receives anesthesia and will not feel pain caused by the needle. The process of obtaining the marrow takes about an hour.

The bone marrow is an example of an organ within the body where two types of stem cells co-exist: Hematopoietic stem cells that form blood and immune cells, and mesenchymal stem cells that form bone. Adult stem cells, which are found throughout the body, can be considered as a set of young cells. These cells can self-renew indicating that their numbers are maintained throughout life. The day-to-day function of an adult stem cell is to maintain, replenish and repair many tissues of the body.

The answer to this question depends on the type of stem cell. While stem cells can replicate (termed expansion) without changing into a different cell type, some suffer the consequence of genetic changes as a result of extensive replication. Extensive replication can lead to genetic changes that cause the stem cells to mature, termed terminal differentiation, such that they are no longer stem cells.

The embryo is formed in early stages of fetal development and contains the embryonic stem cell. During development, the embryonic stem cells begin the process of forming tissues that will eventually compose the organs of the fetus. Embryonic stem cells give rise to all of the tissues of the embryo, excluding the placenta. Gilbert DM, Med Sci Monit 2004;10:RA99; Rossant J, Stem Cells 2001;19:477; Nature 2001;414:122-8; Yamazaki Y et al.

The use of embryonic stem cells in research is controversial because some individuals consider a stem cell as the earliest form of human life, and they believe they should not be tampered with. The use of adult stem cells, which are derived at birth, is not ethically controversial.

Using stem cells to combat cancer is an interesting prospect. Research into this area is very new and novel. One research group found that they could use mesenchymal stem cells to deliver a cancer-toxic protein to developing tumors. Studies like this combine stem cells and gene therapy.

There are issues that have to be considered as a person undergoes stem cell therapy. An obvious concern is the development of unwanted tissue types in the region undergoing treatment. For example, we would not want bone to be formed in the liver if the goal was to regenerate the liver. Rejection is another concern, even though current clinical practice ensures a match between donor and host. Some adult stem cells appear to be resistant to rejection.