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What are stem cells?
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A stem cell is essentially a “blank” cell that is capable of becoming a differentiated cell in the body, such as a nerve cell, a muscle cell, any organ cell or any other type of cell. The primary roles of stem cells in a living organism are to maintain and repair the tissue in which they are found. They can be used to repair or replace tissue and cells in the body whether they are damaged from injury or aging and the first body part replacements have already been done in humans.

There is a hierarchy of stem cells that starts with the most undifferentiated, totipotent, which can become anything including a human being. These can only be derived from the blastocyst stage of an embryo during the first four or five days after fertilization. The next stage of differentiation is pluripotent cells, which can develop into any tissue, organ or adult cell type. These can be derived from adult stem cell sources and this is the level of undifferentiated state that has been achieved in animal studies with iPS cells. Multipotentent progenitor cells are the next level of differentiation and have the potential to most any type of cell in the body. These cells are committed to becoming a specific type of cell.

There is now work being done with induced pluripotent stem cells (iPS) which are derived from a person’s tissue such as skin or teeth, and taken back to an undifferentiated state where they can be turned on to become other kinds of tissue. We expect to see iPS cells to be a major source of stem cells in the decades to come.

There are several general categories types of cells from the source point of view. Embryonic derived and fetal derived stem cells are the more controversial types of cells. The embryonic cells are derived from the inner cell mass of the blastocyst, an early stage embryo, which reaches this stage about four to five days after fertilization. The fetal stem cells are taken from the more developed aborted fetuses. Many believe that this is biological waste that would be thrown away and argue for using them for saving lives. Others have objections to this source and now even the Vatican supports the use of adult stem cells.

There are few if any controversies with adult stem cells, although there is much confusion and misunderstanding about them. Even the media creates so much confusion around stem cells that many people don’t make a distinction between adult and embryonic stems cells and those people who do, are confused about the difference.

Adult stem cells derived from a person’s own body are called autologous. These come from bone marrow, fat (adipose tissue) and blood. Each source provides a different mixture of specific stem cell types.

Adult stem cells are also derived from other people and for instance the more than 50,000 stem cell transplants that are performed around the world each year are from other people. These stem cells are called allogeneic. But they also come from a very rich source—umbilical cord blood and tissue as well as the placenta and amniotic fluid from full term births. Many people mistake this for embryonic stem cells and they are absolutely not—they are adult stem cells. They are also commonly stored by freezing them, by families when a child is born. There are many advantages to using adult stem cells and even the Vatican supports their use.
A history of stem cells
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In the early 1900’s European researchers realized that the various type of blood cells e.g white blood cells, red blood cells and platelets all came from a particular “stem cell”. However, it was not until 1963 that the first quantitative descriptions of the self-renewing activities of transplanted mouse bone marrow cells were documented.

Research into adult stem cells in animals and in humans has been ongoing since this time, and bone marrow transplants – actually a transplant of adult stem cells – have in fact been used in patients receiving radiation and chemotherapy since the 1950’s. This was the beginning of the history of research on adult stem cells. The primary roles of adult stem cells in a living organism are to maintain and repair the tissue in which they are found.

The use of stem cells in treating humans has a long history. The first bone marrow transplant was performed in 1959 by the Frence onologist George Mathe. Stem cell transplantation was pioneered using bone-marrow-derived stem cells by a team in the U.S. from the 1950s through the 1970s. The first physician to perform a successful human bone marrow transplant on a disease other than cancer occurred in 1968. Today over 50,000 people around the globe are treated with adult stem cells each year.

In the 1960s, researchers discovered that bone marrow contains at least two kinds of stem cells. One group, called hematopoietic stem cells, forms all the types of blood cells in the body. The second group, called bone marrow stromal cells or mesenchymal stem cells was discovered a few years later. They can generate bone, cartilage, fat, and fibrous connective tissue.

Developments in biotechnology in the 1980s and 1990s saw the introduction of techniques for targeting and altering genetic material and methods for growing human cells in the laboratory. These advances really opened the doors for human stem cell research.

Then in 1998 James Thomson, a scientist at the University of Wisconsin in Madison, successfully removed cells from spare embryos at fertility clinics and grew them in the laboratory. This research is what launched stem cell research into the limelight, establishing the world’s first human embryonic stem cell line, which still exists today.

Since this discovery, a plethora of research has taken place and now there is a far greater emphasis on adult stem cells due to the fact that they may be more efficacious than embryonic and fetal cells, there has been little or no serious adverse effects from their use and their source is not controversial.