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 All cells in the body are formed from stem cells!  Stem cells are unspecialized cells whose functions in the body have not yet been determined.  Stem cells divide slowly until they are signaled to become differentiated tissue cells such as cardiac muscle cells, nerve cells, or skin cells.

 There are two main types of stem cells in animals and humans:  Embryonic Stem Cells  Adult Stem Cells  Embryonic stem cells are found in embryos.  Adult stem cells are found in certain adult tissues such as bone marrow, muscle, and brain tissue.

 Once an egg is fertilized to form a zygote, it begins to divide into a group of stem cells called an EMBRYO.  These early-stage stem cells are TOTIPOTENT, meaning they can become any kind of cell in the body!

 After several days of development, the embryo becomes a hollow ball of cells called a BLASTOCYST.

 Embryos in the blastocyst stage contain two types of cells:  Embryonic Stem Cells  Trophoblast Cells

 Embryonic stem cells in the blastocyst are called PLURIPOTENT, which means they can become almost any type of cell in the body.  Trophoblast cells make up the area that will eventually become the placenta, which supplies nutrients to the fetus.

 Adult stem cells are found in certain adult tissues such as bone marrow, muscle tissue, and brain tissue.  Unlike embryonic stem cells, adult stem cells are MULTIPOTENT, which means they are restricted as to which cell types they can become.  Adult stem cells generate replacements for cells that are lost due to normal wear and tear on the body, injury, or disease.

 Doctors use adult stem cells found in bone marrow to treat leukemia, other types of cancer, and various blood disorders through bone marrow transplants.

 Over time, the body loses its ability to repair itself from injury, disease, or simply years of use.  Because of their unique nature, stem cells are able to give rise to almost any other type of cell in the body.  Researchers hope that stem cells can one day be used extensively to aid the body in repairing itself.

 For example:  Imagine someone has a heart attack and the heart tissue is damaged. Embryonic stem cells could be added to this tissue, signaled to develop into heart tissue cells, and help repair the damage caused by the heart attack.  Suppose someone is in an accident and nerve tissue is damaged, causing paralysis. Stem cells could be used to create nerve cells and help reverse the paralysis.

Scientists continue to research stem cells and their uses, but there are still many obstacles to overcome before embryonic stem cells can be used to cure disease.

Stem cell research has only just begun.  The first embryonic stem cells were isolated in mice in  Seventeen years later, in 1998, the first human embryonic stem cells were isolated.  More recently, scientists have reported making stem cells without destroying a human embryo.

 Scientists are currently using adult stem cells from bone marrow to treat leukemia and other diseases.  Stem cells found in the umbilical cord of newborns are being used to treat the same types of disorders as those treated by bone marrow stem cells.  Research dealing with stem cells and their uses is an ongoing process and is surrounded by controversy.

 Scientists hope to develop more advanced stem cell therapies.  Possible uses for stem cells in the future include:  generating healthy heart muscle cells from stem cells in a laboratory, and using them to treat a patient with heart disease.  creating nerve cells from stem cells in order to treat paralysis.  using stem cell transplant procedures to treat neurological disorders such as Parkinson’s disease.

 Stem cell research is a controversial topic in biotechnology.  The following represent some of the issues surrounding stem cell research:  Using frozen human embryos for research  Religious beliefs against stem cell use  Governmental funding of stem cell research  Risks involved in stem cell therapies

 What is your opinion about stem cell research?  Do you feel differently about embryonic stem cell research and adult stem cell research?  How might your opinion of stem cell research be affected if you or a loved one were suffering from a disease that could potentially be cured due to stem cell technology?  Do you think the government should fund stem cell research?