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General Stem Cell Education


Stem cell research is the most debated, controversial and misrepresented research. It is important that the public be educated on the key scientific, bioethical and political facts surrounding this research in order to make informed decision on this area. The following statements are answers to important questions related to stem cell research and potential therapies.


What are Stem Cells?

Answer: Stem cells are unique cells that give rise to a cell that produce self-renewal and another cell that has the ability to differentiate into a specialize cell like a nervous tissue, heart tissue and pancreatic tissue.


Are all Stem Cells the same?


Answer: No. There are many different types of stem cells. Stem cells come from a variety of different sources: embryos, fetuses, umbilical cords, placenta and adult tissues. Stem cells are categorized into three categories: pluripotent, multipotent and unipotent. Each class and type of stem cell has advantages and disadvantages. After fertilization between an egg (or ovum) and sperm, an embryo is formed and undergoes cell division to form a blastocyst, a small cluster of stem cells. These primitive stem cells ultimately develop into three germ layers or subcategories of tissues: endoderm, mesoderm and ectoderm. From each of these separate germ layers there is further differentiation into the ultimate specialized tissue.


  • Endoderm germ cells ultimately differentiate into: liver, gut and lung tissue.

  • Mesoderm germ cells ultimately differentiate into: blood, muscle, bone, cartilage, heart, kidney and pancreas tissue.

  • Ectoderm germ cells ultimately differentiate into: nervous tissue and skin tissue.

  • Pluripotent stem cells are stem cells that can differentiate into tissues from all three germ layers.

  • Embryonic stem cells are the most well-known and accepted type of pluripotent stem cell.


In 1998 James Thompson from the University of Wisconsin derived embryonic stem cells from fertilized embryos discarded from in vitro fertilization procedures. Subsequent research has shown that embryonic stem cells are pluripotent and have grown into a variety of different tissue under cultured conditions. Since an embryonic stem cell requires the destruction of a human embryo to produce such a cell line, this type of research is considered ethically and morally controversial.


Since Dr. Thompson's report, Dr. Shinya Yamanaka from the Kyoto University received the 2012 Nobel Prize in Medicine for producing Induced Pluripotent Stem (IPS) cells, which are pluripotent stem cells that avoids the use of human embryos. In this process adult cells are genetically reprogrammed backwards into a very primitive embryonic-like stem cell with the same characteristics as an embryonic stem cell - sparing the need to use and destroy a human embryo.



  • Multipotent stem cells are stem cells that can differentiate into tissues from 1-2 germ layers.

  • Unipotent stem cells are stem cells that can differentiate into tissue from 1 type of germ layer.

  • Another common terminology is the concept of plasticity. Plasticity refers to the potential of a stem cell to differentiate into a variety of different germ layers. A pluripotent stem cell would be considered the most plastic while unipotent stem cells would represent the least plastic stem cells.

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