Embryonic Stem Cells History

Embryonic Stem Cells were first derived from mouse embryos in 1981 by two independent research groups (Evans & Kaufman and Martin). The breakthrough in embryonic stem cell research came in November 1998 when a group led by James Thomson at the University of Wisconsin-Madison first developed a technique to isolate and grow the cells derived from human blastocysts. Normally, Blastocyst-stage embryos that are left over after successful In Vitro Fertilization would not be used but be destroyed. 

Scientists are only allowed to use these discarded blastocysts after assessment by specialized committees that thoroughly check the research goals of these scientists. Of course, scientific research using those blastocysts may be conducted when it contributes to a better understanding of how to generate cells and tissues that can cure a patient?s disease or be used to treat severe injuries. Currently, in the United States , scientific research is limited by a ban on the use of federal funds for research with Embryonic Stem Cells derived after August 9th, 2001.

Embryonic stem cell researchers are currently attempting to grow the cells in the laboratory (i.e. in culture flasks: ?In Vitro?) beyond the first stages of cell development. It is important to make sure the Embryonic stem cells are fully differentiated into the desired cell type (i.e. tissue) before they are transplanted into the patient, as Undifferentiated Embryonic stem cells may develop into a tumor after transplantation. Further more, scientists are trying to develop techniques to prevent rejection of implanted cells by the patient (i.e. host-versus-graft response).  

One of the possibilities to prevent rejection is by creating embryonic stem cell clones that are genetically identical to the patient. This can be achieved by fusing an egg cell, the nucleus (containing the genetic material: DNA) of which is removed, with a patient?s cell. The fused cell produced (containing only the DNA of the patient) is allowed to grow to the size of a few tens of cells, and Stem Cells are then extracted. Because they are genetically compatible with the patient, the patient?s immune system will not reject differentiated cells derived from these Embryonic stem cells. More commonly, they are obtained for research purposes from uncloned blastocysts, such as those discarded from In Vitro Fertilization clinics. Such cells might be rejected if transplanted into a patient, as they do not contain identical genetic information. A possible solution for this is to derive as many well-characterized embryonic stem cell lines from different genetic and ethnic backgrounds and use the cell line that is most similar to the patient; treatment can then be tailored to the patient, minimizing the risk of rejection.