Ethical Embryonic Stem (ES) Cells
Scientists Convert Human Skin Cells to ES Cells by Adding Four Genes
Scientists have created ES cells without destroying an embryo or cloning a patient.
Back in June, researchers in Japan were able to turn a mouse skin cell into a mouse embryonic stem (ES) cell. Now the same Japanese researchers and a group in Wisconsin have repeated the experiment using human cells.
This research is important because it creates ES cells without destroying an embryo and it eliminates the need for human cloning. These are two of the major ethical hurdles in using ES cells in medicine.
The Promise of Embryonic Stem Cells
Many diseases are incurable because the body cannot make new cells to replace old damaged ones. Examples include diseases like Type 1 diabetes and Parkinson’s disease as well as injuries like damaged spinal cords.
Theoretically, ES cells can be used to treat these conditions. These cells can make new copies of themselves forever and they can turn into different kinds of cells. This means that a scientist could take ES cells and make new pancreatic cells to cure someone’s Type 1 diabetes. Or new nerve cells to heal a damaged spine or brain.
The Ethical Hurdles
ES cells hold a lot of promise but they come with ethical baggage. In order to get ES cells, an embryo usually has to be destroyed. To people who view these few cells as a life, this is not acceptable.
The other ethical problem has to do with the fact that the most useful ES cells would be those that came from the patient. These “personalized” ES cells would not be rejected by the body. Unfortunately, a patient’s ES cells are usually long gone by the time he or she needs a cure.
To get around this problem, scientists have proposed the idea of cloning a patient to get his or her ES cells. The clone would only grow to 50 or 100 cells before it was destroyed (this is called therapeutic cloning). This brings up the ethical dilemma of possibly growing a full clone. And the need to destroy the cloned embryo remains.
Making ES Cells from Skin Cells
Most cells have the same DNA. What makes one cell different from another is which of the genes in that DNA a particular cell uses. And which genes were used by the previous cells to get to that particular cell.
So an ES cell has a certain set of genes on. As the ES cell progresses to a skin cell, some genes are turned off and others are turned on. What the researchers did was add four genes to a skin cell to turn it into an ES cell.
Each group used a different set of four genes. The Japanese group added OCT3/4, SOX2, KLF4, and c-MYC. The Wisconsin group added OCT4, SOX2, NANOG, and LIN28. Both sets of genes worked to turn skin cells into ES cells.
The stem cells they made can be personalized by using a patient’s skin cell. And no embryo has to be destroyed. This line of research eliminates the ethical but not the technical hurdles.
The previous mouse research showed that the ES cells that are generated from skin cells caused cancer in about 20% of the mice tested. The fact that each group used different genes suggests that maybe a set of genes could be found that will not cause the patient to get cancer.
It is important to remember too that ES cell treatments are still only theoretical at this point. No one has yet cured a disease using ES cells. This research knocks down the ethical barrier so that scientists can more fully explore whether ES cells will work to cure disease or not.
