Induced Pluripotent Stem Cells: The Ethical Embryonic Alternative

Bioethics   |   Rebecca Taylor   |   Jul 21, 2011   |   2:53PM   |   Washington, DC

Biology’s new “supermodel” — induced pluripotent stem cells. At least that is what The Scientist is calling them. 

Induced pluripotent stem cells (iPSC) are adult cells that have been reprogrammed back to a pluripotent state.  A pluripotent cell is simply a cell can become most or all of the 200 cell types of the body.  iPSCs behave like embryonic stem cells, which are naturally pluripotent, but iPSCs not require the destruction of an embryo. They are the perfect alternative to therapeutic cloning or somatic cell nuclear transfer (SCNT).  SCNT creates a cloned embryo that would be destroyed for the pluripotent stem cells inside.

Many scientists have called SCNT “the most promising” way to make pluripotent stem cells because it would create embryonic stem cells that are a genetic match to a patient.  The problem with SCNT is that to make pluripotent stem cells that are a genetic match, human eggs are needed and a cloned embryo is created and destroyed.  Induced pluripotent stem cells also creates pluripotent stem cells that are a genetic match to a patient because the reprogrammed adult cell is from the patient.  But iPSCs technology does not require eggs or cloned embryos to do it.

In fact, the idea of reprogramming an adult cell back to a pluripotent state is credited to Japanese scientist who wanted another way to get patient-specific pluripotent stem cells without creating and destroying embryos. Dr. Shinya Yamanaka, stated in the New York Times:

“When I saw the embryo, I suddenly realized there was such a small difference between it and my daughters,  I thought, we can’t keep destroying embryos for our research. There must be another way.”

Dr. Yamanaka and embryonic stem cell pioneer James Thomson independently created the first iPS cells.  James Thomson also recognized that destroying embryos for research was problematic.  Thomson told the New York Times:

“If human embryonic stem cell research does not make you at least a little bit uncomfortable, you have not thought about it enough.”

And now iPSCs are coming into their own proving that ethics and science make good partners.  Researchers are finding that iPSCs are great for creating models of disease.  Previously, scientists would have to create a mouse or other animal that exhibited the symptoms of a human disease that they were interested in studying.  Now they can take a skin cell from a person with a disease, reprogram that cell back to a pluripotent state, and then differentiate them into cells of interest whether they be neurons or fat cells.  iPSCs can continue to grow in culture and be frozen giving researchers a nearly limitless supply of diseased cells to work on.  This is especially useful in brain disorders because isolating neurons from the brain of a patient is dangerous.

For all of these reasons and more, The Scientist, calls iPSCs the “new supermodel” for understanding human disease:

Move over mice. Human induced pluripotent stem (iPS) cells are making strides to become the next best thing in translational research—disease-specific human cells grown in a dish. Using a variety of approaches, researchers have generated stem cells from mature adult cells of disease-afflicted patients and subsequently differentiated them into the various tissue types involved in the disease.

“The idea is that you can have a pluripotent stem cell line from a patient that already contains all the genetic background of the disease,” says Gustavo Mostoslavsky, a stem cell researcher at the Boston University School of Medicine. Now that the generation of iPS cells is “routine,” he adds, scientists can use the method to generate in vitro disease models, from which they can learn about molecular causes, as well as potential preventions and treatments.The strategy is proving particularly valuable for neurodegenerative diseases, in which it is not easy to safely and ethically extract affected cells of the brain. Instead, researchers can remove more accessible cells, such as those of the skin, regress them into a pluripotent state, and then re-differentiate them into neurons. Furthermore, iPS cells can be expanded in culture and/or frozen for years, providing an unlimited supply of cells from a single patient that can be used to create any cell types needed for the study of a particular disease, now or in the future.

Among the diseases that are being modeled with iPS cells are amyotrophic lateral sclerosis (ALS), spinal muscular atrophy (SMA), Parkinson’s and Rett Syndrome.  I am particularly excited about the Rett Syndrome model because I spent years sequencing the MECP2 gene of little girls looking for the mutations that cause Rett Syndrome.

And iPSC technology can be used to create models for many other diseases as well. Dr. Yamanaka envisioned iPSC technology as an alternative to creating and destroying human embryos for research.  It is because he recognized the value of life in its earliest stages that induced pluripotent stem cells were born and now are revolutionizing the way we study human disease. Note: Rebecca Taylor is a clinical laboratory specialist in molecular biology, and a practicing pro-life Catholic who writes at the bioethics blog Mary Meets Dolly. She has been writing and speaking about Catholicism and biotechnology for five years and has been interviewed on EWTN radio on topics from stem cell research and cloning to voting pro-life. Taylor has a B.S. in Biochemistry from University of San Francisco with a national certification in clinical Molecular Biology MB (ASCP).