What makes a stem cell so much more valuable, from a scientific perspective, than any other cell in the body? Stem cells are the chameleons of the cell world, meaning they can transform into any other cell type. A heart cell, for example, is just that: a cell that’s part of the heart. The same goes for skin cells, hair cells, brain cells and nearly every other cell in the human body.
But, a stem cell, on the other hand, can make a lot more choices about what it can do and become. Just like any cell that actively grows and divides, a stem cell can divide and just form an exact copy of itself: another stem cell. But, more miraculously, a stem cell can grow and instead form a completely different type of cell.
However, a stem cells ability to transform fades with age. By adulthood, the stem cells present in the body have already received directions for what type of cell they need to produce. For instance, a blood stem cell can produce fresh blood cells, but not any other cell type.
Only embryonic stem cells, those taken from an embryo, have the capacity to form all the cells in the body. These stem cells, when placed in the right environment, can become a blood cell, kidney cell, brain cell, or any other cell type imaginable. From a therapeutic perspective, it makes sense that scientists and medical professionals would want to work with embryonic stem cells, since the possibilities for their use are endless.
But, in the past, acquiring these valuable stem cells in an acceptable manner proved difficult. In order to obtain these stem cells, scientists needed to fertilize a human egg in the laboratory and then ultimately destroy it to separate out the stem cells. As a result, federal funding for stem cell research that led to harm of a human embryo was banned, and public opinion branded stem cell research unethical.
But, over the past decade, scientists have worked tirelessly to prove the importance of stem cell research and show just how revolutionary it can be to modern medicine. And, after overcoming seemingly insurmountable difficulties, scientists have made a stem cell that’s just like an embryonic stem cell, except it doesn’t actually come from an embryo.
These ground-breaking stem cells are called Induced Pluripotent Stem cells, or iPS cells. iPS cells are skin cells that have been turned into stem cells. They behave and function like typical stem cells, even though they started out as just regular body cells. Just as the name alludes to, these cells are induced to become stem cells in a laboratory, as this transformation is not known to occur naturally in humans.
How are scientists making these stem cells? It starts by taking a skin cell sample from an adult patient and growing them in a petri dish in the laboratory. Next, these cells must be reprogrammed to think they are stem cells and not skin cells. To do this, scientists take advantage of normal biology and the fact that all cells in the body contain all the same genetic material, or genes.
The only thing different between a stem cell and skin cell is which genes are turned on and which genes aren’t important and kept off. A gene acts as the blueprint for a protein, and it’s these proteins that control what a cell will become. Genes in the on position can produce proteins needed to turn a cell into a stem cell or skin cell, for instance. What scientists can do is add a group of proteins normally found in stem cells, called the Yamanaka factors, to the skin cells growing in the petri dish in order to turn back the clock and turn these skin cells into stem cells again. Hence, the skin cells have been induced to become pluripotent stem cells (iPS cell).
With this new, ethical source of iPS cells, scientists can now explore how they can be used to treat disease. As mentioned earlier, stem cells can produce other cell types when placed in the right environment. This is because stem cells receive information from their environment, or their niche, in order to know exactly how to behave. So, if a scientist wants to form heart cells, they can recreate the heart environment in the petri dish containing the stem cells. In this case, the scientists are fooling the stem cells into thinking they are in the heart. The stem cells, wanting to “fit in,” will slowly begin to turn into heart cells as they grow. Scientists can use this method with iPS cells to create new treatments for disease.
For a patient suffering from Alzheimer’s disease, this could mean making new, healthy brain cells from the iPS cells. Scientists could also create new blood cells for patients suffering from Sickle Cell disease, or replace heart cells damaged after a heart attack.
The best part about this type of treatment is that the transplanted cells originate from the patient who needs the transplant, so there is minimal risk that the cells will be recognized by the body as foreign and destroyed. This is a major problem with current transplant procedures, since they use organs and tissues from anonymous donors and our bodies can detect cells that aren’t our own and destroy them.
Ultimately, this newfound ability to generate stem cells puts scientists one step closer toward their end goal, but there’s still a lot of work to be done. For example, figuring out how to re-create a specific environment, such as the heart or liver, is not easy. Also, even if scientists are able to form the cell type they want, finding a way to transplant these back into the patient and have the cells survive is another obstacle that must be overcome. Much success has been achieved thus far directing cells to become eye cells, which has proved just how promising iPS cells are for the treatment of disease.
The first human trial using iPS cell technology was this past September in Japan. Scientists and ophthalmologists believe iPS cells hold great potential in the treatment of macular degeneration, or breakdown of the retina in the eye, which eventually leads to blindness. Current technologies for treatment of this disease aim to slow down disease progression, but it’s ultimately untreatable.
During this trial, scientists turned iPS cells into retinal cells and transplanted them into the damaged retina. The hope was that these new cells could replace the damaged cells and help to regenerate a healthy retina. Only time will tell how successful this treatment will be, but even so, the discovery and existence of iPS cells has already transformed the future of modern science. There are high hopes for where iPS technology will go from here, with thoughts that one day, stem cells like these can be used to recreate entire organs, like the liver, to be used in organ transplants.
With an ever-aging population and debilitating diseases plaguing our society, there will always be a need for better treatments and more advanced technologies. Rarely there arises such a technology that can revolutionize how we treat a single disease, let alone multiple diseases that affect all different parts of the body. Induced Pluripotent Stem cells hold that potential, and could stand amongst the greatest and most impactful scientific advances for the treatment of disease.