Stem cell cultures in a lab at the Reeve-Irvine Research Center at the University of California Irvine. Image credit: Sandy Huffaker/Getty Images
Stem cells are the zenith of tissue regeneration and coveted for research on treating difficult diseases. Unlike other cells, stem cells are blank slates that can be turned into any type of specialized cell. For years, the only reliable sources for obtaining these cells were discarded or frozen embryos, but many ethical and religious objections served as roadblocks to research. However, in 2006, Japan's Shinya Yamanaka made a groundbreaking discovery: he found that adult cells could be reprogrammed into any other cell types by adding four genes to make them behave like embryonic stem cells. The adult cells treated this way are called induced pluripotent stem cells (iPS cells).
Yamanaka received the Nobel Prize for this discovery in 2012, though two years later he came clean about poor record keeping in a 2000 paper after a colleague, Haruko Obokata, admitted to improper obtaining of images in her stem cell studies; her papers were retracted after publication.
Scandals notwithstanding—and Yamanaka’s work has upheld, despite these controversies—iPS cells are being studied and developed in numerous labs around the world to create human tissue and potentially treat a variety of human diseases and illnesses. Here are seven key facts about these fascinating cells.
1. iPS CELLS AND EMBRYONIC STEM CELLS ARE NOT THE SAME, BUT VERY SIMILAR.
Both iPS cells and embryonic stem cells are self-renewing, which means they can produce copies of themselves indefinitely. Both cells can be reprogrammed into any kind of cell. But the two groups of cells are not exactly the same. Scientists continue to study the iPS cell mechanisms, because some of their genes behave differently than their embryonic counterparts.
2. THEY MAY ONE DAY PROVIDE ALL THE REPLACEMENT CELLS A PERSON NEEDS.
Or at least that’s the hope. Because iPS cells can be induced to become any kind of cell (by introducing additional genes), they may one day provide an unlimited supply of replacement cells and tissues for diseases and illnesses. Plus, when they are derived from a patient’s own cells, the body is more likely to accept them.
3. THEY MOST OFTEN COME FROM SKIN CELLS.
Currently the most common source of iPS cells is skin, but others are being derived from blood cells and mesenchymal stem cells, which make up connective tissues.
4. PEOPLE WITH TYPE 1 DIABETES COULD ONE DAY BE CURED BY THEIR OWN IPS CELLS.
In type 1 diabetes, the cells in charge of producing the hormone insulin are destroyed. Researchers made a significant breakthrough in developing a potential cure for type 1 diabetes when they found a way to turn iPS cells into insulin-producing cells and transplant them into the abdomens of diabetic mice. In theory, insulin-producing cells could one day be generated from a diabetic patient’s skin cells and used to restore function to the pancreas.
5. THEY HAVE SUCCESSFULLY HALTED DECLINING VISION IN HUMANS.
In 2013, scientists at the Riken Center for Developmental Biology in Kobe, Japan, took skin cells from a 70-year-old patient with age-related macular degeneration and cultivated retinal cells from them. Then, they transplanted these cells into the patient’s eye in the hopes of halting her macular degeneration. In the year and seven months since the patient’s surgery, her decline in vision has stopped, and her body hasn’t rejected the transplanted tissue.
6. MICE WITH HYPOTHYROIDISM APPEAR TO BE CURED BY IPS CELLS.
People with thyroid cancer or disorders such as hypothyroidism that require removal of the thyroid often must take lifelong medications, which come with their own unpleasant side effects. A recent study in Cell Stem Cell showed that iPS cells from mice could be converted into thyroid cells. When these cells were transplanted into the mice, they functioned as a thyroid gland, essentially curing the animals of hypothyroidism. The same could potentially work in humans one day.
7.IPS-DERIVED NEURON CELLS COULD OFFER RELIEF FOR PARKINSON'S.
Parkinson’s disease is a common neurodegenerative disease in which certain types of brain cells called dopaminergic neurons start to die. In recent years, studies and clinical trials have looked into turning stem cells and iPS cells into dopaminergic neurons and transplanting them into the brains of people with Parkinson’s disease. Some have yielded promising—but very preliminary—results.