In 2006, researchers at Kyoto University in Japan established conditions that resulted in specialized adult cells that could be genetically “reprogrammed” to assume a stem cell-like state. These adult cells, called induced pluripotent stem cells (iPSCs), were successfully reprogrammed to an embryonic stem cell-like state. This was achieved by introducing genes important for maintaining the essential properties of embryonic stem cells (ESCs). Since then, scientists have greatly improved the techniques to engineer iPSCs, creating a powerful new way to “de-differentiate” cells. iPSCs give scientists an alternative, pluripotent cell to human embryonic which could help with some of the ethical concerns surrounding ESCs.
Induced pluripotent cells provide scientists and doctors tools for drug development, modeling disease, and improving transplantation medicine. Induced pluripotent cells also offer potential resources for cell-replacement therapies and regenerative medicine. One of the challenges with stem cell therapy progress has been with immune rejection – the patient’s body attacks the injected stem cells because it doesn’t view them as belonging there. But, with induced pluripotent cells, the source cells are derived from the patient so immune rejection would be much less common.
A field that has greatly prospered since the introduction of iPS cell technology is that of drug testing and development. Scientists can buy different human cells types derived from human iPS cells to test the efficacy or toxicity of new drugs. In the past, scientists used engineered cell lines or rats/mice to model human disease. The opportunity for scientists to use human iPS cells to study human diseases in corresponding human cell types has helped boost the efficacy and process of drug discovery.
The ability to reprogram cell types opens doors for treating numerous diseases including: Parkinson’s disease, diabetes, cardiovascular disease, Alzheimer’s disease and others. In the case of Alzheimer’s disease, scientists can take a patient’s skin or blood cells who is afflicted with Alzheimer’s, and reprogram the cells to produce iPS cells. Then, these iPS cells can be differentiated into numerous cell types found in our brains. These differentiated cells can provide information about what is different between these cells compared to someone who is not afflicted with Alzheimer’s disease. Understanding the disease better is one of the biggest steps forward to finding effective treatments and prevention methods.
Many diseases stem from genetic defects. Scientists are working to understand the link between disease and genotype. CRISPR is a gene editing technology which helps with understanding this link better. CRISPR is an acronym for Clustered Regularly Interspaced Short Palindromic Repeat. The name refers to the unique organization of short, partially palindromic repeated DNA sequences found in the genomes of bacteria and other microorganisms (Harvard, 2014). With CRISPR, a genetic defect from a patient-derived iPS cell can be corrected and then correlated with the original to assist scientists with identifying which genetic elements trigger disease progression.
Despite some of the setbacks and slow-downs of induced pluripotent cell science, the October issue of The Scientist stated that stem-cell based regenerative medicine is getting closer to clinical application. Scientists around the world are employing pluripotent cells to create various therapeutic cell types for diabetes and Parkinson’s disease. In 2010, the Geron Corporation began the first FDA-approved clinical trial using human ESCs to treat spinal cord injury. Costs associated with clinical trials continues to be an obstacle for both patients and scientists. The Astellas Institute for Regenerative Medicine (formerly Advanced Cell Technology) is pursuing an embryonic stem cell treatment for macular degeneration, and launched a Phase 2 clinical trial last year.
The May 2017 edition of Science Daily reported that researchers have learned more about how stem cells develop into organs. These scientists were able to grow and purify the earliest lung progenitors that emerge from human stem cells, and then differentiate these cells into tiny ‘bronchospheres’ that model cystic fibrosis. Scientists are hopeful that these findings will reveal, ‘personalized medicine’ methods for treating lung disease.
Since their introduction in 2006, induced pluripotent stem cells have created quite a stir. Although their potential has yet to be realized, in time, they will take medicine places that are exciting and promising for those who suffer from disease and life-altering conditions.