First, by their nature, pluripotent stem cells can potentially be used to create any cell or tissue the body might need to counter a wide range of diseases, from diabetes to spinal cord injury, to childhood leukemia, to heart disease.
Second, pluripotent stem cells can potentially be customized to provide a perfect genetic match for any patient. This means that patients could receive transplants of tissue and cells without tissue matching and tissue rejection problems, and without the need to take powerful immune-suppressing drugs for the rest of their lives. Although this vision hasn’t yet been achieved, researchers at Boston Children’s Hospital have successfully treated mouse models of human disease using this strategy and hope that the same can be done with patients.
Disease in a dish:
Third, pluripotent stem cells make excellent laboratory models for studying how a disease unfolds, which helps scientists pinpoint and track the very earliest disease-causing events in cells. Immune deficiencies, Type 1 diabetes, muscular dystrophy, and myriad other disorders are rooted in fetal development. In the lab, researchers can recapture these early origins—observing where the first muscle cell comes from, or the first blood cell, and how this differs when the patient has a genetic disease. Using this information, doctors may be able to intervene and correct the genetic defect before the disease advances.
Each type of pluripotent stem cell has different characteristics that make it useful in different ways, and each has different lessons to teach.
- Induced pluripotent cells (iPS cells) offer a unique chance to model human disease and are already being used to make new discoveries about premature aging, congenital heart disease, cancer, and more. Because they’re made from a person’s own cells, they can potentially be manipulated to fix the disease-causing defect and then used to create healthy cells for transplant that won’t be rejected by the immune system. Many people also see iPS cells as a positive alternative to pluripotent stem cells from embryos or eggs.
- Embryonic stem cells (ES cells) are the gold standard for the biological concept of pluripotency. Scientists are working with ES cells to learn more about what endows a cell with pluripotency and to discover safer, better ways to create iPS cells. Each type of ES cell is important for different reasons:
- ES cells made from donated early embryos are irreplaceable tools for understanding the earliest stages of human development and how specific tissues form. Because they’re not customized to individual patients, their value is mainly in research.
- ES cells made through nuclear transfer (ntES cells), like iPS cells, offer the opportunity to create customized, rejection-proof cells and tissues for transplantation. ntES cells are thought to be the most genetically pristine source for creating genetically-matched cells, so may provide a faster and safer route to the clinic.
- ES cells made through parthenogenesis (pES cells) also offer the opportunity to create customized, rejection-proof cells. Though less genetically pristine than ntES cells, they are less technically cumbersome to produce. Through genetic typing, they could potentially be banked to create a selection of off-the-shelf cell-based treatments.