What are stem cells and why are they revolutionary?

The answer

Stem cells are undifferentiated cells capable of self-renewal and differentiation into specialized cell types. Embryonic stem cells are pluripotent, meaning they can become any cell type in the body. Adult stem cells, found in bone marrow, brain, skin, and other tissues, are more limited, typically generating only the cell types of their tissue of origin. The 2006 discovery by Shinya Yamanaka that adult cells could be reprogrammed into induced pluripotent stem cells (iPSCs) using four transcription factors revolutionized the field, earning a Nobel Prize in 2012. Stem cell therapies already save lives through bone marrow transplants for blood cancers and are being developed for treating spinal cord injuries, Parkinson's disease, heart failure, macular degeneration, and type 1 diabetes. Lab-grown organoids derived from stem cells now allow scientists to study disease and test drugs on miniature human organs grown in culture dishes.