#pluripotency

(The first few cells of a zygote are actually totipotent: they can form not only all the cells in a human body, but also all the cells to make up a placenta.)

Pluripotent stem cells are of significant biological interest; scientific dreams of growing new organs and stalling neurodegenerative damage rely on their availability. But they have been the focus of significant ethical controversy. Pluripotent stem cells are naturally only found in embryos, and that's where they came from for early stem cell research.

Human embryonic stem cells are derived from embryos discarded by in vitro fertilization clinics, which often fertilize multiple eggs to increase their chances of success, but only advance pregnancy with one. No embryo has ever been created for stem cell research, and all embryos used for scientific research would have died regardless of their research use. Still, the ethical ramifications remain murky and controversial.

Enter induced pluripotent stem cells.

"In 2006, researchers at Kyoto University in Japan identified conditions that would allow specialized adult cells to be genetically "reprogrammed" to assume a stem cell-like state.

Through research on embryonic stem cells (though often using nonhuman embryos), the scientists found genes responsible for making embryonic stem cells pluripotent. Since then, other research has been able to replicate this finding without the use certain genes that promote tumors.

(This is a constant challenge of working with stem cells. Cancer cells are no longer bound by normal rules about when to multiply, often because they have turned on genes from embryonic development that direct cells to grow and divide. Overlap between embryonic development and tumor development exists in the very definitions of those processes.)

Because of this research, it is now possible to take skin cell samples from an adult and create embryonic-like stem cells from them. 

It's important to note that an embryo cannot be created this way, so don't get too excited about the future of cloning - the cells aren't totipotent, meaning they cannot develop into a placenta, and thus cannot support embryo growth. However, by influencing their environments regulating their development, they can be induced to grow into a variety of different cell types.

Sidestepping the ethical dilemma of embryonic stem cells is a major advantage to induced pluripotency, but it isn't the only one. When stem cells are created from an adult patient, they are guaranteed to be a genetic and immunological match. Although directing such cells to develop into complex structures (i.e. growing new organs) remains unrealistic, it is possible to grow new cells to replenish failing populations, and the first disease treatments using induced pluripotent stem cells are beginning clinical trials.

It should be noted that as of 2016, no such treatments have cleared trials, so any clinic claiming to be using stem cell treatments is either making use of dangerously unregulated science or, more likely, lying. The only approved medical uses for stem cells are grafting stem cell tissue from a donor, as in a bone marrow transplant.

Current efforts using induced pluripotent stem cells are developing treatments for a variety of diseases: from macular degeneration, to regrow damaged rods and cones in the eye; to multiple sclerosis and other autoimmune disorders, to "reboot" immune systems; to Parkinson's disease, to introduce new dopamine-producing neurons to supplement failing ones.

They were part of a large number of genes that regulate differentiation and cell division during embryonic development but there is not an adequate theory to explain why those particular genes are necessary and sufficient to make an adult cell behave as if it is an embryonic cell. Although the proteins that OCT4 and SOX2 code for stick to each other (bind) and together regulate (turn on) a large number of other genes that are known to prevent differentiation and therefore would maintain the potential of a cell to turn into many different types of specialized cells, a characteristic of stem cells. OCT4 (short for the name octamer-binding transcription factor 4; see how we name genes) is a master regulator of pluripotency, that is, the potential to differentiate into many types of cells. This is a critical attribute in cells of the early embryo. It is in a class of genes first discovered in the lowly (or mighty!) fruit fly. SOX2 (short for sex determining region box 2) is critical to self-renewal. This means that every time a stem cell divides at least 1 daughter cell is also a stem cell. This is why these cells can potentially supply an unlimited number of cells for research or therapy. cMYC (short for myelocytomatosis viral oncogene homologue; cytoplasmic) was discovered because it was mutated or broken in Burkitt lymphoma a cancer of blood cells. It regulates as many of 15% of all other genes (that’s like more than 4,000 genes)!! It is a key regulator of cell division and in addition to turning other genes on and off it also controls proteins that modify chromatin to allow other regulators access to genes.