pluripotency

Pluripotency is the power to become any of the body's own cell types — nerve, muscle, blood, skin, gut, and all the rest — yet not, on its own, a whole organism. It sits one rung below the all-powerful totipotency of the fertilized egg. A pluripotent cell is like a master key cut to open every interior room of a building, but not the front gate that would let it build the building from scratch.

The benchmark for true pluripotency is the ability to give rise to cells from all three germ layers — the three foundational tissue layers that an early embryo organizes itself into, and from which every organ later forms. One layer eventually yields skin and nerves, another muscle, bone, and blood, and the third the gut and lungs. A cell that can produce descendants in all three has demonstrated the full breadth that pluripotency promises, not just a lucky few lineages.

Pluripotency is the prize that makes certain stem cells so coveted and so studied. A pluripotent cell is, in principle, a universal starting material from which any tissue might be grown for repair or for laboratory study. That same near-limitless flexibility is also why such cells must be handled with care: a cell that can become anything must be coaxed precisely toward the one thing you want, and away from forming disorganized growths.