What is the real debate? When we discuss stem cell research pros and cons, is the debate truly about adult v. embryonic? If so, why is that fact frequently obfuscated?
It is the nascent (i.e., early) stage that provides the remarkable potential to develop into many different types in the body. They serve as a sort of repair system for the body. Theoretically, they can divide without limit to replenish other cells as long as the person or animal is still alive.
What happens when division occurs? Potentially, it either remains in the nascent state or develops a more specialized function (e.g., muscle, RBC, brain, etc.).
In the nascent stage, it may turn into liver, skin , nerve, etc. In the early-stage (hence, the term "stem"), they possess varied abilities to differentiate (i.e., turn) and become more specialized.
What exactly are "embryonic stem cells"? They come from embryos that are four to five days old.
In this nascent stage, it is called a blastocyst. Blastocysts have approximately 50 to 150 cells.
In this stage, they are classified as "pluripotent" (i.e., they can divide into more stem cells or they can specialize and become any tissue). Therein lies the gist of the argument for the use of them in the embryonic phase, a phase in which they have the highest potential for use to regenerate or repair diseased tissue and organs in people.
Thus, the term "the master cells of the human body". They can divide and replicate themselves, as well as other structures.
They are found in various parts of the human body at every stage of development from embryo, where they can turn into any of the 300 different types that make up the adult body.
In the "adult" (a/k/a "somatic") phase, they exist throughout the body. They are found inside of different types of tissue. Additionally, one may find them in adult tissue, and cord-blood may be harvested from the umbilical cord following birth.
They have been found in, among others, the following tissues: (1) brain; (2) bone marrow; (3) blood; (4) blood vessels; (5) skeletal muscles; (6) skin; and (7) the liver. Adult stem cells remain in a quiescent (i.e., non-dividing) state for years until activated by disease or tissue injury.
There are three principal processes in which they play a central role in an organism: (1) development; (2) repair of damaged tissue; and (3) cancer resulting from division gone awry.
They were first used in Medicine to regenerate healthy blood and immune cells in cancer patients following chemotherapy. From this, the field of "regenerative medicine" emerged. This is a field in which scientists focus on the use of cord-blood for the treatment of both brain injury and juvenile diabetes.
Once matured, they eventually become bones, heart muscle, nerve, and other organs and tissue. Observing this transformation provides a better understanding of how a variety of diseases and conditions develop.
They have the potential to renew themselves through a process called mitosis. During this process, they may differentiate into many different specialized types.
Although there are 300 trillion of them, most have specialized functions. These specialized functions include production of blood, lung tissue, brain tissue, skin, and liver cells.
For the most part, they cannot do anything other than that for which they were specifically designed. Contrariwise, nascent stages, they do not have specialized function. Therefore, they are immature and possess the potential to develop into many different kinds. Thus, the moniker "'all-purpose".
A lack of specialization suggests that they possess the ability to reproduce themselves, indefinitely. Furthermore, under the right conditions, they may develop and mature, producing nerve, skin, pancreas, and other tissues possessing specialized functions.
The body contains over 200 types, each with a specific job. As blood, they carry oxygen. As muscle, they contract so that we can move. As nerves, they transmit chemical signals.
The primary purpose: make new cells. They do this by undergoing an amazing differentiation-process, changing into many types.
When they divide, one of them often remains in its original state, while the other specializes (e.g., heart, blood, brain, or other type). It is amazing that they appear to be able to divide and replenish themselves - without any apparent limit.