Stem cells for regeneration. Introduction
Let’s start by saying that biological regeneration has been defined as the ability of certain living organisms to restore lost or injured tissue, or to regrow a part of their body that has been lost due to accidental or physiological causes.
In the animal kingdom, it is known that planarians can completely rebuild their body from each of their severed parts. Other animals that possess remarkable regenerative capacity include hydras, starfish, crustaceans, and lizards. The ability of lizards to regenerate their tails is common knowledge.
In humans, the term "regeneration" has classically been used to describe the process by which specialized tissue that has been lost is replaced by the proliferation of undamaged specialized cells. This mechanism is limited to only a few tissues, such as the liver.
But, on the other hand…we have all heard about stem cells.
Those cells that are capable of repairing old or damaged tissue, and which also have the power to transform into whatever cell is needed. The evidence that our aging is linked to a decrease of stem cells in our body is overwhelming. Many studies suggest that a decrease of stem cells in our body is what acts as a biological clock against aging.
We shall define stem cells as those pluripotent cells capable of transforming into any cell in the body, a skin cell, a blood cell, an insulin-producing cell in the pancreas, of any type... No other cell in the body has the natural capacity to generate new types of cells.
The study of stem cells is helping us to understand more about how diseases occur. On the other hand, it is possible to generate healthy cells to replace cells affected by the disease (yes, regenerative medicine). For example in type I diabetes, in sclerosis ..... Stem cells can be targeted to become specific cells that can be used in people to regenerate and repair tissues that have been damaged or affected by the disease.
It has had other uses, such as testing the safety and efficacy of new drugs. Researchers might use a variety of stem cells before using experimental drugs on people. That way, they can do a safe test on the quality and safety of the drug.
Stem cells come mainly from:
Embryonic stem cells. These stem cells come from embryos that are 3 to 5 days old. At this stage, an embryo is called a blastocyst and has about 150 cells.
Perinatal stem cells. According to some studies, there are stem cells in umbilical cord blood as well as in amniotic fluid. These stem cells can develop into specialized cells.
Adult stem cells. The stem cells can be found in tissues like fat and bone marrow, in the case of adults. Compared to embryonic stem cells, adult stem cells have a more limited capacity to generate different cells in the body.