There are three main types of stem cells: embryonic stem cells and adult stem cells (found mainly in bone marrow and the umbilical cord), which have natural sources, and induced pluripotent stem cells, which were obtained by scientists in the laboratory in 2006.

1- Embryonic stem cells.

2- Adult stem cells.

3- Induced pluripotent stem cells.


Embryonic stem cells are the cells responsible for multiplying into new cells for an embryo as it develops into a baby. They are pluripotent, which means they can turn into any cell in the human body.


Adult stem cells are cells that multiply to supply new cells to a growing organism, replacing damaged cells. They are multipotent, which means they can only turn into certain types of cells, such as blood cells or skin cells.


When you get hurt and scrape your knee, for example, adult stem cells work to replace what was damaged; therefore, such cells may be found in any part of the body.


One of these sources is bone marrow, which can be collected from adults for donation. However, there are some cases in which other sources are more effective for treatment, such as umbilical cord stem cells.


These can be collected right after birth and stored for future use and, since they have not been exposed to radiation, viruses and other agents, they have a greater potential for multiplication.


In the case of bone marrow, for example, a battery of tests is required to ensure that the donor's conditions will not affect the health of the person who will receive the material.


Examples:

1. Hematopoietic stem cells (HSCs).

2. Mesenchymal stem cells.

3. Extracellular vesicles (EVs).

4. Exosomes.


Induced pluripotent stem cells (iPSCs), in turn, are somatic cells reprogrammed to an embryonic state through the expression of specific ectopic transcription factors, making them a promising target for regenerative medicine.