Every multicellular organism is composed of different types of cells, derived from precursor cells, called stem cells. or mother cells or stem cells, whose differentiation process that generates specialized cells — from the skin, bones and cartilages, blood, muscle, nervous system, and other human organs and tissues—it is regulated, in each case, by the expression of specific genes. They are responsible for the formation of the embryo and also for the maintenance of tissues in adult life.
Stem cells can multiply, regenerating damaged tissues, because they have the ability to transform into cells identical to the tissues where they were implanted. Thus, they are classified as:
Totipotents: can form all tissues. They form within the first 72 hours after fertilization of the egg. Ex: blastomere.
Pluripotent: they can specialize in any body tissue, but they cannot themselves develop into an adult, as they do not develop extra-embryonic tissue, such as the placenta.
Multipotent: they can give rise to other types of cells, but in a limited way, as they have ability to differentiate to produce the specialized cell type of the tissue from which it originates. Ex: blood stem cell.
Unipotent: ability to develop or differentiate into only one cell type. Ex: skin cells.
The use of toti and pluripotent cells is more advantageous compared to multi and unipotent ones, since they can provide a greater number of cell types and be more abundant: in tissues, in quantity smaller; in the umbilical cord and placenta, in large quantities and, in embryos, in the early stages of cell traction.
In this aspect, a range of ethical issues come into play, as these cells can be obtained from newly fertilized embryos and, thus, those created for in vitro fertilization, but that will not be used (available embryos) or those created specifically for research, clones, aborted fetal organs, etc., have great potential for use. To add: umbilical cord blood cells at birth and some adult tissues such as bone marrow can also be used.
The use of stem cells for therapeutic purposes may represent the only hope for the treatment of numerous diseases or for patients who have suffered disabling spinal cord injuries that prevent their movements.
By Mariana Araguaia
Graduated in Biology
Brazil School Team
Genetics - Biology - Brazil School