Editorial - Journal of Cell Biology and Metabolism (2021) Volume 3, Issue 4
An introduction to stem cells
- Corresponding Author:
- Rosy Franco Managing Editor, Journal of Cell Biology and Metabolism, United Kingdom E-mail: [email protected]
Accepted date: September 03, 2021
Despite increasing awareness of the situations under which stem cells should be used, there is currently no commonly accepted definition of the word. The idea of "stem cell" is inextricably tied with growth via multiplication rather than cell expansion, according to this more modern perspective. Various classification strategies for tissues based on their development mode have been presented. This classification identifies three main types of tissues: renewing, expanding, and static, and it applies to the adult rather than the embryo. The intestinal epithelium and skin are obvious examples of the first, whereas the liver is an example of the second. Although recent research has demonstrated that neurogenesis does continue in adulthood, for example, in the creation of neurons that migrate to the olfactory bulbs, the third group was held to comprise the central nervous system. There are several issues with such classification methods, including the assignment of organs like the mammary gland, which may go through one or more cycles of notable growth, differentiation, and subsequent involution depending on the circumstances of the individual.
Any attempt to come up with a globally accepted definition of the phrase stem cell will almost certainly fail. Nonetheless, in both developing and adult multicellular organisms, certain characteristics can be attributed to specific cells to identify them from the rest of the tissues to which they belong. These cells, for the most part, retain the ability to self-renew as well as produce progeny that are more limited in terms of mitotic potential and the sorts of differentiated cells to which they can give rise. Kinetic investigations, on the other hand, support the idea that in many tissues, a subpopulation of cells called "transit-amplifying" cells can stand between true stem cells and their differentiated derivatives, with a restricted and, in some circumstances, highly delimited self-renewal capacity. This kind of cell creation has the advantage of minimizing the total number of division cycles that stem cells must go through during an organism's lifetime. In vivo, unlimited self-renewal capacity is not generally required in stem cells, and distinguishing between stem and transitamplifying cells can be difficult in practice.
Since its first appearance in the literature in the nineteenth century, the phrase "stem cell," like many other terminologies in biology, has been employed in a variety of contexts. E.B. used the word only for the ancestral cell of the germline of the parasitic nematode worm Ascaris megalocephaly in the first edition of his major treatise on cell biology. Elegant investigations of this organism's early development revealed that just one cell retained a complete set of chromosomes during consecutive cleavage divisions and that this cell alone gave rise to the entire complement of adult germ cells.
Recent investigations on cell lineage in worms have revealed that the developmental potential of the germ-line precursor cell alters dramatically with each succeeding cleavage division. As a result, neither early cleavage division product keeps identity with the mother blastomere, implying that self-renewal, which is now thought to be a hallmark attribute of stem cells, is not a component of this lineage. Wilson's stem cell would be classified as a "progenitor," "precursor," or "founder" cell in modern embryological terminology.
Studies on cell lineage in other invertebrates' embryos, particularly in marine species, revealed a degree of invariance in cleavage patterns that allowed the origin of most larval tissues to be determined. Somatic tissues were frequently observed to arise from single blastomeres in such species. As a result, all mesentoblasts and entoblasts in many mollusks and annelids are descended from the 4d blastomere. Invertebrates with a more varied lineage, such as Drosophila, and all vertebrates, on the other hand, both somatic tissues and the germline generally arise from many cells rather than just one. In general, all stem cells qualify as progenitor cells, albeit this is not always the case, as the germline in worms demonstrates.