Stem Cells
Stem cells are cells that have the potential to multiply and differentiate into numerous different cell types of the body during early life and growth. They also act as a form of internal repair system in many tissues where they divide without limit to replace other cells during the lifetime of a person or animal. In this paper, the unique properties of stem cells, different types, and differences between these types of stem cells, and potential application of stem cells will be explored.
Stem cells are distinguishable from other cell types by 3 essential attributes: they are capable of proliferating and renewing themselves for extended periods, they are unspecialized, and they can differentiate to become specialized cell types. Differentiated cell types like muscle cells do not replicate but stem cells can divide and multiply as many times as possible so long as optimal conditions for division are present. Upon dividing, the new stem cells if still unspecialized can continue proliferate. These stem cells are unspecialized because they lack tissue-specific attributes that enable tissue cells to carry out specialized roles. Lastly, stem cells can through a process called differentiation, give rise to specialized cell types like nerve and brain cells. The process of differentiation of these cells is controlled by internal signals (genes) and external signals such as chemicals elaborated by other cell types and specific molecules in the microenvironement. The dynamics of the process of stem cell differentiation are yet be fully elucidated.
There are two types of stem cells: embryonic stem cells and somatic/adult/non-embryonic stem cells. Embryonic stem cells are derived from embryos during the pre-implantation stage. These cells are then grown in culture mediums as cell cultures in laboratories. Embryonic cells that remain undifferentiated after proliferating in cell culture for 6 or more months are called pluripotent cells. Unspecialized embryonic cells can be stimulated to differentiate spontaneously by allowing them to clump together or artificially through insertion of specific genes or alteration of the chemical composition of their culture medium. Research on how undifferentiated stem cells can be induced to form specialized stem cells is still ongoing though because scientists are yet to be able to reliably direct the formation of specific cell types from embryonic cells.
Adult stem cells are undifferentiated cells found amongst specialized cells of a tissue or organ. These cells can proliferate and differentiate to give rise to one or all of the major cell types of a tissue or organ. Both embryonic and somatic stem cells play essential roles in the body. The inner embryonic stem cells in a 3-to-5-day-old embryo multiply to give rise to the many specialized cell types, tissues, and organs that make the whole body of an organism. Discrete somatic stem cells in some adult tissues, on the other hand, proliferate to yield replacements for cells lost through normal wear and tear, disease, or injury. The latter type of cells remains quiescent until when they are needed.
Somatic stem cells differ from embryonic cell types because the latter are pluripotent that is, they can differentiate to form all types of body cells whilst the former can only form cells of a specific tissue. Somatic stem cells can, however, be reprogrammed genetically to form embryonic stem cells.
On account of their unique properties, stem cells can be directed to generate specific cells and tissues. These cells and tissues can then be transplanted and be used to replace diseased or destroyed cells and tissues into patients with diseases like diabetes and injures such as spinal cord injury. Human stem cells can additionally be used to test novel treatments for instance cancer medications. This area of medicine is called regenerative medicine and the therapy cell-based therapy. Research on the viability of these and other areas of application of stem cells is still ongoing though.
In conclusion, stem cells are cells that have the potential to multiply and form numerous types of specialized cells and tissues. There are two types of stem cells, embryonic and somatic stem cells. These cells play crucial roles in growth, differentiation, and repair of body cells and tissues. They possess unique properties that distinguish them from specialized cells. On account of their ability to proliferate and differentiate, they are being currently investigated as potential forms of therapies for conditions such as spinal cord injury and burns.
References
National Institutes of Health (2009). Stem cell basics. Retrieved from http://stemcells.nih.gov/staticresources/info/basics/SCprimer2009.pdf
