Greek mythology says that Prometheus stole fire from Zeus and gave it to mortals. Zeus then punished him for his crime by having him bound to a rock while a great eagle ate his liver every day only to have it grow back to be eaten again the next day.
Recovery of loss, is a primary desire of an individual at loss. Lost my headphones. Found them in my room. Incase I lose my ear, can I get it back? Can I be as lucky as Prometheus? It seems unlikely but there is slight hope that I could rely on science and progress in the medical field. Mother cells with power to engender could solve this problem; stem cells.
Stem cells are defined functionally as cells that have capacity to self renew as well as the abilty to generate differentiated cells.The fascinating ability to differentiate into almost any kind of cell is termed as plasticity.
A stem cell may be:
- Totipotent: It’s the most versatile type. Zygote is the only totipotent entity a mammal comes across.
- Pluripotent: On the fourth day of development, the totipotent cells split into two layers. The outer layer gives rise to placenta and the inner layer can give rise to any tissue. However, the inner layer cannot survive without the outer layer. These cells do not remain totipotent and become pluripotent. Unlike totipotent cells, they cannot give rise to a complete organism.
Most of what we know about stem cells has come from mice in labs.
Two characteristic features of these mother cells:
- They can divide for indefinite period of time in cultures.
- They can give rise to specialized cells.
- ESC (Embryonic Stem Cells): Derived from embryos that develop from eggs fertilized in vitro.
- EGSCs (Embryonic Germ Stem Cells): Collected from fetus later in development. The cells are taken from gonadal ridge.
- Adult Stem Cells (Somatic Stem Cells):
Derived from adult organisms. They help maintain and repair tissues. The use of adult-derived stem cells, from blood, skin and other tissues, has been demonstrated to be effective for treating different diseases in animal models. The best part is that the use of adult derived stem cells are not viewed as living by pro-life advocates. Hence, this part of the research is ethical enough.
Signals both from inside and outside may trigger stem cell differentiation. Genes control the internal signals. External signals include chemicals secreted by other cells, physical contact with other cells and growth factors.
A major focus in stem cell research is the manipulation of cells to differentiate into a targeted population. In the past several years, this field has been flooded with reports on differentiating stem cells into various mature cells both in vitro and in vivo. One of the important extracellular signals that controls stem cell fate is the secretion of growth and differentiation factors. TGF-ß family members have remarkable instructive effects in both ES cell and neural crest stem cell differentiation. Molecules from the Wnt family also play a significant supportive role in diverse cell differentiation. In addition to secreted factors, integral membrane proteins as well as integrins and the extracelluar matrix also contribute to the microenvironment of stem cells in determining their fate.
Stem cells can play a vital role in regenerative or reparative medicine.In addition,stem cells can be used to screen new drugs and understanding birth defects. Pluripotent stem cells offer the possibility of a renewable source of replacement cells and tissues to treat a myriad of diseases, conditions, and disabilities including Parkinson’s disease, amyotrophic lateral sclerosis, spinal cord injury, burns, heart disease, diabetes, and arthritis.
Stem Cells can indeed turn out to be cellular fountain of youth and health.
Urooj Zahra is a fourth year medical student in Fatima Jinnah Medical College, Lahore, Pakistan.