Regeneration of Kidneys by Stem Cells

 Stem Cells

What is a Stem Cell?

Stem Cell is a clonal, self-renewal entity that is multipotent and thus can generate several differentiated cell types. They are biological cells found in most of the multicellular organisms. Stem cells are basic currency of organ repair. The term "stem cell" by itself can be misleading. There are embryonic stem cells, adult stem cells, cancer stem cells, and reprogrammed iPS cells, each with very different potential to treat disease.


Properties of Stem cells:

  • Self-renewal: the ability to go through numerous cycles of cell division while maintaining the undifferentiated state.
  • Potency: the capacity to differentiate into specialized cell types. In the strictest sense, this requires stem cells to be either totipotent or pluripotent—to be able to give rise to any mature cell type, although multipotent or unipotent progenitor cells are sometimes referred to as stem cells. Apart from this it is said that stem cell function is regulated in a feed back mechanism.


On the basis of Potency, stem cells are of five types-

  • Totipotent stem cells can differentiate into embryonic and extraembryonic cell types. Such cells can construct a complete, viable organism. These cells are produced from the fusion of an egg and sperm cell. Cells produced by the first few divisions of the fertilized egg are also totipotent.
  • Pluripotent stem cells are the descendants of totipotent cells and can differentiate into nearly all cells, i.e. cells derived from any of the three germ layers.
  • Multipotent stem cells can differentiate into a number of cells, but only those of a closely related family of cells.
  • Oligopotent stem cells can differentiate into only a few cells, such as lymphoid or myeloid stem cells.
  • Unipotent cells can produce only one cell type, their own.

On the basis of there source and location of development they are of following types-

Embryonic stem cells- Embryonic stem cells are isolated from inner mass of blastocyst. A blastocyst is an early stage embryo, approximately four to five days old. Adult stem cells is found in various tissues. ES cells are pluripotenet and give rise during development to all derivatives of the three primary germ layers: ectoderm, endoderm and mesoderm. They do not contribute to the extra-embryonic membranes or the placenta. The endoderm is composed of the entire gut tube and the lungs, the ectoderm gives rise to the nervous system and skin, and the mesoderm gives rise to muscle, bone, blood—in essence, everything else that connects the endoderm to the ectoderm.

Fetal Stem cells-

The primitive stem cells located in the organs of fetuses are referred to as fetal stem cells.

Reference:

 http://en.wikipedia.org/wiki/Stem_cell
http://en.wikipedia.org/wiki/Adult_stem_cell
http://www.cirm.ca.gov/about-stem-cells/stem-cell-basics/stem-cell-basics
http://www.google.co.in/imgres/

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Adult Stem cells-

These are the undifferentiated cells which are found throughout the body after development. They multiply by cell division to replenish dying cells and regenerate damaged tissues. They are also known as somatic stem cells and germline stem cells and are found in both children as well as adults.

Adult stem cells have the ability to generate entire organ from few cells. The best part is that they are derived from adult tissues rather than destroyed human embryos which ultimately does not leads to any controversies.

Pluripotent stem cells, i.e. cells that can give rise to any fetal or adult cell type, can be found in a number of tissues, including umbilical cord blood. Other adult stem cells are multipotent, meaning they are restricted in the types of cell they can become, and are generally referred to by their tissue origin (such as mesenchymal stem cell, adipose-derived stem cell, endothelial stem cell, etc.). A great deal of adult stem cell research has focused on investigating their capacity to divide or self-renew indefinitely, and their potential for differentiation

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 Amniotic Stem cells

Amniotic stem cells are multipotent and can differentiate in cells of adipogenic, osteogenic, myogenic, endothelial, hepatic and also neuronal lines. These stem cells are very active, expand extensively without feeders and are not tumorigenic.

Induced Pluripotent stem cells

Induced Pluripotent stem cells, also called as iPS cells, are reprogrammed to give rise to pluripotent characteristics. They are derived from non-pluripotent cells- typically adult somatic stem cells, by inducing forced expression of specific genes. They are similar to ES cells. They do not lead to any controversies as they are derived from patient’s own somatic cells.