Adult stem cell

Stem cells are a class of undifferentiated cells that are able to differentiate into specialized cell types.

stem cells are two types:

• embryonic stem cells.

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• adult stem cells.

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• Both types are generally characterized by their potency, or potential to differentiate into different cell types.

Definition of adult stem cells :�

*Adult stem cells are undifferentiated cell types.

* found among differentiated cells in an organ or in tissue.

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* Their primary role is to maintain and repair the tissue in which they are found.

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Properties of adult stem cells :�

• Self renewal for long period.
• Un specialized and can give rise to specialized cells.
• They don’t have tissue specific structure to perform specialized function.

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: Long term self renewal stem cells�

Important questions of scientists:�

1. why can embryonic stem cells proliferate for a year or more in the laboratory without differentiating, but most non-embryonic stem cells cannot ?

2. what are the factors in living organisms that normally regulate stem cell proliferation and self-renewal?

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Efforts of scientists to find the answers :to these questions�

: Specificity of adult stem cells

Types Of Adult Stem Cells: �

 �Hematopoietic stem cells:

>Hematopoietic stem cells are found in the bone marrow and give rise to all the blood cell types.

�Mammary stem cells:�

>Mammary stem cells provide the source of cells for growth of the mammary gland during puberty and gestation

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>play an important role in carcinogenesis of the breast.

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Mesenchymal stem cells:�

>Mesenchymal stem cells (MSCs) are of stromal origin and may differentiate into a variety of tissues.

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>MSCs are attractive for clinical therapy due to their ability to differentiate, provide trophic support, and modulate innate immune response.

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Intestinal stem cells:�

>Intestinal stem cells divide continuously throughout life

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>use a complex genetic program to produce the cells lining the surface of the small and large intestines.

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Neural stem cells:�

_{>stem cells in the adult brain of new neurons. `\}

_‘Normally, adult neurogenesis is restricted to two areas of the brain - the subventricular zone, and the dentate gyrus of the hippocampal formation. Under certain circumstances, such as tissue damage in ischemia, neurogenesis can be induced in other brain regions, including the neocortex

Neural stem cells share many properties with haematopoietic stem cells (HSCs).

Endothelial stem cells:

>Endothelial Stem Cells are one of the three types of Multipotent stem cells found in the bone marrow.

>They are a rare and controversial group with the ability to differentiate into endothelial cells.

>line blood vessels.

Olfactory adult stem :cells��

• harvested from the human olfactory mucosa cells, which are found in the lining of the nose and are involved in the sense of smell.

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:Testicular cells�

Multipotent stem cells with a

claimed equivalency to

embryonic stem cells have been derived from

spermatogonial progenitor cells

found in the testicles , The

extracted stem cells are known

as human adult germ line

stem cells (GSCs) Multipotent

stem cells have also been

derived from germ cells found

in human testicles.

*Risks:

It had been clear that therapeutic use of ES cells has

: significant risks�

1-ithas observed in experiment done on mice that it causes tumor�2-Ig incompatibility.

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For these reasons there are 3 methods of therapeutic cloning. �1-nucleous of oocyte replaced by nucleus of adult cell�followed by embryonic development then inner cell mass used for desired differentiation�2-transfer of nucleus of an animal to cell of oocyte

Presentation : Radwa Bakr _ Rania �Farid _ Rehab Elkady.��Power Point : Rahma samir. ��Info : Radwa _ Rania _ Rehab _Rania Fahmy and Rahma. �