Adult stem cells

definition
properties
characteristics
types
maintainance
cell proliferation in development and differentiation

1. BY EMANI APARNA I M PHARM DEPT OF PHARMACOLOGY 1

2. WHAT ARE ADULT STEM CELLS? Adult stem cells are undifferentiated cells, found throughout the body after development, that multiply by cell division to replenish dying cells and generate damaged cells. Somatic stem cells. Adult stem cells is centered on its ability to divide or self renew indefinitely and generate all the cell types of the organ from which they originate, potentially regenerating the entire organ from a few cells. 2

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4. WHERE ARE ADULT STEM CELLS FOUND? Adult stem cells have been discovered in many different types of organs and tissues, and there are probably more, yet to be discovered from researchers places, where adult stem cells may reside. Some of these tissues are: Blood vessels Bone marrow Gut Heart brain 4

5. Liver Ovarian epithelium Peripheral blood Skeletal muscle Skin teeth Testis Usually ,only a very small number of stem cells reside in a tissue/organ and they cant be found throughout its in entirely. Instead they usually reside in a very limited area of that tissue or organ which is called as “ stem cell niche ” 5

6. DEFINING PROPERTIES Stem cells possess two properties : Self renewal : ability to go through numerous cycles of cell division while still maintaining its undifferentiated state. two types of cell division 1. systemic division 2. a systemic cell division Potency: refers to the ability of a stem cell to develop into other cell types of specialized cells, for instance neurons, platelets , muscle cells and epithelial cells. Higher the number of distinct cell types a stem cell can develop into, the higher its potency. Eg : hematopoietic stem cells 6

7. Any adult stem cell will have one of the following degrees: MULTIPOTENT: Adult stem cells that can differentiate into many cell types, that all however belong to the same family! Eg : hematopoietic stem cells OLIGOPOTENT: A dult stem cells that can only differentiate into very limited number of very closely related cells. For instance, vascular stem cells have the capacity to become either endothelial or smooth muscle cells 7

8. UNIPOTENT: Adult stem cells with the ability to produce only one type of cell. Their existence is still hypothesized, as a true example of unipotent stem cell is yet to be found 8

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10. TYPES Hematopoietic stem cells : bone marrow and gives rise to all blood types Mammary stem cells: growth of mammary glands during puberty and gestation and play an important role in carcinogenesis of the breast. Intestinal stem cells : divide continuously throughout life and use a complex program to produce the cells lining the surface of the small and large intestine . 10

11. Endothelial stem cells : one of the three types of multipotent stem cells found in the bone marrow Mesenchymal stem cells : are of stromal origin and may differentiate into variety of tissues. Isolated from placenta, adipose tissue,lung,bone marrow and blood. Neural stem cells : stem cells in brain has been postulated following the discovery that the process of neurogenesis the birth of new neurons ,continues into adulthood . 11

12. olfactory stem cells : multipotent stem cells, found in the olfactory mucosa, the upper region of the nasal cavity. They can develop into heart, liver, kidney, brain and nerve cells. Skin stem cells : basal layer of the epidermis and at the base of hair follicles. The have the capacity to develop into keratinocyt es . 12

13. FIRST TRANSPLANTED HUMAN ORGAN GROWN FROM ADULT STEM CELLS A Colombian female adult named C laudia castillo whose trachea had collapsed due to tuberculosis . Researchers have harvested a section of trachea from a donor and stripped off the cells that could cause an immune reaction ,leaving a grey trunk of cartilage. This section of trachea was then “ seeded “ with stem cells taken from Ms Castillo’s bone marrow and a new section of trachea was grown in the laboratory for four days. The new section was then transplanted into the left bronchus of the patient. 13

14. Because stem cells were harvested from one own bone marrow it was not necessary for her to be given anti - rejection medication and when the procedure was reported four months later the patients immune system was showing no signs of rejecting the transplant. 14

15. MAINTAINANCE OF ANIMAL TISSUES All tissues need essential basics in order to grow and replicate. This support is provided by the connective matrix which comprises connective tissue and blood vessels, which provide nutrients, oxygen and a waste removal service. These vessels are made of specialized endothelial cells. Tissues also need to communicate so as to act in a co- ordinated manner. Nerve cells serve to allow communication between tissues and signal actions 15

16. An essential step in tissue maintenance is renewal of dead or damaged cells in a manner which preserves the tissue integrity. Three major phenomena allow for this to occur: 1.Cell signal their neighbors as to their state of growth. If more cells are required due to increased cell death, growth factors are secreted to stimulate growth of that particular cell. 16

17. 2.secondly,tissue structure is maintained by selective cell adhesion. Cells selectively attach to their own kind, or to selective structural components. These interactions are determined by adhesion molecules on their cell membranes. 3.Thirdly,tissue identity is maintained by cell memory at gene level. Once a cell has differentiate to its final cell type, it divides to produce more of same type. A liver cell will divide to make more liver cells, a heart cell more heart cells. This process ensures the preservation of different tissue types in the body. 17

18. CELL PROLIFERATION IN DEVELOPMENT AND DIFFERENTIATION Early development is characterized by the rapid proliferation of embryonic cells which then differentiate to produce the many specialized types of cells that make up the tissues and organs of multicellular animals. As cells differentiate, their rate of proliferation usually decreases, and most cells in adult animals are arrested in the Go stage of the cell cycle. A few types of differentiated cells never divide again, but most cells are able to resume proliferation as required to replace cells that have been lost as a result of injury or death. 18

19. In addition, some cells divide continuously throughout life to replace cells that have a high rate of turnover in adult animals. Cell proliferation is thus carefully balanced with cell death to maintain a constant number of cells in adult tissues and organs. 19

20. stem cells divide to produce daughter cells that can either differentiate or remain as stem cells, thereby serving as a source for the production of differentiated cells throughout life. 20

21. EG: Blood cell proliferation Erythrocytes Granulocytes Platelets Lymphocytes Life span-few days to months. Continually produced by the division of a common stem cell in the bone marrow. 21

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23. Descendants of the pluripotent stem cell then become committed to specific differentiation pathways. These cells continue to proliferate and undergo several rounds of division as they differentiate. Once they become fully differentiated,however,they cease proliferation, so the maintenance of differentiated blood cell populations is dependant on continual proliferation of the pluripotent stem cell. 23

24. MEDICAL APPLICATIONS OF ADULT STEM CELLS Leukemia and related bone/blood cancers bone marrow utilizing bone marrow transplants. Diseases such as liver cirrhosis, spinal cord injury, pheripheral vascular disease. Used in treatment of: diabetics Rheumatoid arthritis Parkinsonism disease Osteoarthritis Alzheimers disease 24

25. Baldness Learning defects Anti-cancer Heart infarction Replace missing teeth Repair hearing Restore vision Wound healing Crohn disease 25

26. 26 Strs Jeevan blood bank and research center, Chennai Relicord ,Navi Mumbai Baby Cell, Mumbai All over India Karnataka

27. REFERNCES stem cells wikipedia stem cells freak www.stemcell.childrenhospital.org www.stemcell.nih.gov www.stemcellindia.org 27

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