Epithelia stem cells

Epithelia stem cells

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  Adult Stem Cells,Homeostasis, and Regenerative Medicine
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  What are AdultStem Cells? • An adult stem cell is an undifferentiated (or partially-differentiated) cell found in tissues and organs • They can self-renew and differentiate to become most or all of the specialized cell types within their specific tissue lineage. • Adult stem cells – Maintain cell populations – Help you heal – Play a role in aging
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  Homeostasis • The abilityto regulate internal conditions, usually by a system of feedback controls Stabilize health and functioning, regardless of the outside changing conditions. • One piece of homeostasis is the constant or periodic generation of new cells to replace old, damaged, and dying cells • Adult stem cells fulfill this role through the process of regeneration
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  How Regeneration Works •Adult stem cells normally remain quiescent (non- dividing) for relatively long periods of time until they are activated by signals to maintain tissues • When activated they divide through a process called asymmetric cell division • Through this process they are able to maintain their populations and differentiate into the desired cell types by the creation of a progenitor cell • A progenitor cell, in contrast to stem cells, is already far more specific: they are pushed to differentiate into their "target" cell.
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  Asymmetric Cell Division 1.Proliferates 2. Maintains pop. 3. Creates Progenitor Cell Progenitor cell Stem cell Stem cell
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  Location of AdultStem Cells • Adult stem cells and progenitor cells reside through out your body • These stem cells reside in a specific area of each tissue called the “stem cell niche” • This niche is a particular microenvironment that fosters the growth of resident stem cells • Mutations in cells, signals they receive, and changes in the microenvironment can activate a stem cell
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  Types of AdultStem Cells Hematopoietic stem cells: blood and immune system Mesenchymal stem cells: bone, cartilage, fat, muscle, tendon/ligament Neural stem cells: neurons, glial cells Epithelial stem cells: skin, linings
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  Hematopoietic stem cells Giverise to all the blood cell types: • Myeloid (monocytes and macrophages, neutrophils, basophils, eosinophils, erythrocytes, megakaryocytes/platelets, dendritic cells) • Lymphoid (T-cells, B-cells, NK-cells) Found in the bone marrow from very early on in development, as well as in umbilical cord blood and placental tissue
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  Mesenchymal stem cells •These stem cells will differentiate into: – cartilage cells (chondrocytes) – muscle cells (myocytes) – fat cells (adipocytes) – tendons, ligaments, and connective tissue (epithelial cells including osteoblasts) • These cells are located throughout the body • Bone marrow, fat, and cord blood are easiest to isolate Smooth muscle cells (red) © CIRM
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  Neural stem cells •They are located in: • Subventricular zone lining the lateral ventricles, where they give rise to newly-born neurons that migrate to the olfactory bulb via the rostral migratory stream • Subgranular zone, part of the dentate gyrus of the hippocampus • Neural stem cells (also called Neural precursor cells) give rise to neurons, oligodendrocytes, and astrocytes Top: Section of the hippocampus, blue dots are neural stem cells Left: Mature neuron (red) © CIRM
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  Epithelial stem cells •Give rise to epithelial cells which constitute 60 percent of the differentiated cells in the body. • Responsible for covering the internal (i.e. intestinal lining) and external surfaces (i.e. skin) of the body, including the lining of vessels, glands, and other cavities. • Epithelial stem cells are also found in the bulge region of the hair follicle Retinal pigment epithelial cells © CIRM
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  Adult Stem CellTherapies Bone Marrow Transplant
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  Tissue Specific Organs •In November 2008, scientists in Spain carried out a trachea transplant for a woman whose windpipe had been damaged by tuberculosis. • The doctors took adult stem cells and some other cells from the healthy right airway of the woman needing the trachea transplant, grafted those cells onto the stripped- down donated (cadaver) trachea, and marinated the trachea in chemicals in a lab to coax the trachea into rebuilding itself.
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  Clinical Trials Clinical trialsare conducted in phases. The trials at each phase have a different purpose and help scientists answer different questions: Phase I trials: researchers test an experimental drug or treatment in a small group of people (20-80) for the first time to evaluate its safety, determine a safe dosage range, and identify side effects. Phase II trials: the experimental study drug or treatment is given to a larger group of people (100-300) to see if it is effective and to further evaluate its safety. Phase III trials: the experimental study drug or treatment is given to large groups of people (1,000-3,000) to confirm its effectiveness, monitor side effects, compare it to commonly used treatments, and collect information that will allow the experimental drug or treatment to be used safely. Phase IV trials: post marketing studies delineate additional information including the drug's risks, benefits, and optimal use.
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  Risk vs. Benefitsof Participating in a Clinical Trial Risk • The patient must stop taking other treatments before the trial • There may be unpleasant, serious or even life-threatening side effects to experimental treatment. • The experimental treatment may not be effective for the participant, or given a placebo • The protocol may require more of their time and attention than would a non-protocol treatment, including trips to the study site, more treatments, hospital stays or complex dosage requirements. Benefit • Play an active role in their own health care. • Gain access to new research treatments before they are widely available. • Obtain expert medical care at leading health care facilities during the trial. • Help others by contributing to medical research. • The patient may get better as a result of the experimental treatment. • Patients who receive the placebo are usually, but not always, given access to the treatment once the trial ends
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  Stem Cell Tourism •In what is called “stem cell tourism” patients travel to other countries with less restrictions to receive stem cell therapies. • Sometimes experimental and can be dangerous • There are many legitimate therapies going through national regulatory processes in these countries. • December 2008 study of stem cell clinic web sites • Sites claimed to treat a range of diseases that go beyond the scope of the early evidence on stem cells' efficacy • Played up the benefits and talked little about risks • Each treatment costs around $21,500