Where are stem cells located in the adult body?
2777285#0
Adult stem cells are undifferentiated cells, found throughout the body after development, that multiply by cell division to replenish dying cells and regenerate damaged tissues. Also known as somatic stem cells (from Greek Σωματικóς, meaning "of the body"), they can be found in juvenile as well as adult animals and humans, unlike embryonic stem cells.
Adult stem cell
27783#1
In mammals, there are two broad types of stem cells: embryonic stem cells, which are isolated from the inner cell mass of blastocysts, and adult stem cells, which are found in various tissues. In adult organisms, stem cells and progenitor cells act as a repair system for the body, replenishing adult tissues. In a developing embryo, stem cells can differentiate into all the specialized cells—ectoderm, endoderm and mesoderm (see induced pluripotent stem cells)—but also maintain the normal turnover of regenerative organs, such as blood, skin, or intestinal tissues.
Stem cell
27783#21
Most adult stem cells are lineage-restricted (multipotent) and are generally referred to by their tissue origin (mesenchymal stem cell, adipose-derived stem cell, endothelial stem cell, dental pulp stem cell, etc.). Muse cells (multi-lineage differentiating stress enduring cells) are a recently discovered pluripotent stem cell type found in multiple adult tissues, including adipose, dermal fibroblasts, and bone marrow. While rare, muse cells are identifiable by their expression of SSEA-3, a marker for undifferentiated stem cells, and general mesenchymal stem cells markers such as CD105. When subjected to single cell suspension culture, the cells will generate clusters that are similar to embryoid bodies in morphology as well as gene expression, including canonical pluripotency markers Oct4, Sox2, and Nanog.
Stem cell
2777285#16
Discoveries in recent years have suggested that adult stem cells might have the ability to differentiate into cell types from different germ layers. For instance, neural stem cells from the brain, which are derived from ectoderm, can differentiate into ectoderm, mesoderm, and endoderm. Stem cells from the bone marrow, which is derived from mesoderm, can differentiate into liver, lung, GI tract and skin, which are derived from endoderm and mesoderm. This phenomenon is referred to as stem cell transdifferentiation or plasticity. It can be induced by modifying the growth medium when stem cells are cultured "in vitro" or transplanting them to an organ of the body different from the one they were originally isolated from. There is yet no consensus among biologists on the prevalence and physiological and therapeutic relevance of stem cell plasticity. More recent findings suggest that pluripotent stem cells may reside in blood and adult tissues in a dormant state. These cells are referred to as "Blastomere Like Stem Cells" and "very small embryonic like" – "VSEL" stem cells, and display pluripotency in vitro. As BLSC's and VSEL cells are present in virtually all adult tissues, including lung, brain, kidneys, muscles, and pancreas Co-purification of BLSC's and VSEL cells with other populations of adult stem cells may explain the apparent pluripotency of adult stem cell populations. However, recent studies have shown that both human and murine VSEL cells lack stem cell characteristics and are not pluripotent.
Adult stem cell
3070443#6
Adult stem cells are found in juvenile or adult tissues. Adult stem cells are multipotent: they can generate a limited number of differentiated cell types (unlike pluripotent embryonic stem cells). Types of adult stem cells include hematopoietic stem cells and mesenchymal stem cells. Hematopoetic stem cells are found in the bone marrow and generate all cells of the immune system all blood cell types. Mesenchymal stem cells are found in umbilical cord blood, amniotic fluid, and adipose tissue and can generate a number of cell types, including osteoblasts, chondrocytes, and adipocytes. In medicine, adult stem cells are mostly commonly used in bone marrow transplants to treat many bone and blood cancers as well as some autoimmune diseases. (See Hematopoietic stem cell transplantation)
Stem-cell line
7988175#2
His lab in the Terrence Donnelly Centre for Cellular and Biomolecular Research, carries out various neuroscience and developmental biology research projects. In 1994 his paper on neural stem cells in the adult mammalian forebrain was published in the journal "Neuron". This work first established that adult mammalian neural stem cells were located in the subependyma of the forebrain lateral ventricle, where two types of lineage related precursor cells, progenitor cells and stem cells, were shown to be present. Proliferation of these cell types were characterized in further experiments that were reported in articles in "Development" and the "Journal of Neuroscience". Of note, Derek's lab produced the first report of stem cells in the adult mammalian eye, published in 2000 in "Science". Further work, which was published in the journal, "Neuron", 2001, documented how embryonic stem cells were shown to differentiate directly to neural stem cells through a default mechanism. Derek's lab continues to investigate the nature of stem cells, embryonic and adult, the concept of immortal cells, and the differentiation of embryonic stem cells, capable of forming any tissue in the body, to neural stem cells.
Derek van der Kooy
27783#18
The primitive stem cells located in the organs of fetuses are referred to as fetal stem cells.
There are two types of fetal stem cells:Adult stem cells, also called somatic (from Greek σωματικóς, "of the body") stem cells, are stem cells which maintain and repair the tissue in which they are found. They can be found in children, as well as adults.
Stem cell
22511551#1
Stem cells are cells found in all multi-cellular organisms. They were isolated in mice in 1981, and in humans in 1998. In humans there are many types of stem cells, each with varying levels of potency. Potency is a measure of a cell's differentiation potential, or the number of other cell types that can be made from that stem cell. Embryonic stem cells are pluripotent stem cells derived from the inner cell mass of the blastocyst. These stem cells can differentiate into all other cells in the human body and are the subject of much scientific research. However, since they must be derived from early human embryos their production and use in research has been a hotly debated topic as the emt introduce new cells into adult bodies for possible treatment of cancer, diabetes, neurological disorders and other medical conditions. Stem cells have been used to repair tissue damaged by disease or age. Cloning also might be done with stem cells. Pluripotent stem cells can also be derived from Somatic cell nuclear transfer which is a laboratory technique where a clone embryo is created from a donor nucleus. Somatic cell nuclear transfer is also tightly regulated amongst various countries.
Stem cell laws and policy in the United States
10213576#0
Stem-cell niche refers to a microenvironment, within the specific anatomic location where stem cells are found, which interacts with stem cells to regulate cell fate. The word 'niche' can be in reference to the "in vivo" or "in vitro" stem-cell microenvironment. During embryonic development, various niche factors act on embryonic stem cells to alter gene expression, and induce their proliferation or differentiation for the development of the fetus. Within the human body, stem-cell niches maintain adult stem cells in a quiescent state, but after tissue injury, the surrounding micro-environment actively signals to stem cells to promote either self-renewal or differentiation to form new tissues. Several factors are important to regulate stem-cell characteristics within the niche: cell–cell interactions between stem cells, as well as interactions between stem cells and neighbouring differentiated cells, interactions between stem cells and adhesion molecules, extracellular matrix components, the oxygen tension, growth factors, cytokines, and the physicochemical nature of the environment including the pH, ionic strength (e.g. Ca concentration) and metabolites, like ATP, are also important. The stem cells and niche may induce each other during development and reciprocally signal to maintain each other during adulthood.
Stem-cell niche
27783#24
With the increasing demand of human adult stem cells for both research and clinical purposes (typically 1–5 million cells per kg of body weight are required per treatment) it becomes of utmost importance to bridge the gap between the need to expand the cells in vitro and the capability of harnessing the factors underlying replicative senescence. Adult stem cells are known to have a limited lifespan in vitro and to enter replicative senescence almost undetectably upon starting in vitro culturing.
Multipotent stem cells are also found in amniotic fluid. These stem cells are very active, expand extensively without feeders and are not tumorigenic. Amniotic stem cells are multipotent and can differentiate in cells of adipogenic, osteogenic, myogenic, endothelial, hepatic and also neuronal lines.
Amniotic stem cells are a topic of active research.
Stem cell
2777285#23
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. Using genetic reprogramming, pluripotent stem cells equivalent to embryonic stem cells have been derived from human adult skin tissue. 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. In mice, pluripotent stem cells can be directly generated from adult fibroblast cultures.
Adult stem cell