World Library  
Flag as Inappropriate
Email this Article

Adult stem cell

Article Id: WHEBN0002777285
Reproduction Date:

Title: Adult stem cell  
Author: World Heritage Encyclopedia
Language: English
Subject: Stem-cell line, Cellular differentiation, Embryonic stem cell, Stem cell laws and policy in the United States, Cancer stem cell
Collection: Biotechnology, Stem Cells
Publisher: World Heritage Encyclopedia

Adult stem cell

Adult stem cell
Transmission electron micrograph of an adult stem cell displaying typical ultrastructural characteristics.
Latin Cellula praecursoria
Code TH H1.
Anatomical terminology

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 human bodies.

Scientific interest in adult stem cells is centered on their ability to divide or self-renew indefinitely, and generate all the mice and rats.

Stem cell division and differentiation. A – stem cells; B – progenitor cell; C – differentiated cell; 1 – symmetric stem cell division; 2 – asymmetric stem cell division; 3 – progenitor division; 4 – terminal differentiation


  • Defining properties 1
  • Lineage 2
  • Multidrug resistance 3
  • Signaling pathways 4
  • Plasticity/Adult stem cell pluripotency 5
  • Aging 6
  • Types 7
    • Hematopoietic stem cells 7.1
    • Mammary stem cells 7.2
    • Intestinal stem cells 7.3
    • Mesenchymal stem cells 7.4
    • Endothelial stem cells 7.5
    • Neural stem cells 7.6
    • Olfactory adult stem cells 7.7
    • Neural crest stem cells 7.8
    • Testicular cells 7.9
  • Adult stem cell therapies 8
    • Sources 8.1
    • Clinical applications 8.2
    • First transplanted human organ grown from adult stem cells 8.3
  • Adult stem cells and cancer 9
  • See also 10
  • News and external links 11
  • References 12

Defining properties

A stem cell possesses two properties:

  • Self-renewal, which is the ability to go through numerous cycles of cell division while still maintaining its undifferentiated state.
  • multipotency or multidifferentiative potential, which is the ability to generate progeny of several distinct cell types, (for example glial cells and neurons) as opposed to unipotency, which is the term for cells that are restricted to producing a single-cell type. However, some researchers do not consider multipotency to be essential, and believe that unipotent self-renewing stem cells can exist.[1] These properties can be illustrated with relative ease in vitro, using methods such as clonogenic assays, where the progeny of a single cell is characterized. However, it is known that in vitro cell culture conditions can alter the behavior of cells, proving that a particular subpopulation of cells possesses stem cell properties in vivo is challenging, and so considerable debate exists as to whether some proposed stem cell populations in the adult are indeed stem cells.


To ensure the safety of others, stem cells undergo two types of cell division (see Stem cell division and differentiation diagram). Symmetric division gives rise to two identical daughter cells, both endowed with stem cell properties, whereas asymmetric division produces only one of those stem cells and a progenitor cell with limited self-renewal potential. Progenitors can go through several rounds of cell division before finally differentiating into a mature cell. It is believed that the molecular distinction between symmetric and asymmetric divisions lies in differential segregation of cell membrane proteins (such as receptors) between the daughter cells.

Multidrug resistance

Adult stem cells express

  1. ^ Mlsna, Lucas J. (2010). "Stem Cell Based Treatments and Novel Considerations for Conscience Clause Legislation".   ISSN:1549-3199. LCCN:2004212209. OCLC:OCLC 54703225.
  2. ^ Chaudhary PM, Roninson IB (July 1991). "Expression and activity of P-glycoprotein, a multidrug efflux pump, in human hematopoietic stem cells". Cell 66 (1): 85–94.  
  3. ^ Dontu G, Jackson KW, McNicholas E, Kawamura MJ, Abdallah WM, Wicha MS (2004). "Role of Notch signaling in cell-fate determination of human mammary stem/progenitor cells". Breast Cancer Research 6 (6): R605–15.  
  4. ^ Beachy PA, Karhadkar SS, Berman DM; Karhadkar; Berman (November 2004). "Tissue repair and stem cell renewal in carcinogenesis". Nature 432 (7015): 324–31.  
  5. ^ Clarke, D. L.; Johansson, CB; Wilbertz, J; Veress, B; Nilsson, E; Karlström, H; Lendahl, U; Frisén, J (2000). "Generalized Potential of Adult Neural Stem Cells". Science 288 (5471): 1660–3.  
  6. ^ Krause, Diane S.; Theise, Neil D.; Collector, Michael I.; Henegariu, Octavian; Hwang, Sonya; Gardner, Rebekah; Neutzel, Sara; Sharkis, Saul J. (2001). "Multi-Organ, Multi-Lineage Engraftment by a Single Bone Marrow-Derived Stem Cell". Cell 105 (3): 369–77.  
  7. ^ a b Kucia, M; Reca, R; Campbell, F R; Zuba-Surma, E; Majka, M; Ratajczak, J; Ratajczak, M Z (2006). "A population of very small embryonic-like (VSEL) CXCR4+SSEA-1+Oct-4+ stem cells identified in adult bone marrow". Leukemia 20 (5): 857–69.  
  8. ^ Zuba-Surma, Ewa K.; Kucia, Magdalena; Wu, Wan; Klich, Izabela; Lillard, James W.; Ratajczak, Janina; Ratajczak, Mariusz Z. (2008). "Very small embryonic-like stem cells are present in adult murine organs: ImageStream-based morphological analysis and distribution studies". Cytometry Part A 73A (12): 1116.  
  9. ^ Danova-Alt, Ralitza; Heider, Andreas; Egger, Dietmar; Cross, Michael; Alt, Rüdiger; Ivanovic, Zoran (2 April 2012). Ivanovic, Zoran, ed. "Very Small Embryonic-Like Stem Cells Purified from Umbilical Cord Blood Lack Stem Cell Characteristics". PLoS ONE 7 (4): e34899.  
  10. ^ Szade, Krzysztof; Bukowska-Strakova, Karolina; Nowak, Witold Norbert; Szade, Agata; Kachamakova-Trojanowska, Neli; Zukowska, Monika; Jozkowicz, Alicja; Dulak, Jozef; Asakura, Atsushi (16 May 2013). Asakura, Atsushi, ed. "Murine Bone Marrow Lin−Sca-1+CD45− Very Small Embryonic-Like (VSEL) Cells Are Heterogeneous Population Lacking Oct-4A Expression". PLoS ONE 8 (5): e63329.  
  11. ^ Miyanishi M, Mori Y, Seita J, Chen JY, Karten S, Chan CKF, et al. Stem Cell Reports. Stem Cell Reports. 2013 Jul 23;:1–11.
  12. ^ Miyanishi, Masanori; Mori, Yasuo; Seita, Jun; Chen, James Y.; Karten, Seth; Chan, Charles K.F.; Nakauchi, Hiromitsu; Weissman, Irving L. (31 July 2013). "Do Pluripotent Stem Cells Exist in Adult Mice as Very Small Embryonic Stem Cells?". Stem Cell Reports 1 (2): 198–208.  
  13. ^ a b Behrens A, van Deursen JM, Rudolph KL, Schumacher B (2014). "Impact of genomic damage and ageing on stem cell function". Nat. Cell Biol. 16 (3): 201–7.  
  14. ^
  15. ^ a b Liu S, Dontu G, Wicha MS (2005). "Mammary stem cells, self-renewal pathways, and carcinogenesis". Breast Cancer Research 7 (3): 86–95.  
  16. ^ Van Der Flier, L. G.; Clevers, H. (2009). "Stem Cells, Self-Renewal, and Differentiation in the Intestinal Epithelium". Annual Review of Physiology 71: 241–260.  
  17. ^ Barker, N.; Ridgway, R. A.; Van Es, J. H.; Van De Wetering, M.; Begthel, H.; Van Den Born, M.; Danenberg, E.; Clarke, A. R.; Sansom, O. J.; Clevers, H. (2008). "Crypt stem cells as the cells-of-origin of intestinal cancer". Nature 457 (7229): 608–611.  
  18. ^ a b Phinney DG, Prockop DJ (November 2007). "Concise review: mesenchymal stem/multipotent stromal cells: the state of transdifferentiation and modes of tissue repair—current views". Stem Cells 25 (11): 2896–902.  
  19. ^ Shi S, Bartold PM, Miura M, Seo BM, Robey PG, Gronthos S (August 2005). "The efficacy of mesenchymal stem cells to regenerate and repair dental structures". Orthod Craniofac Res 8 (3): 191–9.  
  20. ^ Altman J, Das GD (June 1965). "Autoradiographic and histological evidence of postnatal hippocampal neurogenesis in rats". The Journal of Comparative Neurology 124 (3): 319–35.  
  21. ^ Lewis PD (March 1968). "Mitotic activity in the primate subependymal layer and the genesis of gliomas". Nature 217 (5132): 974–5.  
  22. ^ Alvarez-Buylla A, Seri B, Doetsch F (April 2002). "Identification of neural stem cells in the adult vertebrate brain". Brain Research Bulletin 57 (6): 751–8.  
  23. ^ Bull ND, Bartlett PF (November 2005). "The adult mouse hippocampal progenitor is neurogenic but not a stem cell". The Journal of Neuroscience 25 (47): 10815–21.  
  24. ^ Reynolds BA, Weiss S; Weiss (March 1992). "Generation of neurons and astrocytes from isolated cells of the adult mammalian central nervous system". Science 255 (5052): 1707–10.  
  25. ^ Doetsch F, Petreanu L, Caille I, Garcia-Verdugo JM, Alvarez-Buylla A (December 2002). "EGF converts transit-amplifying neurogenic precursors in the adult brain into multipotent stem cells". Neuron 36 (6): 1021–34.  
  26. ^ Marshall GP, Laywell ED, Zheng T, Steindler DA, Scott EW (March 2006). "In vitro-derived "neural stem cells" function as neural progenitors without the capacity for self-renewal". Stem Cells 24 (3): 731–8.  
  27. ^ Bjornson CR, Rietze RL, Reynolds BA, Magli MC, Vescovi AL; Rietze; Reynolds; Cristina Magli; Vescovi (January 1999). "Turning brain into blood: a hematopoietic fate adopted by adult neural stem cells in vivo". Science 283 (5401): 534–7.  
  28. ^ Murrell W, Féron F, Wetzig A, et al. (June 2005). "Multipotent stem cells from adult olfactory mucosa". Developmental Dynamics 233 (2): 496–515.  
  29. ^ Sieber-Blum M, Hu Y (December 2008). "Epidermal neural crest stem cells (EPI-NCSC) and pluripotency". Stem Cell Rev 4 (4): 256–60.  
  30. ^ Kruger GM, Mosher JT, Bixby S, Joseph N, Iwashita T, Morrison SJ (August 2002). "Neural Crest Stem Cells Persist in the Adult Gut but Undergo Changes in Self-Renewal, Neuronal Subtype Potential, and Factor Responsiveness". Neuron 35 (4): 657–69.  
  31. ^ "Testicle cells may aid research". BBC. 25 March 2006. 
  32. ^  
  33. ^ Rick Weiss (25 March 2006). "Embryonic Stem Cell Success". Washington Post. 
  34. ^ "Promising New Source Of Stem Cells: Mouse Testes Produce Wide Range Of Tissue Types".  
  35. ^ Barbara Miller (20 September 2007). "Testicles yield stem cells in science breakthrough". Australian Broadcasting Corporation. 
  36. ^ J.R. Minkel (19 September 2007). "Testes May Prove Fertile Source of Stem Cells".  
  37. ^ "Stem Cells in Adult Testes Provide Alternative to Embryonic Stem Cells for Organ Regeneration".  
  38. ^ Rob Waters (8 October 2008). "Testicle Stem Cells Become Bone, Muscle in German Experiments".  
  39. ^ Nora Schultz (9 October 2008). "A Source of Men's Stem Cells – Stem cells from human testes could be used for personalized medicine.".  
  40. ^ Maggie Fox ( 
  41. ^ Liao, YH; Verchere, CB; Warnock, GL (April 2007). "Adult stem or progenitor cells in treatment for type 1 diabetes: current progress.". Canadian Journal of Surgery 50 (2): 137–42.  
  42. ^ Mimeault, M; Hauke, R; Batra, S K (1 August 2007). "Stem Cells: A Revolution in Therapeutics—Recent Advances in Stem Cell Biology and Their Therapeutic Applications in Regenerative Medicine and Cancer Therapies". Clinical Pharmacology & Therapeutics 82 (3): 252–264.  
  43. ^ Christoforou, N; Gearhart, JD (May–Jun 2007). "Stem cells and their potential in cell-based cardiac therapies.". Progress in cardiovascular diseases 49 (6): 396–413.  
  44. ^ Raff, M (2003). "Adult stem cell plasticity: Fact or Artifact?". Annual Review of Cell and Developmental Biology 19: 1–22.  
  45. ^ Smith, S; Neaves, W; Teitelbaum, S; Prentice, D. A.; Tarne, G. (8 June 2007). "Adult Versus Embryonic Stem Cells: Treatments". Science 316 (5830): 1422–1423.  
  46. ^ Huang, C; et al. (2015). "Environmental physical cues determine the lineage specification of mesenchymal stem cells". Biochim Biophys Acta 1850: 1261–6.  
  47. ^ Ratajczak MZ, Machalinski B, Wojakowski W, Ratajczak J, Kucia M (2007). "A hypothesis for an embryonic origin of pluripotent Oct-4(+) stem cells in adult bone marrow and other tissues". Leukemia 21 (5): 860–7.  
  48. ^ "Me too, too – How to make human embryonic stem cells without destroying human embryos". The Economist. 22 November 2007. 
  49. ^ Gina Kolata (22 November 2007). "Man Who Helped Start Stem Cell War May End It". New York Times. 
  50. ^ Gina Kolata (21 November 2007). "Scientists Bypass Need for Embryo to Get Stem Cells". New York Times. 
  51. ^ Anne McIlroy (21 November 2007). "'"Stem-cell method hailed as 'massive breakthrough. Globe and Mail. Canada. 
  52. ^ Alice Park (20 November 2007). "A Breakthrough on Stem Cells". Time Magazine. 
  53. ^ Barrilleaux B, Phinney DG, Prockop DJ, O'Connor KC (2006). "Review: ex vivo engineering of living tissues with adult stem cells". Tissue Eng. 12 (11): 3007–19.  
  54. ^ Gimble JM, Katz AJ, Bunnell BA (2007). "Adipose-derived stem cells for regenerative medicine". Circ. Res. 100 (9): 1249–60.  
  55. ^ Gardner RL (March 2002). "Stem cells: potency, plasticity and public perception". Journal of Anatomy 200 (Pt 3): 277–82.  
  56. ^ Takahashi K, Yamanaka S (2006). "Induction of pluripotent stem cells from mouse embryonic and adult fibroblast cultures by defined factors". Cell 126 (4): 663–76.  
  57. ^ Bone Marrow Transplant Retrieved on 21 November 2008
  58. ^ Srivastava A, Bapat M, Ranade S, Srinivasan V, Murugan P, Manjunath S, Thamaraikannan P, Abraham S (2010). "Autologous Multiple Injections of in Vitro Expanded Autologous Bone Marrow Stem Cells For Cervical Level Spinal Cord Injury - A Case Report". Journal of Stem Cells and Regenerative Medicine. 
  59. ^ Terai S, Ishikawa T, Omori K, Aoyama K, Marumoto Y, Urata Y, Yokoyama Y,Uchida K, Yamasaki T, Fujii Y, Okita K, Sakaida I (2006). "Improved liver function in patients with liver cirrhosis after autologous bone marrow cell infusion therapy". Stem Cells 24 (10): 2292–8.  
  60. ^ Subrammaniyan R, Amalorpavanathan J, Shankar R, Rajkumar M, Baskar S,Manjunath SR, Senthilkumar R, Murugan P, Srinivasan VR, Abraham S (2011). "Application of autologous bone marrow mononuclear cells in six patients with advanced chronic critical limb ischemia as a result of diabetes: our experience". Cytotherapy 13 (8): 993–9.  
  61. ^ Dedeepiya V, Rao Y Y, Jayakrishnan G, Parthiban JKBC, Baskar S, Manjunath S, Senthilkumar R and Abraham S (2012). "Index of CD34+ cells and mononuclear cells in the bone marrow of spinal cord injury patients of different age groups- A comparative analysis". Bone Marrow Research 2012: 1.  
  62. ^ Fischer UM, Harting MT, Jimenez F, et al. (June 2009). "Pulmonary passage is a major obstacle for intravenous stem cell delivery: the pulmonary first-pass effect". Stem Cells and Development 18 (5): 683–92.  
  63. ^ Wakitani S, Nawata M, Tensho K, Okabe T, Machida H, Ohgushi H (2007). "Repair of articular cartilage defects in the patello-femoral joint with autologous bone marrow mesenchymal cell transplantation: three case reports involving nine defects in five knees". Journal of Tissue Engineering and Regenerative Medicine 1 (1): 74–9.  
  64. ^ >>Centeno; et al. "Regeneration of meniscus cartilage in a knee treated with percutaneously implanted autologous mesenchymal stem cells, platelate lysate, and dexamethasome". 
  65. ^ Centeno CJ, Busse D, Kisiday J, Keohan C, Freeman M, Karli D (December 2008). "Regeneration of meniscus cartilage in a knee treated with percutaneously implanted autologous mesenchymal stem cells". Medical Hypotheses 71 (6): 900–8.  
  66. ^ Centeno CJ, Busse D, Kisiday J, Keohan C, Freeman M, Karli D (2008). "Increased knee cartilage volume in degenerative joint disease using percutaneously implanted, autologous mesenchymal stem cells". Pain Physician 11 (3): 343–53.  
  67. ^ Centeno CJ, Schultz JR, Cheever M, Robinson B, Freeman M, Marasco W (2010). "Safety and complications reporting on the re-implantation of culture-expanded mesenchymal stem cells using autologous platelet lysate technique". Curr Stem Cell Res Ther 5 (1): 81–93.  
  68. ^ >PR Newswire. "The International Society for Stem Cell Research Releases New Guidelines to Shape Future of Stem Cell Therapy Regulation needed as new study reveals clinics exaggerate claims and omit risks". 
  69. ^ "Claudia Castillo: The pioneer's story".  
  70. ^ Michael Kahn (18 November 2008). "Woman gets first trachea transplant without drugs". Reuters. 
  71. ^ Kate Devlin (18 November 2008). "British doctors help perform world's first transplant of a whole organ grown in lab". The Daily Telegraph. United Kingdom. 
  72. ^ Tanya Thompson (19 November 2008). "World first as woman gets organ made from stem cells". The Scotsman. UK. 
  73. ^ Jeremy Laurance (19 November 2008). "The medical miracle".  
  74. ^ Rose, David (19 November 2008). "Claudia Castillo gets windpipe tailor-made from her own stem cells". The Times. London: The Times Newspapers Ltd. Retrieved 20 November 2008. 
  75. ^ Bioinfobank FAQ:Stem cells in adult tissues Retrieved on 21 November 2008
  76. ^ Cogle CR, Guthrie SM, Sanders RC, Allen WL, Scott EW, Petersen BE (August 2003). "An overview of stem cell research and regulatory issues". Mayo Clinic Proceedings. Mayo Clinic 78 (8): 993–1003.  


  • NIH Stem Cell Information Resource, resource for stem cell research
  • Nature Reports Stem Cells Background information, research advances and debates about stem cell science
  • UMDNJ Stem Cell and Regenerative Medicine, provides educational materials and research resources
  • Stem Cell Research at Johns Hopkins University

News and external links

See also

In recent years, acceptance of the concept of adult stem cells has increased. There is now a hypothesis that stem cells reside in many adult tissues and that these unique reservoirs of cells not only are responsible for the normal reparative and regenerative processes but are also considered to be a prime target for genetic and epigenetic changes, culminating in many abnormal conditions including cancer.[75][76]

Adult stem cells and cancer

In 2008 the first full transplant of a human organ grown from adult stem cells was carried out by Paolo Macchiarini, at the Hospital Clínic of Barcelona on Claudia Castillo, a Colombian female adult whose trachea had collapsed due to tuberculosis. Researchers from the University of Padua, the University of Bristol, and Politecnico di Milano 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 over four days. The new section of trachea was then transplanted into the left main bronchus of the patient.[69][70][71][72][73] Because the stem cells were harvested from the patient's own bone marrow Professor Macchiarini did not think it was necessary for her to be given anti-rejection (immunosuppressive) medication and when the procedure was reported four months later in The Lancet, the patient's immune system was showing no signs of rejecting the transplant.[74]

First transplanted human organ grown from adult stem cells

Early regenerative applications of adult stem cells has focused on intravenous delivery of blood progenitors known as Hematopetic Stem Cells (HSC's). CD34+ hematopoietic Stem Cells have been clinically applied to treat various diseases including spinal cord injury,[58] liver cirrhosis [59] and Peripheral Vascular disease.[60] Research has shown that CD34+ hematopoietic Stem Cells are relatively more numerous in men than in women of reproductive age group among spinal cord Injury victims.[61] Other early commercial applications have focused on Mesenchymal Stem Cells (MSCs). For both cell lines, direct injection or placement of cells into a site in need of repair may be the preferred method of treatment, as vascular delivery suffers from a "pulmonary first pass effect" where intravenous injected cells are sequestered in the lungs.[62] Clinical case reports in orthopedic applications have been published. Wakitani has published a small case series of nine defects in five knees involving surgical transplantation of mesenchymal stem cells with coverage of the treated chondral defects.[63] Centeno et al. have reported high field MRI evidence of increased cartilage and meniscus volume in individual human clinical subjects as well as a large n=227 safety study.[64][65][66][67] Many other stem cell based treatments are operating outside the US, with much controversy being reported regarding these treatments as some feel more regulation is needed as clinics tend to exaggerate claims of success and minimize or omit risks.[68]

Adult stem cell treatments have been used for many years to successfully treat leukemia and related bone/blood cancers utilizing bone marrow transplants.[57] The use of adult stem cells in research and therapy is not considered as controversial as the use of embryonic stem cells, because the production of adult stem cells does not require the destruction of an embryo.

Clinical applications

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.[47] Using genetic reprogramming, pluripotent stem cells equivalent to embryonic stem cells have been derived from human adult skin tissue.[48][49][50][51][52] 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.).[53][54] 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.[55] In mice, pluripotent stem cells can be directly generated from adult fibroblast cultures.[56]


The therapeutic potential of adult stem cells is the focus of much scientific research, due to their ability to be harvested from the patient.[41][42][43] In common with embryonic stem cells, adult stem cells have the ability to differentiate into more than one cell type, but unlike the former they are often restricted to certain types or "lineages". The ability of a differentiated stem cell of one lineage to produce cells of a different lineage is called transdifferentiation. Some types of adult stem cells are more capable of transdifferentiation than others, but for many there is no evidence that such a transformation is possible. Consequently, adult stem therapies require a stem cell source of the specific lineage needed, and harvesting and/or culturing them up to the numbers required is a challenge.[44][45] Additionally, cues from the immediate environment (including how stiff or porous the surrounding structure/extracellular matrix is) can alter or enhance the fate and differentiation of the stem cells.[46]

Adult stem cell therapies

Multipotent stem cells have also been derived from germ cells found in human testicles.[40]

Multipotent stem cells with a claimed equivalency to embryonic stem cells have been derived from spermatogonial progenitor cells found in the testicles of laboratory mice by scientists in Germany[31][32][33] and the United States,[34][35][36][37] and, a year later, researchers from Germany and the United Kingdom confirmed the same capability using cells from the testicles of humans.[38] The extracted stem cells are known as human adult germline biggmacc stem cells (GSCs)[39]

Testicular cells

Hair follicles contain two types of stem cells, one of which appears to represent a remnant of the stem cells of the embryonic neural crest. Similar cells have been found in the gastrointestinal tract, sciatic nerve, cardiac outflow tract and spinal and sympathetic ganglia. These cells can generate neurons, Schwann cells, myofibroblast, chondrocytes and melanocytes.[29][30]

Neural crest stem cells

Olfactory adult stem cells have been successfully harvested from the human olfactory mucosa cells, which are found in the lining of the nose and are involved in the sense of smell.[28] If they are given the right chemical environment these cells have the same ability as embryonic stem cells to develop into many different cell types. Olfactory stem cells hold the potential for therapeutic applications and, in contrast to neural stem cells, can be harvested with ease without harm to the patient. This means they can be easily obtained from all individuals, including older patients who might be most in need of stem cell therapies.

Olfactory adult stem cells

Neural stem cells share many properties with haematopoietic stem cells (HSCs). Remarkably, when injected into the blood, neurosphere-derived cells differentiate into various cell types of the immune system.[27]

Neural stem cells are commonly cultured in vitro as so called neurospheres – floating heterogeneous aggregates of cells, containing a large proportion of stem cells.[24] They can be propagated for extended periods of time and differentiated into both neuronal and glia cells, and therefore behave as stem cells. However, some recent studies suggest that this behaviour is induced by the culture conditions in progenitor cells, the progeny of stem cell division that normally undergo a strictly limited number of replication cycles in vivo.[25] Furthermore, neurosphere-derived cells do not behave as stem cells when transplanted back into the brain.[26]

The existence of stem cells in the adult brain has been postulated following the discovery that the process of neurogenesis, the birth of new neurons, continues into adulthood in rats.[20] The presence of stem cells in the mature primate brain was first reported in 1967.[21] It has since been shown that new neurons are generated in adult mice, songbirds and primates, including humans. Normally, adult neurogenesis is restricted to two areas of the brain – the subventricular zone, which lines the lateral ventricles, and the dentate gyrus of the hippocampal formation.[22] Although the generation of new neurons in the hippocampus is well established, the presence of true self-renewing stem cells there has been debated.[23] Under certain circumstances, such as following tissue damage in ischemia, neurogenesis can be induced in other brain regions, including the neocortex.

Neural 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, the cells that line blood vessels.

Endothelial stem cells

Mesenchymal stem cells (MSCs) are of stromal origin and may differentiate into a variety of tissues. MSCs have been isolated from placenta, adipose tissue, lung, bone marrow and blood, Wharton's jelly from the umbilical cord,[18] and teeth (perivascular niche of dental pulp and periodontal ligament).[19] MSCs are attractive for clinical therapy due to their ability to differentiate, provide trophic support, and modulate innate immune response.[18]

Mesenchymal stem cells

Intestinal stem cells divide continuously throughout life and use a complex genetic program to produce the cells lining the surface of the small and large intestines.[16] Intestinal stem cells reside near the base of the stem cell niche, called the crypts of Lieberkuhn. Intestinal stem cells are probably the source of most cancers of the small intestine and colon.[17]

Intestinal stem cells

[15] Mammary stem cells provide the source of cells for growth of the

Mammary stem cells

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


Hematopoietic stem cells


Stem cell function becomes impaired with age, and this contributes to progressive deterioration of tissue maintenance and repair.[13] A likely important cause of increasing stem cell dysfunction is age-dependent accumulation of DNA damage in both stem cells and the cells that comprise the stem cell environment.[13] (See also DNA damage theory of aging.)


[12][11][10][9] 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.[8] As BLSC's and VSEL cells are present in virtually all adult tissues, including lung, brain, kidneys, muscles, and pancreas[7] These cells are referred to as "Blastomere Like Stem Cells" (Am Surg. 2007 Nov;73:1106-10) and "very small embryonic like" - "VSEL" stem cells, and display pluripotency in vitro.[7] This phenomenon is referred to as stem cell [6] 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.[5] 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.

Plasticity/Adult stem cell pluripotency

These developmental pathways are also strongly implicated as stem cell regulators.[4]
The Notch pathway has been known to developmental biologists for decades. Its role in control of stem cell proliferation has now been demonstrated for several cell types including haematopoietic, neural, and mammary[3] stem cells.

Adult stem cell research has been focused on uncovering the general molecular mechanisms that control their self-renewal and differentiation.

Signaling pathways

targeted therapies for the treatment of clinical depression. neural stem cell onto the cell. This complicates the design of drugs, for instance multidrug resistance Many pharmaceuticals are exported by these transporters conferring [2]

This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.

Copyright © World Library Foundation. All rights reserved. eBooks from Project Gutenberg are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.