Stem cells

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Haematopoietic stem cells are the common ancester to all blood cells in the body and are found in the bone marrow [1].

However, embryonic stem cells have the potential to differentiate into any cell type found in an organism [2]. These cells are therefore given the term totipotent as they can form all cell types of the body including placental.

These cells that give rise to all blood cells are called pluripotent stem cells. Differentiation of these cells begins during development of the foetus and continues throughout life. The pluripotent stem cell differentiates into stem cells, sometimes referred to as colony forming units, for different lineages of blood cells, including the lymphoid (T and B cells), myeloid, erythrocytic and megakaryoblastic lineages. Along with being primarily found in the bone marrow, stem cells can also be isolated from foetal blood in umbilical cords.Stem cells which express embryonic stem cell markers have been isolated in dental pulp[3].

Differentiation of stem cells into the functional blood cells is triggered by specific cell surface interactions with the stromal cells of the marrow and specific cytokines produced by these and other cells. Specific cytokines that promote hematopoietic cell growth and terminal differentiation are released by helper T cells, dendritic cells, macrophages, and other cells in response to infections and on activation[4].

Some cytoplasmic factors are known to induce somatic cells nuclei into a pluripotent state[5]. This has been proven in research using cytoplasmic factors from oocytes and using these factors on transplanted somatic cells[6].

References

  1. Alberts, B., Bray, D., Hopkin, K., Johnson, A., Lewis, J., Raff, M., Roberts, K., Walter, P., (2008) Essential Cell Biology, 5th edition, New York: Garland Science
  2. Becker, W. M., Kleinsmith L. J., Hardin, J., Bertoni, G. P., (2009) The World of the Cell, 7th edition, San Francisco: Pearson Education
  3. Kerkis, Irina; Kerkis, Alexandre; Dozortsev, Dmitri; Stukart-Parsons, GaËlle Chopin; Gomes Massironi, SÍLvia Maria; Pereira, Lygia V.; Caplan, Arnold I.; Cerruti, Humberto F. (2006). "Isolation and Characterization of a Population of Immature Dental Pulp Stem Cells Expressing OCT-4 and Other Embryonic Stem Cell Markers". Cells Tissues Organs 184 (3–4): 105–16
  4. Murray P R, Rosenthal K S, Pfaller M A et al. 2013, Medical Microbiology, Seventh Edition, Philadelphia PA, Elsevier Saunders
  5. Human Embryonic Stem Cells Derived By Somatic Cell Nuclear Transfer. (2013). Cell, [online] 153(6), pp.1228-1238. Available at: http://www.sciencedirect.com/science/article/pii/S0092867413005710 [Accessed 22 Oct. 2015].
  6. Human Embryonic Stem Cells Derived By Somatic Cell Nuclear Transfer. (2013). Cell, [online] 153(6), pp.1228-1238. Available at: http://www.sciencedirect.com/science/article/pii/S0092867413005710 [Accessed 22 Oct. 2015].
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