Progenitor cell

A progenitor cell is a biological cell that, like a stem cell, has a tendency to differentiate into a specific type of cell, but is already more specific than a stem cell and is pushed to differentiate into its "target" cell.[1] The most important difference between stem cells and progenitor cells is that stem cells can replicate indefinitely, whereas progenitor cells can divide only a limited number of times. Controversy about the exact definition remains and the concept is still evolving.[2]

Neural progenitors (green) in olfactory bulb with astrocytes (blue).

Example of the pattern of division of a progenitor cell which results in the production of an intermediate progenitor cell.

The terms "progenitor cell" and "stem cell" are sometimes equated.[3]

Properties

Most progenitors are described as oligopotent. In this point of view, they may be compared to adult stem cells. But progenitors are said to be in a further stage of cell differentiation. They are in the “center” between stem cells and fully differentiated cells. The kind of potency they have depends on the type of their "parent" stem cell and also on their niche. Some progenitor cells were found during research, and were isolated. After their marker was found, it was proven that these progenitor cells could move through the body and migrate towards the tissue where they are needed. Many properties are shared by adult stem cells and progenitor cells.

Research

Progenitor cells have become a hub for research on a few different fronts. Current research on progenitor cells focuses on two different applications: regenerative medicine and cancer biology. Research on regenerative medicine has focused on progenitor cells, and stem cells, because their cellular senescence contributes largely to the process of aging.[4] Research on cancer biology focuses on the impact of progenitor cells on cancer responses, and the way that these cells tie into the immune response. [5]

The natural aging of cells, called their cellular senescence, is one of the main contributors to aging on an organismal level.[6]There are a few different ideas to the cause behind why aging happens on a cellular level. Telomere length has been shown to positively correlate to longevity.[7][8]Increased circulation of progenitor cells in the body has also positively correlated to increased longevity and regenerative processes.[9]Endothelial Progenitor Cells (EPCs) are one of the main focuses of this field. They are valuable cells because they directly precede endothelial cells, but have characteristics of stem cells. These cells can produce differentiated cells to replenish the supply lost in the natural process of aging, which makes them a target for aging therapy research.[10]This field of regenerative medicine and aging research is still currently evolving.

Recent studies have shown that Haematopoietic Progenitor Cells contribute to immune responses in the body. They have been shown to respond a range of pro-inflammatory cytokines. They also contribute to fighting infections by providing a renewal of the depleted resources caused by the stress of an infection on the immune system. Pro-inflammatory cytokines and other factors released in relation to infections will activate Haematopoietic Progenitor Cells to differentiate to replenish the lost resources. [11]

Examples

The characterization or the defining principle of progenitor cells, in order to separate them from others, is based on the different cell markers rather than their morphological appearance.[12]

• Satellite cells found in muscles. They play a major role in muscle cell differentiation and injury recoveries.
• Intermediate progenitor cells formed in the subventricular zone.[13] Some of these transit amplifying neural progenitors migrate via rostral migratory stream to the olfactory bulb and differentiate further into specific types of neural cells.
• Radial glial cells found in developing regions of the brain, most notably the cortex. These progenitor cells are easily identified by their long radial process.
• Bone marrow stromal cells found in the epidermis and make up 10% of progenitor cells. They are often classed as stem cells due to their high plasticity and potential for unlimited capacity for self-renewal.
• Periosteum contains progenitor cells that develop into osteoblasts and chondroblasts.
• Pancreatic progenitor cells are among the most studied progenitors.[14] They are used in research to develop a cure against diabetes type-1.
• Angioblasts or endothelial progenitor cells (EPC). These are very important for research on fracture and wounds healing.[15]
• Blast cells are involved in generation of B- and T-lymphocytes, which participate in immune responses.[16][14]
• Boundary cap cells from the neural crest form a barrier between the cells of the central nervous system and cells of the peripheral nervous system.[17]

Development of the human cerebral cortices

Before embryonic day 40 (E40), progenitor cells generate other progenitor cells; after that period, progenitor cells produce only dissimilar mesenchymal stem cell daughters. The cells from a single progenitor cell form a proliferative unit that creates one cortical column; these columns contain a variety of neurons with different shapes.[18]

See also

• Induced progenitor stem cells
• Endothelial progenitor cell

References

1. Lawrence BE, Horton PM (2013). Progenitor Cells : Biology, Characterization and Potential Clinical Applications. Nova Science Publishers, Inc. p. 26.
2. Seaberg RM, van der Kooy D (March 2003). "Stem and progenitor cells: the premature desertion of rigorous definitions". Trends in Neurosciences. 26 (3): 125–31. doi:10.1016/S0166-2236(03)00031-6. PMID 12591214.
3. "progenitor cell" at Dorland's Medical Dictionary
4. Ahmed AS, Sheng MH, Wasnik S, Baylink DJ, Lau KW (February 2017). "Effect of aging on stem cells". World Journal of Experimental Medicine. 7 (1): 1–10. doi:10.5493/wjem.v7.i1.1. PMC 5316899. PMID 28261550.
5. Wildes TJ, Flores CT, Mitchell DA (February 2019). "Concise Review: Modulating Cancer Immunity with Hematopoietic Stem and Progenitor Cells". Stem Cells. 37 (2): 166–175. doi:10.1002/stem.2933. PMC 6368859. PMID 30353618.
6. Gilbert SF (15 June 2016). Developmental biology. Barresi, Michael J. F., 1974- (Eleventh ed.). Sunderland, Massachusetts. ISBN 978-1-60535-470-5. OCLC 945169933.
7. Boccardi V, Herbig U (August 2012). "Telomerase gene therapy: a novel approach to combat aging". EMBO Molecular Medicine. 4 (8): 685–7. doi:10.1002/emmm.201200246. PMC 3494068. PMID 22585424.
8. Bernardes de Jesus B, Vera E, Schneeberger K, Tejera AM, Ayuso E, Bosch F, Blasco MA (August 2012). "Telomerase gene therapy in adult and old mice delays aging and increases longevity without increasing cancer". EMBO Molecular Medicine. 4 (8): 691–704. doi:10.1002/emmm.201200245. PMC 3494070. PMID 22585399.
9. Biehl JK, Russell B (March 2009). "Introduction to stem cell therapy". The Journal of Cardiovascular Nursing. 24 (2): 98–103, quiz 104-5. doi:10.1097/JCN.0b013e318197a6a5. PMC 4104807. PMID 19242274.
10. Balistreri CR (2017). Endothelial progenitor cells : a new real hope?. Cham: Springer. ISBN 978-3-319-55107-4. OCLC 988870936.
11. King KY, Goodell MA (September 2011). "Inflammatory modulation of HSCs: viewing the HSC as a foundation for the immune response". Nature Reviews. Immunology. 11 (10): 685–92. doi:10.1038/nri3062. PMC 4154310. PMID 21904387.
12. Morgan JE, Partridge TA (August 2003). "Muscle satellite cells". The International Journal of Biochemistry & Cell Biology. 35 (8): 1151–6. doi:10.1016/s1357-2725(03)00042-6. PMID 12757751.
13. Noctor SC, Martínez-Cerdeño V, Kriegstein AR (May 2007). "Contribution of intermediate progenitor cells to cortical histogenesis". Archives of Neurology. 64 (5): 639–42. doi:10.1001/archneur.64.5.639. PMID 17502462.
14. Awong G, Zuniga-Pflucker JC (June 2011). "Thymus-bound: the many features of T cell progenitors". Frontiers in Bioscience. 3: 961–9. doi:10.2741/200. PMID 21622245.
15. Barber CL, Iruela-Arispe ML (April 2006). "The ever-elusive endothelial progenitor cell: identities, functions and clinical implications". Pediatric Research. 59 (4 Pt 2): 26R–32R. doi:10.1203/01.pdr.0000203553.46471.18. PMID 16549545.
16. Carotta S, Nutt SL (March 2008). "Losing B cell identity". BioEssays. 30 (3): 203–7. doi:10.1002/bies.20725. PMID 18293359.
17. Monk KR, Feltri ML, Taveggia C (August 2015). "New insights on Schwann cell development". Glia. 63 (8): 1376–93. doi:10.1002/glia.22852. PMC 4470834. PMID 25921593.
18. Mason JO, Price DJ (October 2016). "Building brains in a dish: Prospects for growing cerebral organoids from stem cells". Neuroscience. 334: 105–118. doi:10.1016/j.neuroscience.2016.07.048. PMID 27506142.