Editing Macrophage (section)

=== Role in wound healing ===
Macrophages are essential for [[wound healing]].<ref name="Scholar and Stadelmann">de la Torre J., Sholar A. (2006). [http://www.emedicine.com/plastic/topic477.htm Wound healing: Chronic wounds]. Emedicine.com. Accessed 20 January 2008.</ref> They replace [[polymorphonuclear neutrophil]]s as the predominant cells in the wound by day two after injury.<ref name="Expert Reviews">{{cite journal | journal = Expert Reviews in Molecular Medicine | volume = 5 | date = 21 March 2003 | publisher = Cambridge University Press | url = http://www-ermm.cbcu.cam.ac.uk/03005829a.pdf | title = The phases of cutaneous wound healing | archive-url = https://web.archive.org/web/20081217120738/http://www-ermm.cbcu.cam.ac.uk/03005829a.pdf| archive-date=17 December 2008}}</ref> Attracted to the wound site by growth factors released by platelets and other cells, [[monocyte]]s from the bloodstream enter the area through blood vessel walls.<ref name="Lorenz">{{cite book | vauthors = Lorenz HP, Longaker MT | chapter = Wounds: biology, pathology, and management. | veditors = Li M, Norton JA, Bollinger RR, Chang AE, Lowry SF, Mulvihill SJ, Pass HI, Thompson RW | title = Essential practice of surgery | date = 2003 | pages = 77–88 | publisher = Springer | location = New York, NY | isbn = 978-0-387-22744-3 | chapter-url = http://recon.stanford.edu/Articles/LorenzWH.pdf | archive-url = https://web.archive.org/web/20051031002654/http://recon.stanford.edu/Articles/LorenzWH.pdf| archive-date=31 October 2005}}</ref> Numbers of monocytes in the wound peak one to one and a half days after the injury occurs. Once they are in the wound site, monocytes mature into macrophages. The [[spleen]] contains half the body's monocytes in reserve ready to be deployed to injured tissue.<ref name="Swirski">{{cite journal | vauthors = Swirski FK, Nahrendorf M, Etzrodt M, Wildgruber M, Cortez-Retamozo V, Panizzi P, Figueiredo JL, Kohler RH, Chudnovskiy A, Waterman P, Aikawa E, Mempel TR, Libby P, Weissleder R, Pittet MJ | title = Identification of splenic reservoir monocytes and their deployment to inflammatory sites | journal = Science | volume = 325 | issue = 5940 | pages = 612–616 | date = July 2009 | pmid = 19644120 | pmc = 2803111 | doi = 10.1126/science.1175202 | bibcode = 2009Sci...325..612S }}</ref><ref name="Jia">{{cite journal | vauthors = Jia T, Pamer EG | title = Immunology. Dispensable but not irrelevant | journal = Science | volume = 325 | issue = 5940 | pages = 549–550 | date = July 2009 | pmid = 19644100 | pmc = 2917045 | doi = 10.1126/science.1178329 | bibcode = 2009Sci...325..549J }}</ref>

The macrophage's main role is to phagocytize bacteria and damaged tissue,<ref name="Scholar and Stadelmann"/> and they also [[Debridement|debride]] damaged tissue by releasing proteases.<ref name="Deodhar and Rana">{{cite journal | vauthors = Deodhar AK, Rana RE | title = Surgical physiology of wound healing: a review | journal = Journal of Postgraduate Medicine | volume = 43 | issue = 2 | pages = 52–56 | year = 1997 | pmid = 10740722 | url = http://www.jpgmonline.com/article.asp?issn=0022-3859;year=1997;volume=43;issue=2;spage=52;epage=6;aulast=Deodhar }}</ref> Macrophages also secrete a number of factors such as growth factors and other cytokines, especially during the third and fourth post-wound days. These factors attract cells involved in the proliferation stage of healing to the area.<ref name="Rosenberg and de la Torre, 2006">Rosenberg L., de la Torre J. (2006). [http://www.emedicine.com/plastic/topic457.htm Wound Healing, Growth Factors]. Emedicine.com. Accessed 20 January 2008.</ref> Macrophages may also restrain the contraction phase.<ref name="springerlink.com">{{cite journal | vauthors = Newton PM, Watson JA, Wolowacz RG, Wood EJ | title = Macrophages restrain contraction of an in vitro wound healing model | journal = Inflammation | volume = 28 | issue = 4 | pages = 207–214 | date = August 2004 | pmid = 15673162 | doi = 10.1023/B:IFLA.0000049045.41784.59 | s2cid = 9612298 }}</ref> Macrophages are stimulated by the low [[oxygen]] content of their surroundings to produce factors that induce and speed [[angiogenesis]]<ref name="Greenhalgh">{{cite journal | vauthors = Greenhalgh DG | title = The role of apoptosis in wound healing | journal = The International Journal of Biochemistry & Cell Biology | volume = 30 | issue = 9 | pages = 1019–1030 | date = September 1998 | pmid = 9785465 | doi = 10.1016/S1357-2725(98)00058-2 }}</ref> and they also stimulate cells that re-epithelialize the wound, create granulation tissue, and lay down a new [[extracellular matrix]].<ref name="Stashak">{{cite journal| vauthors = Stashak TS, Farstvedt E, Othic A |date=June 2004|title=Update on wound dressings: Indications and best use|journal=Clinical Techniques in Equine Practice|volume=3|issue=2|pages=148–163|doi=10.1053/j.ctep.2004.08.006 }}</ref>{{better source needed|date=August 2017}} By secreting these factors, macrophages contribute to pushing the wound healing process into the next phase.