The And Its Effects On The Human Body - 831 Words

Implanted biomaterials provoke an inflammatory response, known as the foreign body reaction {Daghighi, 2014 #119}. Following formation of adsorbed protein layer, a cascade of inflammatory processes occurs on the biomaterial surface and the extent of these events depends on the implantation procedure, target tissue/organ and properties of the adsorbed protein layer {Anderson, 2008 #54}. The presence of specific adsorbed proteins (especially vitronectin) in the layer influences the inflammatory cell interaction with biomaterials and subsequent inflammatory responses {Brodbeck, 2003 #56;Jenney, 2000 #55;McNally, 2008 #504;Wilson, 2005 #57}. Currently, expression of at least 11 integrin subunits has been identified in immune cells {Luo, 2007†¦show more content†¦Interestingly, it has been shown that fibrinogen-mediated acute inflammatory responses to implanted biomaterials are induced by the RGD sequences in fibrinogen {Tang, 1996 #297}. The discovery of numerous resident tissue macrophages (OsteoMacs) on the endosteum and periosteum of bone may impact the bone formation process and is likely to play an important factor in the future design of implant materials for bone {Pettit, 2008 #233}. As mentioned above, the onset of inflammatory response is associated with bleeding at the fracture site that results in the development of a local hematoma. Inflammatory cells like polymorphonuclear leukocytes infiltrate the hematoma and tissue adjacent to the site of implant placement and secrete cytokines and growth factors {Anderson, 2011 #499;Forster, 2012 #321;Brodbeck, 2005 #500}. This process is controlled and regulated by various chemotactic and chemokinetic factors inherent in the inflammatory response {Ziats, 1988 #501}. This acute phase resolves between a few hours to days and progresses to a type of inflammation characterized by chronic infiltration of macrophages and lymphocytes, which interplay to regulate their adhesion to the surface of the biomaterial and their proliferation {Anderson, 2011 #499;Hu, 2001 #49;Luttikhuizen, 2006 #472;Brodbeck, 2005 #500}. Integrins mediate adhesion of monocytes and macrophages to adsorbed conditioning films on implanted biomaterial sur faces containing fibronectin {Keselowsky,