{"158481":{"#nid":"158481","#data":{"type":"news","title":"Study Suggests Immune System Can Boost Regeneration of Peripheral Nerves","body":[{"value":"\u003Cp\u003EModulating immune response to injury could accelerate the regeneration of severed peripheral nerves, a new study in an animal model has found. By altering activity of the macrophage cells that respond to injuries, researchers dramatically increased the rate at which nerve processes regrew.\u003C\/p\u003E\u003Cp\u003EInfluencing the macrophages immediately after injury may affect the whole cascade of biochemical events that occurs after nerve damage, potentially eliminating the need to directly stimulate the growth of axons using nerve growth factors. If the results of this first-ever study can be applied to humans, they could one day lead to a new strategy for treating peripheral nerve injuries that typically result from trauma, surgical resection of tumors or radical prostectomy.\u003C\/p\u003E\u003Cp\u003E\u201cBoth scar formation and healing are the end results of two different cascades of biological processes that result from injuries,\u201d said Ravi Bellamkonda, Carol Ann and David D. Flanagan professor in the Wallace H. Coulter Department of Biomedical Engineering and member of the Regenerative Engineering and Medicine Center at Georgia Tech and Emory University. \u201cIn this study, we show that by manipulating the immune system soon after injury, we can bias the system toward healing, and stimulate the natural repair mechanisms of the body.\u201d\u003C\/p\u003E\u003Cp\u003EBeyond nerves, researchers believe their technique could also be applied to help regenerate other tissue \u2013 such as bone. The research was supported by the National Institutes of Health (NIH), and reported online Sept. 26, 2012, by the journal \u003Cem\u003EBiomaterials\u003C\/em\u003E.\u003C\/p\u003E\u003Cp\u003EAfter injury, macrophages that congregate at the site of the injury operate like the conductor of an orchestra, controlling processes that remove damaged tissue, set the stage for repair and encourage the replacement of cells and matrix materials, said Nassir Mokarram, a Ph.D. student in the Coulter Department of Biomedical Engineering and Georgia Tech\u2019s School of Materials Science and Engineering. Converting the macrophages to a \u201cpro-healing\u201d phenotype that secretes healing compounds signals a broad range of other processes \u2013 the \u201cplayers\u201d in the symphony analogy.\u003C\/p\u003E\u003Cp\u003E\u201cIf you really want to change the symphony\u2019s activity from generating scarring to regeneration of tissue, you need to target the conductor, not just a few of the players, and we think macrophages are capable of being conductors of the healing symphony,\u201d said Mokarram.\u003C\/p\u003E\u003Cp\u003EMacrophages are best known for their role in creating inflammation at the site of injuries. The macrophages and other immune system components battle infection, remove dead tissue \u2013 and often create scarring that prevents nerve regeneration. However, these macrophages can exist in several different phenotypes depending on the signals they receive. Among the macrophage phenotypes are two classes \u2013 M2a and M2c \u2013 that encourage healing.\u003C\/p\u003E\u003Cp\u003EBellamkonda\u2019s research team used an interleukin 4 (IL-4) cytokine to convert macrophages within the animal model to the \u201cpro-healing\u201d phenotypes. They placed a gel that released IL-4 into hollow polymeric nerve guides that connected the ends of severed animal sciatic nerves that had to grow across a 15 millimeter gap to regenerate. The IL-4 remained in the nerve guides for 24 hours or less, and had no direct influence on the growth of nerve tissue in this short period of time.\u003C\/p\u003E\u003Cp\u003EThree weeks after the injury, the nerve guides that released IL-4 were almost completely filled with re-grown axons. The treated nerve guides had approximately 20 times more nerve regeneration than the control channels, which had no IL-4-treated macrophages.\u003C\/p\u003E\u003Cp\u003EResearch is now underway to develop the technique for determining how soon after injury the macrophages should be treated, and what concentration of IL-4 would be most effective.\u003C\/p\u003E\u003Cp\u003E\u201cWe believe immune cells are the \u2018master knobs\u2019 that modulate the biochemical cascade downstream,\u201d Mokarram said. \u201cThey are among the \u2018first-responders\u2019 to injury, and are involved for almost the whole regeneration process, secreting several factors that affect other cells. With IL-4, we are doing something very early in the process that is triggering a cascade of events whose effects last longer.\u201d\u003C\/p\u003E\u003Cp\u003ETissue engineering approaches have focused on encouraging the growth of nerve cells, using special scaffolds and continuous application of nerve growth factors over a period of weeks. Instead, the Bellamkonda group believes that influencing the immune system soon after injury could provide a simpler and more effective treatment able to restore nerve function.\u003C\/p\u003E\u003Cp\u003E\u201cBeyond neural tissue engineering, the implications of this approach can be significant for other types of tissue engineering,\u201d said Mokarram. \u201cNeural tissue may be just a model.\u201d\u003C\/p\u003E\u003Cp\u003EAs part of their paper, the researchers defined a state they termed \u201cregenerative bias\u201d that predicts the probability of a regenerative outcome. The Bellamkonda group discovered that when it quantified the ratio of healing macrophages to scar-promoting macrophages at the site of injury early after the injury, the ratio \u2013 or regenerative bias \u2013 predicted whether or not the nerve regenerated after many weeks.\u003C\/p\u003E\u003Cp\u003E\u201cThe significance of this finding is that IL-4 and other factors may be used to make sure the regenerative bias is high so that nerves, and perhaps other tissues, can regenerate on their own after injury,\u201d Bellamkonda said.\u003C\/p\u003E\u003Cp\u003EThe research team also included Alishah Merchant, Vivek Mukhatyar and Gaurangkumar Patel, all from the Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory University.\u003C\/p\u003E\u003Cp\u003E\u003Cem\u003EThis research was supported by the National Institutes of Health under grants NS44409, NS65109 and 1R41NS06777. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National lnstitutes of Health.\u003C\/em\u003E\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003ECITATION\u003C\/strong\u003E: Mokarram N, et al., Effect of modulating macrophage phenotype on peripheral nerve repair, Biomaterials (2012), \u003Ca href=\u0022http:\/\/dx.doi.org\/10.1016\/j.biomaterials.2012.08.050\u0022 title=\u0022http:\/\/dx.doi.org\/10.1016\/j.biomaterials.2012.08.050\u0022\u003Ehttp:\/\/dx.doi.org\/10.1016\/j.biomaterials.2012.08.050\u003C\/a\u003E\u003Cbr \/\u003E\u003Cbr \/\u003E\u003Cbr \/\u003E\u003Cstrong\u003EResearch News \u0026amp; Publications Office\u003C\/strong\u003E\u003Cbr \/\u003E\u003Cstrong\u003EGeorgia Institute of Technology\u003C\/strong\u003E\u003Cbr \/\u003E\u003Cstrong\u003E75 Fifth Street, N.W., Suite 309\u003C\/strong\u003E\u003Cbr \/\u003E\u003Cstrong\u003EAtlanta, Georgia\u0026nbsp; 30308\u0026nbsp; USA\u003C\/strong\u003E\u003Cbr \/\u003E\u003Cbr \/\u003E\u003Cstrong\u003EMedia Relations Contact\u003C\/strong\u003E: John Toon (404-894-6986)(\u003Ca href=\u0022mailto:jtoon@gatech.edu\u0022\u003Ejtoon@gatech.edu\u003C\/a\u003E).\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003EWriter\u003C\/strong\u003E: John Toon\u003C\/p\u003E","summary":null,"format":"limited_html"}],"field_subtitle":[{"value":"Research seeks the \u0027master knob\u0027 to turn on nerve repair"}],"field_summary":[{"value":"\u003Cp\u003EModulating immune response to injury could accelerate the regeneration of severed peripheral nerves, a new study in an animal model has found. By altering activity of the macrophage cells that respond to injuries, researchers dramatically increased the rate at which nerve processes regrew.\u003C\/p\u003E","format":"limited_html"}],"field_summary_sentence":[{"value":"Researchers have shown that modulating the immune response to injury can boost nerve regeneration."}],"uid":"27303","created_gmt":"2012-10-02 09:03:07","changed_gmt":"2016-10-08 03:12:54","author":"John Toon","boilerplate_text":"","field_publication":"","field_article_url":"","dateline":{"date":"2012-10-02T00:00:00-04:00","iso_date":"2012-10-02T00:00:00-04:00","tz":"America\/New_York"},"extras":[],"hg_media":{"158441":{"id":"158441","type":"image","title":"Polymer Nerve Guide","body":null,"created":"1449178883","gmt_created":"2015-12-03 21:41:23","changed":"1475894794","gmt_changed":"2016-10-08 02:46:34","alt":"Polymer Nerve Guide","file":{"fid":"195354","name":"immune-regeneration127.jpg","image_path":"\/sites\/default\/files\/images\/immune-regeneration127_0.jpg","image_full_path":"http:\/\/www.tlwarc.hg.gatech.edu\/\/sites\/default\/files\/images\/immune-regeneration127_0.jpg","mime":"image\/jpeg","size":1200499,"path_740":"http:\/\/www.tlwarc.hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/immune-regeneration127_0.jpg?itok=3MCj5EfA"}},"158461":{"id":"158461","type":"image","title":"Polymer Nerve Guide2","body":null,"created":"1449178883","gmt_created":"2015-12-03 21:41:23","changed":"1475894794","gmt_changed":"2016-10-08 02:46:34","alt":"Polymer Nerve Guide2","file":{"fid":"195355","name":"immune-regeneration171.jpg","image_path":"\/sites\/default\/files\/images\/immune-regeneration171_0.jpg","image_full_path":"http:\/\/www.tlwarc.hg.gatech.edu\/\/sites\/default\/files\/images\/immune-regeneration171_0.jpg","mime":"image\/jpeg","size":908889,"path_740":"http:\/\/www.tlwarc.hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/immune-regeneration171_0.jpg?itok=LVTJSUkY"}},"158431":{"id":"158431","type":"image","title":"Growth of Axons","body":null,"created":"1449178883","gmt_created":"2015-12-03 21:41:23","changed":"1475894794","gmt_changed":"2016-10-08 02:46:34","alt":"Growth of Axons","file":{"fid":"195353","name":"immune-regeneration80.jpg","image_path":"\/sites\/default\/files\/images\/immune-regeneration80_0.jpg","image_full_path":"http:\/\/www.tlwarc.hg.gatech.edu\/\/sites\/default\/files\/images\/immune-regeneration80_0.jpg","mime":"image\/jpeg","size":1338267,"path_740":"http:\/\/www.tlwarc.hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/immune-regeneration80_0.jpg?itok=1p2DmvFa"}},"158471":{"id":"158471","type":"image","title":"Regrowth of nerve tissue","body":null,"created":"1449178883","gmt_created":"2015-12-03 21:41:23","changed":"1475894794","gmt_changed":"2016-10-08 02:46:34","alt":"Regrowth of nerve tissue","file":{"fid":"195356","name":"immune-regeneration29.jpg","image_path":"\/sites\/default\/files\/images\/immune-regeneration29_0.jpg","image_full_path":"http:\/\/www.tlwarc.hg.gatech.edu\/\/sites\/default\/files\/images\/immune-regeneration29_0.jpg","mime":"image\/jpeg","size":1383998,"path_740":"http:\/\/www.tlwarc.hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/immune-regeneration29_0.jpg?itok=Fqg2SxjM"}}},"media_ids":["158441","158461","158431","158471"],"groups":[{"id":"1188","name":"Research Horizons"}],"categories":[{"id":"146","name":"Life Sciences and Biology"}],"keywords":[{"id":"45231","name":"immune response"},{"id":"45251","name":"macrophage"},{"id":"7266","name":"nerve"},{"id":"9511","name":"Nerve regeneration"},{"id":"45241","name":"peripheral nerve"},{"id":"2471","name":"Ravi Bellamkonda"},{"id":"3264","name":"Wallace H. Coulter Department of Biomedical Engineering"}],"core_research_areas":[{"id":"39441","name":"Bioengineering and Bioscience"},{"id":"39471","name":"Materials"}],"news_room_topics":[],"event_categories":[],"invited_audience":[],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[{"value":"\u003Cp\u003EJohn Toon\u003C\/p\u003E\u003Cp\u003EResearch News \u0026amp; Publications Office\u003C\/p\u003E\u003Cp\u003E(404) 894-6986\u003C\/p\u003E\u003Cp\u003E\u003Ca href=\u0022mailto:jtoon@gatech.edu\u0022\u003Ejtoon@gatech.edu\u003C\/a\u003E\u003C\/p\u003E","format":"limited_html"}],"email":["jtoon@gatech.edu"],"slides":[],"orientation":[],"userdata":""}}}