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Generative tissue
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<h2 id="overview">Overview</h2> <p>gTissue is a type of living <a href="/facts/Tissue_(biology)/H7CpML7A">Tissue (biology)</a>, hence an ensemble of cells and extracellular matrix that carry out a particular function. However, gTissue is created surgically, grown in a patient, and has a unique cellular and biochemical make-up that make it distinct from other tissues of the body. gTissue was discovered through research in the fields of <a href="/facts/Tissue_Engineering/Tx77KG1S">Tissue Engineering</a> and <a href="/facts/Regenerative_Medicine/RplB5P22">Regenerative Medicine</a> and first created as a dense <a href="/facts/Connective_tissue/mal3fc7k">connective tissue</a> between the brain and skull during the repair of canine <a href="/facts/Dura_mater/vcb6bz93">dura mater</a>.<a class="footnote-ref" id="fnref:1" href="#fn:1"><sup>1</sup></a> It has since been successfully created in humans for a wide range of clinical applications in <a href="/facts/Soft_tissue/cHBwqLpP">soft tissue</a> healing and repair.<a class="footnote-ref" id="fnref:2" href="#fn:2"><sup>2</sup></a> Essentially, the gTissue is created by implanting certain types of non-inflammatory ECM biomaterials that are adopted by the host, including repopulation with <a href="/facts/Host_cell/L6mop0kh">host cells</a> and <a href="/facts/Blood_vessel/FG3GjPNW">blood vessels</a>, becoming a living tissue. To date, the types of gTissue created can be characterized as variants of soft connective tissues including <a href="/facts/Dermis/WAm7Fd6P">dermis</a>, <a href="/facts/Tendon/M0Kdf7Fy">tendon</a>, <a href="/facts/Ligament/xAf6lB1z">ligament</a>, and <a href="/facts/Fascia/KnQE4bPq">fascia</a>. </p> <h2 id="generation-of-adoption">Generation of (Adoption)</h2> <p>Initially the cell-free ECM biomaterial is implanted and progressively adopted by the host. Immediately upon surgical implantation, the porous material becomes soaked in blood. This seeds the material with a population of circulating <a href="/facts/Stem_cell/qgB9dFrI">stem cells</a>, and <a href="/facts/Growth_factor/D1xnRbcH">growth factors</a> to support gTissue development.<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a> As generation progresses, the growth factors, <a href="/facts/Cytokine/SdWpWABH">cytokines</a>, and <a href="/facts/Fibrin/BFar47y5">fibrin</a> provisional matrix signals host cells to repopulate the matrix. To support the metabolic activity of these cells, a vascular network is simultaneously created within the ECM biomaterial. At this stage the material has been adopted and has the characteristics of a living <a href="/facts/Tissue_(biology)/H7CpML7A">tissue (biology)</a>. Under some conditions, following adoption with host cells and <a href="/facts/Vasculature/WXwudzzc">vasculature</a>, gTissue can persist indefinitely without any histological evidence of significant change. For example, when created to below the skin of the face in <a href="/facts/Cosmetic_surgery/zLCAX9hN">cosmetic procedures</a> intended to add bulk, the gTissue is adopted and stays a living, metabolically active tissue, subdermally.<a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a> </p> <h2 id="adaptation-of">Adaptation of</h2> <p>While gTissue can live indefinitely following adoption without significant change, there are environmental conditions that support the adaption of the tissue. The adaptation of gTissue is one reason it considered a generative tissue. Adaptation includes any change to the gTissue to meet particular environmental demands placed on it, based on the location of implantation. For example, during tendon augmentation procedures, the <a href="/facts/Collagen/KsyAb72K">collagen</a> fiber architecture of the extracellular matrix can transition to an aligned structure similar to native tendon, oriented along the long axis of loading, to meet the mechanical loading requirements.<a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a> Or when used as an underlay beneath the muscles of the <a href="/facts/Abdominal_wall/AEEQ1Fmr">abdominal wall</a> to support the repair of a <a href="/facts/Hernia/ffJnB19e">hernia</a>, gTissue is adapted forming a new <a href="/facts/Mesothelium/0PDq8h0o">mesothelium</a> lining the peritoneal side in order to prevent <a href="/facts/Adhesion/NuVQPk4z">adhesions</a> to, or <a href="/facts/Abrasion_(medical)/cDrHUjy3">abrasion</a> of, the <a href="/facts/Bowel/nK2zwqBS">bowel</a> or <a href="/facts/Small_intestine/1AQ8RJ4m">small intestines</a>. </p> <h2 id="requirements">Requirements</h2> <p>In order to create gTissue, a surgeon must start by selecting and ECM biomaterial with appropriate characteristics to support the type of healing and repair desired. The ECM biomaterial must be non-inflammatory. Biomaterials that evoke a strong inflammatory response are rapidly remodeled into <a href="/facts/Scar/XSQ92JoG">scar tissue</a>.<a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a> The ECM biomaterial must also not cause a chronic, low grade inflammatory response, or the material will be steadily degraded and therefore disappear with time.<a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a> Examples of ECM biomaterials that meet these requirements and have been successfully used to create gTissue include SurgiMend,<a class="footnote-ref" id="fnref:8" href="#fn:8"><sup>8</sup></a> TissueMend,<a class="footnote-ref" id="fnref:9" href="#fn:9"><sup>9</sup></a> and Durepair.<a class="footnote-ref" id="fnref:10" href="#fn:10"><sup>10</sup></a> Additionally, the surgeon must be aware of how the anatomical location and surgical procedure affect host adoption and adaptation in order to grow the desired gTissue. For example, if the gTissue is to persist without change to add bulk, the implanted ECM biomaterial must be placed under low tension. </p> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>Zerris et al. Journal of Biomedical Materials Research Part B, Volume 83B Issue 2, Pages 580 - 588, 2007 Article <a href="https://archive.today/20130105072810/http://www3.interscience.wiley.com/journal/114228858/abstract" target="_blank">https://archive.today/20130105072810/http://www3.interscience.wiley.com/journal/114228858/abstract</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>Cornwell, Landsman, James. Extracellular Matrix Biomaterials for Soft Tissue Repair. Clin Podiatr Med Surg 26 (2009) 507–523 Article <a href="http://www.podiatric.theclinics.com/article/S0891-8422(09)00068-8/abstract" target="_blank">http://www.podiatric.theclinics.com/article/S0891-8422(09)00068-8/abstract</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>Cornwell, Landsman, James. Extracellular Matrix Biomaterials for Soft Tissue Repair. Clin Podiatr Med Surg 26 (2009) 507–523 Article <a href="http://www.podiatric.theclinics.com/article/S0891-8422(09)00068-8/abstract" target="_blank">http://www.podiatric.theclinics.com/article/S0891-8422(09)00068-8/abstract</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>Cornwell, Landsman, James. Extracellular Matrix Biomaterials for Soft Tissue Repair. Clin Podiatr Med Surg 26 (2009) 507–523 Article <a href="http://www.podiatric.theclinics.com/article/S0891-8422(09)00068-8/abstract" target="_blank">http://www.podiatric.theclinics.com/article/S0891-8422(09)00068-8/abstract</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>Cornwell, Landsman, James. Extracellular Matrix Biomaterials for Soft Tissue Repair. Clin Podiatr Med Surg 26 (2009) 507–523 Article <a href="http://www.podiatric.theclinics.com/article/S0891-8422(09)00068-8/abstract" target="_blank">http://www.podiatric.theclinics.com/article/S0891-8422(09)00068-8/abstract</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> <li id="fn:6"><p>Valentin JE, Badylak JS, McCabe GP, et al. Extracellular matrix bioscaffolds for orthopaedic applications. A comparative histologic study. J Bone Joint Surg Am 2006;88(12):2673–86. Article Archived 2009-08-12 at the Wayback Machine <a href="http://www.ejbjs.org/cgi/content/abstract/88/12/2673" target="_blank">http://www.ejbjs.org/cgi/content/abstract/88/12/2673</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> <li id="fn:7"><p>Hwang K, Hwang JH, et al. Experimental study of autologous cartilage, acellular cadaveric dermis, lyophilized bovine pericardium, and irradiated bovine tendon: applicability to nasal tip plasty. J Craniofac Surg 2007;18(3):551–8 Article on Pubmed <a href="https://www.ncbi.nlm.nih.gov/pubmed/17538317" target="_blank">https://www.ncbi.nlm.nih.gov/pubmed/17538317</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li> <li id="fn:8"><p>SurgiMend, TEI Biosciences Inc. Website Archived 2016-07-10 at the Wayback Machine <a href="http://www.teibio.com" target="_blank">http://www.teibio.com</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li> <li id="fn:9"><p>TissueMend, Stryker Orthopaedics Website Archived 2017-07-25 at the Wayback Machine <a href="http://www.stryker.com/en-us/products/Orthopaedics/SoftTissueRepair/index.htm" target="_blank">http://www.stryker.com/en-us/products/Orthopaedics/SoftTissueRepair/index.htm</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></p></li> <li id="fn:10"><p>Durepair, Medtronic Website <a href="http://www.medtronic.com/" target="_blank">http://www.medtronic.com/</a> <a href="#fnref:10" class="footnote-back-ref">↩</a></p></li> </ol>