Monotrauma is associated with enhanced remote inflammatory response and organ damage, while polytrauma intensifies both in porcine trauma model.

AIM: Severely injured patients experience substantial immunological stress upon traumatic insult. Next to the direct local tissue injury also other organs, which are not directly injured such as liver and lung, are frequently affected by a so-called remote organ damage (ROD) after trauma. Thus, we studied the inflammatory response of lung and liver either after isolated femur fracture as example for ROD, or after multiple trauma in a porcine polytrauma model. METHODS: Twenty-four male pigs (Sus scrofa) underwent either isolated standardized femoral fracture (monotrauma, MT, n = 12) or polytrauma (PT, n = 12). PT consisted of a femur fracture, lung contusion, liver laceration, hemorrhagic shock, subsequent resuscitation and surgical fracture fixation. Six animals served as controls (sham). After 72 h inflammatory changes were determined by analyses of the interleukin (IL)-6 gene expression and tissue infiltration of polymorphonuclear leukocyte (PMN, myeloperoxidase staining). ROD in MT, and lung as well as liver damage in PT were assessed histologically by hematoxylin-eosin staining. Expression of phosphorylated p65 NF-κB was evaluated by immunohistology. RESULTS: IL-6 increased in lungs and liver in both groups MT and PT, respectively, compared to sham. Similarly, PMN infiltration of the lungs and liver increased significantly after both MT and PT compared to sham. Histological evaluation demonstrated tissue damage notably in lungs after MT, while tissue damage after PT was found in both lung and liver after PT. p65 NF-κB tended to an increase upon MT, and was significantly enhanced after PT in both tissues. CONCLUSION: Our data indicate that remote organ damage after MT notably in lungs was associated with an enhanced inflammatory response. Severe polytrauma substantially intensifies this response and organ damage in the underlying model.

Development and preparation of a low-immunogenicity porcine dermal scaffold and its biocompatibility assessment.

Acellular dermal matrix (ADM) has been widely used in repair and reconstruction of tissue defect. Therapeutic effect of porcine ADM (PADM) is inferior to that of human ADM (HADM). Relatively high immunogenicity and the resulting strong inflammatory response are major issue in application of PADM. We therefore treated reticular layer PADM (Rl-PADM) with matrix metalloproteinase-7 (MMP-7) and obtained a low-immunogenicity porcine dermal scaffold (LIPDS). Highly immunogenic components, tissue structure, cytocompatibility, and postgrafting histological changes of LIPDS were further investigated. Compared with Rl-PADM, LIPDS showed that the epithelial root sheath, cell debris, laminin, and type IV collagen were almost entirely removed, the structure remained normal, and the interfibrous space was relatively enlarged. Cytocompatibility of LIPDS was similar to that of HADM but superior to Rl-PADM. With regard to the extent of tissue ingrowth in terms of host fibroblasts infiltration and vascularization, LIPDS exhibited clear advantages over Rl-PADM after they had been subcutaneously transplanted in a rat model. In addition, no excessive inflammatory response was observed in LIPDS group up to 28 days postgraft, and the morphosis of collagenous fibers kept essentially normal. However, there were stronger inflammatory response and obvious collagen spallation in Rl-PADM group. The processes of integration and remodeling after the LIPDS grafting were similar to those of a normal wound healing response. The LIPDS graft was vascularized at a relatively high speed. Thus, as an implantable scaffold material, LIPDS is a superior template for guiding tissue regeneration and remodeling.