Evaluation of Extracellular Matrix Remodeling in Full-thickness Skin Grafts in Mice.

Abdominal hernia is a protruding weakness in the abdominal wall. It affects abdominal strength and life quality and can lead to complications due to intestinal entrapment. Autologous full-thickness skin graft (FTSG) has recently become an alternative material for reinforcement in the surgical repair of large abdominal hernias instead of synthetic mesh. FTSG eventually integrates with the abdominal wall, but the long-term fate of the graft itself is not fully understood. This has implications as to how these grafts should be optimally used and handled intraoperatively. This study investigates the remodeling of FTSG in either the onlay or the intraperitoneal position 8 weeks after FTSG transplantation in an experimental mouse model. There was a significant presence of fibroblasts, indicated by vimentin and S100A4 staining, but there were significant variations among animals as to how much of the graft had been remodeled into dense connective tissue. This correlated significantly with the proportion of vimentin-positive cells in the dense connective tissue. We also found that collagen hybridizing peptide staining intensity, a marker of active remodeling, was significantly associated with the proportion of S100A4-positive cells in the dense connective tissue of the FTSG.

Full-thickness skin grafts to reinforce the abdominal wall: a cross-sectional histological study comparing intra- and extraperitoneal onlay positions in mice.

INTRODUCTION: In the repair of complex abdominal wall hernia, there can be a strong preference to avoid synthetic or biological implants as reinforcement material. Autologous full-thickness skin grafts (FTSG) have shown promising results. However, there are few clinical data on the use of FTSG in an intraperitoneal position and rudimentary knowledge about postoperative histological appearance of tissue remodelling and repair. OBJECTIVE: To investigate the histological appearance of FTSG in the intraperitoneal onlay mesh (IPOM) position. METHODS: Isogeneic FTSG was positioned in the IPOM (10 mice) and the onlay position (10 mice). After eight weeks, tissues were harvested for histological analysis. Tissue structure, inflammation and cell survival were investigated with histological and immunohistochemical staining. RESULTS: Morphology was similar in both positions. Luciferase staining indicated both onlay and IPOM graft cell survival, with microvascular networks present. In both positions, FTSG showed ongoing tissue remodelling processes and cystic formations containing hair and epidermis. Low-grade acute phase and chronic inflammation were present. Integration was observed in 50% of the mice with similar appearances in IPOM and onlay grafts. CONCLUSION: FTSG is tolerated, with comparable results either inside or outside the abdominal cavity, and in line with historic histological evaluations. The results suggest further research on FTSG as a potential future reinforcement material in selected cases of complex abdominal wall hernia repair.

Evaluating full-thickness skin grafts in intraperitoneal onlay mesh position versus onlay position in mice.

BACKGROUND: Importance: Hernia surgery requires reinforcement material with few side effects when used in the intraperitoneal position. Autologous skin grafting may meet this requirement, but animal experiments are obligatory before being applied in humans. OBJECTIVE: To compare survival and effects of isogeneic full-thickness skin grafts in the intraperitoneal onlay mesh (IPOM) position in mice, with a control group using the onlay position. Primary end point was graft survival and secondary end point adhesion formation and inflammation through NF-κB activity. METHODS: Design: Intervention study with 8-week follow-up in accordance with ARRIVE criteria, performed between 2015 and 2016. SETTING: Animal laboratory. PARTICIPANTS: Transgenic C57BL/6 mice with isogeneic background were used. Recipients were female wild-type phenotype mice >3 mo (n = 24). Donors were male or female mice >7 mo, with phenotype-positive for the luciferase gene (n = 20) or positive for NF-κB-luciferase gene (n = 4). INTERVENTION: Full-thickness skin was grafted in the IPOM position and compared with grafts in the onlay position as controls. Survival was evaluated by regular longitudinal postoperative luminescence imaging over 8 wk. Adherence formation was evaluated macroscopically after sacrifice. Inflammation of full-thickness skin grafts in IPOM position of NF-κB mice was evaluated in four additional mice. Main outcome and measure: Survival of grafts, evaluated by luminescence. RESULTS: Ten animals received grafts in the IPOM position, and 10 in the onlay position as controls. Graft survival after 8 wk was 100% (20/20). Average luminescence at the end of the 8-week period was 999,597 flux (min 162,800, max 2,521,530) in the IPOM group (n = 10) and 769,708 flux (min 76,590, max 2,164,080) in the onlay control group (n = 10). No adhesions requiring sharp dissection (Jenkins' scale >2) were seen. Four animals with grafts in the IPOM position showed peak inflammation (NF-κB activity) 5 d after surgery subsiding toward the end of follow-up. CONCLUSIONS: Full-thickness skin survives as well in the IPOM position as in the onlay control position, and few adherences develop. Further studies are required to fully characterize the tissue remodeling and repair processes associated with IPOM skin grafting. The result is relevant in the search for alternative reinforcement materials to be used in complex hernia surgery in humans.