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Background: Synthetic mesh material is of great importance for surgical incisional hernia repair. The physical and biochemical characteristics of the mesh influence mechanical stability and the foreign body tissue reaction. The influence on bacterial infections, however, remains ill-defined. The aim of the present study was to evaluate the influence of a modified mesh structure with variation in filament linking on the occurrence of bacterial infection that is indicated by the occurrence of CD68 + , CD4 + , and CD8 + cells in two different materials., Methods: A total of 56 male Sprague Dawley rats received a surgical mesh implant in a subcutaneous abdominal position. The mesh of two different polymers (polypropylene (PP) and polyvinylidenfluoride (PVDF)) and two different structures (standard structure and bold structure with higher filament linking) were compared. During the implantation, the meshes were infected with Staphylococcus (S.) aureus . After 7 and 21 days, meshes were explanted, and the early and late tissue responses to infection were histologically evaluated., Results: Overall, the inflammatory tissue response was higher at 7 days when compared to 21 days. At 7 days, PP meshes of the standard structure (PP-S) showed the strongest inflammatory tissue response in comparison to all the other groups. At 21 days, no statistically significant difference between different meshes was detected. CD8 + cytotoxic T cells showed a significant difference at 21 days but not at 7 days. PP meshes of both structures showed a higher infiltration of CD8 + T cells than PVDF meshes. CD4 + T helper cells differed at 7 days but not at 21 days, and PVDF meshes in a bold structure showed the highest CD4 + T cell count. The number of CD68 + macrophages was also significantly higher in PP meshes in a standard structure when compared to PVDF meshes at 21 days., Conclusion: The inflammatory tissue response to S. aureus infection appears to be highest during the early period after mesh implantation. PP meshes showed a higher inflammatory response than PVDF meshes. The mesh material appears to be more important for the risk of infection than the variation in filament linking.

The effect of liver cirrhosis on vascular remodeling in vivo remains unknown. Therefore, this study investigates the influence of cholestatic liver cirrhosis on carotid arterial remodeling. A total of 79 male Sprague Dawley rats underwent bile duct ligation (cirrhotic group) or sham surgery (control group) and 28 days later left carotid artery balloon dilatation; 3, 7, 14 and 28 days after balloon dilatation, the rats were euthanized and carotid arteries were harvested. Histological sections were planimetrized, cell counts determined, and systemic inflammatory parameters measured. Up to day 14 after balloon dilatation, both groups showed a comparable increase in neointima area and degree of stenosis. By day 28, however, both values were significantly lower in the cirrhotic group (% stenosis: 20 ± 8 vs. 42 ± 10, p = 0.010; neointimal area [mm 2 ]: 0.064 ± 0.025 vs. 0.138 ± 0.025, p = 0.024). Simultaneously, cell density in the neointima ( p = 0.034) and inflammatory parameters were significantly higher in cirrhotic rats. This study demonstrates that cholestatic liver cirrhosis in rats substantially increases neointimal cell consolidation between days 14 and 28. Thereby, consolidation proved important for the degree of stenosis. This may suggest that patients with cholestatic cirrhosis are at lower risk for restenosis after coronary intervention.

Cirrhotic patients often suffer from cirrhotic cardiomyopathy (CCM). Previous animal models of CCM were inconsistent concerning the time and mechanism of injury; thus, the temporal dynamics and cardiac vulnerability were studied in more detail. Rats underwent bile duct ligation (BDL) and a second surgery 28 days later. Cardiac function was assessed by conductance catheter and echocardiography. Histology, gene expression, and serum parameters were analyzed. A chronotropic incompetence (P d31 < 0.001) and impaired contractility at rest and a reduced contractile reserve (P d31 = 0.03, P dob-d31 < 0.001) were seen 31 days after BDL with increased creatine (P d35 , P d42 , and P d56 < 0.05) and transaminases (P d31 < 0.001). A total of 56 days after BDL, myocardial fibrosis was seen (P d56 < 0.001) accompanied by macrophage infiltration (CD68: P group < 0.001) and systemic inflammation (TNFα: P group < 0.001, white blood cell count: P group < 0.001). Myocardial expression of peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α) was increased after 31 (P d31 < 0.001) and decreased after 42 (P d42 < 0.001) and 56 days (P d56 < 0.001). Caspase-3 expression was increased 31 and 56 days after BDL (P d31 = 0.005; P d56 = 0.005). Structural changes in the myocardium were seen after 8 weeks. After the second surgery (second hit), transient myocardial insufficiency with secondary organ dysfunction was seen, characterized by reduced contractility and contractile reserve.

Severity assessment in animals is an ongoing field of research. In particular, the question of objectifiable and meaningful parameters of score-sheets, as well as their best combination, arise. This retrospective analysis investigates the suitability of a score-sheet for assessing severity and seeks to optimise it for predicting survival in 89 male Sprague Dawley rats ( Rattus norvegicus ), during an experiment evaluating the influence of liver cirrhosis by bile duct ligation (BDL) on vascular healing. The following five parameters were compared for their predictive power: (i) overall score; (ii) relative weight loss; (iii) general condition score; (iv) spontaneous behaviour score; and (v) the observer's assessment whether pain might be present. Suitable cut-off values of these individual parameters and the combination of multiple parameters were investigated. A total of ten rats (11.2%; 10/89) died or had to be sacrificed at an early stage due to pre-defined humane endpoints. Neither the overall score nor any individual parameter yielded satisfactory results for predicting survival. Using retrospectively calculated cut-off values and combining the overall score with the observer's assessment of whether the animal required analgesia (dipyrone) for pain relief resulted in an improved prediction of survival on the second post-operative day. This study demonstrates that combining score parameters was more suitable than using single ones and that experienced human judgement of animals can be useful in addition to objective parameters in the assessment of severity. By optimising the score-sheet and better understanding the burden of the model on rats, this study contributes to animal welfare., Competing Interests: This work was supported by B Braun-Stiftung [grant number BBST-D-18-00022]. MMe’s appropriations were funded by RWTH Aachen University (programme ROTATION). RHT received funds in part from the German Research Foundation (Deutsche Forschungsgemeinschaft - DFG; FOR-2591; grant numbers TO 542/5-1 and TO 542/6-1; 2016). The funders had no influence on the study design, data collection and analysis, decision to publish or preparation of the manuscript. JCK, MAH, MJH, MU, MMo, AB, RR and MH declare no potential conflict of interest., (© The Author(s) 2023.)

(1) Introduction: The intraperitoneal onlay mesh technique (IPOM) is widely used to repair incisional hernias. This method has advantages but suffers from complications due to intraperitoneal adhesion formation between the mesh and intestine. An ideal mesh minimizes adhesions and shows good biocompatibility. To address this, newly developed multifilamentous polyethylene (PET) meshes were constructed from sub-macrophage-sized monofilaments and studied regarding biocompatibility and adhesion formation. (2) Methods: We investigated fine (FPET, 72 filaments, 11 µm diameter each) and ultra-fine multifilament (UFPET, 700 filaments, 3 µm diameter each) polyethylene meshes for biocompatibility in subcutaneous implantation in rats. Adhesion formation was analyzed in the IPOM position in rabbits. Geometrically identical mono-filamentous polypropylene (PP) Bard Soft ® PP meshes were used for comparison. Histologic and immune-histologic foreign body reactions were assessed in 48 rats after 7 or 21 days (four mesh types, with two different mesh types per rat; n = 6 per mesh type). Additionally, two different mesh types each were placed in the IPOM position in 24 rabbits to compile the Diamond peritoneal adhesion score after the same timeframes. The biocompatibility and adhesion score differences were analyzed with the Kruskal-Wallis nonparametric statistical test. (3) Results: Overall, FPET and, especially, UFPET showed significantly smaller foreign body granulomas compared to PP meshes. Longer observation periods enhanced the differences. Immunohistology showed no significant differences in the cellular immune response and proliferation. UFPET demonstrated significantly reduced peritoneal adhesion formation compared to all other tested meshes after 21 days. (4) Conclusions: Overall, FPET and, especially, UFPET demonstrated their suitability for IPOM hernia meshes in animal models by improving major aspects of the foreign body reaction and reducing adhesion formation.

Gastrointestinal anastomoses are an important source of postoperative complications. In particular, the ideal suturing material is still the subject of investigation. Therefore, this study aimed to evaluate a newly developed suturing material with elastic properties made from thermoplastic polyurethane (TPU); Polyvinylidene fluoride (PVDF) and TPU were tested in two different textures (round and a modified, "snowflake" structure) in 32 minipigs, with two anastomoses of the small intestine sutured 2 m apart. After 90 days, the anastomoses were evaluated for inflammation, the healing process, and foreign body reactions. A computer-assisted immunohistological analysis of staining for Ki67, CD68, smooth muscle actin (SMA), and Sirius red was performed using TissueFAXS. Additionally, the in vivo elastic properties of the material were assessed by measuring the suture tension in a rabbit model. Each suture was tested twice in three rabbits; No major surgical complications were observed and all anastomoses showed adequate wound healing. The Ki67+ count and SMA area differed between the groups (F (3, 66) = 5.884, p = 0.0013 and F (3, 56) = 6.880, p = 0.0005, respectively). In the TPU-snowflake material, the Ki67+ count was the lowest, while the SMA area provided the highest values. The CD68+ count and collagen I/III ratio did not differ between the groups (F (3, 69) = 2.646, p = 0.0558 and F (3, 54) = 0.496, p = 0.686, respectively). The suture tension measurements showed a significant reduction in suture tension loss for both the TPU threads; Suturing material made from TPU with elastic properties proved applicable for intestinal anastomoses in a porcine model. In addition, our results suggest a successful reduction in tissue incision and an overall suture tension homogenization.

Liver cirrhosis has been associated with an increased risk of coronary artery disease and clinical complications following percutaneous coronary revascularization. The present study is based on the hypothesis that cirrhosis may influence intimal hyperplasia following PCI. Sera from 10 patients with alcoholic liver cirrhosis and 10 age-matched healthy controls were used to stimulate cultured human coronary artery smooth muscle cells (HCASMC) for 48 h. HCASMC proliferation, migration, gene expression and apoptosis were investigated. Serum concentrations of growth factors and markers of liver function were also determined in patients and healthy controls. Treatment of HCASMC with patient sera reduced cell proliferation and migration ( p < 0.05 vs. healthy controls), whereas apoptosis was unaffected ( p = 0.160). Expression of genes associated with a synthetic vascular smooth muscle cell phenotype was decreased in cells stimulated with serum from cirrhotic patients (RBP1, p = 0.001; SPP1, p = 0.003; KLF4, p = 0.004). Platelet-derived growth factor-BB serum concentrations were lower in patients ( p = 0.001 vs. controls). The results suggest the presence of circulating factors in patients with alcoholic liver cirrhosis affecting coronary smooth muscle cell growth. These findings may have implications for clinical outcomes following percutaneous coronary revascularization in these patients.

To investigate whether acute liver failure (ALF) leads to secondary acute myocardial injury, 100 ALF patients that were retrospectively identified in a single center based on ICD 10 codes and 8 rats from an experimental study that died early after bile duct ligation (BDL) were examined. Creatine kinase (CK), creatine kinase-MB isoenzyme (CKMB) and cardiac troponin-I (cTnI) were analyzed as markers of myocardial injury. For histological analysis, hematoxylin-eosin (HE), elastic Van Gieson (EVG), CD41 and myeloperoxidase were used to stain rat hearts. Major adverse cardiac events (MACEs) were a critical factor for mortality (p = 0.037) in human ALF. Deceased patients exhibited higher levels of CKMB than survivors (p = 0.023). CKMB was a predictor of mortality in ALF (p = 0.013). Animals that died early after BDL exhibited increased cTnI, CKMB, tumor necrosis factor α (TNFα) and interleukin-6 (IL-6) levels compared to controls (cTnI: p = 0.011, CKMB: p = 0.008, TNFα: p = 0.003, IL-6: p = 0.006). These animals showed perivascular lesions and wavy fibers, microthrombi and neutrophilic infiltration in the heart. MACEs are decisive for mortality in human ALF, and elevated CKMB values indicate that this might be due to structural myocardial damage. Accordingly, CKMB was found to have predictive value for mortality in ALF. The results are substantiated by data from a rat BDL model demonstrating diffuse myocardial injury., Competing Interests: The authors have declared that no competing interests exist.

Background: Aorto-esophageal fistulae (AEFs) are a rare but serious and life-threatening disease of the mediastinum. Especially, AEF in the presence of infected stent grafts, for example, after thoracic endovascular aortic repair (TEVAR) is only curable by a multistage interdisciplinary surgical approach. This study presents the results of our four-stage approach consisting of bridging TEVAR, esophagectomy, complete stent removal followed by total bovine tube aortic replacement (TBTAR), and finally esophageal reconstruction., Methods: A case series of four patients from our department receiving a four-stage treatment of AEF is presented in this study. Retrospective database analysis focusing on overall survival, duration of intensive care unit and total hospital stay until discharge, complications, surgical time frame, and completion of chosen surgical treatment course was performed., Results: Overall, four patients surgically treated for AEF since May 2015 were included. A 30-day mortality was 0%, and overall survival at 1 year was 75%. All patients survived more than 5 months and could be discharged after TEVAR and esophagectomy. TBTAR could be performed in two of four patients (50%). Esophageal reconstruction was completed in all patients. Average follow-up was 20.3 ± 1.7 months or until death., Conclusion: The acute management of AEF using this approach seems satisfactory, especially for reducing acute short-term mortality. Complete restoration of the circulatory system and digestive tract remains challenging and is associated with high morbidity. We support the application of bridging TEVAR with a staggered approach to further surgical treatment individually tailored to the patient., Competing Interests: None., (Thieme. All rights reserved.)

Background: The incidence of incisional hernia is with up to 30% one of the frequent long-term complication after laparotomy. After establishing minimal invasive operations, the laparoscopic intraperitoneal onlay mesh technique (lap. IPOM) was first described in 1993. Little is known about the foreign body reaction of IPOM-meshes, which covered a defect of the parietal peritoneum. This is becoming more important, since IPOM procedure with peritoneal-sac resection and hernia port closing (IPOM plus) is more frequently used., Methods: In 18 female minipigs, two out of three Polyvinylidene-fluoride (PVDF) -meshes (I: standard IPOM; II: IPOM with modified structure [bigger pores]; III: IPOM with the same structure as IPOM II + degradable hydrogel-coating) were placed in a laparoscopic IPOM procedure. Before mesh placement, a 2x2cm peritoneal defect was created. After 30 days, animals were euthanized, adhesions were evaluated by re-laparoscopy and mesh samples were explanted for histological and immunohistochemichal investigations., Results: All animals recovered after implantation and had no complications during the follow-up period. Analysing foreign body reaction, the IPOM II mesh had a significant smaller inner granuloma, compared to the other meshes (IPOM II: 8.4 µm ± 1.3 vs. IPOM I 9.1 µm ± 1.3, p < 0.001). The degradable hydrogel coating does not prevent adhesions measured by Diamond score (p = 0.46). A peritoneal defect covered by a standard or modified IPOM mesh was a significant factor for increasing foreign body granuloma, the amount of CD3+ lymphocytes, CD68+ macrophages and decrease of pore size., Conclusion: A peritoneal defect covered by IPOM prostheses leads to an increased foreign body reaction compared to intact peritoneum. Whenever feasible, a peritoneal defect should be closed accurately before placing an IPOM-mesh to avoid an excessive foreign body reaction and therefore inferior biomaterial properties of the prosthesis.

Objective: A simple but reliable and safe anaesthetic procedure is required for surgical interventions in small rodents. Combined ketamine and xylazine injections are often used in rats for less invasive surgery, possibly with spontaneous breathing and without airway management. However, there are important pitfalls to be avoided by special precautions and monitoring, as shown subsequently., Study Design: Observational study., Animals: Twenty-four anaesthetic procedures for bile duct ligation, sham operation or carotid artery dilatation in 20 male Sprague-Dawley rats, preoperatively weighing between 440 and 550 g., Methods: Intolerable high mortality rates occurred in the first 7 postoperative days while establishing a new experimental model in rats using ketamine-xylazine anaesthesia. Rats were spontaneously breathing ambient air during the first 12 surgeries without airway management. An observed high mortality rate in these animals led to a change in the trial protocol: the insufflation of 2 litres of oxygen per minute via nose cone during the following 12 rat surgeries. Retrospective comparison of the outcome (without oxygen vs. with oxygen insufflation) was conducted., Results: The perioperative mortality rate could be significantly reduced from 58% (7/12) to 17% (2/12) (p = 0.036) by oxygen insufflation via nose cone. Significantly different levels of intraoperative oxygen saturation (SpO2; 89 ± 4% [without oxygen] vs. 97 ± 0.5% [with oxygen], p < 0.0001), but no significant differences in heart rate (HR; 267 ± 7 beats minute-1 [bpm] [without oxygen] vs. 266 ± 6 bpm [with oxygen], p = 0.955) were observed., Conclusions and Clinical Relevance: In summary, rats under ketamine-xylazine anaesthesia are susceptible to hypoxia. This may lead to increased delayed mortality related to hypoxia induced lung failure. Apparently, this is an underestimated problem. We highly recommend using additional oxygen insufflation in spontaneously breathing rats under ketamine-xylazine anaesthesia with basic monitoring such as measurement of oxygen saturation., Competing Interests: The authors have declared that no competing interests exist.

Organotypic full-thickness skin grafts (OTSG) are already an important technology for treating various skin conditions and are well established for skin research and development. These obvious benefits are often impaired by the need of laborious production, their noncomplete autologous composition, and, most importantly, their lack of included vasculature. Therefore, our study focused on combining a prevascularized dermal layer with an epidermis to cultivate full-thickness skin grafts incorporating capillary-like networks. It has been shown that prevascularization accelerates ingrowth of tissue-engineered grafts, and it is a prerequisite to circumvent diffusion limits due to graft thickness. To obtain such a graft, we chose a dermal layer incorporating human umbilical vein endothelial cells (HuVEC) amid human dermal fibroblasts within a fibrin-based scaffold, seeded apically with human foreskin keratinocytes (hfKC). Our research investigated the used concept's feasibility, as well as the effect of hfKC addition on the development of a well-connected capillary-like network after approximately 21 days. In addition, we evaluated the utilization of a custom-made constant flow bioreactor for simplified cultivation of these grafts, therefore possibly easing graft production and presumably increasing their cost effectiveness. Skin grafts were assessed by conventional two-dimensional histology. In addition, software-assisted three-dimensional evaluation of the capillary-like structure networks was performed by two-photon laser scanning microscopy (TPLSM) and subsequent image processing was done with ImagePro(®) Analyzer 7.0 software, thereby evaluating its platform technology power in the field of prevascularized skin grafts. All samples showed a capillary-like structure network, but we could report a significant reduction of its total length after 14 days of tri-culture with 5×10(5)/cm(2) seeded hfKC, possibly indicating nutritional deficiencies for this particular high cell density experimental setup. Lower concentrations of hfKC did not affect the formation of the capillary-like structures significantly. The developed bioreactor simplified cultivation of prevascularized OTSG. However, a flow-dependent reduction of capillary-like structures in 1 and 5 mL/min flow conditions occurred. We conclude that our technique for creating prevascularized OTSG is feasible. In addition, TPLSM is well suited for analyzing the prevascularization process. We hypothesize that the handling benefits of our bioreactor can be preserved by using considerably lower flow rates while not impairing the forming of capillary-like structure networks.