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Background During cardiac surgery with heart-lung-machine support, abdominal swabs are routinely used to adsorb blood from the operation field. In part, abdominal swabs exhibit procoagulant activity, which is usually considered harmless. However, coagulation induction and abnormal clot formation on the surface of abdominal swabs in the operation field may, if the blood is retransfused into the extracorporeal circuit, lead to severe thromboembolic complications. The aim of the present study was to elucidate the origin of the unexpected blood clotting upon contact with hypercoagulant swabs. Methods The coagulant properties of three abdominal swabs were characterized using a simple clotting test and human whole blood, which was anticoagulated with different heparin concentrations. Eluates prepared from the abdominal swabs and the color stabilizer polydiallyamine (PDAA) were incubated with blood and blood clotting was investigated. Furthermore, the effects of the abdominal swabs on blood clotting time and on heparin were investigated. Results Our data show that the three abdominal swabs as well as the respective eluates exhibit distinctive coagulant properties. The abdominal swab with the highest hypercoagulant effect significantly reduced blood clotting time and also led to a reduction in free heparin. PDAA does not induce activation of the coagulation system. Conclusion The data indicate that the hypercoagulant swab reduces the clotting time and the concentration of free heparin. Abdominal swabs used during complex cardiac surgery with heart-lung-machine support should definitely be tested for their coagulant properties using appropriate tests before clinical applications, as it cannot be specified what leads to their hypercoagulant property.

Jochen Reinbold,1 Teresa Hierlemann,1 Lukas Urich,1 Ann-Kristin Uhde,1 Ingrid Müller,2 Tobias Weindl,3 Ulrich Vogel,4 Christian Schlensak,1 Hans Peter Wendel,1 Stefanie Krajewski1 1Department of Thoracic and Cardiovascular Surgery, University Hospital Tübingen, Tübingen, 2Department of Pharmaceutical Engineering, Albstadt-Sigmaringen University of Applied Science, Albstadt, 3Aimecs® GmbH Medical Solutions, Pfarrkirchen, 4Institute of Pathology and Neuropathology, Tübingen, Germany Abstract: Polypropylene mesh implants are routinely used to repair abdominal wall defects or incisional hernia. However, complications associated with mesh implantation, such as mesh-related infections, can cause serious problems and may require complete surgical removal. Hence, the aim of the present study was the development of a safe and efficient coating to reduce postoperative mesh infections. Biodegradable poly(lactide-co-glycolide acid) microspheres loaded with rifampicin as an antibacterial agent were prepared through single emulsion evaporation method. The particle size distribution (67.93±3.39 µm for rifampicin-loaded microspheres and 64.43±3.61 µm for unloaded microspheres) was measured by laser diffraction. Furthermore, the encapsulation efficiency of rifampicin (61.5%±2.58%) was detected via ultraviolet–visible (UV/Vis) spectroscopy. The drug release of rifampicin-loaded microspheres was detected by UV/Vis spectroscopy over a period of 60 days. After 60 days, 92.40%±3.54% of the encapsulated rifampicin has been continuously released. The viability of BJ fibroblasts after incubation with unloaded and rifampicin-loaded microspheres was investigated using an MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, which showed no adverse effects on the cells. Furthermore, the antibacterial impact of rifampicin-loaded microspheres and mesh implants, coated with the antibacterial microspheres, was investigated using an agar diffusion model with Staphylococcus aureus. The coated mesh implants were also tested in an invivo mouse model of staphylococcal infection and resulted in a 100% protection against mesh implant infections or biofilm formation shown by macroscopic imaging, scanning electron microscopy, and histological examinations. This effective antibacterial mesh coating combining the benefit of a controlled drug delivery system and a potent antibacterial agent possesses the ability to significantly reduce postoperative implant infections. Keywords: postoperative infections, drug delivery system, antibacterial implant coating, Staphylococcus aureus, antibiotic

Long-term performance of implanted cardiovascular grafts can be ensured if living endothelium overgrows their surface. Surface modifications to implants are therefore being sought that can encourage endothelialization while preventing thrombus formation until the natural endothelium is formed. In the present study, heparin was covalently attached to a fibrin mesh grown from a polyvinyl chloride (PVC) substrate surface by the catalytic action of surface immobilized thrombin on a fibrinogen solution. The coating prevented platelet activation, thrombin generation and clot formation, and reduced inflammatory reactions when exposed to fresh human whole blood circulating in a Chandler loop model. In addition, in vitro seeded human umbilical vein and human saphenous vein endothelial cells showed considerably enhanced attachment and proliferation on the coating. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 2995-3005, 2017.

BACKGROUND Chitosan is used in a wide field of applications and therapies and has been reported to be an effective hemostyptic. The objective of this study was to provide further information about the use of chitosan as a hemostyptic agent also taking into focus its hemocompatible effects. METHODS Human whole blood (n=5) was anticoagulated with heparin, treated with different chitosan concentrations (0, 2.5, 5, 7.5, 10, 12.5, 25 mg/mL) and incubated at 37°C for 30 minutes. Before and after incubation different parameters for coagulation and hemocompatibility were evaluated. RESULTS Blood treated with high chitosan concentrations showed enhanced coagulation, which we evaluated with activated clotting time, activated partial thromboplastin time and concentration of thrombin-antithrombin complexes. Furthermore, we observed an activation of blood platelets, complement cascade and granulocytes in the groups treated with chitosan. CONCLUSION Our data indicate that chitosan activates human blood coagulation and hence has good properties as a hemostyptic agent. However, inflammatory parameters were upregulated after direct contact with human blood indicating that systemic administration of chitosans should not be performed whereas the topical use of chitosan as a hemostypticum should not present any hazard with regard to adverse inflammatory reactions at the site of application.