Impact of surface coating and systemic anticoagulants on hemostasis and inflammation in a human whole blood model.

BACKGROUND: Surface compatibility with blood is critical both for scientific investigations on hemostasis and clinical applications. Regarding in vitro and ex vivo investigations, minimal alteration in physiological hemostasis is of particular importance to draw reliable conclusions on the human coagulation system. At the same time, artificial coagulation activation must be avoided, which is relevant for the patient, for example to prevent stent graft occlusion. The aim was to evaluate the advantages and disadvantages of antithrombotic and antifouling surface coatings in the context of their suitability for ex vivo incubation and the study of coagulation properties. METHODS: We investigated the impact of different protocols for surface coating of synthetic material and different anticoagulants on hemostasis and platelet activation in ex vivo human whole blood. Blood samples from healthy donors were incubated in coated microtubes on a rotating wheel at 37°C. Two protocols for surface coating were analyzed for hemostatic parameters and metabolic status, a heparin-based coating (CHC, Corline Heparin Conjugate) without further anticoagulation and a passivating coating (MPC, 2-methacryloyloxethyl phosphorylcholine) with added anticoagulants (enoxaparin, ENOX; or fondaparinux, FPX). Employing the MPC-based coating, the anticoagulants enoxaparin and fondaparinux were compared regarding their differential effects on plasmatic coagulation by thrombelastometry and on platelet activation by flowcytometry and platelet function assays. RESULTS: Using the CHC coating, significant coagulation cascade activation was observed, whereas parameters remained mostly unchanged with MPC-based protocols. Extended incubation caused significantly elevated levels of the soluble membrane attack complex. Neither ENOX nor FPX caused a relevant impairment of platelet function or activation capacity and thrombelastometric parameters remained unchanged with both protocols. For translational purposes, we additionally modeled endotoxemia with the MPC-based protocols by incubating with lipopolysaccharide plus/minus thrombin. While coagulation parameters remained unchanged, elevated Interleukin 8 and Matrix Metalloproteinase 9 demonstrated preserved immune cell responsiveness. CONCLUSIONS: The MPC-based protocols demonstrated better hemocompatibility compared to CHC, and ENOX and FPX proved useful for additional anticoagulation. Furthermore, this simple-to-use whole blood model may be useful for experimental analyses of the early coagulatory and immunological response without decalcification.

Integration of Scientific Competence into Gross Anatomy Teaching Using Poster Presentations: Feasibility and Perception among Medical Students.

Scientific competences as defined in the German competency framework describes the ability to think independently and act scientifically, and forms a central component of medical education. This report describes its integration into anatomical teaching. On the basis of the findings in dissection courses from two consecutive years, students worked on either a case report (n = 70) or an original work (n=6) in the format of a scientific poster while learning to use primary literature. Posters were evaluated by juror teams using standardized evaluation criteria. Student perception of the project was estimated by quantitative and qualitative data obtained from the faculty´s course evaluation and an online-survey. Overall, students worked collaboratively and invested extra-time (median [MD] 3.0 hours) in poster creation. Primary literature was integrated in 90.8% of the posters. Overall poster quality was satisfactory (46.3 ±8.5 [mean ±standard deviation] out of 72 points), but several insufficiencies were identified. Students integrated information gained from the donor´s death certificate, post-mortem full-body computer tomography (CT) scan (22.4%) and histopathological workup (31.6%) in their case reports. Students were positive about the experience of learning new scientific skills (MD 4 on a six-point Likert scale), but free text answers revealed that some students experienced the project as an extra burden in a demanding course. In summary, it was feasible to introduce students to science during the dissection course and to increase interest in science in approximately a third of the survey respondents. Further adjustments to ensure the posters´ scientific quality might be necessary in the future.