Director of Clinic Prof. Dr. med. Joachim K. Krauss, Department of Neurosurgery, MHH
Representative at the NIFE Prof. Dr. Kerstin Schwabe
Neuroelectrodes for stimulation and recording; Implant associated infections
Electrophysiological measurements in the awake and anesthetized rodent (single cell recordings, local field potentials), chronic stimulation of intracranial electrodes, behavioral paradigms (motor and cognitive behavior), implant-associated infections by biofilms in rodents
Neuroelectrodes for stimulation and recording
Electrodes that enable long-term, medically safe, spatially high-resolution electrophysiological recording and stimulation in the central nervous system are used as neuroelectric interfaces, e.g. in deep brain stimulation. In our group, we characterize in awake and anesthetized rodents electrodes with behavioral, electrophysiological, and immunohistochemical methods.
Within the framework of a DFG-funded cooperation with the Barcikowski group, Technical Chemistry I, University Duisburg-Essen, we demonstrated that the deposition of colloidal PtIr nanoparticles on electrodes contributes to the impedance optimization of recording and stimulation electrodes, without influencing the biocompatibility of the electrodes (Angelov et al., 2016 J Nanobiotechnology).
Implant-associated infections are one of the main causes of implant failure and a major challenge in many surgical areas. As a rule, these infections are caused by bacteria that adhere to the implant surface, organize in complex biofilms and induce chronic inflammation with destructive changes in the surrounding tissue. A systemic drug therapy is rarely successful, since bacteria organized in biofilms are often resistant to antibiotics and immune defense.
Within the frame of BIOFABRICATION and in collaboration with the group of Stiesch (implant-associated infections) we have established a rat model that allows investigating the biofilm formation and tissue reaction after intraoperative contamination of a transcranial screw including the involvement of the underlying brain (Glage et al., 2017 Acta Neurochirurgica). With this animal model, the effect of a release of antibacterial active ingredients by functionalized implant surfaces in biofilm-associated infections can be investigated.
Bacterial growth on a transcranial titanium screw (A) and inflammatory reaction of the surrounding tissue (B) after intraoperative colonization with Staphylococcus aureus
Pictures show a large biofilm formation with predominantly alive (green) and isolated dead bacteria (red, A1), as well as the inflammatory reaction in the surrounding tissue with multi-core giant cells (arrows) as manifestation of a foreign body reaction (B1). The bar charts show the mean + standard error for animals with bacterial colonization and vehicle-treated animals (control) for the evaluation on days 2, 10 and 21 after bacterial colonization with assessment of bacterial growth using a score (A2) and the total score for the inflammation parameters (B2). Significant differences between the groups are marked with an asterisk (*), differences to day 2 with a circle (°; ANOVA with post-hoc Tukey test at p <0.05). This model is suitable for preclinical screening of new implant materials and surfaces before their suitability is verified in more complex procedures.