title: Influence of probe flexibility and gelatin embedding on neuronal density and glial responses to brain implants.
abstract: To develop long-term high quality communication between brain and computer, a key issue is how to reduce the adverse foreign body responses. Here, the impact of probe flexibility and gelatine embedding on long-term (6w) tissue responses, was analyzed. Probes of same polymer material, size and shape, flexible mainly in one direction, were implanted in rat cerebral cortex (nimplants = 3 x 8) in two orientations with respect to the major movement direction of the brain relative to the skull: parallel to (flex mode) or transverse to (rigid mode). Flex mode implants were either embedded in gelatin or non-embedded. Neurons, activated microglia and astrocytes were visualized using immunohistochemistry. The astrocytic reactivity, but not microglial response, was significantly lower to probes implanted in flex mode as compared to rigid mode. The microglial response, but not astrocytic reactivity, was significantly smaller to gelatin embedded probes (flex mode) than non-embedded. Interestingly, the neuronal density was preserved in the inner zone surrounding gelatin embedded probes. This contrasts to the common reports of reduced neuronal density close to implanted probes. In conclusion, sheer stress appears to be an important factor for astrocytic reactivity to implanted probes. Moreover, gelatin embedding can improve the neuronal density and reduce the microglial response close to the probe.
authors: Neuronano Research Center (NRC), Department of Experimental Medical Science, Lund University, Lund, Sweden.
authors: Per
authors: P
authors: Köhler
authors: Neuronano Research Center (NRC), Department of Experimental Medical Science, Lund University, Lund, Sweden.
authors: Anette
authors: A
authors: Wolff
authors: Neuronano Research Center (NRC), Department of Experimental Medical Science, Lund University, Lund, Sweden; Department of Measurement Technology and Industrial Electrical Engineering, Electrical Measurements, The Faculty of Engineering at Lund University, Lund, Sweden.
authors: Fredrik
authors: F
authors: Ejserholm
authors: Neuronano Research Center (NRC), Department of Experimental Medical Science, Lund University, Lund, Sweden; Department of Measurement Technology and Industrial Electrical Engineering, Electrical Measurements, The Faculty of Engineering at Lund University, Lund, Sweden.
authors: Lars
authors: L
authors: Wallman
authors: Neuronano Research Center (NRC), Department of Experimental Medical Science, Lund University, Lund, Sweden.
authors: Jens
authors: J
authors: Schouenborg
authors: Neuronano Research Center (NRC), Department of Experimental Medical Science, Lund University, Lund, Sweden.
authors: Cecilia E
authors: CE
authors: Linsmeier
mesh_terms: D000818:Animals; D001253:Astrocytes / Q000187:drug effects / Q000473:pathology; D062207:Brain-Computer Interfaces; D002540:Cerebral Cortex / Q000187:drug effects / Q000473:pathology; D004567:Electrodes, Implanted; D005780:Gelatin / Q000627:therapeutic use*; D009457:Neuroglia / Q000187:drug effects / Q000473:pathology; D009474:Neurons / Q000187:drug effects* / Q000473:pathology; D011108:Polymers / Q000627:therapeutic use; D019736:Prostheses and Implants / Q000009:adverse effects*; D051381:Rats
chemical_list: D011108:Polymers; D005780:Gelatin