Minimal Tissue Reaction after Chronic Subdural Electrode Implantation for Fully Implantable Brain–Machine Interfaces

Abstract

There is a growing interest in the use of electrocorticographic (ECoG) signals in brain–machine interfaces (BMIs). However, there is still a lack of studies involving the long-term evaluation of the tissue response related to electrode implantation. Here, we investigated biocompatibility, including chronic tissue response to subdural electrodes and a fully implantable wireless BMI device. We implanted a half-sized fully implantable device with subdural electrodes in six beagles for 6 months. Histological analysis of the surrounding tissues, including the dural membrane and cortices, was performed to evaluate the effects of chronic implantation. Our results showed no adverse events, including infectious signs, throughout the 6-month implantation period. Thick connective tissue proliferation was found in the surrounding tissues in the epidural space and subcutaneous space. Quantitative measures of subdural reactive tissues showed minimal encapsulation between the electrodes and the underlying cortex. Immunohistochemical evaluation showed no significant difference in the cell densities of neurons, astrocytes, and microglia between the implanted sites and contralateral sites. In conclusion, we established a beagle model to evaluate cortical implantable devices. We confirmed that a fully implantable wireless device and subdural electrodes could be stably maintained with sufficient biocompatibility in vivo.

Electrocorticographic effects of acute ketamine on non-human primate brains

“…ECoG signal analysis is a valuable tool for mapping the cortical regions associated with epileptic events [29]. It is also widely used as a translational tool in many neuroscience studies to reveal the sensory and auditory processing mechanisms [30,31]. There is considerable interest in developing translational models to elucidate the underlying neural and neurochemical mechanisms involved in NMDA receptor functions.…”

Miniature battery-free epidural cortical stimulators

“…After 25 days, the resistance stabilized at about 2.25 kilohm, which could be due to anatomical changes in the animal including thickening of the dura or tissue regrowth in the burr hole cavity. These are known foreign body responses that can occur in subdural and epidural implants but do not present a safety concern ( 44 ). The fact that the DOT continued to deliver effective brain stimulation despite this increase in impedance supports its effectiveness as a chronic therapy even in the presence of foreign body responses.…”

Cell-membrane-inspired polymers for constructing biointerfaces with efficient molecular recognition

“…Therefore, surfaces that are gentler and more compatible with living organisms must be created. 36,37 To develop biodevices for molecular diagnosis, such as protein chips and DNA chips, surface treatment methods that prevent non-specific adsorption of target biomolecules and the decrease in bioactivity due to structural changes are required to improve the final signal-to-noise ratio. 38,39 The revolutionary developments in biotechnology are expected to drastically change society by resolving medical and other global problems in pharmaceutical, food, environmental, and energy-related industries, and to create a more prosperous and healthy society.…”

“…Therefore, surfaces that are gentler and more compatible with living organisms must be created. 36,37…”