In situ characterization of the brain-microdevice interface using device-capture histology.

Accurate assessment of brain-implantable microdevice bio-integration remains a formidable challenge. Prevailing histological methods require device extraction prior to tissue processing, often disrupting and removing the tissue of interest which had been surrounding the device. The Device-Capture Histology method, presented here, overcomes many limitations of the conventional Device-Explant Histology method, by collecting the device and surrounding tissue intact for subsequent labeling. With the implant remaining in situ, accurate and precise imaging of the morphologically preserved tissue at the brain/microdevice interface can then be collected and quantified. First, this article presents the Device-Capture Histology method for obtaining and processing the intact, undisturbed microdevice-tissue interface, and imaging using fluorescent labeling and confocal microscopy. Second, this article gives examples of how to quantify features found in the captured peridevice tissue. We also share histological data capturing (1) the impact of microdevice implantation on tissue, (2) the effects of an experimental anti-inflammatory coating, (3) a dense grouping of cell nuclei encapsulating a long-term implant, and (4) atypical oligodendrocyte organization neighboring a long term implant. Data sets collected using the Device-Capture Histology method are presented to demonstrate the significant advantages of processing the intact microdevice-tissue interface, and to underscore the utility of the method in understanding the effects of the brain-implantable microdevices on nearby tissue.