Micro-CT and Histological Evaluation of an Neural Interface Implanted Within a Blood Vessel

<italic>Objective:</italic> Recently, we reported the development of a stent-mounted electrode array (Stentrode) capable of chronically recording neural signals from within a blood vessel with high fidelity. Preliminary data suggested incorporation of the Stentrode into the blood vessel wall was associated with improved recording sensitivity. We now investigate neointimal incorporation of the Stentrode, implanted in a cohort of sheep for up to 190 days. <italic>Methods:</italic> Micro-CT, obtained from the Imaging and Medical Beamline at the Australian Synchrotron, and histomorphometic techniques developed specifically for evaluation of cerebral vasculature implanted with a stent-electrode array were compared as measures to assess device incorporation and vessel patency. <italic>Results:</italic> Both micro-CT analysis and histomorphometry, revealed a strong correlation between implant duration and the number of incorporated stent struts. <10% (26/268) of stent struts were covered in neointima in sheep implanted for <2 weeks, increasing to >78% (191/243) between 2 and 4 weeks. Average strut-to-lumen thickness from animals implanted >12 weeks was comparable across both modalities, <inline-formula><tex-math notation="LaTeX">$339 \pm 15\, \mu{\rm m}$</tex-math></inline-formula> measured using micro-CT and <inline-formula><tex-math notation="LaTeX">$331 \pm 19\, \mu{\rm m}$</tex-math></inline-formula> (<inline-formula><tex-math notation="LaTeX">$n = 292$</tex-math></inline-formula>) measured histologically. There was a strong correlation between lumen areas measured using the two modalities (<inline-formula><tex-math notation="LaTeX">$p < 0.001$</tex-math></inline-formula>), with no observation of vessel occlusion observed from any of the 12 animals implanted for up to 190 days. <italic>Conclusion:</italic> Micro-CT and the histomorphometric techniques we developed are comparable and can both be used to identify incorporation of a Stentrode implanted in cerebral vessels. <italic>Significance:</italic> This study demonstrates preliminary safety of a stent-electrode array implanted in cerebral vasculature, which may facilitate technological advances in minimally invasive brain–computer interfaces.

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