Behavioral and cellular consequences of high-electrode count Utah Arrays chronically implanted in rat sciatic nerve.

Area of Science:

• Biocompatibility of medical devices
• Peripheral nerve regeneration
• Neuromodulation technologies

Background:

• Peripheral nerve electrodes are crucial for restoring function in neurological disorders.
• Assessing the biocompatibility of high-electrode count intrafascicular arrays is essential before clinical application.
• Understanding device-tissue interactions, including foreign body response and functional outcomes, is critical.

Purpose of the Study:

• To investigate the behavioral and histological consequences of implanting High Density Utah Slanted Electrode Arrays (HD-USEAs) in rat sciatic nerves.
• To evaluate the biocompatibility of these advanced neural interfaces.
• To determine the long-term effects of chronic HD-USEA implantation.

Main Methods:

• HD-USEAs were implanted in rat sciatic nerves for one and two months.
• Behavioral assessments included wheel running, paw withdrawal reflexes, and footprint analysis.
• Histological evaluations focused on nerve morphology and macrophage presence at the tissue-device interface.

Main Results:

• Chronic HD-USEA implantation (up to 8 weeks) led to transient behavioral deficits that recovered over time.
• Nerve morphology showed variable degeneration and regeneration distal to the implant site.
• Macrophages at the tissue-device interface exhibited a variable response, with axons remaining close to electrode tips.

Conclusions:

• HD-USEAs did not cause significant global effects in rats up to two months post-implantation.
• The consequences of HD-USEAs are comparable to existing peripheral nerve electrodes.
• These findings support the potential of HD-USEAs for clinical neuromodulation applications.