Neurobiochemical changes in the vicinity of a nanostructured neural implant

Scientific Reports, 2016 · DOI: 10.1038/srep35944 · Published: October 24, 2016

Simple Explanation

Neural interface technologies, like recording and stimulation electrodes, are being tested to help patients with conditions like spinal cord injuries or amputations. A key challenge is their limited lifespan due to the body's response, which leads to neuron loss and scar tissue forming around the implant. This study explores whether using nanostructured surfaces on implants can improve their compatibility with brain tissue. The researchers compared nanostructured silicon surfaces to microstructured ones, focusing on how they affect neuron survival and scar tissue formation. The findings suggest that nanostructured surfaces may help more neurons survive near the implant compared to microstructured surfaces. This could mean that electrodes with nanostructured coatings might be able to record brain signals for longer periods.

Study Duration

8 Weeks

Participants

3 Wistar rats

Evidence Level

Not specified

Key Findings

1
No significant difference was observed in the severity of gliosis (scar tissue formation) in the vicinity of the different implant surfaces.
2
The number of surviving neurons close to the nanostructured surface was higher than that of the microstructured ones.
3
Significant difference was also shown between the flat and nanostructured Si surfaces implying that nanotopography is favoured by neurons within the distance relevant in single cell neural recording.

Research Summary

The study investigates the chronic effect of micro- and nanostructured surfaces on living brain tissue eight weeks after implantation, focusing on glial scar formation and recording failure. GFAP staining decreased with distance from the implant site, with no significant difference in the immediate vicinity (50 μm) between surface properties, indicating a uniform glial scar formation. Significantly more neurons were present adjacent to nanostructured surfaces compared to others in the first 50 μm, suggesting that surface topography alters the effect of implantation regarding neuron preservation.

Practical Implications

Improved Long-Term Recordings

Si nanopillars may lead to improved long-term recordings due to higher neuronal survival.

Passive Surface Modification

Nanostructuring poly-Si thin film can be performed during the fabrication of microsystems at a wafer scale, simplifying the manufacturing process.

ECM Interaction

Nanostructured surfaces have the potential to reduce the inflammatory process and prevent secondary neuronal cell death by mimicking the physiological ECM structures.

Study Limitations

1
The early steps of gliosis is probably mostly induced by the injury.
2
Some bleeding is inevitable, but the extent of it depends on the position of the implant and its distance from the larger blood vessels.
3
Micromotions in the brain tissue which is the main reason, why tethered electrodes are reported to cause more tissue damage

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