PhD Scientific Days 2018

Budapest, April 19–20, 2018

Biocompatibility of the SU-8 in the central nervous system

Tóth, Estilla Zsófia

Estilla Zsófia Tóth1, Lucia Wittner1, Richárd Fiáth1,2, Domokos Meszéna1,2, Ildikó Pál1, Edit Lelle Győri1,2, Domonkos Pinke2, Zsófia Bereczki3, Gábor Orbán1,4, Anita Pongrácz5, István Ulbert1,2, Gergely Márton1, Kinga Tóth1
1. Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary
2. Pázmány Péter Catholic University, Faculty of Information Technology and Bionics, Budapest, Hungary
3. Budapest University of Technology and Economics, Department of Control Engineering and Information Technology, Budapest, Hungary
4. Óbuda University Doctoral School on Materials Sciences and Technologies, Budapest, Hungary
5. Institute of Technical Physics and Materials Science, Centre for Energy Research, Hungarian Academy of Sciences, Budapest, Hungary

Language of the presentation

English

Text of the abstract

Inroduction:
Multichannel microelectrodes implanted in the brain are important both in basic science and in clinics. The advantage of the SU-8 material compared with the silicon is that it is more flexible, allowing a smoother coupling with the soft brain tissue.
Despite the widening use of SU-8 nowadays, a detailed systematic quantitative
study concerning its biocompatibility in the central nervous system was not
performed yet.
Aims:
In this project, we examined the biocompatibility of the SU-8 photoresist
polymer by studying the neuron density near the device surface and by assessing
the gliosis surrounding the device.
Methods:
62 probes were implanted in the brains of 31 rats. After 2 months, neurons or
glial cells were labeled with NeuN- or GFAP-immunostaining. Neuronal densities
were calculated in 20 µm wide regions up to 400 µm on the 4 sides of the
tracks. The density values of each sector were normalized to the average values
of the 200 to 400 µm regions. The severity of the gliosis around the probe
tracks was investigated in qualitative analyses at light and electron
microscopic levels.
Results:
The density of neurons significantly decreased in the first 20 µm. The average
normalized densities were 0.24±0.28 in the 0-20 µm distance. From 40 µm the
density of neurons was control-like.
We examined the brain tissue around the track at the electron microscopic level
to check whether the increased staining intensity near the track outline is a
result of the increased amount of glial processes. We could detect more
GFAP-positive glial processes near the track (40µm) than in a larger distance
(180µm).
Conclusion:
Our results indicate that SU-8 material enables a better neuronal survival in
the close vicinity of the implant than the different types of silicone based
probes which cause a significant neuronal loss typically between 50 and 100
microns from the implant surface.

Data of the presenter

Doctoral School: Neurosciences("János Szentágothai")
Program:Funkcionális Idegtudományok
Supervisor: István Ulbert
E-mail adress: tothestilla@gmail.com