title: Short and long term biocompatibility of NeuroProbes silicon probes.
abstract: Brain implants provide exceptional tools to understand and restore cerebral functions. The utility of these devices depends crucially on their biocompatibility and long term viability. We addressed these points by implanting non-functional, NeuroProbes silicon probes, without or with hyaluronic acid (Hya), dextran (Dex), dexamethasone (DexM), Hya+DexM coating, into rat neocortex. Light and transmission electron microscopy were used to investigate neuronal survival and glial response. The surface of explanted probes was examined in the scanning electron microscope. We show that blood vessel disruption during implantation could induce considerable tissue damage. If, however, probes could be inserted without major bleeding, light microscopical evidence of damage to surrounding neocortical tissue was much reduced. At distances less than 100 microm from the probe track a considerable neuron loss ( approximately 40%) occurred at short survival times, while the neuronal numbers recovered close to control levels at longer survival. Slight gliosis was observed at both short and long term survivals. Electron microscopy showed neuronal cell bodies and synapses close (<10 microm) to the probe track when bleeding could be avoided. The explanted probes were usually partly covered by tissue residue containing cells with different morphology. Our data suggest that NeuroProbes silicon probes are highly biocompatible. If major blood vessel disruption can be avoided, the low neuronal cell loss and gliosis should provide good recording and stimulating results with future functional probes. We found that different bioactive molecule coatings had small differential effects on neural cell numbers and gliosis, with optimal results achieved using the DexM coated probes.
authors.affiliation: Institute for Psychology, Hungarian Academy of Sciences, Budapest, Hungary.
authors.forename: László
authors.initials: L
authors.lastname: Grand
authors.forename: Lucia
authors.initials: L
authors.lastname: Wittner
authors.forename: Stanislav
authors.initials: S
authors.lastname: Herwik
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Göthelid
authors.forename: Patrick
authors.initials: P
authors.lastname: Ruther
authors.forename: Sven
authors.initials: S
authors.lastname: Oscarsson
authors.forename: Hercules
authors.initials: H
authors.lastname: Neves
authors.forename: Balázs
authors.initials: B
authors.lastname: Dombovári
authors.forename: Richárd
authors.initials: R
authors.lastname: Csercsa
authors.forename: György
authors.initials: G
authors.lastname: Karmos
authors.forename: István
authors.initials: I
authors.lastname: Ulbert
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000009:adverse effects; D001808:Blood Vessels / Q000473:pathology; D002470:Cell Survival; D003907:Dexamethasone / Q000009:adverse effects; D003911:Dextrans / Q000009:adverse effects; D005911:Gliosis / Q000209:etiology / Q000473:pathology; D006820:Hyaluronic Acid / Q000009:adverse effects; D020300:Intracranial Hemorrhages / Q000150:complications / Q000473:pathology; D008422:Materials Testing; D019579:Neocortex / Q000166:cytology / Q000601:surgery / Q000648:ultrastructure; D009457:Neuroglia / Q000473:pathology / Q000502:physiology / Q000648:ultrastructure; D009474:Neurons / Q000473:pathology / Q000502:physiology / Q000648:ultrastructure; D019736:Prostheses and Implants / Q000009:adverse effects; D051381:Rats; D017208:Rats, Wistar; D017655:Silicon Compounds / Q000009:adverse effects; D013569:Synapses / Q000648:ultrastructure; D013997:Time Factors
chemical_list: D001672:Biocompatible Materials; D003911:Dextrans; D017655:Silicon Compounds; D003907:Dexamethasone; D006820:Hyaluronic Acid