Ricerc@Sapienza

We explored the mechanisms underlying microglia cell-carbon nanotube interactions in order to
investigate whether electrical properties of Carbon-Nanotubes (CNTs) could affect microglia brain cells
function and phenotype. We analyzed the effects induced by highly electro-conductive Multi-Walled-
Carbon-Nanotubes (a-MWCNTs), on microglia cells from rat brain cortex and compared the results with
those obtained with as prepared not conductive MWCNTs (MWCNTs) and redox-active Double-Walled-
Carbon-Nanotubes (DWCNTs). Cell viability and CNT capacity to stimulate the release of nitric oxide (NO),
pro-inflammatory (IL-1b, TNF-a) and anti-inflammatory (IL-10, TGF-b1) cytokines and neurotrophic
factors (mNGF) were assessed.
Electro-conductive MWCNTs, besides not being cytotoxic, were shown to stimulate, at 24 h cell
exposure, classical "M100 microglia activation phenotype, increasing significantly the release of the main
pro-inflammatory cytokines. Conversely, after 48 h cell exposure, they induced the transition from
classical "M100 to alternative "M200 microglia phenotype, supported by anti-inflammatory cytokines and
neuroprotective factor mNGF release. The analysis of cell morphology change, by tubulin and CD-
206 þ labelling showed that M2 phenotype was much more expressed at 48 h in cells exposed to a-
MWCNTs than in untreated cells.
Our data suggest that the intrinsic electrical properties of CNTs could be exploited to modulate
microglia phenotype and function stimulating microglia anti-inflammatory potential.