In vitro neuroprotection by either extracellular or endogenouse human CysC.

<p><b>A.</b> Light microscopy pictures of N2a cells incubated for 48 hours in medium containing serum or in serum-free medium in the absence or presence of different concentrations of CysC. Scale bar represents 100 µm. <b>B.</b> Neuronal survival was measured by counting live cells, and expressed as percentage of neuronal survival in cultures incubated in serum-containing medium. Data are the mean and SEM of 4 experiments. <b>C. D.</b> Primary rat cortical neurons were cultured in neurobasal medium in the presence (<b>C</b>) or absence (<b>D</b>) of B27-supplement and different concentrations of human CysC for 24 hours. Cell survival analyzed by the MTS assay is expressed as percentage of live cells in cultures incubated in B27-supplemented medium without CysC. Data are the mean and SEM of 3 experiments. F and P values determined by one way ANOVA for (C) were 85.09 and <0.0001 and for (D) 34.00 and <0.0001. <b>E</b> Primary cortical neurons isolated from brains of CysC knockout (CysCko), transgenic mice overexpressing human CysC (CysCtg), or wild type (WT) mice were incubated in B27-supplement containing or lacking media. Survival is expressed as percentage of live cells in wild type cultures incubated in B27-supplemented medium. For groups incubated with B27 the F and P values determined by one way ANOVA were 20.60 and 0.0007 and for groups incubated without B27 were 68.93 and <0.0001.