No contact PAM protects neurons against Aβ25-35-mediated toxicity and the condition medium of DPM aggravated Aβ-mediated neurotoxicity. The protocol of no contact co-culture experiment and conditioned medium transferring experiment are described in the Methods section and illustrated in the upper panel of A and B, respectively. A. Cortical neurons were co-cultured but not contacted to the coverslip and was not seeded with microglia (black columns), seeded with PAM (gray columns), or seeded with DPM (white column). The cultures were treated with 5 μM or 20 μM fibril Aβ25-35 for 24 h. The coverslip was removed and then the viability of neurons was detected using MTT reduction assay. Results are means ± S.D. from four independent experiments. Significant differences between neurons co-cultured with coverslip seeded and not seeded with microglia are indicated by **, P < 0.01. B. Cortical neurons were cultured in normal medium (black columns), conditioned medium from Aβ-treated PAM (gray columns) or Aβ-treated DPM (white columns). Three different species of Aβ including fAβ25-35, oAβ, and fAβ were used. Neuronal viability was assessed using an MTT reduction assay. The results are the mean ± S.D. from four independent experiments. Significant differences between neurons and neurons incubated with microglial condition medium are indicated by *, P < 0.05.