Figure 5.

The culture medium was collected from different ex vivo conditions presented in the diagram and incubated with oligomeric Aβ₄₂. After 24 h incubation, the culture medium did not notably reduce the level of Aβ₄₂. Thus, the cultured glial cells incubated on top of the human AD sections did not secrete notable levels of Aβ₄₂ degrading proteases outside the cell, suggesting that the Aβ degradation was principally an intracellular process. In addition, in the samples where only astrocytes were cultured with brain sections without protease inhibitors, there was no increase in the level of added Aβ₄₂ peptides when these were compared to medium only collected from the top of the brain sections (with no astrocytes). This indicates that the astrocytes had degraded intracellularly the Aβ derived from the sections and did not simply displace it into the medium.