Figure 3. NP exposure increases numbers of HNPC proliferating Ki67-+ cells. A.

AgNP-exposure for two weeks increased the cell proliferation in HNPCs, seen as increased numbers of Ki67+ cells (green). Representative images of 6 spheres per section from two independent experiments. Blue staining, DAPI. Au 20∶800, gold 20 nm and 800 particles/cell; Au 80∶800, gold 80 nm and 800 particles/cell; Ag 20∶800, silver 20 nm and 800 particles/cell; Ag 80∶800, silver 80 nm and 800 particles/cell; AgNO₃ 1.0, silver nitrate 1.0 mg/ml. Scale bars equal 214 µm. B. Only AgNPs significantly induced cell proliferation in HNPCs. Evaluation of the data presented under A, showing the number of Ki67-+ cells/mm² of the HNPC neurospheres. Au 20∶50, gold 20 nm and 50 particles/cell; Au 20∶800, gold 20 nm and 800 particles/cell; Au 80∶50, gold 80 nm and 50 particles/cell; Au 80∶800, gold 80 nm and 800 particles/cell; Ag 20∶50, silver 20 nm and 50 particles/cell; Ag 20∶800, silver 20 nm and 800 particles/cell; Ag 80∶50, silver 80 nm and 50 particles/cell; Ag 80∶800, silver 80 nm and 800 particles/cell; AgNO₃ 0.5, silver nitrate 0.5 mg/ml; AgNO₃ 1.0, silver nitrate 1.0 mg/ml. *p<0.05 compared to control, **p<0.01 compared to control.