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. 2020 Mar 3;3:95. doi: 10.1038/s42003-020-0817-4

Fig. 7. ATRAM-BSA-PLGA NPs evade uptake by differentiated human monocytic leukemia THP-1 cells.

Fig. 7

a, b Confocal laser scanning microscopy images of THP-1 cells incubated with Dox-TPP loaded PLGA (a) or ATRAM-BSA-PLGA (b) NPs for 1–4 h at pH 7.4. Scale bar = 5 µm. c, d Flow cytometry analysis of cellular uptake of Dox-TPP loaded PLGA, crosslinked BSA-PLGA and ATRAM-BSA-PLGA NPs in THP-1 cells: c plot of side scatter (SSC) vs fluorescence signal for THP-1 cells that were either untreated (ctrl), or treated with Dox-TPP loaded PLGA, crosslinked BSA-PLGA or ATRAM-BSA-PLGA NPs for 2 h at pH 7.4; d quantification of cellular uptake of the NPs from the flow cytometry analysis (n = 4). e Schematic representation of sequestration of PLGA NPs, but not crosslinked BSA-PLGA or ATRAM-BSA-PLGA NPs, by macrophages (e.g., monocytes). f Cell viability of THP-1 cells treated with Dox-TPP loaded PLGA, crosslinked BSA-PLGA or ATRAM-BSA-PLGA NPs for 48 h at pH 7.4. Cell viability was assessed using the MTS assay, with the % viability determined from the ratio of the absorbance of the treated cells to the control cells (n = 4). g Release of inflammatory cytokines, tumor necrosis factor-alpha (TNF-α) and interleukin-1 beta (IL-1β), by THP-1 cells exposed to Dox-TPP loaded PLGA, crosslinked BSA-PLGA or ATRAM-BSA-PLGA NPs for 24 h at pH 7.4. Cells treated with lipopolysaccharide (LPS) were used as a positive control for inflammation. TNF-α and IL-1β levels in the culture medium were assayed using a commercial ELISA kit (n = 4). *P < 0.05, **P < 0.01 or non-significant (ns, P > 0.05) compared with controls.