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Figure 4. Therapeutic concept and experimental validation of PLGA NPs for siRNA-mediated PD-L1 silencing. This figure illustrates the use of PLGA NPs as a nanoplatform for siRNA-mediated PD-L1 silencing to enhance intracellular delivery and reduce tumor immune evasion. It conceptually shows how NP-enabled gene silencing may mitigate PD-L1-associated resistance mechanisms and improve responsiveness to immunotherapy. Model: pancreatic cancer. Key readouts: NP uptake, intracellular siRNA delivery, PD-L1 knockdown, and inhibition of IFN-γ-induced PD-L1 upregulation. (A) Confocal imaging of Blue #96 cells treated with Cy5.5-scRNA@PLGA NPs, showing robust cellular uptake at a concentration of 2 mg/mL; (B) FACS histogram of Blue #96 cells treated with Cy5.5-scRNA@PLGA, showing substantial cellular uptake of the NPs; (C) Western blot analysis of Blue #96 cells after transfection with siPD-L1@PLGA NPs, showing a marked decrease in PD-L1 expression 2-3 days after treatment; (D) FACS histogram of PD-L1 expression under different treatments, showing that siPD-L1@PLGA reduced IFN-γ-induced PD-L1 expression, whereas scPD-L1@PLGA did not. Reprinted from Multidisciplinary Digital Publishing Institute under a CC BY 4.0 license^[64]. PLGA: Poly(lactic-co-glycolic acid); NPs: nanoparticles; siRNA: small interfering RNA; PD-L1: programmed death-ligand 1; IFN-γ: interferon-γ; scPD-L1: scrambled siRNA; FACS: fluorescence-activated cell sorting; MFI: mean fluorescence intensity.