Intracellular drug retention and migration capacity determine macrophage-based drug delivery

Living cells are increasingly explored as drug carriers for their active targeting capacity; however, efficient intracellular loading in vitro often fails to translate into effective delivery in vivo.In this study, bulk RNA sequencing was performed on murine bone marrow-derived macrophages loaded with PLGA particles of different sizes (0.2 um, 1 um, and 3 um) under conditions yielding equivalent intracellular particle mass per cell. After particle loading, cells were washed and further cultured in particle-free medium for 6 to 8 hours to allow nanoparticle efflux, mimicking the circulation phase prior to tissue recruitment.Transcriptomic profiling was used to investigate how intracellular payload size regulates oxidative stress responses, cytoskeletal organization, migratory signaling pathways, and inflammatory programs. Differential gene expression and pathway enrichment analyses revealed that nanoparticle loading induces oxidative stress and suppresses key migration-related pathways, whereas microparticle loading preserves transcriptional programs associated with macrophage motility and homeostasis.These data provide mechanistic insights into how intracellular drug properties govern macrophage migration and delivery fidelity in cell-based drug delivery systems.