Augmenting macropinocytosis enhances the apoptotic body-mediated tumor deep penetration of nanomedicines

Overcoming the penetration barrier of nanomedicines remains a paramount challenge in antitumor therapy. Apoptotic bodies (ApoBDs), which are naturally generated from apoptotic cells, can mediate a potent neighboring effect by transferring drug to neighboring tumor cells via macropinocytosis. To amplify this process, we developed a tumor microenvironment-responsive nanoplatform (named as AD-NVs@CPP) to selectively enhance chemokine (C-X-C motif) receptor 4 (CXCR4) receptor-stimulated macropinocytosis. This platform was constructed by co-encapsulating doxorubicin (DOX) and the hypoxia-activated prodrug AQ4N into homologous tumor cell membrane-derived nanovesicles (AD-NVs), followed by biomineralization of a calcium phosphate (CaP) shell that incorporated a CXCR4-targeting peptide (RFFE-SHAPAKPVSLSYR). The resultant AD-NVs@CPP exhibited a core-shell structure with a hydrodynamic diameter of ∼180 nm and achieved a high peptide encapsulation efficiency of 81.6 % ± 8.2 %. The CaP shell demonstrated excellent pH-responsive dissolution, releasing ∼50 % of the peptide within 24 h at pH 6.5 (vs. negligible release at pH 7.4), which consequently promoted cellular uptake and enhanced cytotoxicity under acidic conditions in vitro. Additionally, AD-NVs@CPP-induced ApoBDs served as efficient drug reservoirs, delivering drugs to adjacent cells with an IC50 value of 0.98 µg/mL (in terms of protein concentration). In vivo, AD-NVs@CPP significantly prolonged the blood circulation time (increasing the half-life of DOX compared to the free drug solution) and improved tumor accumulation. Crucially, it enabled programmed drug penetration: AQ4N was selectively delivered into deep hypoxic tumor regions, mediating comprehensive tumor growth inhibition while maintaining a favorable safety profile. This work provides a robust strategy for achieving deep tumor penetration through the synergistic enhancement of macropinocytosis and the ApoBD-mediated neighboring effect.