Cascade active-targeting nanoplatform via multi-ligand regulation for spleen-selective mRNA delivery.

mRNA vaccines represent a promising platform for cancer immunotherapy. Spleen-targeted delivery offers a particularly attractive approach, as the spleen serves as a central hub containing dendritic cells (DCs) and naïve T cells, thereby enabling potent immune activation. However, current spleen-targeted delivery systems primarily rely on passive targeting, which is limited by the complex physiological barriers in vivo. In this study, we pioneered a cascade active-targeting platform using multi-ligand functionalization to accomplish cascade mRNA delivery to specific tissue, systematically overcoming the physiological barriers. The spleen-selective platform (Os-LLNs) incorporates SP (a phagocytosis inhibitor of macrophage), mannose (a DCs-targeted ligand), and WRK (a cell-penetrating peptide). Os-LLNs have been proved that could extend circulation in vivo through SP-ligand mediated "don't eat me" signal against macrophages, enhance specific binding with DCs in the spleen via mannose receptor and promote the internalization of DCs via WRK mediated cellular penetration. Moreover, mRNA vaccines formulated with Os-LLNs elicited robust immune responses in vivo and showed significant anti-tumor efficacy. This study presents a promising spleen-targeted mRNA vaccine platform for anti-tumor treatment and offers a strategy for designing active-targeted delivery systems.