Co-administration of macropinocytosis inhibitory nanoparticles (MiNP) for enhanced nanoparticle circulation time and target tissue accumulation following subcutaneous injection

A signficant barrier to the application of nanoparticles for precision medicine is the mononuclear phagocyte system (MPS), a diverse population of phagocytic cells primarily located within the liver, spleen and lymph nodes. The majority of nanoparticles are indiscriminantly cleared by the MPS via macropinocytosis before reaching their intended targets, resulting in side effects and decreased efficacy. This work demonstrates that the biodistribution and desired tissue accumulation of targeted nanoparticles can be significantly enhanced by co-injection with polymeric micelles containing the actin depolymerizing agent latrunculin A. These macropinocytosis inhibitory nanoparticles (MiNP) were found to selectively inhibit non-specific uptake of a second "effector" nanoparticle in vitro without impeding receptor-mediated endocytosis. In tumor bearing mice, co-injection with MiNP in a single multi-nanoparticle formulation significantly increased the accumulation of folate-receptor targeted nanoparticles within tumors. Furthermore, subcutaneous co-administration with MiNP allowed effector nanoparticles to achieve serum levels that rivaled a standard intravenous injection. This effect was only observed if the effector nanoparticles were injected within 24 h following MiNP administration, indicating a temporary avoidance of MPS cells. Co-injection with MiNP therefore allows reversible evasion of the MPS for targeted nanoparticles and presents a previously unexplored method of modulating and improving nanoparticle biodstribution following subcutaneous administration. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=194 SRC="FIGDIR/small/267054v1_ufig1.gif" ALT="Figure 1"> View larger version (54K): org.highwire.dtl.DTLVardef@e2e675org.highwire.dtl.DTLVardef@883af7org.highwire.dtl.DTLVardef@1d74912org.highwire.dtl.DTLVardef@fe6bd9_HPS_FORMAT_FIGEXP M_FIG C_FIG TOC Text: Polymeric macropinocytosis inhibiting nanoparticles reduce non-specific uptake of an "effector" nanoparticle by cells of the mononuclear phagocyte system. This macropinocytosis specific inhibition allows for greater accumulation and uptake of targeted nanoparticles in tissues of interest thereby increasing their efficacy and reducing side effects.