Advances in Tumor Inhibition by Repolarized M2 Macrophages

The tumor microenvironment (TME) plays a crucial role in the occurrence, growth, and metastasis of tumors. Tumor-associated macrophages (TAMs), derived from bone marrow precursor cells, exhibit functional plasticity by polarizing into either pro-tumor M2 or anti-tumor M1 phenotypes depending on the microenvironment. This paper explores the advantages and limitations of targeted drug delivery systems using nanocarriers for the repolarization of M2 macrophages into M1 macrophages within the TME. While passive targeted transport techniques allow drug-carrying nanomedicine to selectively accumulate in tumor regions, the efficacy is often hindered by the host's immune response and the inherent toxicity of certain nanomaterials. This review summarizes the current landscape of nanocarriers, emphasizing the need for future research to explore novel nanomaterials and expand the database of drug delivery systems to optimize therapeutic outcomes. Moreover, the potential of polarized macrophage-targeted therapies remains underexplored, suggesting a critical area for future breakthroughs.