Superparamagnetic Iron Oxide Nanoparticles Combined With CD47 Monoclonal Antibody Against Osteosarcoma By Activating Macrophages

Objective Osteosarcoma(OS)is a kind of malignant bone tumor which often occurs in adolescents.It has high heterogeneity and is easy to relapse and metastasize,so new and effective treatment is urgently needed.In recent years,the rise of tumor immunotherapy brings new hope for OS.Macrophages are the most abundant immune cells in tumor microenvironment.However,different subtypes of macrophages have different effects on tumor.M1 macrophages have inhibitory effect on tumor,while M2 macrophages play a role in promoting tumor occurrence and development.At the same time,the CD47 protein on the surface of tumor cells can help tumor cells escape the phagocytosis of macrophages.In this study,superparamagnetic iron oxide nanoparticles(SPION)was used to stimulate macrophages to polarize to M1 phenotype,and CD47 monoclonal antibody(CD47m Ab)was used to block CD47-SIRP-α signal pathway to enhance the tumor clearance ability of macrophages,so as to explore a new way for immunotherapy of OS.Methods Different phenotypic macrophages have different markers.M1 macrophages mainly express CD86,tumor necrosis factor-α(TNF-α),reactive oxygen species(ROS)and so on.The phenotypic transformation of macrophages treated with SPION was detected by flow cytometry and Western blotting.The effect of SPION combined with CD47 m Ab on the phagocytosis of OS by macrophages was further evaluated by flow cytometry.And the inhibitory effect of M1 polarized macrophages on the proliferation and migration of OS was studied by related experiments.Results The experimental results show that there are a large number of CD47 protein that can help OS cells escape immune surveillance in OS tissues.At the same time,OS tissues are rich in M2 macrophages that promote tumor growth.Our results show that SPION can promote macrophages to polarize to M1 phenotype by stimulating NFκB p65 phosphorylation,and the polarized M1 macrophages show stronger phagocytic ability and can significantly inhibit the proliferation and migration of OS cells.Blocking CD47-SIRP-α signal pathway by CD47 m Ab can promote the phagocytosis of macrophages to OS.The combined effect of SPION and CD47 m Ab can enhance the ability of macrophages to phagocytize OS cells.At the same time,SPION can inhibit the proliferation and migration of OS by polarizing macrophages.Conclusions This experiment shows that SPION combined with CD47 m Ab can effectively activate macrophages and promote phagocytosis,proliferation inhibition and migration inhibition of macrophages to OS.SPION combined with CD47 m Ab can play a great role in tumor immunity participated by macrophages and enhance the anti-tumor effect of macrophages,which provides a new idea for the immunotherapy of OS.