Zheng Zhang,1 Xiang Sun,2 Zihan Gao,1 Xin Lv,1 Hui Jia,1 Bin Huang,2 Chengwan Xia,1 Xudong Yang1 

1Nanjing Stomatological Hospital, Affiliated Hospital of Medical School, Institute of Stomatology, Nanjing University, Nanjing, Jiangsu, People’s Republic of China; 2Key Laboratory for Bio-Electromagnetic Environment and Advanced Medical Theranostics, School of Biomedical Engineering and Informatics, Nanjing Medical University, Nanjing, Jiangsu, People’s Republic of China

Correspondence: Xudong Yang, Nanjing Stomatological Hospital, Affiliated Hospital of Medical School, Research Institute of Stomatology, Nanjing University, Nanjing, Jiangsu, People’s Republic of China, Email yangxd66@163.com Chengwan Xia, Nanjing Stomatological Hospital, Affiliated Hospital of Medical School, Research Institute of Stomatology, Nanjing University, Nanjing, Jiangsu, People’s Republic of China, Email 2665927917@qq.com

Introduction: Oral squamous cell carcinoma (OSCC) has a poor prognosis due to its immunosuppressive tumor microenvironment (TME), in which tumor-associated macrophages (TAMs) play a pivotal role in promoting disease progression and therapeutic resistance. This study examines whether Prussian blue nanoparticles (PB NPs) could reprogram TAMs and block tumor-stroma communication in OSCC.
Methods: PB NPs were synthesized using polyvinylpyrrolidone-assisted coprecipitation and characterized by transmission electron microscopy, dynamic light scattering, and UV-Vis spectroscopy. In vitro, their effects on macrophage polarization were assessed via immunofluorescence, Western blotting (CD206/CD86), and ELISA (TGF-β 1/IL-6/TNF-α). The impact on OSCC-macrophage interaction was evaluated using CCK-8 assays, transwell co-culture systems with conditioned media. In vivo, xenograft-bearing mice were used to assess PB NP effects on OSCC-TAM crosstalk. Tumor growth, Ki67 proliferation index, and TAM phenotypes (CD206+/CD86+) were analyzed. Systemic biocompatibility was further assessed through CCK-8 in vitro and hematological profiling and histopathological examination in vivo.
Results: PB NPs (diameter 57.43 ± 22.25 nm; zeta potential − 17.36mV) were successfully made and showed good biocompatibility in vitro and in vivo. In vitro, they shifted M2 TAMs toward anti-tumor M1 phenotypes, reducing CD206 and TGF-β 1 while increasing CD86 and pro-inflammatory cytokines (IL-6, TNF-α). This change disrupted OSCC-TAM communication, limiting tumor growth and migration. In vivo, PB NPs reduced tumor volume, lowered the Ki67+ cell ratio, and increased the intratumoral M1/M2 macrophage ratio.
Conclusion: Prussian blue nanoparticles effectively modulate the immunosuppressive TME in OSCC by shifting TAM polarization from the pro-tumor M2 phenotype to the anti-tumor M1 phenotype, thereby interrupting critical tumor-stroma interactions. Given their intrinsic immunomodulatory properties and favorable biosafety profile, PB NPs represent a promising and safe therapeutic strategy targeting the TME in OSCC.

Keywords: Prussian blue nanoparticles, tumor microenvironment, tumor-associated macrophages, oral squamous cell carcinoma