Cisplatin-Loaded M1 Macrophage-Derived Vesicles Have Anti-Cancer Activity in Osteosarcoma
Namrata Anand, J. Robert McCorkle, David Schweer, Lan Li, Kristen S. Hill, Melissa A. Fath, Derek B. Allison, Christopher L. Richards, Jill Kolesar
Abstract
Osteosarcoma (OS) is a relatively rare bone malignancy that primarily affects children and young adults and is associated with significant morbidity and mortality. Cisplatin is a mainstay of treatment, but its efficacy is limited by off-target toxicities. Immunotherapy is not effective due to a poor antigenic tumor microenvironment. Here, we address these challenges by using manufactured M1 macrophage-derived vesicles (MVs) loaded with cisplatin. Human blood and mouse RAW 264.7 M1 macrophages were used to prepare empty (E-MVs) and cisplatin-loaded MVs (C-MVs). Human OS cell lines were used in vitro and in a tibia xenograft mouse model to evaluate the anti-cancer and immune-stimulating abilities of MVs. C-MVs had lower IC50s but equivalent DNA damage in OS cell lines when compared with free cisplatin. E-MVs and C-MVs were observed to accumulate in the tumor in OS tumor-bearing mice. C-MVs significantly reduced tumor burden and prolonged survival in a mouse model of OS. Animals dosed with free cisplatin experienced weight loss and renal and hepatic toxicity, while equivalent doses of C-MVs did not cause these effects. In addition, both E-MVs and C-MVs showed immunomodulation of the tumor microenvironment with a significant increase in the M1/M2 macrophages ratio (7-fold and 22-fold, respectively) and increased levels of TNF-α in serum (1.8-fold and 2.1-fold, respectively) compared to control mice. Collectively, these experiments support further development of C-MVs for the treatment of OS.