Hybrid cellular membrane nanovesicles amplify macrophage immune responses against cancer recurrence and metastasis

Effectively activating macrophages against cancer is promising but challenging. In particular, cancer cells express CD47, a ‘don’t eat me’ signal that interacts with signal regulatory protein alpha (SIRPα) on macrophages to prevent phagocytosis. Also, cancer cells secrete stimulating factors, which polarize tumor-associated macrophages from an antitumor M1 phenotype to a tumorigenic M2 phenotype. Here, we report that hybrid cell membrane nanovesicles (known as hNVs) displaying SIRPα variants with significantly increased affinity to CD47 and containing M2-to-M1 repolarization signals can disable both mechanisms. The hNVs block CD47-SIRPα signaling axis while promoting M2-to-M1 repolarization within tumor microenvironment, significantly preventing both local recurrence and distant metastasis in malignant melanoma models. Furthermore, by loading a stimulator of interferon genes (STING) agonist, hNVs lead to potent tumor inhibition in a poorly immunogenic triple negative breast cancer model. hNVs are safe, stable, drug loadable, and suitable for genetic editing. These properties, combined with the capabilities inherited from source cells, make hNVs an attractive immunotherapy.


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Xiaoyuan Chen
Aug 18, 2020 CytExpert software 2.0, Microsoft Office Excel 2007 All statistical analyses were performed on Graphpad Prism 5.0. All flowcytometry data were analyzed on CytExpert software 2.0. Bioluminescent and fluorescent images were analyzed on Living image software 4.5.5.
The authors declare that all data supporting the results in this study are available in the paper and Supplementary Information. Source data are available from the corresponding authors upon reasonable request.

nature research | reporting summary
October 2018

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All studies must disclose on these points even when the disclosure is negative. No sample size calculation was performed. Instead, we relied on journal guidelines for a minimum of n = 4 for in vitro and some in vivo tests. For antitumor efficacy and immunology assay, 5-8 animals per group were used. In addition, we adhered to sample size requirements necessary for determining statistical significance.
No data were excluded.
Experiments were repeated and experimental findings were reproducible. All the experiments were performed with at least 3 replicates.
All samples/organisms were randomly allocated into experimental groups.
Bioluminescence imaging were conducted by an independent operator, who was unaware of the treatment conditions. Immunofluorescence slides and images were coded by a lab member who was not involved in this study. Mice were analyzed in a blinded fashion. Mice were tagged with a code after transplantation and all the investigators were blinded during harvesting of tissues and data recording. For all in vitro experiments, the lead investigator was aware of the treatment group as it was very important to know clear difference between samples for downstream assays. All antibodies were verified by the supplier and each lot has been quality tested.
B16F10 murine melanoma, 4T1 murine mammary carcinoma, and 293T human embryonic kidney cell lines were all purchased from the American Type Culture Collection (ATCC). Luciferase-tagged B16F10 and 4T1 cells were established by transfection of B16F10 and 4T1 cells with vectors carrying luciferase and puromycin resistance gene. For construction of SIRP! variant-engineered cells, the cells were sorted and sub-cloned after being transduced by lentivirus expressing cell membrane bound S!V (S!V is an engineered high-affinity SIRP! variant fused with murine SIRP! transmembrane domain).
The cell line B16F10, 4T1, and 293T were certified according to the information of surface makers and morphology provided by the manufacturers. Transfected cell lines were verified using positive or negative controls according to manufacturers' suggestions and compared with the data provided by manufacturers.
All cell lines were tested for mycoplasma contamination. No mycoplasma contamination was found.
No commonly misidentified cell lines were used.