‘Golden’ exosomes as delivery vehicles to target tumors and overcome intratumoral barriers

Exosomes are promising vectors for anti-tumor therapy, due to their biocompatibility, low immunogenicity, and innate ability to interact with target cells. However, promoting clinical application of exosome-based therapeutics requires elucidation of key issues, including exosome biodistribution, tumor targeting and accumulation, and the ability to overcome tumor barriers that limit the penetration of various nano-carriers and drugs.

A team led by researchers at Bar-Ilan University examined these parameters in exosomes derived from mesenchymal stem cells (MSC-exo) and from the A431 squamous cell carcinoma line (A431-exo), which both have potential use in cancer therapy. Using a novel technique combining gold nanoparticle (GNP) labeling of exosomes and non-invasive computed tomography imaging (CT), the researchers longitudinally and quantitatively tracked the two intravenously-injected exosome types in A431 tumor-bearing mice. CT imaging up to 48 h and subsequent ex vivo analysis revealed tumor homing abilities of both exosome types, yet there was significantly higher tumor accumulation of MSC-exo as compared to A431-exo. Moreover, MSC-exo demonstrated the ability to penetrate the tumor and distribute throughout its bulk, while non-encapsulated GNPs remained concentrated at the tumor periphery. Histological analysis showed penetration of MSC-exo not only into the tumor tissue, but also into tumor cell cytoplasm. While the proportion of biodistribution between organs at 48 h was similar for both exosome types, more rapid clearance was indicated for A431-exo. Thus, these findings demonstrate an effect of exosome type on tumor targeting abilities and biodistribution, and suggest that MSC-exo may have superior abilities for tumor-targeted therapy.

Cohen O, Betzer O, Elmaliach-Pnini N, Motiei M, Sadan T, Cohen-Berkman M, Dagan O, Popovtzer A, Yosepovich A, Barhom H, Michaeli S, Popovtzer R. (2021) ‘Golden’ exosomes as delivery vehicles to target tumors and overcome intratumoral barriers: in vivo tracking in a model for head and neck cancer. Biomater Sci [Epub ahead of print. [abstract]

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