Exosome-Based Imaging-Guided Cancer Therapy Activates Immune Cells

Researchers from Sogang University, Chung-Ang University, and the Daegu Gyeongbuk Institute of Science and Technology in South Korea have developed an exosome-based technology capable of treating tumor cells through two unique, simultaneous methods: guided laser irradiation and anti-cancer immunity.

The team of scientists, led by Dr. Hyuncheol Kim, used tumor-derived re-assembled exosomes (R-Exo), extracellular vesicles released by tumor cells, as the basis for their anti-cancer technology, and loaded the exosomes with the photosensitizing pigment chlorin e6, an organic molecule with structural similarities to chlorophyll.

Their findings were published in the Journal of Controlled Release under the title, “Exosome-based photoacoustic imaging guided photodynamic and immunotherapy for the treatment of pancreatic cancer.”

R-exo, which share a lipid bilayer membrane structure similar to that of a normal cell, bear membrane proteins that permit their targeting to cancerous cells, providing a platform for the more precise delivery of therapeutic agents to cancerous cells but not normal, healthy cells.

Upon exposure to certain wavelengths of light, chlorin e6 “can efficiently generate reactive oxygen species inside tumor cells.” Reactive oxygen species are toxic molecules that promote cell death, and when produced in cancerous cells, ultimately the destruction of tumors.

By loading R-exo with the chemotherapeutic pigment chlorin e6, the researchers were able to “zap” cancerous cells using imaging-guided laser irradiation. Neither the “original average size” nor the membrane protein composition of R-exo were altered by the loading of chlorin e6.

R-exo enabled chlorin e6 to be targeted to cancerous cells while avoiding its uptake by normal cells, thus minimizing off-target effects.

In addition to their chemotherapeutic use, the scientists discovered that chlorin e6-containing R-exo “increased the release of cytokines,” mediators of inflammation and immune cell activation that could contribute to propagating the anti-cancer immune response.

The scientists concluded that their approach “enables photoacoustic imaging-guided photodynamic and immune-combination therapy for the treatment of cancer.”

Notably, this publication described laboratory studies of their technology and not evaluation in humans.

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Jang Y, Kim H, Yoon S, et al. (2021) Exosome-based photoacoustic imaging guided photodynamic and immunotherapy for the treatment of pancreatic cancer. Journal of Controlled Release, 330: 293-304.