Fluorescence intensity and lifetime imaging of lipofuscin-like autofluorescence for label-free predicting clinical drug response in cancer

Conventional techniques for in vitro cancer drug screening require labor-intensive formalin fixation, paraffin embedding, and dye staining of tumor tissues at fixed endpoints. This way of assessment discards the valuable pharmacodynamic information in live cells over time. Here, we found endogenous lipofuscin-like auto-fluorescence acutely accumulated in the cell death process. Its unique red autofluorescence could report the apoptosis without labeling and continuously monitor the treatment responses in 3D tumor-culture models. Lifetime imaging of lipofuscin-like red autofluorescence could further distinguish necrosis from apoptosis of cells. Moreover, this endogenous fluorescent marker could visualize the apoptosis in live zebrafish embryos during development. Overall, this study validates that lipofuscin-like autofluorophore is a generic cell death marker. Its characteristic autofluorescence could label-free predict the efficacy of anti-cancer drugs in organoids or animal models.

Automated summary

Conventional techniques for in vitro cancer drug screening lack the ability to assess pharmacodynamic information in live cells over time. This study found that endogenous lipofuscin-like autofluorescence can acutely accumulate during cell death and serve as a marker for apoptosis. The unique red autofluorescence of this marker can monitor treatment responses in 3D tumor-culture models and distinguish between necrosis and apoptosis. Furthermore, it can visualize apoptosis in live zebrafish embryos. Overall, this study validates the effectiveness of lipofuscin-like autofluorescence as a generic cell death marker for predicting the efficacy of anti-cancer drugs.