FLIVO® (FLuorescence in vIVO) is a powerful method for assessing caspase activity. FLIVO allows for the in vivo detection of caspase-mediated apoptosis in living animals and cells. In a recent publication, “Selective Targeting of Cancer Stem Cells (CSCs) Based on Photodynamic Therapy (PDT) Penetration Depth Inhibits Colon Polyp Formation in Mice”, FLIVO was used to evaluate cell death in live animals. This is a key advantage of FLIVO, that it can be used in whole live animals.
Fluorescent red SR-FLIVO was diluted in PBS at a dose determined by body weight of the animal, and then intravenously injected into the animal. After 1 hour, mice were sacrificed, and their colons were isolated. SR-FLIVO was detected using a conventional laser scanning confocal microscope.
Selectively killing cancer stem cells (CSCs) without harming normal stem cells could present an important therapeutic approach. Leucine-rich repeat-containing G-protein coupled receptor 5 (Lgr5) is a colorectal cancer stem cell marker. However, because Lgr5 is also expressed in normal stem cells, proving the efficacy of treatments solely targeting Lgr5+ cancer cells are problematic. Researchers adapted a photodynamic treatment method involving cellular radiative transfer between green fluorescent protein (GFP)-expressing cells and a rose bengal photosensitizer. Following treatment, tumors comprised of GFP-Lgr5+ cells were reduced with minimal effect on non-cancerous GFP-Lgr5+ stem cells, thus demonstrating the potential for an Lgr5-targeted therapy for colon cancer prevention in high-risk patients.
Kim JK, Byun MR, Maeng CH, Kim YR, Choi JW. Selective Targeting of Cancer Stem Cells (CSCs) Based on Photodynamic Therapy (PDT) Penetration Depth Inhibits Colon Polyp Formation in Mice. Cancers (Basel). 2020 Jan 14;12(1):203. doi: 10.3390/cancers12010203. PMID: 31947553; PMCID: PMC7017170.