In Situ Observation of mtDNA Damage during Hepatic Ischemia-Reperfusion.

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Hepatic ischemia-reperfusion (IR) injury is a severe pathophysiological event during liver surgery or transplantation and could lead to liver failure or even death. The energy supply of mitochondria plays an essential role in preventing IR injury. Mitochondrial DNA (mtDNA) is involved in maintaining the balance of energy by participating in an oxidative phosphorylation process. However, the exact relationship between IR and mtDNA remains unclear by reason of the lack of an accurate real-time analysis method. Herein, we fabricated a mitochondria-targeting fluorescent probe (mtDNA-BP) to explore mtDNA stability and supervise the changes in mtDNA in IR liver. By virtue of pyridinium electropositivity and suitable size, mtDNA-BP could accumulate in mitochondria and insert into the mtDNA groove, which made mtDNA-BP fluoresce strongly. This is attributed to the reduction of the intramolecular rotation energy loss that is restricted by DNA. By in situ fluorescence imaging, we observed in real time that mtDNA damage was aggravated by deteriorating IR injury, so the ROS-mtDNA-mediated IR damage signal pathway was speculated. Furthermore, on the basis of mtDNA-BP real-time response capability for mtDNA, we established a drug-screening method for inhibiting IR injury and found superior therapeutic performance of two potential drugs: pioglitazone and salidroside. This work contributes to our understanding of mtDNA-related disease and provides a new drug analysis method.