*Purpose: Ischemia induces altered bioenergetics within cells with increased mitochondrial swelling and reactive oxygen species and that ultimately degrade of cellular function. Ischemia reperfusion injury IRI induces mitochondrial fragmentation resulting in cell death and injury. Additionally, energetically related injuries are worse in metabolically stressed tissues such as steatotic liver, making them more susceptible to ischemia. Therapeutic interventions that target to improve mitochondrial health to repair, reprogram or replace mitochondria to restore respiratory functions are beneficial for prevention of disease.

*Methods: In Vivo studies: Liver injury was assessed by serum alanine aminotransferase (ALT; mU/ml) after 60 mins of ischemia and 24 hrs of reperfusion. 20-wk old B6 (lean and diet induced obese, DIO) mice were i.v. injected with mitochondria (Mito), isolated from healthy mouse liver (Mito; 50 mcg protein equivalent) 1 day before (-1d) or at time of reperfusion (@R). Functional (ALT), histological (H&E) and molecular (RTPCR) analysis were done. In Vitro studies: Huh7 and HepG2 human hepatocytes cell lines were used to evaluate uptake and therapeutic use of mitochondria using Seahorse analyzer. Palmitic and Oleic acids, PA/OA were used to induce lipid accumulation in hepatocytes to mimic steatotic liver. Mitochondria for in vitro studies was isolated from HEK293 cells.

*Results: DIO mice had significantly worse liver function compared to lean mice after IRI (ALT: 4090±236 vs 10308±304, p<0.001). Mito (-1d or @R) treated lean (ALT: -1d, 2288±157; @R, 1548±134, p<0.01) and DIO (ALT: -1d, 6811±656; @R, 2201±183, p<0.001) mice were significantly protected compared to vehicle treated mice after IRI. Mice treated with mito had higher liver gene expression of Pgc1a & Ppar and lower levels of Tnfa & Nos2 compared to vehicle treated mice. Mito treated mice had lower Suzuki score with less congestion, hemorrhage and necrosis of hepatocytes. Additionally, mito treated IRI DIO mice had less steatosis compared to vehicle treated IRI mice. In in vitro studies, Mito are taken up by hepatocytes in a dose dependent manner and Mito have significantly higher levels of extra- and intracellular ATP and higher basal oxygen consumption rate (OCR). Mito treated cells had significantly higher mRNA levels of Pgc1a. PA/OA treated cells had decreased ATP and basal OCR that was maintained at higher levels in cells treated with mito.

*Conclusions: Our data demonstrates that treatment with healthy mitochondria enhances recipient cells energy production to help replace damaged mitochondria by inducing Pgc1a to rescue cellular functions. Our current study demonstrates that treatment with healthy mitochondria can be used as therapeutic modality for prevention of hepatic IRI.

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