Optical Cryoimaging Reveals a Heterogeneous Distribution of Mitochondrial Redox State in ex vivo Guinea Pig Hearts and its Alteration during Ischemia and Reperfusion

Ranji, Mahsa; Motlagh, Mohammad Masoudi; Salehpour, Fahimeh; Sepehr, Reyhaneh; Heisner, James S.; Dash, Ranjan K.; Camara, Amadou K.S.

doi:10.1109/jtehm.2016.2570219

Cited by 15 publications

(22 citation statements)

References 47 publications

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“…Our previous study showed increased reactive oxygen species (ROS) in cultured Tmem135 TG fibroblasts [ 11 ], which may be also increased in the Tmem135 TG heart. Using optical cryo-imaging [ 23 – 25 ], we examined the redox state of the Tmem135 TG heart ( Fig 5 ). This method detects changes in the oxidation state of mitochondrial metabolic coenzymes NADH (NAD in the reduced form) and FAD (FADH 2 in its oxidized form), and provides a quantitative marker for oxidative stress (the ratio of NADH/FAD; the redox ratio) in tissues [ 23 – 25 ].…”

Section: Resultsmentioning

confidence: 99%

“…The snap-frozen hearts, stored at −80°C until the day of study, were imaged in our custom-made cryo-imager at the Biophotonics Lab, University of Wisconsin-Milwaukee. We have reported extensively on the cryo-imaging system in previous studies [ 23 – 25 ]. In brief, a microtome blade sequentially slices the embedded tissue.…”

Section: Methodsmentioning

confidence: 99%

“…Major NADH and FAD signals captured originate from mitochondria with negligible contributions from cytoplasmic sources [ 26 , 27 ]. The 3D rendered images using z-stacks of all the image slices for both NADH and FAD signals, and the NADH to FAD redox ratio of each heart was calculated voxel by voxel as previously explained [ 23 – 25 ]. The intensity histogram distribution of redox ratio (NADH/FAD) for each heart was determined, and the mean value (RR) calculated as a quantitative marker for the oxidative state of the tissue.…”

Section: Methodsmentioning

confidence: 99%

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The effect of Tmem135 overexpression on the mouse heart

et al. 2018

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Tissues with high-energy demand including the heart are rich in the energy-producing organelles, mitochondria, and sensitive to mitochondrial dysfunction. While alterations in mitochondrial function are increasingly recognized in cardiovascular diseases, the molecular mechanisms through which changes in mitochondria lead to heart abnormalities have not been fully elucidated. Here, we report that transgenic mice overexpressing a novel regulator of mitochondrial dynamics, transmembrane protein 135 (Tmem135), exhibit increased fragmentation of mitochondria and disease phenotypes in the heart including collagen accumulation and hypertrophy. The gene expression analysis showed that genes associated with ER stress and unfolded protein response, and especially the pathway involving activating transcription factor 4, are upregulated in the heart of Tmem135 transgenic mice. It also showed that gene expression changes in the heart of Tmem135 transgenic mice significantly overlap with those of aged mice in addition to the similarity in cardiac phenotypes, suggesting that changes in mitochondrial dynamics may be involved in the development of heart abnormalities associated with aging. Our study revealed the pathological consequence of overexpression of Tmem135, and suggested downstream molecular changes that may underlie those disease pathologies.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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The effect of Tmem135 overexpression on the mouse heart

et al. 2018

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“…The z-sampling was 30 µm, defined by slicing thickness. Freezing, embedding and imaging procedures have been previously described [12,13].…”

Section: Cryoimagingmentioning

confidence: 99%

“…investigation to obtain a real-time information of RR in the tissue [13]. It may offer a stronger utility tool to monitor the liver function at the time of liver transplantation.…”

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confidence: 99%

Optical imaging for the assessment of hepatocyte metabolic state in ischemia and reperfusion injuries

Cour¹,

Mehrvar²,

Kim³

et al. 2017

Biomed. Opt. Express

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Deterioration in mitochondrial function leads to hepatic ischemia and reperfusion injury (IRI) in liver surgery and transplantation. 3D optical cryoimaging was used to measure the levels of mitochondrial coenzymes NADH and FAD, and their redox ratio (NADH/FAD) gave a quantitative marker for hepatocyte oxidative stress during IRI. Using a rat model, five groups were compared: control, ischemia for 60 or 90 minutes (Isc60, Isc90), ischemia for 60 or 90 minutes followed by reperfusion of 24 hours (IRI60, IRI90). Ischemia alone did not cause a significant increase in the redox ratio; however, the redox ratio in both IRI60 and IRI90 groups was significantly decreased by 29% and 71%, respectively. A significant correlation was observed between the redox ratio and other markers of injury such as serum aminotransferase levels and the tissue ATP level. The mitochondrial redox state can be successfully measured using optical cryoimaging as a quantitative marker of hepatic IR injury.

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