Fluorescence spectroscopy and imaging of myocardial apoptosis

Abstract

Chance, "Fluorescence spectroscopy and imaging of myocardial apoptosis", . December 2006. Fluorescence spectroscopy and imaging of myocardial apoptosis AbstractFluorometry is used to detect intrinsic flavoprotein (FP) and nicotinamide adenine dinucleotide NADH signals in an open-chest rabbit model of myocardial ischemia-reperfusion injury. Myocyte apoptosis has been shown clinically to contribute to infarct size following reperfusion of ischemic myocardium. A noninvasive means of assessing apoptosis in this setting would aid in the treatment of subsequent ventricular remodeling. We show that in vivo fluorometry can be useful in apoptosis detection in open-chest surgeries. Specific changes in myocardial redox states have been shown to indicate the presence of apoptosis. Two main mitochondrial intrinsic fluorophores, NADH and FP signals, were measured during normoxia, ischemia, and reperfusion experimental protocol. Ischemia was induced by occlusion of the largest branch of the circumflex coronary artery and fluorescence signals are collected by applying two different fluorescence techniques: in vivo fluorometry and postmortem cryoimaging. The first technique was employed to detect FP and NADH signals in vivo and the latter technique uses freeze trapping and lowtemperature fluorescence imaging. The heart is snap frozen while still in the chest cavity to make a "snapshot" of the metabolic state of the tissue. After freezing, the ischemic area and its surrounding border zone were excised and the sample was embedded in a frozen buffer for cryoscanning. These two data sets, in vivo fluorometry and low temperature redox scanning, show consistent extreme oxidation of the mitochondrial redox states (higher redox ratio) suggesting the initiation of apoptosis following reperfusion. This represents the first attempt to assess myocyte apoptosis in the beating heart. The heart is snap frozen while still in the chest cavity to make a "snapshot" of the metabolic state of the tissue. After freezing, the ischemic area and its surroundings border zone were excised and the sample was embedded in a frozen buffer for cryo-scanning. These two data sets, in vivo fluorometry and low temperature redox scanning, show consistent extreme oxidation of the mitochondrial redox states (higher 2 redox ratio) suggesting the initiation of apoptosis following reperfusion. This represents the first attempt to assess myocyte apoptosis in the beating heart.

Retinal flavoprotein fluorescence correlates with mitochondrial stress, apoptosis, and chemokine expression

“…This ratio serves as an indicator of the mitochondrial redox status because NAP(P)H oxidation correlates with FP oxidation but the fluorescence of the two molecules is inversely related. This method may also be used for in vivo experimental measurements and has been used on rabbit hearts and rodent brains during surgery to assess mitochondrial functional changes due to electrical stimulation and ischemia/reperfusion injury (Reinert et al, 2004; Shibuki et al, 2003; Shino et al, 1998; Ranji et al, 2006; Rajpurohit et al, 1999). Recently, Cano et al, 2008, used this technique to show that cultured HRPE cells incubated with increasing concentrations of H 2 O 2 or tert-butyl hydroperoxide had declining NAD(P)H fluorescence and increased FPF, indicative of impaired oxidative phosphorylation, oxidant-induced injury, and cell death.…”

PAMAM Structure‐Based Multifunctional Fluorescent Conjugates for Improved Fluorescent Labelling of Biomacromolecules

“…Keywords: biomacromolecules · dansyl chloride · dendrimers · fluorescence · fluorescent probes ganisms, [18,19] the imaging of angiogenesis, [20] intra-operative sentinel lymph node mapping, [21][22][23] the determination of protein kinase activity, [24] apoptosis imaging, [25] the functional state of cells and the detection of tumour cells. [26] A disadvantage of fluorescent labels over radioactive labels is their relatively low sensitivity.…”

Compact point-detection fluorescence spectroscopy system for quantifying intrinsic fluorescence redox ratio in brain cancer diagnostics

“…However, the same trend was not observed in the superficial and basal cells of precancerous tissues. Ranji et al 2 used in vivo fluorescence spectroscopy and imaging to study redox ratio change in myocardial apoptosis, in which the redox ratio was defined as the ratio of the fluorescence intensity of FAD and the sum of the fluorescence intensities of FAD and NADH. The higher redox ratios measured in vivo and in snap-frozen hearts were both correlated with the initiation of apoptosis following heart reperfusion.…”