Shedding Light on Life: Optical Assessment of Mitochondrial Function and Tissue Vitality in Biology and Medicine
Prof. Avraham Mayevsky
The discovery of the mitochondrion, an intracellular micro-organelle, 120 years ago, led to very intensive research activities that have recently evolved into a new field, named "Mitochondrial Medicine". The involvement of mitochondrial dysfunction in various pathophysiological conditions, developed in experimental and clinical situations, is widely documented. Nevertheless, real time monitoring of mitochondrial function In-vivo is very rare. The pressing question is how the mitochondria of intact tissues behave under In-vivo conditions as compared to isolated mitochondria that had been described by Chance and Williams over 50 years ago (JBC 217: 409-427,1955; Nature 176:250-254, 1955). This subject has been recently discussed in detail (Mayevsky and Rogatsky. Am. J Physiol. Cell Physiol. 292:C615-C649, 2007). We reviewed the subject of evaluating mitochondrial function by monitoring NADH fluorescence together with microcirculatory blood flow, Hemoglobin oxygenation and tissue reflectance. These 4 parameters represent the vitality of the tissue (oxygen supply/demand) and could be monitored in vivo, using optical spectroscopy, in animal models as well as in clinical practice. Monitoring the vitality of specific organs, i.e. the brain, kidney or muscle, provides information on the particular organ itself; furthermore, the specific organ monitoring can also indicate the vitality of the entire body.
It is a well known physiological hypothesis that, under emergency conditions, the sympathetic nervous system will give preference to the most vital organs in the body, namely the brain, heart and adrenal glands. The less vital organs, such as the skin, GI-tract, and Urethral wall, will become hypoperfused and their mitochondrial activity will be inhibited. The monitoring of the less vital organs may reveal critical tissue conditions that may manifest an early phase of body deterioration.
The aim of the current presentation is to review the experimental and preliminary clinical results accumulated using a new integrated medical device – the "CritiView" which enabled, for the first time, monitoring 4 parameters from the tissue using a single optical probe. The CritiView is a computerized optical device that integrates hardware and software in order to provide real time information on tissue vitality.Testing the effects of various O2 deprivation conditions in small animal models, showed statistically significant correlations between the CritiView and the individual predicate device for all 4 monitored parameters. In preliminary clinical testing, we used a 3-way Foley catheter that includes a bundle of optical fibers enabling the monitoring of the 4 parameters, representing the vitality of the urethral wall (a less vital organ).We found that the exposure of patients to metabolic imbalances in the operation room led to changes in tissue blood flow and inhibition of mitochondrial function in the urethral wall.
In conclusion, the new device" CritiView" could provide reliable, real time data on mitochondrial function and tissue vitality in experimental animals as well as in patients
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