Translational Application of Measuring Mitochondrial Functions in Blood Cells Obtained from Patients with Acute Poisoning

Attenuation of mitochondrial dysfunction in a ventricular fibrillation swine model of cardiac arrest treated with carbon monoxide

BACKGROUND

Out-of-hospital cardiac arrest (OHCA) affects over 360,000 adults in the United States each year with a 50-80% mortality. Despite aggressive supportive care and use of targeted temperature management, half of adults do not live to hospital discharge and nearly one-third of survivors have significant neurologic injury. Development of neuroprotective therapeutics is critical to improving outcomes. One promising readily available agent that has shown benefit is carbon monoxide (CO).

METHODS

We utilize a swine model of ventricular fibrillation (VF) arrest to assess the therapeutic effect of CO on cellular measures. All animals underwent VF arrest followed by cardiopulmonary resuscitation until achievement of return of spontaneous circulation (ROSC) or the 20 min mark. One hour following ROSC, animals were randomized to the Cardiac Arrest group (VF alone) versus the CO group (VF treated with CO). Animals in the CO group were administered low dose CO of 200 ppm for two hours. At three hours post-ROSC period, all animals were euthanized for tissue and blood collection for mitochondrial respiration (cortical and hippocampal tissue) and the downstream biomolecular analysis.

RESULTS

The primary findings were an overall improvement in mitochondrial respiration and ATP concentrations in the brain from animals in the Carbon Monoxide group. In addition, we also report the use of cell-free DNA as a biomarker to localize the site of tissue injury and our non-invasive optical measuring device to assess cerebral metabolism.

CONCLUSIONS

CO may be a potential therapeutic to attenuate cellular injury in post-arrest.

Blood Cells as a Cellular Biomarker for Mitochondrial Function in a Experimental Model of Acute Carbon Monoxide Poisoning with Treatment

INTRODUCTION

Carbon monoxide (CO) is a leading cause of environmental poisoning in the United States with substantial mortality and morbidity. The mechanism of CO poisoning is complex and includes hypoxia, inflammation, and mitochondrial dysfunction. Currently both biomarkers and therapies for CO poisoning are limited and require new approaches.

METHODS

Rats (~ 300 g) were divided into four groups of ten rodents per group (exposure): Control (room air), CO-400 (400 ppm), CO-1000 (1000 ppm) and CO-2000 (2000 ppm). Rodents received the assigned exposure through a secured tracheotomy tube over 120 min followed by 30 min of re-oxygenation at room air for a total of 150 min. Five additional rodents in each group were administered a succinate prodrug (NV354) at the start of exposure for the duration of the experiment until the reoxygenation period as separate experiments. Cortical brain tissue and whole blood were obtained for mitochondrial respiration. Stored plasma and snap frozen tissue stored at -80oC were used to obtain protein quantification with Western Blotting.

RESULTS

All animals in the Sham, CO-400, and CO-1000 groups survived until the end of the exposure period; no animals in the CO-2000 groups survived the exposure and were counted as attrition. We observed a dose-dependent decrease in key respiratory states in both isolated brain mitochondria and peripheral blood mononuclear cells (PBMCs), and, PBMCs respiration more positively correlated with isolated brain mitochondria when compared to carboxyhemoglobin (COHb). There was no significant difference in mitochondrial respiratory states in animals treated with NV354 compared to the untreated group.

CONCLUSIONS

The primary findings from this study include: (1) A dose-dependent decrease with key respiration states with higher concentrations of CO; (2) PBMCs had a higher correlation to isolated brain mitochondria respiration when compared to COHb; and (3) there was no treatment effect with the use of NV354.

Impairment of platelet mitochondrial respiration in patients with chronic kidney disease with and without diabetes

Chronic kidney disease (CKD) and diabetic kidney disease (DKD) are major public health problems, and their burden is growing relentlessly with the aging of the global population. Their early recognition is now a public health priority, and there is an unmet need for the identification of specific biomarkers in minimally invasive or non-invasive samples. Mitochondrial dysfunction plays a pivotal role in the development and progression of both CKD and DKD and circulating platelets have emerged as an ideal candidate for the assessment of the respiratory function. The present study assessed mitochondrial respiration in platelets isolated from the peripheral blood of patients with DKD and CKD compared to healthy controls. The study included a total number of 89 subjects, as follows: 30 DKD patients divided into three subgroups based on the urinary albumin-to-creatinine ratio (uACR): 20 normoalbuminuric, 10 microalbuminuric, and 10 macroalbuminuric, 29 CKD patients (positive controls) and 20 healthy individuals (negative controls). Platelets were isolated by differential centrifugations and a high-resolution respirometry protocol was adapted to assess mitochondrial respiration dependent on complex I (CI) and complex II (CII). A significant reduction of the CI-supported active respiration was found in the normoalbuminuric DKD patients and further decreased in the microalbuminuric DKD subgroup. Both CI and CII-dependent coupled respiration and the maximal uncoupled respiration were significantly reduced in the macroalbuminuric DKD subgroup. In conclusion, mitochondrial respiration impairment in peripheral platelets is evident from the early stages of DKD. Moreover, platelet mitochondrial respiration was more severely impaired in patients with macroalbuminuric DKD as compared to those with CKD. Further, more extensive follow-up studies are warranted to determine whether platelet respiratory mitochondrial dysfunction could serve as a peripheral biomarker for kidney mitochondrial dysfunction and/or as a prognostic tool in DKD.

Sample Preparation as a Critical Aspect of Blood Platelet Mitochondrial Respiration Measurements-The Impact of Platelet Activation on Mitochondrial Respiration

Blood platelets are considered as promising candidates as easily-accessible biomarkers of mitochondrial functioning. However, their high sensitivity to various stimulus types may potentially affect mitochondrial respiration and lead to artefactual outcomes. Therefore, it is crucial to identify the factors associated with platelet preparation that may lead to changes in mitochondrial respiration. A combination of flow cytometry and advanced respirometry was used to examine the effect of blood anticoagulants, the media used to suspend isolated platelets, respiration buffers, storage time and ADP stimulation on platelet activation and platelet mitochondria respiration. Our results clearly show that all the mentioned factors can affect platelet mitochondrial respiration. Briefly, (i) the use of EDTA as anticoagulant led to a significant increase in the dissipative component of respiration (LEAK), (ii) the use of plasma for the suspension of isolated platelets with MiR05 as a respiration buffer allows high electron transfer capacity and low platelet activation, and (iii) ADP stimulation increases physiological coupling respiration (ROUTINE). Significant associations were observed between platelet activation markers and mitochondrial respiration at different preparation steps; however, the fact that these relationships were not always apparent suggests that the method of platelet preparation may have a greater impact on mitochondrial respiration than the platelet activation itself.

Diagnosis of acute intoxications in critically ill patients: focus on biomarkers - part 2: markers for specific intoxications

In medical intensive care units, acute intoxications contribute to a large proportion of all patients. Epidemiology and a basic overview on this topic were presented in part one. The purpose of this second part regarding toxicological biomarkers in the ICU setting focuses on specific poisons and toxins. Following the introduction of anion and osmol gap in part one, it's relevance in toxic alcohols and other biomarkers for these poisonings are presented within this publication. Furthermore, the role of markers in the blood, urine and cerebrospinal fluid for several intoxications is evaluated. Specific details are presented, amongst others, for cardiovascular drug poisoning, paracetamol (acetaminophen), ethanol, pesticides, ricin and yew tree intoxications. Detailed biomarkers and therapeutic decision tools are shown for carbon monoxide (CO) and cyanide (CN^-) poisoning. Also, biomarkers in environmental toxicological situations such as mushroom poisoning and scorpion stings are presented.

Prophylaxis of mitochondrial dysfunction caused by cellular decompression from hyperbaric exposure

Mitochondrial dysfunction occurring in response to cellular perturbations can include altered mitochondrial motility and bioenergetic function having intracellular heterogeneity. Exogenous mitochondrial directed therapy may correct these dysfunctions. Using in vitro approaches, we find that cell perturbations induced by rapid decompression from hyperbaric conditions with specific gas exposures has differential effects on mitochondrial motility, inner membrane potential, cellular respiration, reactive oxygen species production, impaired maintenance of cell shape and altered intracellular distribution of bioenergetic capacity in perinuclear and cell peripheral domains. Addition of a first-generation cell-permeable succinate prodrug to support mitochondrial function has positive overall effects in blunting the resultant bioenergy responses. Our results with this model of perturbed cell function induced by rapid decompression indicate that alterations in bioenergetic state are partitioned within the cell, as directly assessed by a combination of mitochondrial respiration and dynamics measurements. Reductions in the observed level of dysfunction produced can be achieved with application of the cell-permeable succinate prodrug.