Peripheral blood mononuclear cells to detect mitochondrial dysfunction in horses: a preliminary study

Mitochondrial dysfunction has emerged as a ubiquitous cause of disease in human and animals. In the equine species, muscle fibers were analyzed to detect and assess defective mitochondrial function. Using respirometry, a so-called “mitochondrial syndrome” has been reported in equine atypical myopathy, which is characterized by a severe decrease of mitochondrial respiratory capacity in affected individuals [1] .
Up to now, respirometric studies in horses have been successfully conducted on skeletal muscles samples. However, the muscle biopsy procedure is rather invasive and therefore difficult to use in equine clinical routine. Despite the fact that peripheral blood mononuclear cells (PBMC) have been used in human medicine to assess mitochondrial function, there is only one study comparing PBMC and skeletal muscle oxidative capacity in monkeys so far [2]. Therefore, the aim of this study was to test whether mitochondrial function can be assessed on equine blood cells with respirometry, according to the fact that blood is a biological sample easier to collect than muscle.
Whole blood was collected in 9 ml EDTA tubes in four horses. Cells of interest (PBMC) were isolated with a density-separation medium (Lymphoprep™) within one hour of sampling, following a standardized procedure. Electron paramagnetic resonance as well as the respirometric analysis were performed within the following 4 hours.
The preliminary tests show that recorded respirations are similar to those documented in humans. However, a lack of reproducibility of respirometric analysis with PBMC taken from the same horses was observed. Therefore, a correlation between skeletal muscle fiber and PBMC mitochondrial bioenergetics in the equine species is, up to now, not possible to be established. Nevertheless, an efficient PBMC isolation protocol was established and mitochondrial respiration with respirometry was obtained. The cause of the variations within the same individual is still under examination.