Human peripheral blood mononuclear cells (PBMCs) are used for various applications in many scientific fields, including the study of immunological and bioenergetic issues, such as those related to aging processes or degenerative diseases1,2. PBMCs are heterogeneous in composition and consist of lymphocytes (B cells, T cells, and NK cells), monocytes, and dendritic cells. The cells sometimes show great individual differences and variations within a subject, so standardized procedures for handling these cells are required. Important parameters such as viability and purity of the isolation are the basic requirements for its handling and are additionally influenced by environmental factors such as the time of collection, the melatonin level, whether the subject is fasting, and others3,4.
Based on studies on bioenergetics of PBMCs, we describe here a method for the isolation, cryopreservation, and cultivation of PBMCs that is suitable for other methods as well. While muscle biopsy is considered the gold standard for mitochondrial energy metabolism5, the examination of blood cells is a rapid, minimally invasive procedure. In addition to this, more and more studies suggest that the changes in mitochondrial function in aging and Alzheimer's disease (AD) occur not only in the brain but also in the periphery6,7,8,9,10. The method also allows investigations of other conditions and diseases, including diabetes mellitus and obesity11,12,13. Gene expression patterns in multiple sclerosis patients can be analyzed, or immune function and influences on it in general14,15,16.
PBMCs generally rely on oxidative phosphorylation (OXPHOS) to generate adenosine triphosphate (ATP)17,18. Therefore, PBMCs cover a wide range of applications as surrogates. In previous reports, the energy metabolism of PBMCs has been used to address organ dysfunctions, such as in early heart failure19, septic shock20 or sex-associated differences4 in mitochondrial function. A generalized method for cryopreservation isolation and cultivation of PBMCs would have advantages in the comparability of results obtained at different institutes. There is a great deal of variation in the protocols for each step21,22, the goal of this method is to provide a guideline for bioenergetic measurements in PBMCs.
In this article we describe a method for measuring bioenergetic parameters in PBMCs. We explain the methods for isolating, cryopreserving and measuring bioenergetics of PBMCs from human blood. This method can be used to determine bioenergetic parameters in patients and evaluate them in a clinical context. To apply these measurements, researchers need access to a patient population from which fresh blood samples can be obtained.