Summary

Cryopreservation and Bioenergetic Evaluation of Human Peripheral Blood Mononuclear Cells

Published: October 20, 2023
doi:

Summary

Isolated peripheral blood mononuclear cells can be used for the analysis of immune functions and disorders, metabolic diseases, or mitochondrial functions. In this work, we describe a standardized method for the preparation of PBMCs from whole blood and the subsequent cryopreservation. Cryopreservation makes this time and place independent.

Abstract

The physiological functions of eukaryotic cells rely on energy mainly provided by mitochondria. Mitochondrial dysfunction is linked to metabolic diseases and aging. Oxidative phosphorylation plays a decisive role, as it is crucial for the maintenance of energetic homeostasis. PBMCs have been identified as a minimally invasive sample to measure mitochondrial function and have been shown to reflect disease conditions. However, measurement of mitochondrial bioenergetic function can be limited by several factors in human samples. Limitations are the amount of samples taken, sampling time, which is often spread over several days, and locations. Cryopreservation of the collected samples can ensure consistent collection and measurement of samples. Care should be taken to ensure that the parameters measured are comparable between cryopreserved and freshly prepared cells. Here, we describe methods for isolating and cryopreserving PBMCs from human blood samples to analyze the bioenergetic function of the mitochondria in these cells. PBMC cryopreserved according to the protocol described here show only minor differences in cell number and viability, adenosine triphosphate levels, and measured respiratory chain activity compared with freshly harvested cells. Only 8-24 mL of human blood is needed for the described preparations, making it possible to collect samples during clinical studies multicentrally and determine their bioenergetics on site.

Introduction

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.

Protocol

All protocols described in this manuscript for blood collection, isolation and analysis have been reviewed and approved by the Institutional Review Board at the University of Giessen, Germany. The consent of the patients to include their samples in the study was obtained. All steps for isolation and cell culture are carried out under a biological safety cabinet. 1. Venipuncture Prepare all equipment needed for blood collection including disinfection spray, sterile …

Representative Results

Cell viability and number To achieve successful isolation and cryopreservation, cell count and viability should be as high as possible. Before and after cryopreservation, the cells are counted, and their viability is determined to ensure the health and quality of the cells. Figure 3 is a representative illustration of PBMCs before and after cryopreservation, cell count and viability hardly differ. This indicates successful isolation and preservation of PBMCs. <p cl…

Discussion

This protocol provides a means of isolating and cryopreserving peripheral blood mononuclear cells (PBMCs) from human blood in a manner suitable for bioenergetic analyses. The described method offers the possibility to isolate PBMCs gently and in large quantities, with high viability and sufficient cells for bioenergetic measurements. It has the disadvantage that even with minimal interruptions, long isolations occur, but subsequent cryopreservation allows a time-independent measurement of bioenergetics. With this method,…

Disclosures

The authors have nothing to disclose.

Acknowledgements

We would like to thank the clinical team of the University Hospital Giessen-Marburg for the blood collection. This work was funded by the Justus Liebig university.

Materials

0.1 M Triethanolamine-HCl-Buffer (pH = 8,0) Self-prepared
0.5 M Triethanolamine-HCl-Buffer Self-prepared
1.0 M Tris-HCl-Buffer (pH = 8,1) Self-prepared
1.01 mM DTBB Self-prepared
10 % Triton X-100 Self-prepared
10 mM Oxalacetat Self-prepared
14–20 G sterile blood draw needles Multi Adapter Sarstedt Safety-Multifly Sarstedt 156353_v
37% HCl Carl Roth GmbH & Co. KG
70% Ethanol (EtOH) Self-prepared
Acetyl-CoA Pancreac Applichem A3753
ADP Sigma-Aldrich A5285
Alcohol wipes  (70% isopropyl alcohol)
Antimycin A Sigma-Aldrich A8674
Aqua (bidest.) With MilliQ Academic (self-made)
Ascorbate Sigma-Aldrich A4034
ATP-Standard Sigma-Aldrich 6016949
Biocoll Seperating Solution Biochrom 6115
Biological safty cabinet MSC Advantage Thermo Fisher Scientific Inc.
Carbonylcyanid-p-trifluoromethoxy-phenylhydrazon (FCCP) Sigma-Aldrich C2920
Cell counter TC20 Automated Cell Counter Bio-Rad
Centrifuge Heraeus Megafuge 16 R Thermo Fisher Scientific Inc.
Counting slides, dual chamber for cell counter Bio-Rad 1450016
Cryotube Cryo.S Grainer Bio-One 126263-2DG
Digitonin Sigma-Aldrich 37008
Dimethylsulfoxid (DMSO) Merck 102952
Disinfection spray
Disposable gloves latex, rubber, or vinyl.
Distrips (12.5 ml) DistriTips Gilson F164150
Dulbecco’s Phosphate Buffered Saline (DPBS; 10x) Gibco (Thermo Scientific) 15217168
Ethanol (EtOH 100%) Carl ROTH GmbH & Co. KG 9065.3
Fetal bovine serum (FBS) Sigma-Aldrich F9665
Frezer (-80°C) Thermo Fisher Scientific Inc.
Glutamate Sigma-Aldrich G1626
Holder/adapter 
Incubator Midi 40 CO2 Thermo Fisher Scientific Inc.
Injection syringe Hamilton
Malate Sigma-Aldrich M-1000
MIR05 Self-prepared
Mr. Frosty Freezing Container Thermo Fisher Scientific Inc. 10110051
Multireader CLARIOstar BMG Labtech
Nitrogen tank Locator 6 plus Thermo Fisher Scientific Inc.
Oligomycin Sigma-Aldrich O4876
Oxalacetate Sigma-Aldrich
Oxygraph-2k Orobororus Instruments
Penicillin-Streptomycin PAA 15140122
Pipettes Performance Pipettor 10 μL, 100 μL, 1000 μL VWR
Roswell-Park. Memorial-Institute-Medium (RPMI-1640) Gibco (Thermo Scientific) 11530586
Rotenone Sigma-Aldrich R8875
Saccharose Carl ROTH GmbH & Co. KG 9286.2
Sodium azide Sigma-Aldrich S2002
Succinate Sigma-Aldrich S2378
Tetramethylphenylendiamin (TMPD) Sigma-Aldrich T3134
Tourniquet/ Blood pressure cuff
Tris(hydroxymethyl)amino-methane Sigma-Aldrich 108382
Triton X-100 Sigma-Aldrich 108643
Trypanblau Biochrom T6146
Vacuum pump Vaccubrand GmbH & Co.
ViewPlate-96 Perkin Elmer 6005181
Water bath WNB22 Memmert GmbH & Co. KG

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Cite This Article
Dieter, F., Grube, J., Birkenhauer, T., Quentin, A., Eckert, G. P. Cryopreservation and Bioenergetic Evaluation of Human Peripheral Blood Mononuclear Cells. J. Vis. Exp. (200), e65730, doi:10.3791/65730 (2023).

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