Mitochondrial Function in Peripheral Blood Mononuclear Cells, Muscle, and Skin of Long COVID Patients

Not yet recruiting

• Conditions: Long COVID; Post-COVID-19 Condition

• Registration Number: NCT07134673
• Lead Sponsor: Universitair Ziekenhuis Brussel

Brief Summary

Mitochondria are structures inside cells that are responsible for producing energy from nutrients through a series of steps, using oxygen. To have an idea of how well the mitochondria can produce energy, we can measure how much oxygen they use. The goal of this study is to:

1. To compare the oxygen use between people with long COVID and people who completely recovered after COVID-19, using three techniques that measure the oxygen use in blood cells, on the skin and in the muscle

2. To test how similar these three techniques are in measuring the oxygen used in the three different tissues

Participants will:

* Complete surveys,

* Wear an activity tracker (7 days),

* Undergo several non-invasive tests, and

* Donate a blood sample The study will take place in UZ Brussel hospital and will take 2 study visits, approximately 7 days apart.

Detailed Description

Not available

Study Timeline

• Study First Submitted: 2025-06-25
• Status Verified: 2025-08
• Study First Submitted QC: 2025-08-20
• Last Update Submitted: 2025-08-20
• Study First Posted: 2025-08-21
• Last Update Posted: 2025-08-21
• Study Start: 2025-10-01
• Primary Completion: 2026-07
• Study Completion: 2026-07-01

Recruitment & Eligibility

• Status: NOT_YET_RECRUITING
• Sex: All
• Target Recruitment: 54

Inclusion Criteria

Not provided

Exclusion Criteria

Not provided

Study & Design

• Study Type: OBSERVATIONAL
• Study Design: Not specified

Primary Outcome Measures

Name	Time	Method
Mitochondrial oxygen tension (mitoPO2) (mmHg/s)	Second study visit (approximately 7 days after the first study visit)	Cellular Oxygen Metabolism monitoring
Mitochondrial oxygen consumption (mitoVO2)	Second study visit (minimally 7 days after the first study visit)	Cellular Oxygen Metabolism monitoring
Tissue Saturation Index (TSI)	Second study visit (approximately 7 days after the first study visit)	Near-infrared spectroscopy
Basal Oxygen Consumption rate (pmol O2/min)	Blood sample is taken during the second study visit (approximately 7 days after the first study visit) and the PBMCs are cryopreserved until analysis (after all participants have been recruited, estimated to be within 1 year of the start of the study)	Seahorse XF Substrate Oxidation Stress test analysis of the peripheral blood mononuclear cells (PBMCs)

Secondary Outcome Measures

Name	Time	Method
Proportion of participants meeting the criteria for PEM	Second study visit (minimally 7 days after the first study visit)	De Paul Symptom Questionnaire - Post-exertional malaise (DSQ-PEM)
Physical fatigue	Second study visit (approximately 7 days after the first study visit)	Multidimensional Fatigue Inventory (MFI-20)
General fatigue	Second study visit (approximately 7 days after the first study visit)	Multidimensional Fatigue Inventory (MFI-20)
Mental fatigue	Second study visit (approximately 7 days after the first study visit)	Multidimensional Fatigue Inventory (MFI-20)
Reduced activities	Second study visit (approximately 7 days after the first study visit)	Multidimensional Fatigue Inventory (MFI-20)
Reduced motivation	Second study visit (approximately 7 days after the first study visit)	Multidimensional Fatigue Inventory (MFI-20)
Severity and impact of fatigue on daily life	Second study visit (approximately 7 days after the first study visit)	The Fatigue Severity Scale (FSS) contains nine statements that rate the severity of the fatigue symptoms. The statements are rated from 1 to 7, with a low value indicating strong disagreement with the statement and a high value indicating strong agreement with the statement. The total score is the sum of the individual scores, with a higher score indicating a greater impact of fatigue on daily life.
Symptom burden (θ)	First study visit	Item Response Theory (IRT) will be applied to estimate a latent trait representing symptom burden, using Section 2.6 of the WHO Post-COVID-19 Case Report Form. Symptoms will be coded as binary variables (1 = symptom present, 0 = symptom absent). IRT modeling will be used to derive a latent trait estimate (θ) for each individual, reflecting the overall severity or burden of symptoms.
Basal Oxygen Consumption rate (pmol O2/min)	Blood sample is taken during the second study visit (approximately 7 days after the first study visit) and the PBMCs are cryopreserved until analysis (after all participants have been recruited, estimated to be within 1 year of the start of the study)	Seahorse XF Substrate Oxidation Stress test analysis of the peripheral blood mononuclear cells (PBMCs) after substrate pathway inhibitor BPTES is used
Resting Energy Expenditure (kcal/kg body weight/day)	Second study visit (approximately 7 days after the first study visit)	Indirect calorimetry will be used to measure the Resting Energy Expenditure (kcal/day). This value will be divided by the body weight (kg) on that same day.
Maximal Oxygen Consumption rate (pmol O2/min)	Blood sample is taken during the second study visit (approximately 7 days after the first study visit) and the PBMCs are cryopreserved until analysis (after all participants have been recruited, estimated to be within 1 year of the start of the study)	Seahorse XF Substrate Oxidation Stress Test analysis of the peripheral blood mononuclear cells (PBMCs) after substrate pathway inhibitor BPTES is used
Respiratory Quotient	Second study visit (approximately 7 days after the first study visit)	Indirect calorimetry

Trial Locations

Locations (1)

Laarbeeklaan 101; 🇧🇪 Jette, Brussels, Belgium