Ryback, Audrey A, Hillier, Charles B, Loureiro, Camila M et al. · PloS one · 2026 · DOI
Researchers wanted to test whether something in the blood of people with ME/CFS could damage the energy-producing parts of cells (mitochondria) when added to healthy cells in the lab. They tested blood from 67 people with ME/CFS and 53 healthy people on cultured muscle cells and measured how well the cells could use oxygen. Unlike a previous smaller study, they found no difference between the ME/CFS blood and healthy blood samples.
If blood factors from ME/CFS patients could be identified as causing specific cell changes, this could lead to a diagnostic blood test for ME/CFS, which currently lacks objective biomarkers. This study clarifies whether mitochondrial dysfunction via serum factors is a viable mechanism to pursue in ME/CFS research, helping direct future investigative efforts and funding priorities.
This study does not rule out mitochondrial dysfunction in ME/CFS patients themselves—only whether their blood serum causes changes in healthy cells in a laboratory setting. It does not test whether other cell types or tissues might respond differently to ME serum factors, nor does it eliminate other potential blood-based biomarkers. The study also does not determine what biological mechanisms do underlie fatigue in ME/CFS.
About the PEM badge: “PEM required” means post-exertional malaise was an explicit required diagnostic criterion for participant inclusion in this study — not that PEM was studied, observed, or discussed. Studies using criteria that do not require PEM (e.g. Fukuda, Oxford) are tagged “PEM not required”. How the atlas works →
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