BACKGROUND: Repeat blood donation affects erythrocyte health through physiological adaptations. This study examines how repeat donation affects erythrocyte morphology, oxidative stress and erythropoiesis-regulating microRNAs (miRNAs: miR-142, miR-144, miR-451). METHODS: A cross-sectional study included 42 male participants: repeat donors (n = 21, ≥3 donations/year) and first-time donors (n = 21). Whole blood miRNA expression was measured by quantitative reverse transcription polymerase chain reaction (qRT-PCR), hemogram parameters by autoanalysers and oxidative markers (malondialdehyde MDA, glutathione GSH) spectrophotometrically. A Directed Acyclic Graph was constructed for variable selection, and separate linear regression models with Gaussian error distribution were fitted for each miRNA in repeat and first-time donor groups, including 2-year donation count, age, body mass index, smoking, erythrocyte morphology (haemoglobin, mean corpuscular volume, red cell distribution width) and oxidative stress parameters (erythrocyte GSH, plasma GSH, erythrocyte MDA, plasma MDA) as predictors. RESULTS: Univariate analysis revealed a significant 3.17-fold upregulation of miR-142 in repeat donors (p = 0.040); miR-144 and miR-451 remained stable. Linear regression analysis identified two key findings: (1) eGSH was a significant predictor of miR-142 expression in first-time donors (β = -0.080, p = 0.041), representing a fundamental redox-miRNA relationship independent of donation status; and (2) smoking approached significance as a predictor of miR-144 in repeat donors (β = 2.819, p = 0.053), approaching significance and suggesting a possible cumulative oxidative stress threshold. No predictor reached significance for miR-451 in either group, confirming its homeostatic stability. CONCLUSIONS: Repeat blood donation is associated with significant miR-142-3p upregulation. Linear regression analysis reveals a novel eGSH-miR-142 axis as a fundamental erythrocyte physiological mechanism and provides suggestive evidence for a double-hit hypothesis for miR-144 regulation in smoking donors. miR-451 demonstrates donor-independent homeostatic stability with potential as a blood product quality reference marker.
Karaca et al. (Tue,) studied this question.