Presenter’s name (Last, First): Black, Hannah

Qualifications: Bachelor of Medical Science, Master of Public Health, Master of Laboratory Medicine, PhD (Trauma Science) Candidate

Affiliations: School of Medicine and Public Health, University of Newcastle

Other authors:
Dr. Gabrielle Briggs/Bachelor of Biomedical Sciences (Hons), PhD (Medical Biochemistry)/School of Medicine and Public Health, University of Newcastle

Prof. Zsolt Balogh/PhD, University of Szeged – Hungary/School of Medicine and Public Health, University of Newcastle; Trauma Service, John Hunter Hospital, Newcastle

Email: hannah.black@uon.edu.au

---

Background / Introduction:
Trauma patients are frequently transfused, which is an independent predictor of poor outcomes. Mitochondrial DNA (mtDNA) is elevated in patient plasma after injury and surgery. Cell-free mtDNA is associated with major postinjury inflammatory complications. According to recent evidence healthy erythrocytes (naturally have no mitochondria) bind mtDNA and this possible scavenger function may control hyperinflammation. Aim: to determine if RBCs contain mtDNA and how this varies across individuals and blood grups.

Patients / Methods:

Packed Red Blood Cells (PRBC) were separated to cell-free and cell pellet fractions. The cell pellet was washed with buffer to remove unbound mtDNA MtDNA concentration was measured by Quantitative Real-Time Polymerase Chain Reaction (qPCR) assay of the ND3 mitochondrial gene in both the pellet and the cell-free fraction. Concentrations were compared to healthy uninjured individuals and trauma patient plasma. The separated PRBC erythrocytes were treated with DNase enzyme to determine the intra- or extracellular location of the bound mtDNA.

Results:

The concentration of mtDNA in the cell fraction of the PRBC was 78-fold higher than in the cell-free fraction (p=0.005). The erythrocytes in PRBC had a mtDNA concentration comparable to trauma patient plasma content. PRBC mtDNA concentrations did not vary over storage age or with ABO blood group. The concentration of erythrocyte associated mtDNA did not change significantly after treatment with DNase, suggesting the mtDNA’s intracellular location.

Conclusion:

Stored erythrocytes contain mtDNA at higher concentrations than previously reported in PRBC, indicating patients are transfused with more mtDNA than assumed earlier. While our findings suggest that mtDNA is intracellular, the post-transfusion haemolysis may be relevant source of mtDNA. Future studies may determine this mechanism behind transfusion associated inflammatory complications.

Level of Evidence & Study type: Level III

Declarations of Conflict: No conflicts of interest