Tissue specific and cell derived biomarkers in the early management of traumatic and thermal injuries

Lead researchers: Dr. Paul Harrison, Dr. John Hazeldine, Prof Janet Lord.

Aim of this research: We aim to define the tissue and cellular origin of cell-free DNA (cfDNA) and microvesicles in longitudinal blood samples from patients with traumatic and burn injury. We will also develop and implement Point of Care (POC) assays for Citrullinated Histone H3 (CitH3), procoagulant vesicles and full blood counts including Immature Granulocytes (IG) measurement. We hypothesize that measurements will not only significantly contribute to our understanding of the early physiology of injury but result in the availability of novel POC tests that will enable the early identification and treatment stratification of patients with increased risk of morbidity and mortality.

Background: The identification of reliable outcome predictors in severe sepsis is vital for POC Diagnosis and Prognosis and for stratifying patients onto various treatment regimes. Our preliminary studies have demonstrated that the measurement of novel biomarkers can predict mortality, sepsis and multi-organ failure (MOF) in patients with traumatic and thermal injury. These include IG on a full blood counter, Neutrophil Extracellular Traps (NETs) and procoagulant microvesicles. In the Golden Hour study (in Traumatic Brain Injury (TBI) and Orthopaedic Injury) collection of blood samples less than 1 hour after injury reveals that there are many significant early changes in these markers in relation to outcomes and shows the potential importance of very early pre-hospital measurements.

The rapid measurement of cfDNA shows that this can be potentially derived from a number of sources including the injured tissue, NETs, infections and major organs during MOF. Quantitative PCR measurements demonstrate that the majority of cfDNA indeed originates from the nucleus and not the mitochondria. Measurement of the specific NETs marker CitH3 also suggests that neutrophils are also releasing cfDNA. Determination of the exact quantity and source(s) of cfDNA would therefore be very useful for not only confirming the tissue(s) or cells of origin but assessing the degree of injury to a tissue (e.g. in TBI).

How this research is being carried out:  To do this research we will be measuring all biomarkers within existing banks of samples from our clinical cohorts of patients with traumatic (Golden Hour) and thermal injury (SIFTI-1). New samples will continue to be collected from both Golden Hour and SIFTI 2 studies.

How the findings will be measured: We will use a novel PCR approach on extracted cfDNA samples to identify the exact tissue or cellular origin(s) of the cfDNA within existing large banks of plasma samples. Primers will be designed to specifically detect unique methylation patterns that can differentiate between cfDNA from Brain, Skeletal Muscle, Skin, Liver, Kidney, Heart and Neutrophils. The quantification of cell/tissue specific DNA will not only determine the contribution of neutrophil derived cfDNA to the overall signal but confirm if this is occurring immediately after sterile injury and/or before or during subsequent infections.

Lead researchers