Biochemical profiling of proteins and metabolites in wound exudate from chronic wound environments

The lack of fundamental knowledge on the biological processes associated with wound healing represents a significant challenge. Understanding the biochemical changes that occur within a chronic wound could provide insights into the wound environment and enable more effective wound management. We report on the stability of wound fluid samples under various conditions and describe a high-throughput approach to investigate the altered biochemical state within wound samples collected from various types of chronic, ulcerated wounds. Furthermore, we discuss the viability of this approach in the early stages of wound sample protein and metabolite profiling and subsequent biomarker discovery. This approach will facilitate the detection of factors that may correlate with wound severity and/or could be used to monitor the response to a particular treatment. frequency of these chronic wounds has led current research to focus on the wound environment to provide an insight into the problem of non-healing wounds. The disruption to the normal healing process results in the modification of many biochemical factors and biochemical pathways. Therefore, attaining clinical samples from the site of injury will assist in the identification of a variety of biochemical factors that might be indicative of the state of healing. Wound fluid (WF) provides an insight into the local extracellular microenvironment of the wound. It contains a dynamic combination of proteins, peptides, metabolites and other breakdown products that reflect the current status of the wound6. Moreover, it is non-invasive, local to the site of disease, readily available for collection at frequent time points and can potentially be used for diagnostic and prognostic purposes7. However, it is important that any clinical investigation and/or biochemical analysis of WF takes into consideration the downstream implications associated with the sample collection and storage conditions. Of concern are variations in sample storage and handling conditions, the impact of multiple freeze–thaw cycles and the possible benefit of including protease inhibitors, each of which can impact on the information obtained during analysis. Thus, sample stability represents a critical consideration in the analytical pipeline. Introduction Wound care is a costly burden on society, accounting for 3% of the total health care expenditure in developed countries1. In terms of the Australian health budget, these rates equate to an annual cost of $2.61 billion (3% of health spend in 2006)2. Indeed, wound care is the second most commonly billed Medicare item and consumes up to 22–50% of community nursing care time3,4. These figures are expected to increase in line with projected growth of the ageing population and an increasing burden of chronic disease, particularly peripheral vascular disease and diabetes. Currently, chronic wound management is guided by a few subjective tests but still relies heavily on the practitioner’s expertise in the field. The current tests employed essentially identify the aetiology of these lesions but fail to assess wound chronicity and monitor the management of these wounds. In view of this, it is clear that improved diagnostic and prognostic tests are urgently required and this project is focused on addressing this problem. Chronic wounds are a silent epidemic and despite many decades of research these wounds remain one of the greatest clinical and biochemical mysteries1. Chronic wounds are a heterogeneous group of disorders and are broadly classified into venous, diabetic, arterial and pressure wounds5. The