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Haemorrhagic shock (HS) is commonly associated with trauma. Severe haemorrhage causes hypoperfusion of tissues resulting in a global ischaemic state, and resuscitation is performed to restore circulating volume. However, the return of oxygen to ischaemic tissues causes the induction of a systemic inflammatory response, which contributes to cell death leading to organ failure. In trauma patients, failure of more than four organs is linked to certain mortality, highlighting the need for interventions that may reduce or prevent the deterioration in organ function. The aim of this thesis was to investigate the effect of therapeutic approaches on the organ injury and dysfunction induced by HS. Briefly, male Wistar rats were subjected to haemorrhage by withdrawal of blood to reduce the mean arterial pressure to 35 ± 5 mmHg for 90 min. Followed by resuscitation with 20 ml/kg Ringer’s lactate for 10 min and 50% of the shed blood for 50 min. Organ function was determined 4 h after the onset of resuscitation. This model was used to investigate the effect of three different interventions on the organ injury and dysfunction induced. In the first study, administration of bone marrow-derived mononuclear cells (BMMNCs) upon resuscitation resulted in (1) significant attenuation of the organ injury and dysfunction associated with HS, and (2) restoration of the activation of the Akt pro-survival pathway. It is possible that these beneficial effects are mediated by paracrine mediators secreted by BMMNCs, which modulate this pathway, however injection of large numbers of cells is not practical in the acute setting of trauma. Therefore, in the next study erythropoietin (EPO) was used as a daily pre-treatment for three days prior to the induction of haemorrhage, as EPO is a known stimulus of endothelial progenitor cell (EPC) mobilisation. EPO pre-treatment resulted in (1) significant attenuation of the organ injury and dysfunction associated with HS, (2) mobilisation of EPCs (CD34+/flk-1+), and (3) activation of the Akt pro-survival pathway with enhanced activation of eNOS. However, when used clinically EPO is associated with an increased risk of thrombotic events, therefore in the final study a non-erythropoietic analogue of EPO was investigated. Treatment with pyroglutamate helix B surface peptide (pHBSP) resulted in (1) significant attenuation of the organ injury and dysfunction associated with HS, and (2) activation of the Akt pro-survival pathway with enhanced activation of both eNOS and STAT3. Additionally, late pHBSP treatment, up to 60 min after the onset of resuscitation, exerted the highest degree of protection. The findings of this thesis support the view that modulation of the Akt pro-survival pathway is a potential therapeutic target in the treatment of the ischaemia-reperfusion injury associated with severe haemorrhage and resuscitation.

Healthcare associated infections (HCAIs) are a large and growing problem. Bacterial infections of patients and on the medical devices used to treat them represent a significant source of morbidity and mortality. There is also a significant economical impact to the healthcare system attributed to HCAIs. While bacterial infections per se are not a novel problem, the discovery of an adherent polymicrobial phenotype called a biofilm is. A biofilm is defined by its structure and the community of bacteria therein. This study investigated bacteria biofilms in a number of pertinent clinical scenarios. To achieve this, samples were taken from five different but related clinical areas where biofilms are known to infect or are suspected to, namely endotracheal tubes, tracheostomy tubes, burn wounds, chronic wounds and chronic wound dressings. Samples were analysed using microbiological and molecular analysis techniques, the latter included polymerase chain reactions, species-specific PCR and denaturing gradient gel electrophoresis to assess microbial diversity. Fluorescent in-situ hybridization was used subsequently to analyse species orientation and biofilm structure within the biofilm. This study showed a diverse bacterial population in all the samples, with the presence of oral biota in the ETT specimens, changing to commensal bacteria over time. Large threedimensional biofilm structures were present in the specimens confirming the presence of biofilms, and within one of the chronic wound dressings where a complex biofilm was visible within the matrix of the dressing itself. These findings have considerable significance clinically, not only in demonstrating the need for biofilm targeted diagnostic techniques, but also in highlighting the need for specific biofilm treatment modalities in critical care, burn services and chronic wound management.

Over the past decade the concept that the hair follicle plays an important role in cutaneous wound repair has been established. Several elegant lineage tracing studies have demonstrated that hair follicle derived cells contribute to the long term maintenance of the epidermis following repair, while an absence of hair follicles is known to delay repair. The exact mechanisms surrounding hair follicle derived repair are unknown. Moreover, while multiple stem cell niches are present within the hair follicle, their relative importance during wound repair is still unclear. The hair follicle is also a regenerative mini-organ, undergoing regular cycles of growth and regression throughout life, yet surprisingly this has not been previously investigated with respect to wound repair. Data presented in this thesis reveals an unappreciated, yet fundamental link between the independent processes of hair cycle and wound repair, with a substantial acceleration in the rate of repair (~50%) observed in anagen phase. Importantly, the hair follicle appears to play a global role in repair, with differences in the contribution of multiple cell types to wound repair. In addition, this thesis addresses the early kinetics of hair follicle wound response for the first time. Anagen hair follicles are found predisposed to a more rapid and extensive response to injury, suggesting a higher overall percentage of repair derived from the hair follicle in anagen phase. Surprisingly, the bulge stem cell region, while critical for hair cycle appears to play little role in the events immediately following injury, and is not required for initiation of re-epithelialisation. Gene expression profiling reveals numerous genes associated with anagen accelerated repair, and identifies altered modulation of the immune system as a key mechanism. Further, anagen wounds are associated with an upregulation of developmental transcription factors, which may imply a more regenerative healing phenotype. These data reveal numerous targets with the potential to accelerate repair, which now require validation for their therapeutic potential. These targets could be of importance in promoting the repair of chronic wounds, an area of unmet clinical need. More generally, this thesis has established hair cycle as an important experimental variable, which must be controlled for in all future in vivo murine wounding studies.