An investigation into the significance of tissue pH and biofilms on wound healing

• Main Author: Jones, E. M.
• Published: University of Liverpool 2016
• Subjects: 617.1
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.706803

A new paradigm is coming to the forefront of chronic wound research and a potential treatment target; this is the wound pH. Non-healing wounds typically have a more alkaline pH, and from previous experimental studies, it appears that attempts should be made to reduce pH and shift the wound toward an acidic environment. This investigation aimed to determine the effects of pH alone and the combination of altering pH and bacterial biofilms on key wound healing processes in vitro. Normal healthy equine skin fibroblasts (NF) and equine chronic wound fibroblasts (CF) were cultured in pH 6, 7.5 and 9 conditions or planktonic conditioned media (PCM) and biofilm conditioned media (BCM) titrated to pH 6, 7.5 and 9. After 24 hours conditioned media was collected and analysed for the presence of collagen, fibronectin, glycosaminoglycans (GAGs) and tropoelastin. Cell migration was analysed over 48 hours: a scratch was created on a confluent layer of cells, and then cells were incubated in the different conditions and images taken at 0, 24 and 48hours. Scratch images were analysed using ImageJ and percentage wound closure determined. Results revealed that pH had no effect on ECM abundance from CF, however, it was evident that there was a lower amount of these ECM molecules from CF compared to NF. BCM alone affected ECM abundance with no further effects seen with pH alterations. Migration of CF was significantly diminished in pH 9 conditions compared with pH 6 and pH 7.5. NF were not affected by alkaline pH, with similar migration rates observed in pH 7.5 and pH 9 conditions. The reduced rate of migration observed in alkaline conditions may be explained by the reduced abundance of ECM from CF. Cell migration was significantly affected by the combination of BCM and alkaline pH, with significant inhibition compared to other pH and PCM conditions. To my knowledge this is the first study which has investigated the effect of pH on wound related parameters and the combined effect of pH and bacterial biofilms on wound healing. This study demonstrates that pH does play a role in wound healing. However, it is important to note that many other factors are involved in chronic wounds and should be taken into account when developing future research. Findings here warrant further investigation into pH and wound healing in vivo. Simply making sure that the wound remains at neutral pH and does not increase to unfavourable alkaline levels may be sufficient to prevent wounds from progressing to a chronic non-healing state.