Wound healing – High-throughput analysis of synthetic wound healing microenvironment
Completed Project Overview
The aim of this research project was to develop an in vitro model of wound healing that could analyse many different regulatory factors in high-throughput and replace the use of animals in wound healing research. Thanks to the generous funding from the Animal Free Research UK and its supporters, we employed novel micro-fabrication techniques to print arrays of ‘micro-wounds’ within multi-well cell culture plates, and then used a light-based reaction to activate cell migration into the micro-wound area.
Representative images of wound closure before (0h) and after (8h) photo-activation with (left image) or without (right image) an efficient photo-coupler molecule that assists in the migration process to ‘heal’ the wound.
Home Office statistics from 2008 to 2012 indicate that a total of 300,666 animal procedures have been performed on the skin, the majority (81%) of these have been on mice. Of these, an estimate is that over the past five years approximately 25,000 procedures on mice and 30,000 procedures on all animals have been performed in the UK for wound healing studies.
Wound healing procedures performed on animals typically involve making one or more excisional or incisional wounds on the back and tracking wound closure over time both by gross observation and histology. Wounding procedures require general anaesthesia and are classified by the Home Office to have moderate severity. Complications can include pain, infection, dehydration, and death for the animals.
Upon successful optimisation and characterisation of this model system, we then performed a screen of 147 small molecules to identify novel regulators of human skin cell migration and wound repair. Through this analysis we discovered multiple compounds that blocked cell migration, as well as several that accelerated wound closure.
In addition to providing new insights into skin cell migration, this research has established a powerful new tool for wound healing research with several key advantages over animal models. The micro-wound model specifically examines human keratinocyte migration, which is an essential component of the wound healing process and distinctly different between humans and mice. Thus, this system may be more relevant to human wound healing.
Human skin and mouse skin heal through very different mechanisms. While mouse skin is generally looser and heals through contraction, human skin depends more on re-epithelialisation and migration of epidermal keratinocytes. As our model system specifically analyses human keratinocyte migration, it may therefore be more directly relevant to the re-epithelialisation aspect of human wound healing than animal studies.
Our model also allows for precise control over the shape and composition of the micro-wounds, which is not possible in vivo, and for multiple variables to be analysed in high-throughput.
In addition to scaling up the micro-patterning technology we also developed a new image analysis protocol for label-free detection and quantification of micro-wound closure. Establishment of this novel protocol was an important technological step because it allowed us to analyse cell migration with minimal perturbation of the cells and without the need for animal derived antibodies.
These unique features therefore provide greater tuneability and efficiency than is possible with animal studies. Given these clear advantages, we believe that the model system developed during this research project will lead to the replacement of many animals in wound healing research in the future.