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The effect of nano-scale topography on keratinocyte phenotype and wound healing following burn injury

Parkinson, Leigh (2010) The effect of nano-scale topography on keratinocyte phenotype and wound healing following burn injury. PhD thesis, Murdoch University.

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Abstract

Burns are devastating injuries that have profound physical, psychological and social impacts on the patient and their families. The scar that results from injury repair can be aesthetically and functionally debilitating, and patients require long-term rehabilitation. With increasing survival of patients after severe burn injuries, the recovery of function and reduction of scar formation has become increasingly important. One critical aspect of healing known to improve scar outcome is reducing the time taken for wound closure. As a result, new tissue engineering technologies are focused on providing fast wound closure to limit scar formation, with the response of cells to scaffolds and surfaces known to be, in part, dependent on topography. The ability to modulate cell phenotype by manipulation of micron scale features is well established. However, the effect of nano-scale topography on keratinocyte phenotype and wound closure has not yet been characterised and is the focus of this research.

Nanoporous anodic aluminium oxide (AAO) membranes were engineered to study the effect of nano-scale topography on keratinocyte phenotype and wound healing following a burn injury. An advanced two-step anodization method was optimised to prepare large, flexible and highly reproducible membranes with uniformly sized nanopores in hexagonal arrangement. Pore diameters ranging from 41 – 300 nm with interpore distances of 58 – 277 nm were manufactured using different optimised anodizing conditions.

Keratinocyte phenotype was affected by the nanotopography. Cells readily attached to the nanoporous membranes, with the pore size influencing the rate of cell proliferation and migration. A migratory phenotype was induced in keratinocytes, with cells displaying a more rounded morphology and migrating faster across the nanoporous surfaces. Cell proliferation was also affected, with the fastest rate of proliferation observed on the largest pore size tested (300 nm), and the rate differing on each of the membranes. These results showed that keratinocytes are sensitive to nano-scale changes in topography and that this property may be exploited to promote faster wound closure and improve outcome after burn injury.

The largest pore size membrane, 300 nm, which supported both proliferative and migratory cell phenotypes, was used as a dressing to cover a partial thickness burn injury in the pig. Wounds dressed with the membrane had significantly less organising granulation tissue earlier than control wounds, indicating these wounds were more mature. Epidermal layers in the final scars of membrane treated wounds were also thinner, suggesting an advanced restoration of epidermal maturation due to treatment with the nanoporous membrane. Despite this advanced healing at the cellular level, final scar outcome was similar between the control and membrane treated sites, with no macroscopic differences in the scars. The results demonstrate the potential to enhance wound healing with nanoporous topography, and the importance of this level of architecture in modulating cell phenotype. Combinatory therapies, using the membrane as an interactive dressing or delivery vehicle device for cultured cells may further enhance wound repair to result in improved scar outcome.

Item Type: Thesis (PhD)
Notes: Note to the author: If you would like to make your thesis openly available on Murdoch University Library's Research Repository, please contact: repository@murdoch.edu.au. Thank you.
Supervisor(s): Wood, Fiona and Fear, Mark
URI: http://researchrepository.murdoch.edu.au/id/eprint/41684
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