Bioartificial scaffolds fabrication and their use for in vitro testing of wound healing devices

Mandolini, Nicola

Abstract

In the last decades Negative Pressure Wound Therapy (NPWT) has shown its efficacy in wound healing, applying continuous or intermittent subatmospheric pressure to the wound surface by means of dressing systems. While there is general consensus that positive effects originate from a complex interplay of mechanisms such as deformations and exudate removal, uncertainty persists about the optimal mode of application and the consequences of this therapy at a cellular level. A better understanding of the skin mechanobiology in response to therapeutic stimuli using a bioreactor system can help to individualize future wound therapies in a reproducible and controlled environment. This thesis proposed the fabrication of in vitro 3D skin models aiming to reproduce the relationship that occurs between cell types and skin substrate and investigated their use in a bioreactor in order to obtain new knowledge of NPWT mechanisms. Freeze-drying and electrospinning were considered to be the best methodologies to obtain homogenous and standardized 3D structures that were favourable for the purpose. Highly porous pure collagen and collagen-based scaffolds were firstly created using the freeze-drying technique. Various cross-linking methods were assessed and directly compared to establish the most suitable to improve mechanical stability and physical properties. Meanwhile, fibrous structures that could resemble the topography of the extra cellular matrix (ECM) were produced with the electrospinning system using toxic-free solutions and an in-house-developed rotating collector. The prospect to fabricate a hybrid bilayer scaffold, combining the two techniques was also investigated and discussed. Primary human skin fibroblasts were cultured on these structures and cell interaction and viability were evaluated through assays and microscopy techniques. Lastly, a proof-of-concept bioreactor for NPWT investigation was designed and tested on the freeze-dried scaffolds demonstrating the feasibility of this research approach. Results showed that blending methodology used in the freeze-drying can lead to scaffolds with unique physical properties while cross-linking has influence on substrate stiffness that guides cell response. With regard to the electrospinning, the use of the rotating collector was found to be promising in obtaining a bimodal fibre distribution resulting in porous and orientated membranes that simulate the orientation of collagen fibres in the dermis of human skin and could be beneficial for cell infiltration.
To conclude, this study laid the groundwork for further development of these bioartificial scaffolds with improved properties that could be used as skin models and combined in a negative-pressure cell culture system with the aim to advance the understanding of NPWT biological mechanism and its clinical efficacy.

Citation

Mandolini, N. Bioartificial scaffolds fabrication and their use for in vitro testing of wound healing devices. (Thesis). University of Hull. https://hull-repository.worktribe.com/output/4386661

• Thesis Type: Thesis
• Deposit Date: Sep 12, 2023
• Publicly Available Date: Oct 5, 2023
• Keywords: Medical engineering
• Public URL: https://hull-repository.worktribe.com/output/4386661
• Award Date: Sep 7, 2023