Conceptual design and development of a research tool: - the Vagina-on-chip (VOC)

This thesis was submitted for the award of Doctor of Philosophy and was awarded by Brunel University LondonBacterial Vaginosis is one of the most common vaginal infection that affect 50% of women globally between the ages of 14-49, yet its aetiology remains unknown. Antibiotics or vaginal creams are usually prescribed to women to treat the infection however, reoccurrence is common after a year of treatment. Therefore, this condition desperately needs a new approach to developing an effective treatment. The aim of this thesis was to develop a microfluidic platform that can realistically mimic the in vivo vaginal epithelium tissue as an in vitro system which can then be used by clinicians and researchers to gain a better understanding of bacterial vaginosis (BV). The Vagina-on-chip (VOC) was developed using multiple techniques that combined micro-engineering, 3D printing, electrospinning, and cell culture to mimic the mechanical, biochemical and physical aspects of vaginal tissue. VOC platform comprised of three layers, top and bottom microfluidic channels to provide nutrients to the central layer, the membrane held in suspension to support the growth of vaginal tissue. The membrane was fabricated using natural and synthetic polymers via electrospinning technique. Composite membrane made with gelatine (GE) and polycaprolactone (PCL), a mixture of natural and synthetic polymers was found to be the optimal membrane for cell culture. This membrane was chosen due to its fibre size (257.25 ±72.92nm) and wettability CA (29.66 °) which provided a large surface area and hydrophilic exterior to support growth and cell adhesion of vaginal cells. Mechanical testing revealed that composite membrane exhibited similar mechanical properties to vaginal epithelium from non-prolapsed women. The composite membrane had a stress failure at 1.6MPa with strain failure at 12%. Cell viability assays were also conducted on the membranes to test for biocompatibility, which confirmed the composite membrane to be the most appropriate membrane for the VOC platform. Scanning electron microscopy was performed to visualise cell attachment on all membranes which showed the vaginal cells merging to the fibres of PCL/GE, PCL/COL and composite membrane indicating that these as-spun scaffolds promoted cellular attachments and spreading. Together with these results, the first VOC platform prototype was constructed. Due to its early stages in development, further experimentation and optimisation is required to evaluate its performance, to support the growth of vaginal tissue and potentially becoming a realistic research tool to study BV.EPSR