Bioactive-Loaded Scaffolds for Conjunctiva Regeneration

The conjunctiva is a key tissue in maintaining homeostasis and providing protection for the ocular surface of the eye, yet despite its importance, it remains an under-researched tissue.

There are two distinct layers to the tissue, with the outermost layer comprised of stratified epithelial cells, and mucin-secreting goblet cells.

Conjunctival tissue comprises the innermost layer of the eyelid and is responsible for maintaining the tear film via mucin secretion. The tear film itself provides lubrication and a barrier against disease and debris for the ocular surface. Loss of conjunctival function means disruption of mucin production, which is crucial for maintaining the tear film.

A range of diseases can disrupt conjunctival function, often requiring surgical intervention of conjunctival defects for successful treatment.

Repairing these defects is dependent on size, with larger defects being more difficult to repair, relying on autologous grafts or allografts from healthy donor conjunctiva, or other mucosal tissues.

These grafts are not an ideal method of conjunctiva repair, suffering from several drawbacks including a limited supply of donor tissue and scarring at donor sites for autologous grafts, mucosal allografts being unable to adequately perform the same functions as conjunctival tissue, and both types of graft providing insufficient healing of conjunctiva.

An alternative approach to conjunctiva repair could be achieved via tissue engineering of a biomaterial substrate, which can support a stratified epithelium with embedded mucin-secreting goblet cells.

A successful substrate would provide a robust surgical implant, without the need for allogenic grafts of a patient's healthy conjunctival tissue.

We have previously shown that the inclusion of decellularised tissue matrix into electrospun fibres resulted in a significant reduction in fibre diameter (0.6 um to 0.3 um), and improvement of hydrophilicity and cell-supporting ability of the scaffold.

Effects of incorporating this tissue matrix were demonstrated by culturing cells at an air/liquid interface, on a scaffold of poly(E-caprolactone) with decellularised matrix incorporated in the fibres.

The human conjunctival epithelial cells that were cultured on this substrate had stratified up to a thickness of five layers, demonstrating the potential of the scaffold as a mimic for conjunctival tissue.

These findings warranted further investigation of scaffolds loaded with decellularised matrix for the regeneration of conjunctival tissue.

Extracellular vesicles (EVs) have been shown previously to affect cell responses, including tissue homeopathy and cell fate.

Determining if either isolated EVs, or the whole secretome (i.e. decellularised tissue matrix), would be sufficient for epithelial cell stratification, and the development and retention of mucin-secreting goblet cells, could be a key point of investigation into yielding a new therapeutic for conjunctiva regeneration and is the focus of this PhD.

The main aims of this study will be incorporating bioactives into the fibre scaffolds, analysing the tissue and cellular responses (i.e. proliferation, stratification and differentiation), with a focus on the maintenance and retention of goblets cells within the tissue.