Investigation and treatment of trabecular meshwork fibrosis using 3D glaucoma models

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Background: The development of safe and effective therapies to treat fibrosis is a major priority for patients with glaucoma. This ocular disease is characterised by elevated intraocular eye pressure (IOP), resulting from ineffective drainage of the aqueous humour. This in part is caused by the blockage of the aqueous humour outflow due to increased extracellular matrix deposition in the trabecular meshwork (TM)1. Over time the increased pressure can damage structures in the eye resulting in vision loss. Current therapeutic strategies to lower the IOP include indefinite eye-drops, which can cause side effects, or complex filtration surgery. Fibrosis at the time of surgery is reduced by treatment of tissue with anti-metabolites such as mitomycin C at the time of surgery, but this is associated with local toxicity predisposing to leaks, tissue breakdown and infections2. The lack of safe and effective anti-fibrotic treatments presents an important clinical challenge. It is therefore important to identify novel targets for drug development. Scarring and fibrosis of the eye in glaucoma is associated with marked structural and functional reorganisation of the trabecular meshwork, the main site of resistance to fluid outflow in the eye. The pathophysiology of glaucoma, has not yet been fully elucidated and investigators are mainly reliant on in vivo rodent models3. This in part has been due to the lack of meaningful tissue engineered and suitable ex vivo models. In order to identify novel targets and develop new treatments, we have been collaborating with Birmingham and Midlands Eye Centre to successfully collect TM tissue from patients with and without glaucoma. Therefore, this human data source will not only provide us with novel insights into the underlying mechanisms of the disease but also provide us with new pathways to target as a therapeutic strategy.Aims: Our aim is design a novel in vitro 'organ on a chip' model to understand the pathology which occurs in the TM in glaucoma and to identify novel anti-scarring compounds for the treatment of glaucoma. We will achieve this by investigating the mechanisms that control fibrosis in human trabecular meshwork (TM) and the interaction with Schlemm's Canal cells. We will develop co-culture systems in 3D models4 which mimic the human trabecular meshwork/Schlemm's canal and then use this model for testing and screening new anti-scarring treatments. In addition, we will develop dynamic perfusion models within ex vivo assays derived from explant human tissues (Ethics and sourced material in place) to investigate the pressure inducing effects of scarring in the eye. Using aligned optical coherence tomography (OCT) to the 'chip' models we will also define changes in mechanical properties of the engineered human TM alongside cell and molecular outcomes of treatments. Training outcomes: The PhD Candidate will be supervised by an ocular biologist (Dr Hill), a biomaterial scientist (Prof Grover) and tissue engineer (Prof A El Haj) and will have close input from a clinical ophthalmologist (Mr Masood, Glaucoma Consultant) and industrial support from the Cell Guidance Systems Ltd (Dr Michael Jones). The overall aim is to reduce the need to use our rodent glaucoma models to assess new anti-scarring treatments. Within this project the student will expect to receive training on human tissue processing (samples derived from patients), cell culture techniques for developing 3D in vitro models reconstructing collagen and elastin scaffolds (to model the TM) and to develop skills in setting up ex vivo porcine and human models for understanding glaucoma pathology and to assess candidate treatments. Students would learn routine molecular biology techniques (immunocytochemistry, western blots, PCR) in order to characterize the models and assess effects of anti-scarring treatments and have the opportunity for both industrial and international placements.