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

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.

Humanised, 3D tissue models are finding interest due to current overly-simplified immortal cell lines and non-human in vivo models providing poor prediction of drug safety, dosing and efficacy; 43% of drug fails are not predicted by traditional screening and move into phase I clinical trials1. Phase I sees a 48% success rate, phase II a 29% success rate and phase III a 67% success rate [1]. The drug development pipeline is pressurised due to adoption of high throughput screening / combinatorial libraries. However, while R&D spend has increased to meet this growing screening programme, success, measured by launched drugs, remains static [2]. This poor predictive power of the >1 million animals used in the UK each year drives the 12-15 year, £1.85B pipeline, for each new drug launch [3]. Contract research organisations (CROs) are also similarly hit by these problems.

Drive to reduce animal experimentation in toxicology and outright banning of animal testing for e.g. cosmetics in the UK has driven companies to outsource or to adopt the limited number of regulator approved NAT models for e.g. skin [4,5].

Another key area that uses 3D tissues is the field of advanced therapeutic medicinal products (ATMPs), i.e. tissue engineering/regenerative medicine. Regulation is a major ATMP bottleneck. It is thus noteworthy that regulators, such as the UKs Medicines and Healthcare Products Regulatory Agency (MHRA), are receptive to the inclusion of NAT-based data in investigative medicinal product dossiers [6].

The lifETIME CDT will directly address these issues through nurturing of a cohort training not only in the research skills required to conceive and design new NATs, but also in skills based on:

- GMP and manufacture.
- Commercialisation and entrepreneurship.
- Regulation.
- Drug discovery and toxicology - a focus on the end product.
- Policy.
- Public engagement.

Our NAT graduate community will impact on:

- Pharma - access to skills that develop tools to unlock their drug discovery and testing portfolios. By helping train graduates who can create and deploy NATs, they will increase efficiency of drug development pipelines.

- ATMP manufacturers - the same skills and tools used to deliver NAT innovation will help to deliver tissue engineered / combination product ATMPs.

- CROs - access to skills to create platform tools providing more sophisticated approaches to the diverse research challenges they face.

- Catapult Centres - access to skills that provide innovation that can be deployed across the broader healthcare sector.

- Regulatory agencies e.g. MHRA - better education for the next generation of scientists on development of investigational new drug / medicinal product dossiers to speedup approvals.

- Clinicians and NHS - access to more medicines more quickly through provision of highly skilled scientists, manufacturers and regulators. NATs will help drive the stratified/personalised medicine revolution and understand safety and efficacy parameters in human-relevant tissues. Clinicians will also benefit from development of ATMP-based regenerative medicine.

- Patients - benefit from skills for faster and more economically streamlined development of new medicines that will improve lifespan and healthspan.

- Public and Society - benefit from the economic growth of a thriving drug development industry. Benefits will be direct, via jobs creation and access to wider and more targeted healthcare products; and indirect, via increased economic benefit of patients returning to work and increased tax revenues, that in turn feed back into the healthcare systems.


[1]. Cook. Nat Rev Drug Discov 13, 419-431 (2014).
[2]. Pammolli. Nat Rev Drug Discov 10, 428-438 (2011).
[3]. DiMasi. Health Econ 47, 20-33 (2016).
[4]. Cotovio. Altern Lab Anim 33, 329-349 (2005).
[5]. Kandarova. Altern Lab Anim 33, 351-367 (2005).
[6]. https://goo.gl/i6xbmL