Retinal repair using embryonic stem cell-derived cone photoreceptors
Lead Research Organisation:
University College London
Department Name: Institute of Ophthalmology
Abstract
Aim of the project:
The aim of this project is find out if sight loss caused by degeneration of the retina might be restored by transplantation of retinal cone photoreceptor cells grown from embryonic stem cells.
Background:
The retina is the sheet of nerves in the eye that is essential for healthy sight. The light-sensitive cells in the retina are known as photoreceptors, including rods and cones. Degeneration of these cells account for the leading causes of untreatable blindness in the UK, and the commonest condition is age-related macular degeneration which affects as many as 1 in 10 people over the age of 60 years. Most photoreceptors are rods and these cells enable sight in dimly lit conditions, but sight in normally lit conditions relies on healthy cones. Photoreceptor cells that are lost or damaged cannot regenerate and sight loss is currently irreversible. However, it might be possible to restore sight to people with retinal degeneration by providing healthy photoreceptor cells by transplantation. Previous work in the Ali laboratory has demonstrated, in 2 publications in the journal Nature, that rod-mediated sight can be restored by transplantation of rod photoreceptors from a healthy donor when the transplanted cells are at a specific age of development. More recent work in the laboratory has demonstrated that transplantation of cone photoreceptors is also possible. However, transplantation of cones is much less efficient than that of rods, possibly because only a relatively small minority of cone cells are obtained from the donor. It is important to improve the efficiency of cone photoreceptor transplantation so as realise its potential for people with blinding retinal degenerations.
Experimental plan:
Objective 1: to expand the number of healthy cones available for transplantation by promoting their growth in the laboratory from embryonic stem cells.
I propose to expand the number of cone photoreceptor available for transplantation by promoting development of cone cells in 3-dimensional laboratory culture. I will use complementary approaches to manipulate signals that are both extrinsic and intrinsic to developing photoreceptor cells. To find out if the efficiency of cone transplantation is limited by the concomitant delivery of rods, I will enrich the donor population for cones by cell sorting. These experiments will determine if cone-rich populations result in more successful cone photoreceptor transplants.
Objective 2: to transplant cone photoreceptors efficiently into the retina of healthy recipients and those with retinal disease.
Once sufficient cone photoreceptor development has been achieved in the laboratory, I will transplant this cell population into the adult healthy retina. By transplanting cells from different stages of photoreceptor development in culture I will find out which can be most efficient and most durable. Once cone transplantation is optimised in the healthy retina, I will investigate its impact in retinal degeneration by transplanting into recipients that lack normal cone photoreceptors. Given that cones constitute only a small minority of photoreceptors, valuable function might be restored with the replacement of relatively few cells.
The aim of this project is find out if sight loss caused by degeneration of the retina might be restored by transplantation of retinal cone photoreceptor cells grown from embryonic stem cells.
Background:
The retina is the sheet of nerves in the eye that is essential for healthy sight. The light-sensitive cells in the retina are known as photoreceptors, including rods and cones. Degeneration of these cells account for the leading causes of untreatable blindness in the UK, and the commonest condition is age-related macular degeneration which affects as many as 1 in 10 people over the age of 60 years. Most photoreceptors are rods and these cells enable sight in dimly lit conditions, but sight in normally lit conditions relies on healthy cones. Photoreceptor cells that are lost or damaged cannot regenerate and sight loss is currently irreversible. However, it might be possible to restore sight to people with retinal degeneration by providing healthy photoreceptor cells by transplantation. Previous work in the Ali laboratory has demonstrated, in 2 publications in the journal Nature, that rod-mediated sight can be restored by transplantation of rod photoreceptors from a healthy donor when the transplanted cells are at a specific age of development. More recent work in the laboratory has demonstrated that transplantation of cone photoreceptors is also possible. However, transplantation of cones is much less efficient than that of rods, possibly because only a relatively small minority of cone cells are obtained from the donor. It is important to improve the efficiency of cone photoreceptor transplantation so as realise its potential for people with blinding retinal degenerations.
Experimental plan:
Objective 1: to expand the number of healthy cones available for transplantation by promoting their growth in the laboratory from embryonic stem cells.
I propose to expand the number of cone photoreceptor available for transplantation by promoting development of cone cells in 3-dimensional laboratory culture. I will use complementary approaches to manipulate signals that are both extrinsic and intrinsic to developing photoreceptor cells. To find out if the efficiency of cone transplantation is limited by the concomitant delivery of rods, I will enrich the donor population for cones by cell sorting. These experiments will determine if cone-rich populations result in more successful cone photoreceptor transplants.
Objective 2: to transplant cone photoreceptors efficiently into the retina of healthy recipients and those with retinal disease.
Once sufficient cone photoreceptor development has been achieved in the laboratory, I will transplant this cell population into the adult healthy retina. By transplanting cells from different stages of photoreceptor development in culture I will find out which can be most efficient and most durable. Once cone transplantation is optimised in the healthy retina, I will investigate its impact in retinal degeneration by transplanting into recipients that lack normal cone photoreceptors. Given that cones constitute only a small minority of photoreceptors, valuable function might be restored with the replacement of relatively few cells.
Technical Summary
Aim: To determine if sight loss caused by degeneration of the retina can be restored by transplantation of cone photoreceptor cells derived from embryonic stem cells.
Background: Degeneration of the light-sensitive photoreceptor cells (rods and cones) accounts for the majority of people with untreatable blindness. Photoreceptor cells that are lost or damaged cannot regenerate, and the associated sight loss is currently irreversible. However, restoration of sight to people with retinal degeneration might be achieved by transplantation of photoreceptor cells from healthy donors. Previous work in the Ali laboratory has demonstrated that rod-mediated (dark-adapted) sight can be restored by transplantation of rod photoreceptors from a healthy donor when the transplanted cells are at a specific age of development. More recent work in the lab has shown that transplantation of cone photoreceptors, which are critical for normal sight in light-adapted conditions, is also possible. However, transplantation of cone photoreceptors is much less efficient than that of rods, possibly because only a relatively small minority of cone cells are obtained from the donor.
Research Plan: I propose to expand the number of cone photoreceptor available for transplantation by promoting development of cone cells in 3-dimensional laboratory culture from embryonic stem cells. I will use complementary approaches to manipulate signals that are both extrinsic and intrinsic to developing photoreceptor cells. To find out if the efficiency of cone transplantation is limited by the concomitant delivery of rods, I will enrich the donor population for cones by cell sorting. Once sufficient cone photoreceptor development has been achieved in the laboratory, I will transplant this cell population into the adult healthy retina and those with retinal disease. Given that cones constitute only a minority of photoreceptors, valuable function might be restored with the replacement of relatively few cells.
Background: Degeneration of the light-sensitive photoreceptor cells (rods and cones) accounts for the majority of people with untreatable blindness. Photoreceptor cells that are lost or damaged cannot regenerate, and the associated sight loss is currently irreversible. However, restoration of sight to people with retinal degeneration might be achieved by transplantation of photoreceptor cells from healthy donors. Previous work in the Ali laboratory has demonstrated that rod-mediated (dark-adapted) sight can be restored by transplantation of rod photoreceptors from a healthy donor when the transplanted cells are at a specific age of development. More recent work in the lab has shown that transplantation of cone photoreceptors, which are critical for normal sight in light-adapted conditions, is also possible. However, transplantation of cone photoreceptors is much less efficient than that of rods, possibly because only a relatively small minority of cone cells are obtained from the donor.
Research Plan: I propose to expand the number of cone photoreceptor available for transplantation by promoting development of cone cells in 3-dimensional laboratory culture from embryonic stem cells. I will use complementary approaches to manipulate signals that are both extrinsic and intrinsic to developing photoreceptor cells. To find out if the efficiency of cone transplantation is limited by the concomitant delivery of rods, I will enrich the donor population for cones by cell sorting. Once sufficient cone photoreceptor development has been achieved in the laboratory, I will transplant this cell population into the adult healthy retina and those with retinal disease. Given that cones constitute only a minority of photoreceptors, valuable function might be restored with the replacement of relatively few cells.
Planned Impact
Age-related macular degeneration (AMD) is the commonest cause of blindness in the developed world. Inherited retinal degenerations collectively account for a substantial burden of severe and untreatable sight impairment affecting children and young people. My aim is to help realise the potential of stem cells for retinal regeneration in these blinding conditions.
Due to the prevalence of AMD and its impact on the lives of those affected, and the excitement generated by the prospect for stem cell therapies, there is considerable interest across the research community globally in this field. The findings of the proposed project will immediately complement existing research, benefiting the academic community, health researchers and the commercial sector.
Having developed gene and cell therapy approaches for a wide range of ocular disorders and demonstrated proof of principle in clinical application, Professors Ali and Bainbridge have the relevant expertise and infrastructural resources to translate relevant findings into new interventions for the benefit of patients. It is anticipated that development of a new cell intervention from preclinical proof of concept to clinical application will take approximately 5 years.
In the long term, if a clinical application is developed, patients will benefit by having a potentially more effective treatment. This would positively affect quality of life while decreasing the morbidity associated with this condition. Development of new modalities may benefit policy-makers, governments and government agencies by providing a potentially more cost-effective approach to the treatment of this condition. This is important when considering the ageing demographic and its impact on healthcare.
Due to the prevalence of AMD and its impact on the lives of those affected, and the excitement generated by the prospect for stem cell therapies, there is considerable interest across the research community globally in this field. The findings of the proposed project will immediately complement existing research, benefiting the academic community, health researchers and the commercial sector.
Having developed gene and cell therapy approaches for a wide range of ocular disorders and demonstrated proof of principle in clinical application, Professors Ali and Bainbridge have the relevant expertise and infrastructural resources to translate relevant findings into new interventions for the benefit of patients. It is anticipated that development of a new cell intervention from preclinical proof of concept to clinical application will take approximately 5 years.
In the long term, if a clinical application is developed, patients will benefit by having a potentially more effective treatment. This would positively affect quality of life while decreasing the morbidity associated with this condition. Development of new modalities may benefit policy-makers, governments and government agencies by providing a potentially more cost-effective approach to the treatment of this condition. This is important when considering the ageing demographic and its impact on healthcare.
People |
ORCID iD |
| Manjit Mehat (Principal Investigator / Fellow) |
Publications
Bainbridge JW
(2015)
Long-term effect of gene therapy on Leber's congenital amaurosis.
in The New England journal of medicine
Lange C
(2016)
Dimethylarginine dimethylaminohydrolase-2 deficiency promotes vascular regeneration and attenuates pathological angiogenesis.
in Experimental eye research
Mehat M
(2014)
Brachytherapy for benign fundus lesions
in Expert Review of Ophthalmology
Subash M
(2016)
The Effect of Multispot Laser Panretinal Photocoagulation on Retinal Sensitivity and Driving Eligibility in Patients With Diabetic Retinopathy.
in JAMA ophthalmology
| Description | Polymeric Scaffolds Possessing Peptide-Gradients as Bruch's Membrane Mimetics for Implantation of Retinal Pigment Epithelial Cells |
| Organisation | Imperial College London |
| Country | United Kingdom |
| Sector | Academic/University |
| PI Contribution | The Ali/Bainbridge Group will generate embryonic stem cell (ESC)-derived retinal pigmented epithelium (RPE) cells using a novel a 3-D culture system that enables ESCs to self-organise and mimic the morphological development of the retina, as previously published work published by us [A Gonzalez-Cordero, et al. Nature Biotechnology. 2013; DOI: 10.1038/nbt.2643]. ESC-derived RPE cells will be isolated from the 3-D culture systems and cultured on the first generation and optimized systems. Assessment of optimal bio-carrier membrane will be determined through a variety of assays for RPE morphology and function including; ability to form tight junctions, their permeability properties, apical-basal polarity, phagocytosis of outer photoreceptor segments and phenotype. Optimal scaffolds will be defined as those capable to culture, maintain and deliver fully functional monolayer RPE sheets. Priming for in vivo analyses of 'optimal' scaffolds will be investigated by using injection devices used for sub-retinal transplantation. |
| Collaborator Contribution | The Stevens Group will design and synthesise a variety of scaffolds that mimic the Bruch's membrane in terms of mechanical properties and function. PCL-based fibers will be electrospun and functionalised according to previously published work published by us [L. Chow, et al. Advanced Healthcare Materials. 2014; DOI: 10.1002/adhm.201400032]. |
| Impact | 1. D1: Optimisation of polymeric scaffold nanofibrous design. Target: range of diameters (200 nm - 2 microns). 2. D3: In vitro materials characterisation of peptide-functionalised fibrous scaffolds bound to various biomolecules (e.g. HS, laminin and vitronectin) as well as mechanical profiling. 3. D4: In vitro cellular-based studies using RPEs and evaluation of morphology and function. |
| Start Year | 2015 |
| Description | Age related macular degeneration (AMD): Patient day |
| Form Of Engagement Activity | Participation in an open day or visit at my research institution |
| Part Of Official Scheme? | No |
| Geographic Reach | National |
| Primary Audience | Participants in your research and patient groups |
| Results and Impact | Presented poster highlighting the work that I was undertaking in the lab and clinic. Patient feedback forms demonstrated that this was a highly informative meeting. |
| Year(s) Of Engagement Activity | 2014 |
| Description | Retina Day: Patient engagement day |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | National |
| Primary Audience | Patients, carers and/or patient groups |
| Results and Impact | Engage with patients with a variety of different retinal conditions, identify question that they have for researchers currently investigating retinal disease and therapy. Present current areas of research that the group are undertaking in retinal degeneration. |
| Year(s) Of Engagement Activity | 2015 |