Development of stem cell therapy to restore photopic vision

Lead Research Organisation: University College London
Department Name: Institute of Ophthalmology

Abstract

Hereditary retinal disease and age related macular degeneration (AMD) are major causes of irreversible blindness in Europe and involve the loss of the light sensitive cone and rod photoreceptor cells in the retina. Inherited retinal dystrophies affect 1 in 3,000, and age related macular degeneration (AMD) affects 1 in 10 people over the age of 60. The lack of effective treatments for these conditions means there is a requirement to develop new therapies. The replacement of lost photoreceptors by cell transplantation is one possible approach, but transplanted cells need to make functional connections with the host retina. We have recently demonstrated that transplantation of immature photoreceptor cells (precursors) from the developing retina into mouse models of retinal disease results in the integration of new rod photoreceptors that restore low light vision in mice with a non progressive form of inherited blindness. As human vision is dependent upon cone photoreceptors, which provide high acuity daylight and colour vision, as well as rod photoreceptors, which provide low light vision, cone transplantation is likely to be essential for clinical application. In late stage retinitis pigmentosa, despite loss of most rods, patients have useful vision until the last remaining cones degenerate. Furthermore, cone transplantation is critical for optimal retinal repair in patients with AMD as this condition involves degeneration only of the cone-rich macula region of the retina. Since the retina consists of only 5% cones we might be able to restore significant function with the replacement of relatively few cones. In certain instances patients with macular degeneration can fixate and create new pseudo-fovea following training and this might be enhanced if, by transplantation, cone density could be increased outside the degenerate macula.

In this project we will determine the conditions for effective transplantation of cone photoreceptors and the restoration of daylight vision in animal models of degenerative retinal disease, in order to provide the framework for developing similar approaches to treat human disease. We will conduct the following investigations to achieve this goal. (i) We will perform experiments to identify important interactions that may limit the number of new photoreceptors connecting after transplantation and will modify conditions to improve transplantation into the degenerating retina. We will study rod transplantation in order to develop improved protocols for transplanting cones (ii) We will identify and manipulate the genetic controls that may limit cone integration and use our acquired knowledge of how to effectively isolate and transplant rod precursors in order to achieve optimal integration of new functional cone cells. (iii) We will determine the synaptic connectivity of new cone and rod cells as, in order to restore vision, it is necessary for transplanted photoreceptors to form connections with cells of the inner retina (bipolar cells) and we need to know whether this occurs in the degenerating environment. (iv) We will transplant photoreceptor precursors generated from stem cell lines (embryonic stem cell lines) and examine whether these are as good as the cells isolated from the developing retina, which we use in our proof of principle experiments. This is essential as to translate our findings in mice to humans we need to show that photoreceptor precursors from a renewable source, such as embryonic stem cells can effectively restore vision. We will progress from studies involving transplantation of photoreceptor precursors derived from developing mouse retinae, to studies involving transplantation of human stem cell-derived cone precursors that might be useful for clinical application. Each programme component will inform the next step, providing the best opportunity to develop a successful long-term strategy for clinical application.

Technical Summary

Retinal degenerations leading to loss of photoreceptors are the leading cause of untreatable blindness in Europe. Currently there are no treatments that restore lost photoreceptors and visual function. There is clearly a need for new therapeutic approaches. In 2006 we discovered that photoreceptor precursors can be effectively transplanted into the adult retina and recently we have been able to provide the first definitive evidence of restoration of rod-mediated vision, following transplantation into Gnat1-/- animals, a model of congenital stationary night blindness. Our research to date has established principles of effective rod photoreceptor transplantation. We propose that retinal repair by photoreceptor transplantation is one of the most feasible types of CNS repair as new photoreceptors need only make short, single synaptic connections to the inner retinal circuitry to contribute to visual function. As humans rely on cone and not rod vision, cone transplantation is likely to be the most effective strategy for clinical application. We are now seeking to prove the concept that it is possible to restore photopic vision in mouse models of human retinal degenerative diseases by cell transplantation based on our proven strategy for rod transplantation. The following inter-related investigations will be conducted: (i) modify environmental conditions to enhance cell integration and migration (ii) manipulate the genetic controls that limit cone integration, including transplantation of Nrl-/- and Nr2e3-/- cells, lineage tracing and using genetics fluorescent reporters (iv) examine retinal circuitry of transplanted cells using new synaptic labeling methodologies that utilise engineered viral vectors to transduce cells through connecting synapses. (v) transplant photoreceptor precursors generated from ES/iPS cells and demonstrate that that they are functional. This programme aims to provide the framework for developing stem cell therapy to treat human retinal disease.

Planned Impact

Hereditary retinal disease and age related macular degeneration (AMD) leading to photoreceptor loss are the leading causes of untreatable blindness in the UK. Inherited retinal degenerations affect 1 in 3000 of the population whilst AMD affects 1 in 10 people over the age of 60 and its prevalence is increasing. AMD is responsible for over 50% of blind registrations in the UK in patients over 65 years of age. At present, there are no available treatments that offer anything more than a temporary slowing of disease and even then to only a minority of patients. The increasing socio-economic burden of AMD provides an urgent imperative for developing new therapies. We have recently discovered that transplantation of immature photoreceptors improves rod vision in mouse models of retinal degeneration. The proposed programme aims to build on our discovery and to develop stem cell therapy for the treatment of retinal diseases and restoration of photopic vision. By the end of this 5 year programme we aim to have established robust proof-of-concept for stem cell derived photoreceptor transplantation that will support the development of a clinical trial in patients with macular degeneration.

Publications

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Barber AC (2013) Repair of the degenerate retina by photoreceptor transplantation. in Proceedings of the National Academy of Sciences of the United States of America

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Di Foggia V (2016) Induced Pluripotent Stem Cell Therapies for Degenerative Disease of the Outer Retina: Disease Modeling and Cell Replacement. in Journal of ocular pharmacology and therapeutics : the official journal of the Association for Ocular Pharmacology and Therapeutics

 
Description Cross Council Workshop on New Approaches to Improving Hearing Devices (MRC and EPSRC)
Geographic Reach National 
Policy Influence Type Participation in advisory committee
 
Description Department of Health Regenerative Medicine Expert Group
Geographic Reach National 
Policy Influence Type Gave evidence to a government review
 
Description House of Lords Inquiry into regenerative Medicine
Geographic Reach National 
Policy Influence Type Gave evidence to a government review
 
Description Organising Committee, Joint MHRA-MRC-Academy Medical Sciences - ABPI workshops to develop regulatory framework for regenerative medicine involving cell transplantation
Geographic Reach National 
Policy Influence Type Participation in advisory committee
 
Description Participant 'New Strategy for UK Regenerative Medicine' On behalf of the 4 UK Research Council plus Technology Strategy Board
Geographic Reach National 
Policy Influence Type Gave evidence to a government review
 
Description ERC advanced grant
Amount € 2,450,000 (EUR)
Organisation European Research Council (ERC) 
Sector Public
Country Belgium
Start 08/2013 
End 07/2018
 
Description Equipment grant (FACS Cabinet)
Amount £17,560 (GBP)
Funding ID E17000A 
Organisation Moorfields Eye Charity 
Sector Charity/Non Profit
Country United Kingdom
Start 02/2017 
End 01/2018
 
Description Moorfields Eye Hospital Special Trustees Award
Amount £13,500 (GBP)
Organisation Moorfields Eye Hospital NHS Foundation Trust 
Department The Special Trustees of Moorfields Eye Hospital General Fund
Sector Charity/Non Profit
Country United Kingdom
Start 11/2015 
End 10/2016
 
Description Moorfields Eye Hospital Special Trustees Award
Amount £43,000 (GBP)
Organisation Moorfields Eye Hospital NHS Foundation Trust 
Department The Special Trustees of Moorfields Eye Hospital General Fund
Sector Charity/Non Profit
Country United Kingdom
Start 09/2015 
End 09/2016
 
Description Project Grant (Regen Med)
Amount £1,101,688 (GBP)
Funding ID MR/M007871/1 
Organisation Medical Research Council (MRC) 
Sector Public
Country United Kingdom
Start 12/2014 
End 11/2018
 
Description Project Grant (Stargardt)
Amount £539,000 (GBP)
Funding ID MEC 15 12 C 
Organisation Moorfields Eye Charity 
Sector Charity/Non Profit
Country United Kingdom
Start 06/2016 
End 05/2019
 
Description Project grant
Amount £13,613 (GBP)
Funding ID 12.01.16 
Organisation Macular Society 
Sector Charity/Non Profit
Country United Kingdom
Start 11/2015 
End 10/2016
 
Description Project grant through private donation
Amount £500,000 (GBP)
Organisation Moorfields Eye Hospital NHS Foundation Trust 
Department The Special Trustees of Moorfields Eye Hospital General Fund
Sector Charity/Non Profit
Country United Kingdom
Start 10/2012 
End 09/2015
 
Description Public Engagement
Amount £30,000 (GBP)
Funding ID 100847/Z/13/Z 
Organisation Wellcome Trust 
Sector Charity/Non Profit
Country United Kingdom
Start 11/2013 
End 10/2016
 
Description Refurbishment (Human ESC Facility))
Amount £32,000 (GBP)
Funding ID E170001A 
Organisation Moorfields Eye Charity 
Sector Charity/Non Profit
Country United Kingdom
Start 06/2016 
End 12/2016
 
Description Research Grant (J Sowden lead)
Amount £833,500 (GBP)
Funding ID MR/M015688/1 
Organisation Medical Research Council (MRC) 
Sector Public
Country United Kingdom
Start 10/2015 
End 09/2018
 
Description Studentship
Amount £135,000 (GBP)
Organisation Wellcome Trust 
Sector Charity/Non Profit
Country United Kingdom
Start 10/2012 
End 09/2015
 
Description UCL's Wellcome Trust Institutional Strategic Support Fund
Amount £100,000 (GBP)
Organisation Wellcome Trust 
Sector Charity/Non Profit
Country United Kingdom
Start 11/2013 
End 10/2014
 
Description UKRMP Immunomodulation Hub
Amount £185,681 (GBP)
Funding ID MR/L022699/1 
Organisation Medical Research Council (MRC) 
Sector Public
Country United Kingdom
Start 09/2014 
End 08/2017
 
Description UKRMP Partnership Project Award
Amount £27,884 (GBP)
Funding ID RA26A7 
Organisation Medical Research Council (MRC) 
Sector Public
Country United Kingdom
Start 12/2014 
End 11/2017
 
Description Riken Institute, Kobe, Japan 
Organisation RIKEN
Country Japan 
Sector Public 
PI Contribution We trained Japanese group in cell transplantation to retina
Collaborator Contribution Partly funded a collaborative exchange that enabled us to learn latest stem cell differentiation protocols from leading group.
Impact Resulted in an award being made by the Royal Society in recognition of the collaboration and to support a 3 month visit by one of the post doctoral researchers working on the project
Start Year 2008
 
Title Use of nucleic acids to improve vision by extending the photo-sensitivity of functional rod photoreceptors to mesopic and photopic illumination levels 
Description The invention relates to methods of improving vision. Specifically, the invention relates to the use of an isolated or synthetized nucleic acid molecule to extend the light sensitivity of rod photoreceptors in the mesopic and photopic illumination ranges and its use to improve visual function, for example following degeneration or loss of the 'macula'. The invention involves 1) Over-expression of Rgs9-binding protein (RSG9BP; previously known as RGS9 anchor protein - R9AP), a critical component of a protein complex that mediates the deactivation of phototransduction cascade, results in desensitization and "photopic shift" of the rod-driven electroretinogram. The treatment enables the rods to respond to brighter light (up to ~100 fold) than untreated cells at the expense of scotopic function. Furthermore, the increased de-activation of the phototransduction cascade allows rod cells to follow the light with greater temporal precision. AND 2) The use of a light-gated membrane protein that hyperpolarizes cells upon light stimulation. Because this protein responds to light under photopic and mesopic conditions, its expression in rod photoreceptors allows them to function under brighter illumination than the scotopic levels at which they are already functional. Furthermore, the rapid kinetics of the molecule allow cells to follow the light with millisecond precision and do not undergo the bleaching that is characteristic of rod photoreceptors. The invention is particularly relevant as a method to provide improved vision in the photopic and mesopic range where this type of vision has been lost (for example because of Macular Degeneration, a disease where the high density 'patch' of cone photoreceptors in the macula, active in the photopic and mesopic ranges has degenerated). 
IP Reference WO2016001693 
Protection Patent application published
Year Protection Granted 2016
Licensed Commercial In Confidence
Impact Papers in preparation
 
Description BRPS AGM 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Type Of Presentation Keynote/Invited Speaker
Geographic Reach National
Primary Audience Participants in your research and patient groups
Results and Impact British Retinitis Pigmentosa Society AGM

circulated research findings to patients
Year(s) Of Engagement Activity 2008,2009,2010,2011,2012
 
Description Departmental website 
Form Of Engagement Activity A magazine, newsletter or online publication
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact Regular updates to departmental website giving an over view of work being conducted.

Attracted research funds from a donor
Year(s) Of Engagement Activity 2008,2009,2010,2011,2012
 
Description FBI AGM 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Type Of Presentation Keynote/Invited Speaker
Geographic Reach International
Primary Audience Participants in your research and patient groups
Results and Impact AGM Fighting Blindness, Ireland

research circulated to patients
Year(s) Of Engagement Activity 2009,2010,2011,2012
 
Description Radio interviews 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Type Of Presentation Keynote/Invited Speaker
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact Interviews on Radio 4 Today programme, BBC World Service and local radio stations about stem cell therapy for retinal degneration

Interest from public in our research - more email inquiries
Year(s) Of Engagement Activity 2010,2011,2012
 
Description Retina Day 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Patients, carers and/or patient groups
Results and Impact 300 patients and their carers attended a1 day meeting in which we told them about our work on gene and cell therapy. There were talks and posters. Forty people from the lab attended to present and answer questions.
Year(s) Of Engagement Activity 2015
 
Description Retina 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 We organised a day for patients with retinal disorders to hear about our my groups gene and cell therapy research.
350 patients and their families attended. We presented 50 posters and gave 8 short talks.

Increased interest in our website updates and increased donations.
Year(s) Of Engagement Activity 2012