Stem cell based treatment strategy for Age-related Macular Degeneration (AMD)

Stem cell based treatment strategy for Age-related Macular Degeneration (AMD)

Funding Type: 
Disease Team Research I
Grant Number: 
DR1-01444
Award Value: 
$18,904,916
Disease Focus: 
Vision Loss
Collaborative Funder: 
UK
Stem Cell Use: 
Embryonic Stem Cell
Cell Line Generation: 
Embryonic Stem Cell
Status: 
Active
Public Abstract: 
Retinal degeneration represents a group of blinding diseases that are increasingly impacting the health and well being of Californians. It is estimated that by 2020, over 450,000 Californians will suffer from vision loss or blindness due to the age-related macular degeneration (AMD), the most common cause of retinal degeneration diseases in the elderly. AMD is a progressive ocular disease of the part of the retina, called the macula, which enables people to read, visualize faces, and drive. The disease initially causes distortion in central vision, and eventually leads to legal blindness. 

A layer of cells at the back of the eye called the retinal pigment epithelium (RPE), provide support, protection, and nutrition to the light sensitive cells of the retina; the photoreceptors which consist of rods and cones . The dysfunction and/or loss of these RPE cells play a critical role in the loss of the PR’s and hence the blindness in AMD. Effective treatment could be achieved by proper replacement of damaged RPE and retinal cells with healthy ones. More specifically, the regenerated and restored RPE layer would prevent the irreversible loss of the PR’s. However, the lack of a feasible approach to restore the RPE cells has prevented the realization of a potential therapy.

Recent advances in knowledge and technology of human embryonic stem (hES) cells brings new hope for the development of cell replacement treatment. hES cells are capable of unlimited self-replication and production of different cell types. RPE cells derived from hES cells are a potentially unlimited and robust source for regenerating RPE.

We hypothesize that the dysfunction and/or loss of RPE can be overcome by regenerating and restoring the RPE through the transplantation of functionally polarized RPE monolayers derived from hES cells. Such RPE cells derived from hES can then be transplanted into the eye, using minimally invasive surgical procedures saving the PR from dying. 

Our group is composed of unique multidisciplinary members who collectively have more than two decades of experience in efforts to restore sight to the blind as well as retinal cell transplantation and stem cell research. Our plan for this grant is to use our expertise and infrastructure to show to the FDA the success of our preclinical tests using hES derived RPE cells in order to get approval to conduct a clinical trial in patients at risk of vision loss due to AMD.
Statement of Benefit to California: 
Age-related macular degeneration (AMD) is the leading cause of vision loss and blindness among the elderly. Based on the fact that California is one of the most populated state in the Unites States (38 million population in 2007), and a greater percentage of its population will be 65 years or older. It is estimated that over 450,000 of Californians will suffer from AMD with severe vision impairment by 2020. Even using National Eye Institute numbers from 2003 and adjusting it for the population of California, the costs for California exceed $8 billion (http://www.nei.nih.gov/eyedata/hu_estimates.asp). Since the introduction of the anti-VEGF drug Lucentis by Genentech in 2006, the cost for the treatment for AMD has even further sky rocketed. For example, the cost of these monthly injections to treat all of the new cases of neovascular (wet) AMD in 2008 in California alone would exceed 9 billion (single patient costs per year often is approximately $25k/year). Moreover, studies have shown that the devastating consequences of AMD include the progressive loss of independence and productivity, and increased risks of falls, fractures, and depression among diseased population. So this is not only a problem of the individual quality of life, but also an issue of increasing public health burden and concern.

In this study, we will test the feasibility of treating AMD through the transplantation of human embryonic stem cells that have been treated to differentiate into retinal pigment epithelial cells (RPE); one of the key cell types known to primarily degenerate or die in AMD. The approach of regenerating the RPE cell layer has many advantages over regenerating photoreceptors and is much more likely to be achieved in the near future. The biggest advantage to RPE cell layer regeneration is that it is preventative and protects or rescues the photoreceptors from degenerating. Also, since it is not a neuronal cell line it does not need to form synapses with the host; a much more difficult task. The success of our preclinical experimentation with RPE replacement therapy will be seamlessly and quickly transferred into clinical trials to develop novel treatments for AMD. Ultimately, hundreds of thousands of Californians with AMD would benefit from our research, with improvement in quality of life and reduced morbidity. The California economy will significantly benefit from this work through potential reduced costs for health care and social welfare. We also envision that our research would lead to a new industry and hence many more employment opportunities and also add to the revenue generated by the state of California. Also our efforts at the University level in California would lead to new curricula in stem cells and regenerative medicine and thus educate the work force of the future.
Progress Report: 

Year 1

It is estimated that by 2020, over 450,000 Californians will suffer from vision loss or blindness due to the age-related macular degeneration (AMD), the most common retinal degenerative disease in the elderly. AMD is a progressive ocular disease of the part of the retina at the back of the eye, called the macula, which enables people to read, visualize faces, and drive. The disease initially causes distortion in central vision, and eventually leads to legal blindness.
 
 A layer of cells at the back of the eye called the retinal pigment epithelium (RPE)provide support, protection, and nutrition to the light sensitive photoreceptors in the retina. The dysfunction and/or loss of these RPE cells play a critical role in the loss of the PR’s and hence the blindness in AMD. Effective treatment could be achieved by proper replacement of damaged RPE and retinal cells with healthy ones. RPE cells derived from human embryonic stem cells (hESC) are a potentially unlimited and robust source for regenerating RPE (hESC-RPE).
 
 During the first year of our Disease Team Grant we have assembled a closely working team of interdisciplinary scientists and physician scientists at the University of Southern California (USC), Doheny Eye Institute (DEI), University of California Santa Barbara (UCSB), California Institute of Technology (Caltech), and City of Hope (COH). Our scientists work and meet together frequently to discuss progress and we have had 2 highly successful full-day retreats; one at USC and one at UCSB.
 
 We are on track for each of the Year 1 proposed milestones. During the first year we have made a decision on final selection of hESC line; and have developed protocols for the generation and molecular and functional characterization of hESC-RPE and are transferring these protocols to our manufacturing and regulatory partners at City of Hope. COH has had onsite visits to learn protocols at UCSB and USC and we have had a day-long meeting at COH to further refine protocols and procedures. In collaboration with Caltech we have developed a non-biodegradable substrate on which these cells are grown and where they develop characteristics of mature RPE cells. Specialized surgical instruments have been developed at DEI and Caltech to implant the hESC cells grown on substrate under the retina. We have utilized sophisticated instrumentation to image the retina in live animals and have used these instruments to follow rats with progressive retinal degeneration before and after implantation of the hESC. We have demonstrated that hESC rescue the degeneration and integrate well into the host retina. Sections of these retinas are evaluated histologically at the microscopic level using sophisticated quantitative imaging techniques.
 
 Our group is composed of unique multidisciplinary members who collectively have more than two decades of experience in efforts to restore sight to the blind as well as retinal cell transplantation and stem cell research. Our ultimate goal is to submit an Investigational New Drug (IND) Application to the Food and Drug Administration (FDA) by the end of the 4th year of the grant in order to get approval to conduct a clinical trial in patients at risk of vision loss due to AMD.

Year 2

Age-Related Macular Degeneration (AMD) is a devastating disease that can lead to severe vision impairment and blindness. Vision loss in AMD usually is after age 55 and affects almost 2 million Americans. 
 Vision is initiated by light striking and activating specific cells called photoreceptor cells of the neural retina within the eye. There is a small, specialized region in the central portion of the retina called the macula that is particularly important for central, sharp and color vision. It has a high percentage of photoreceptor cells called "cone cells" and it is this region that is most affected by AMD. Thus, with cone cell degeneration in AMD, a person loses their central, sharp vision with color vision affected as well.
 In the normal retina, photoreceptor cells are supported metabolically and structurally by a thin layer of cells next to them called Retinal Pigment Epithelial (RPE)Cells. Without these RPE cells, photoreceptor cells quickly degenerate and die. In AMD, it is thought that dysfunction of RPE cells is an early and critical sign of AMD. Thus, replacing dead or dying RPE cells in AMD could be a way to slow the disease process and even improve vision.
 Our CIRM disease team grant which we call The California Project to Cure Blindness aims to treat AMD through replacement of these dysfunctional RPE cells with fresh RPE cells that will then keep photoreceptor cells alive and functioning. Because only very few RPE cells are present in a human eye, direct RPE transplantation would be very difficult so we rely on the use of human embryonic stem cells (hESCs). Through the work in our CIRM funded disease team grant we have been able to use a particular stem cell line and differentiate into adult-like RPE cells that exhibit many characteristics of normal mature human RPE cells. We believe that implanting these hESCs within the eye next to the retina could be of benefit in AMD in saving the photoreceptors.
 Our technique is to not only implant the hESC derived RPE cells in the eye but to place them on a special ultrathin substrate platform that will maintain them in proper orientation next to the retina. Moreover, implantation can be done with hESC cells that had been allowed to differentiate in tissue culture prior to implantation, insuring that the implanted cells indeed express the characteristics of mature, functional RPE cells.
 In this last year, substantial progress has been made in progressing to our goal of replenishing RPE cells in the AMD retina and restoring vision. First, a specific hESC line has been identified that will differentiate into cells that have many of the morphological and biochemical characteristics of normal adult RPE cells. Second, an appropriate material has been found that can act as a substratum (platform) that will support the RPE cells and allow them to function in a normal manner. Third, we have begun to demonstrated the safety of our procedure as well as its efficacy in slowing vision loss in a rodent model of retina degeneration. Fourth, we also have developed unique surgical techniques that will allow us to safely and effectively place the cells in the animal and ultimately human eyes.
 In parallel to these basic studies, we are advancing our strategies that will let us treat human patients with AMD. Clinical protocols are being established that will be submitted to the US FDA to gain their approval in order to start phase 1 (early) Clinical Trial. In summary, our CIRM grant has allowed us to develop a procedure that should let us treat severe vision loss in AMD. Already, data at 6 months in animal studies has demonstrated the safety of the technique as well as the restoration of functional vision in a model system. Hopefully, this will lead us to a successful human clinical trial with sight restoration in currently untreatable cases of dry AMD.

Year 3

Age-Related Macular Degeneration (AMD) is a devastating disease that can lead to severe vision impairment and blindness. Vision loss in AMD usually is after age 55 and affects almost 2 million Americans. 
 Vision is initiated by light striking and activating specific cells called photoreceptor cells of the neural retina within the eye. There is a small, specialized region in the central portion of the retina called the macula that is particularly important for central, sharp and color vision. It has a high percentage of photoreceptor cells called "cone cells" and it is this region that is most affected by AMD. Thus, with cone cell degeneration in AMD, a person loses their central, sharp vision with color vision affected as well.
 In the normal retina, photoreceptor cells are supported metabolically and structurally by a thin layer of cells next to them called Retinal Pigment Epithelial (RPE)Cells. Without these RPE cells, photoreceptor cells quickly degenerate and die. In AMD, it is thought that dysfunction of RPE cells is an early and critical sign of AMD. Thus, replacing dead or dying RPE cells in AMD could be a way to slow the disease process and even improve vision.
 Our CIRM disease team grant which we call The California Project to Cure Blindness aims to treat AMD through replacement of these dysfunctional RPE cells with fresh RPE cells that will then keep photoreceptor cells alive and functioning. Because only very few RPE cells are present in a human eye, direct RPE transplantation would be very difficult so we rely on the use of human embryonic stem cells (hESCs). Through the work in our CIRM funded disease team grant we have been able to use a particular stem cell line and differentiate into adult-like RPE cells that exhibit many characteristics of normal mature human RPE cells. We believe that implanting these hESCs within the eye next to the retina could be of benefit in AMD in saving the photoreceptors.
 
 Our technique is to not only implant the hESC derived RPE cells in the eye but to place them on a special ultrathin substrate platform that will maintain them in proper orientation next to the retina. Moreover, implantation can be done with hESC cells that had been allowed to differentiate in tissue culture prior to implantation, insuring that the implanted cells indeed express the characteristics of mature, functional RPE cells.
 In this last year, substantial progress has been made in progressing to our goal of replenishing RPE cells in the AMD retina and restoring vision. First, a specific hESC line has been identified that will differentiate into cells that have many of the morphological and biochemical characteristics of normal adult RPE cells. Second, an appropriate material has been found that can act as a substratum (platform) that will support the RPE cells and allow them to function in a normal manner. Third, we have begun to demonstrated the safety of our procedure as well as its efficacy in slowing vision loss in a rodent model of retina degeneration. Fourth, we also have developed unique surgical techniques that will allow us to safely and effectively place the cells in the animal and ultimately human eyes.
 
 In parallel to these basic studies, we are advancing our strategies that will let us treat human patients with AMD. Clinical protocols are being established that will be submitted to the US FDA to gain their approval in order to start phase 1 (early) Clinical Trial. In summary, our CIRM grant has allowed us to develop a procedure that should let us treat severe vision loss in AMD. Already, data at 6 months in animal studies has demonstrated the safety of the technique as well as the restoration of functional vision in a model system. Hopefully, this will lead us to a successful human clinical trial with sight restoration in currently untreatable cases of dry AMD.

Year 4

Age-Related Macular Degeneration (AMD) is a devastating disease that can lead to severe vision impairment and blindness. Vision loss in AMD usually is after age 55 and affects almost 2 million Americans.
 
 Vision is initiated by light striking and activating specific cells called photoreceptor cells of the neural retina within the eye. There is a small, specialized region in the central portion of the retina called the macula that is particularly important for central, sharp and color vision. It has a high percentage of photoreceptor cells called "cone cells" and it is this region that is most affected by AMD. Thus, with cone cell degeneration in AMD, a person loses their central, sharp vision with color vision affected as well.
 
 In the normal retina, photoreceptor cells are supported metabolically and structurally by a thin layer of cells next to them called Retinal Pigment Epithelial (RPE)Cells. Without these RPE cells, photoreceptor cells quickly degenerate and die. In AMD, it is thought that dysfunction of RPE cells is an early and critical sign of AMD. Thus, replacing dead or dying RPE cells in AMD could be a way to slow the disease process and even improve vision.
 
 Our CIRM disease team grant which we call The California Project to Cure Blindness aims to treat AMD through replacement of these dysfunctional RPE cells with fresh RPE cells that will then keep photoreceptor cells alive and functioning. Because only very few RPE cells are present in a human eye, direct RPE transplantation would be very difficult so we rely on the use of human embryonic stem cells (hESCs). Through the work in our CIRM funded disease team grant we have been able to use a particular stem cell line and differentiate into adult-like RPE cells that exhibit many characteristics of normal mature human RPE cells. We believe that implanting these hESCs within the eye next to the retina could be of benefit in AMD in saving the photoreceptors.
 
 Our technique is to not only implant the hESC derived RPE cells in the eye but to place them on a special ultrathin substrate platform that will maintain them in proper orientation next to the retina. Moreover, implantation can be done with hESC cells that had been allowed to differentiate in tissue culture prior to implantation, insuring that the implanted cells indeed express the characteristics of mature, functional RPE cells.
 In this last year, substantial progress has been made in progressing to our goal of replenishing RPE cells in the AMD retina and restoring vision. First, a specific hESC line has been identified that will differentiate into cells that have many of the morphological and biochemical characteristics of normal adult RPE cells. Second, an appropriate material has been found that can act as a substratum (platform) that will support the RPE cells and allow them to function in a normal manner. Third, we have begun to demonstrated the safety of our procedure as well as its efficacy in slowing vision loss in a rodent model of retina degeneration. Fourth, we also have developed unique surgical techniques that will allow us to safely and effectively place the cells in the animal and ultimately human eyes.
 
 In parallel to these basic studies, we are advancing our strategies that will let us treat human patients with AMD. Clinical protocols are being established that will be submitted to the US FDA to gain their approval in order to start phase 1 (early) Clinical Trial. In summary, our CIRM grant has allowed us to develop a procedure that should let us treat severe vision loss in AMD. Already, data at 6 months in animal studies has demonstrated the safety of the technique as well as the restoration of functional vision in a model system. Hopefully, this will lead us to a successful human clinical trial with sight restoration in currently untreatable cases of dry AMD.

© 2013 California Institute for Regenerative Medicine