Funding opportunities

Immune Regulation of Retinal Stem Cell Migration and Survival

Funding Type: 
New Faculty I
Grant Number: 
RN1-00573
Funds requested: 
$2 839 948
Funding Recommendations: 
Not recommended
Grant approved: 
No
Public Abstract: 
Our goal is to speed the development of stem cell treatments for the many blinding diseases that affect the eye and specifically the retina, such as age-related macular degeneration (AMD). Cell transplantation has been attempted for 2 decades without real success. This scientific project will help fill gaps in our knowledge in two areas. 1) It will help us answer how the stem cells get to where they where they need to be to help the eye. 2) How do we make the cells stay (for a long time) and work where need to be. We feel the immune systems reaction to the cells will play a big role in answering these two question. Plus we will do our research in such a way we will meet the standards mandated by the Food and Drug Administration for use in human treatments. This will help us move forward quickly to the treatment of real vision loss in patients. Lastly we will compare stem cells from different sources to find out which source will be the best for eye and retina disease. To answer the question how do the cells get to where they need to be, we have found a way to study cell movement in the eye. This new model allows us to study cells as the move to the retina. Using this model, we can figure out how our delivery of the cells to the eye affects where they ultimately end up in the retina. Also we will see how different types of stem cells may travel more appropriately than others, which will help us chose the best ones for patients. Plus we feel that the immune system whose job it is to keep bad germs away from us, also will influence how these cells travel. We also want to find what keeps the cells where they need to be. We think the stem cell type may make a difference and again we think the immune system will play a role in their long-term survival. Our studies will be aimed at understanding these things that keep the cells from staying where they need to be. We will take steps to figure out the specific proteins or molecules that are involved. If we can figure this out we can take action to change those factors, and provide a way for long-term survival of the cells in the retina. Blindness is tragedy, which more and more Americans suffer with. We believe that stem cell transplantation to the eye and retina could prevent and in some cases reverse blindness. Filling these gaps in our knowledge regarding stem cell movement and how the immune system affect both movement and survival will allow us to advance towards our goal of treating blind patients in the near future.
Statement of Benefit to California: 
Vision loss to an individual can be catastrophic. Blindness can be overwhelming, robbing one of independence, hindering communication, and worsening other health care problems. Vision loss can also prevent gainful employment, as only 1 out of 3 visually impaired people of employment age are in the workforce. In the United States, blindness is one of the public’s biggest health fears only behind cancer and AIDS. Vision loss increases with age as over 20% of those over 65 of age report vision loss. In California, 16% (1.7 million) over 45 years of age have vision loss, and as the Baby Boomers generation continues to age, these numbers are expected to greatly increase. In fact, the Eye Diseases Prevalence Research Group estimates that by the year 2020 the percent of Americans blind will increase by 70%. Problems with the retina encompass the great majority of the reasons for blindness and vision loss in the American population. For those 60 years and over, age-related macular degeneration is the leading cause of vision loss. For people between the age of 25 and 74, the leading cause of blindness is damage to the retina caused by diabetes (diabetic retinopathy). Even for infants, the leading cause of blindness is retinopathy of prematurity. We believe our proposed studies will be of significant value to Californians. Our goal is to speed the development of stem cell therapies for the many blinding diseases of the retina. First, funding this project will help establish California as a leader in retinal stem cell therapies. These advances will allow Californian patients with many blinding disorders to benefit by directly participating in the clinical trials. In addition, answers found in these studies of the eye will apply to other stem cell treatments. Moreover, as retinal problems are common in Californians, the number of Californians that could directly benefit is great. Our proposed projects are focused on the application of human stem cells towards human retinal disease, specifically addressing how stem cells get to where they need to be in the eye what keeps them from staying there. In addition, we will study how the immune system affects the transplantation of these cells and how cell changes (differentiation) makes them more or less successful in migration and survival. Understanding these immune responses will be critical for the success of most future stem cell treatments. Finally, many physicians and even moreso retinal specialists do not stay in academics and research because the financial and personal benefits of private practice are great and research funding continues to decline. These realities mean that there is not an abundance of physicians that commit their careers towards improving eye care in fields such as retinal stem cell therapies. This type of funding of a physician-scientist in the study of retinal disease will help reverse this trend here in California.
Review Summary: 
SYNOPSIS: The goal of this project is to gain a better understanding of how adult and embryonic human embryonic stem cells (hESCs) integrate and survive in the retina, and to repair the retinal pigment epithelium (RPE) in mouse models. The proposal explores the potential of stem cells to treat retinal degeneration, and compares adult and embryonic stem cells as a source of cells that are capable of delaying or diminishing neuronal loss in the retina. In the first aim, the applicant proposes to test the hypothesis that minimally differentiated hESC-derived RPE will migrate less well than fully- or more differentiated hESC-derived RPE cells, and that migration will depend not only on the differentiation status of the cell type involved but will also depend on the site of administration and level of expression of CXCR4. In this and subsequent aims, the project plans to determine the relative efficiency by which human bone marrow-derived CD34+ cells are able to home to the RPE layer in an injury model and contribute to endogenous regeneration in this model and to compare results to these using hESC-derived RPE cells. The applicant is interested in the role that CXCR4 may play on migration and will measure this on differentiating hESCs using laser scanning cytometry. Much of this work will be done in the NOD/SCID/MPSII mouse which will both tolerate xenografts and also has photoreceptor degeneration. In Aim 2, the applicant plans to test the hypothesis that more fully-differentiated hESCs will have better long-term integration and retinal regeneration than adult stem cells and minimally differentiated hESCs. In Aim 3, the plan is to test the hypothesis that xenorecognition in an immunocompetent environment will inhibit tracking, integration and long-term survival of the transplanted hESC-derived RPE. In the third Specific Aim he will explore the immune response(s) to stem cell transplant and the effects this might have on migration, differentiation and survival of transplanted cells. This proposal explores the potential for stem cells to treat retinal degeneration, and compares adult and embryonic stem cells as a source of cells that are capable of delaying or diminishing neuronal loss in the retina. The principal investigator (PI) is particularly interested in isolating retinal pigments epithelial (RPE) cells as a cell that can provide key trophic support for photoreceptors. Loss of the RPE in age-related macular degeneration and retinitis pigmentosa and replacement of these cells is the target of this proposal. He will compare human embryonic stem cells (hESCs) at different stages of development with human adult bone marrow. He is particularly interested in their migration to the retina and will explore different routes of administration. He is interested in the role that CXCR4 may play on migration and will measure this on differentiating HECs using laser scanning cytometry. Much of this work will be done in the NOD/SCID/MPSII mouse which will both tolerate xenografts and also has photoreceptor degeneration. In the third Specific Aim he will explore the immune response(s) to stem cell transplant and the effects this might have on migration, differentiation and survival of transplanted cells. STRENGTHS AND WEAKNESSES OF THE RESEARCH PLAN: These studies aim to contribute to the development of stem cell therapies for diseases such as age related macular degeneration (AMD) and retinitis pigmentosa. It is thus an interesting proposal in a clinically relevant area. The major strengths of this proposal are that the candidate has the potential to become a well-qualified scientist/clinician, he is working with a strong group of colleagues, and the clinical target is of major importance. Unfortunately, the research plan suffers from a number of weaknesses. Although the hypothesis and goals are well articulated, the experiments are poorly designed. In many cases, it is not clear what model system is being used for which experiments, and precise quantitative endpoints are not identified. It is apparent that the investigator has little direct experience with these model systems, as the comparisons between hESC-derived and adult stem cell derived cells are unclear at times. In addition, in the use of abbreviations and model systems there is an unwarranted assumption of knowledge and gene products, and the background material related to model systems and gene products are not provided in enough detail for the reviewer to gain an appreciation of the rationale behind certain experiments and methodologies. For example, it appears that the use of the MPS VII mice bred to be an immunodeficient background which possesses the GUSB mutation will allow human beta glucoronidase expressing human cells to be detected where host cells will not be detected in this system. However, this was not precisely described and the nature of this model is assumed to be known. In addition, what is the RCS rat? Some preliminary data is shown in the NOD\SCID\MPS VII mouse model using human CD34+ cells but there is essentially no data with HESC-derived RPE cells. Therefore, the preliminary data are quite limited in their ability to support the proposed studies. A question could also be raised about whether the RPE might be the best cell to replace. One reviewer commented that there is no evidence to date that these cells are useful in neuroprotection, as noted by the applicant. The reviewer also noted that , in the clinical scenario, delivery or transplantation of cells designed to give rise to RPE might be too late. The PI is relatively untested scientifically to take on such a large series of ambitious experiments, and has a limited scientific background. Some of the data presented in the preliminary data seems to parallel similar experiments published by Li, et. al, Investigative Ophthalmology and Visual Science, 2007 and 2006, and results of Atmaca-Sonmez, et. al, Experimental Eye Research 2006, yet it is interesting that the PI does not reference these papers. There also appears to be significant other literature reporting transplantation of neural progenitor cells to replace the RPE, yet most of these references are not cited and this potential cell type derived from hESCs to repair the retinal epithelium is not considered in this project. The experiments evaluating the role of CXCR4 in determining the ability of stem cells to migrate or home to the RPE are not well-designed. They are based on the premise that hypoxia will upregulate CXCR4 expression. Of course, hypoxia may induce many other changes other than CXCR4 expression which may affect migration and therefore these experiments are not designed in a way that will determine a precise roll of CXCR4 in homing and migration to the RPE. Also, in Aim 1 it is proposed that PEDF expression would be used as a maturational marker. Although the literature appears to suggest that PEDF is a signaling molecule that can increases RPE maturation, it is not clear which cells express this factor or that increased expression would indicate a more mature state of the RPE itself (i.e.—although it is expressed doe not necessarily indicate the maturational effects of PEDF have been achieved. Also in this aim, the investigators propose to select cells expressing RPE65 in differentiating cultures and that these cells would be sorted and purified. However, the feasibility of this is not described. Although his colleagues are working on these cells, more detail of how they are obtained, sorted, etc., would have been appropriate. In many cases, the experimental endpoints are descriptive, nonquantitative, and based on histology and immunostaining. On a minor note, there were several spelling mistakes/typos in this proposal- in a five page application there really should be none. Furthermore, consideration of and reference to studying humans in human clinical trials within the context of the application is really beyond the scientific and funding scope of the project Thus, this is a clinical scientist with good potential addressing a clinically-important question in ophthalmology within a strong visual sciences department. He appears to be establishing strong basic science mentorship relationships, but has a limited scientific background at present. The research proposal is poorly organized, imprecisely written and contains non-quantitative, poorly defined endpoints. The preliminary data is weak and does not reassure reviewers that the project is feasible. QUALIFICATIONS AND POTENTIAL OF THE PRINCIPAL INVESTIGATOR: Dr. Telander is a young clinical investigator with good training and background. He completed his MD/PhD and ophthalmology residency at the University of Minnesota and just recently completed a vitreo-retinal surgery eye fellowship at the Jules Stein Eye Institute in Los Angeles. From 2003 to 2005 he was involved with clinical ophthalmology as an attending physician in Los Angeles. From 2003 to 2005 he was involved with clinical ophthalmology as an attending physician in Los Angeles. Since 2005, he has been an Assistant Professor of Clinical Ophthalmology at UC-Davis Medical Center Department of Ophthalmology and Vision Science. He has received awards for teaching and has been heavily involved in medical school activities while publishing several clinical papers. A concern could be raised about his scientific expertise and training to take on the proposed research. He will rely heavily on his colleagues here, from whom he has garnered a number of letters of support. He has no experience in culturing ES cells as of yet. His mentoring plans seem appropriate. He has strong letters of support from the UC Davis Executive Associate Dean and senior colleagues working in stem cells and vision upon whom he will be reliant. The investigator completed his MD/PhD and ophthalmology residency at the University of Minnesota and just recently completed a vitreo-retinal surgery eye fellowship at the Jules Stein Eye Institute in Los Angeles. From 2003 to 2005 he was involved with clinical ophthalmology as an attending physician in Los Angeles. Since 2005, he has been an Assistant Professor of Clinical Ophthalmology at UC-Davis Medical Center Department of Ophthalmology and Vision Science. He has received awards for teaching and has been heavily involved in medical school activities while publishing several clinical papers. INSTITUTIONAL COMMITMENT TO PRINCIPAL INVESTIGATOR: The institution has a strong institutional stem cell core group of investigators and facilities. There is a strong stem cell research program and visual science group at UC-Davis with numerous stem cell faculty and a commitment on the university’s part to building infrastructure core, resource development and recruiting new faculty. In the ophthalmology group, there are 20 vision scientists with 16 NIH-funded grants. Significant stem cell core facilities are available at UC-Davis through the established stem cell program including FACS sorting core, immunodeficient mouse core, human ESC karyotyping and teratoma services, and plans to build a new state of the art GMP facility. In addition, vector core and auto MACS technologies are available. A significant amount of CIRM funding is already in place at UC-Davis through CIRM Comprehensive Research Grants, CIRM Shared Research Laboratory grants and the CIRM’s Stem Cell Training Program, in addition to other CIRM-funded investigators at UC-Davis including Drs. Zern, Yamoah, and Reddi.The infrastructure in his lab and the core facility at Davis all seem appropriate to carry out the work. The applicant has a limited amount of extramural funding currently, but letters demonstrate a strong commitment to his development as a clinician-scientist from his institution. An NIH-K30- mentored clinical research training program is potentially available to Dr. Telander as formal mentorship training, conditional on his receipt of CIRM funding. It is not apparent that independent lab space is available to Dr. Telander, and institutional resources may be controlled by other investigators. At the moment, it appears he has been provided research space in the labs of Drs. Hjelmelend and Nolta. In addition to these two basic science mentors, he has established clinical mentors in Drs. Morse and Keltner. Additional lab space for Dr. Telander may be assigned in the new state-of-the-art GMP facility that is scheduled to be completed in 2008. There appears to be a commitment to expand stem cell research at UC-Davis both through recruiting new faculty (adding to an already-strong, 110 stem cell investigator-rich program) and new building infrastructure. DISCUSSION: Reviewers commented that this is an accomplished physician in a strong environment with good institutional support, doing research on a clinically-important problem. Unfortunately, the applicant does not have the research background to undertake this ambitious proposal, and the research proposal suffers from lack of scientific rigor. For instance, the CXCR4 experiments are poorly designed - hypoxia does many things other than increase CXCR4. Use of murine bone marrow stem cells is problematic as it is unlikely to yield any useful output; it isn’t always clear why the applicant used both adult and embryonic cells; and the experiments as designed will not elucidate the role of chemokines in homing, which was seen by reviewers as an interesting question. Failure to reference the literature contributed to the feeling that the candidate was very new to the field. Finally, the proposal was poorly written and organized, heavy in acronyms, and had typographical errors, all of which made it difficult to read. On the whole, the panel was supportive of the applicant and the idea being addressed in this application, and felt that the proposal deseved to be re-written with more preliminary data and more careful advice from scientific mentors.
Conflicts: 

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