Funding opportunities

Development of a Stem Cell-based Approach for Treating Corneal Endothelial Cell Deficiency

Funding Type: 
Early Translational IV
Grant Number: 
TR4-06830
Funds requested: 
$1 843 200
Funding Recommendations: 
Not recommended
Grant approved: 
No
Public Abstract: 
Corneal endothelial cell deficiency is one of the leading causes of blindness in human beings. The goal of this proposal is to develop a strategy for transplanting stem-cell derived corneal endothelial cells (CECs) into the eyes of patients with CEC deficiency. In the past, transplantation of CECs from postmortem donors yielded encouraging initial therapeutic effects, but the lack of donor tissues prevents the procedure of corneal endothelial cell transplantation. We therefore propose to convert human pluripotent stem cells including embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) into functional corneal endothelial cells (CECs). We will engineer CEC sheets that are suitable for transplantion in animal model. To establish that these cells are functional, we will assay molecular markers and measure physiological functions of CECs in the culture dish. Next, we will perform CEC transplantation in an animal model that mimic CEC deficiency in humans. Finally, we will test the safety of CEC cells by transplanting them into the relevant immune-deficient animal model to confirm no tumor formation. Our proposed project will pave the way for future use of stem cell-derived CECs in a clinical setting.
Statement of Benefit to California: 
Cornea dysfunction is the second-leading cause of blindness. Approximately 10-million patients worldwide are affected by some form of corneal disease, and many of them require corneal transplantation (or kerotoplasty). In the US, corneal transplantation is the most common organ transplantation (>15,000 cases/year). So far, donor corneal tissues are still the main source of corneal transplantation. However, due to the shortage of donors, only less than 1% patients receive surgery every year. Thus, procuring corneal grafts is a significant unmet medical need. Among the patients receiving cornea engraftment, 40% are related to failing corneal endothelial cells (CECs), which are essential for maintaining stroma hydration for cornea transparency. Recent advancements in stem cell biology have opened new avenues to obtain CECs from pluripotent stem cell-derived neural crest cells. We therefore propose to establish in vitro differentiation protocols of CECs from human embryonic stem cells (hESCs) or induced pluripotent stem cells (iPSCs). The function of stem cell-derived CECs can be evaluated in animal models of CEC deficiency via corneal endothelial cell transplantation procedure. Because hESCs and iPSCs can be expanded in a large quantity under cGMP condition, stem cell-derived CECs would be an unlimited source for CEC cell replacement therapy. Overall, our proposal studies will greatly benefit people in California in their vision care.
Review Summary: 
Corneal dysfunction is a leading cause of blindness affecting millions of patients around the world, many of whom will require a cornea transplant to maintain vision. The objective of this Development Candidate Feasibility award (DCF) proposal is to test the concept that corneal endothelial cells (CECs) derived from human embryonic stem cells (hESCs) and induced pluripotent stem cells (iPSCs) can be used to treat corneal diseases caused by CEC dysfunction. Major project goals include 1) establishing a robust protocol for converting hESCs and iPSCs into CEC-like cells and 2) evaluating the function of these cells in vitro and in a preclinical model that mimics CEC deficiency. The applicant also plans to test the safety of this cell preparation by assessing its potential to cause tumors. Objective and Milestones - The proposed objectives are appropriate for establishing proof of concept, the goal of the DCF award. -The Target Product Profile (TPP) for the generation of CECs for corneal repair is scientifically and clinically reasonable. - Although project milestones are logical based on the study design, the outcomes are vague and lack clear, quantifiable measures of success for the majority of the key activities within each milestone/aim. Rationale and Significance - While corneal disease is a leading cause of blindness worldwide, much of it is stromal in origin (opacity/scar resulting from infection or other ocular surface disease) rather than endothelial and therefore would not be amenable to the treatment described in this proposal. - Reviewers questioned the unmet medical need noting that in developed countries there is no shortage of corneas available for transplant for treatment of corneal endothelial dysfunction. - Overall, the scientific rationale is logical. Feasibility and Design -The preliminary data were not sufficient to convince reviewers that bona fide CECs could be derived from hESC/hiPSC, or that these cells would be purified or enriched appropriately. - Reviewers questioned whether the selected preclinical model is the most appropriate, noting that in contrast to humans, its endothelial cells retain proliferative potential in vivo. - The proposal does not outline the possible effects or consequences of a xenograft transplant in the preclinical model, nor discuss a potential need for immune suppression. - While the plans for generating hESC/iPSC-derived CEC are logical and coherent, it may prove very challenging to develop a cell sheet formulation that will be non-immunogenic and ultimately compatible with Good Manufacturing Practices (GMP). - The research plan does not adequately address possible limitations or alternative approaches. It is not clear whether the membranes proposed for Aim 2 would degrade under the cell sheet or whether uniform cell coverage could be achieved. Similarly, there is no discussion as to how limitations of the surgical technique might impact functional outcome assessment of the transplanted cells. Qualification of the PI and Research Team - The PI has considerable experience in neuroscience and the differentiation of stem cells into a variety of cell types, but limited experience in corneal cell biology. - Although a key collaborator provides necessary expertise in eye disorders, his/her specialty appears to be in the area of retinal rather than corneal biology. - The surgical technique proposed for the preclinical studies is technically challenging. It is unclear if the appropriate expertise is in place on the team to perform the proposed animal studies. Collaborations, Assets, Resources and Environment - The investigators have access to an excellent research environment. The institution is highly supportive of translational research and makes all its facilities and cores available to the investigators. Responsiveness to the RFA - This DCF proposal is fully responsive, as 1) it will assess the feasibility of hESC/iPSC-derived CEC for the improved treatment of corneal diseases affecting the endothelium; and 2) human stem cells are necessary to achieve the outcomes of the proposed research. - Derivation of CEC from hESC/iPSC is novel and not represented within CIRM’s translational portfolio.
Conflicts: 

© 2013 California Institute for Regenerative Medicine