Funding opportunities

Generation of transplantable human limbal epithelial cells from induced pluripotent stem cells for limbal stem cell deficiency

Funding Type: 
Early Translational IV
Grant Number: 
TR4-06793
Funds requested: 
$3 179 449
Funding Recommendations: 
Not recommended
Grant approved: 
No
Public Abstract: 
Corneal blindness affects millions of people. One of its causes is deficiency of corneal epithelial stem cells (LESC) renewing corneal outer lining. LESC deficiency (LSCD) may be due to genetic defects, burns, infections, and inflammation. It causes corneal scarring, blood vessel growth and outgrowth of conjunctiva, all of which lead to vision loss. Keratolimbal grafts allowed in U.S. have 30% 5-year survival. Cultured LESC are transplanted in other countries, with 70% 5-year success rate, but allograft survival is low. We propose to fight LSCD using induced pluripotent stem cells (iPSC). Unlike LESC, iPSC may be banked and standardized. Making iPSC from corneas, rather than from distantly related fibroblasts, and differentiating them back to corneal cells may create a reliable cell source for transplantation. If LSCD affects both eyes, one has to use donor cells, leading to lifelong immunosuppressant use. To address this issue we will use for the first time closely related conjunctival cells to make iPSC and then corneal cells. Conjunctiva cannot substitute for the damaged cornea, but its stem cells can be pushed to become cornea-like cells in specific conditions. This would allow treating LSCD with patient’s own cells. Our innovative study will provide a proof of concept for the target product by developing iPSC-derived cells for future transplantation in LSCD. The standardized product will be amenable to safety and toxicity tests, and would lead to animal and human trials.
Statement of Benefit to California: 
Eye burns, chronic inflammation, and infections damage corneolimbal stem cells (LESC) often causing limbal stem cell deficiency (LSCD), which compromises vision. Burns represent 7-10% of eye injuries. About 15-20% of burns to the face involve at least one eye and are a frequent occupational hazard. An estimated 20% of population suffers from an eye trauma in their lifetime. The rate of eye injuries is estimated to be about 120,000 annually for California with 38 million residents. About 24,000 people in California have aniridia, a genetic defect usually resulting in untreatable LSCD. Thus, LSCD is a serious and hard to treat eye condition. In the U.S., only limbal grafts are allowed, which restricts the number of cases where this treatment may bring long-term benefit to the patient, and cannot be used if both eyes are damaged. To address this unmet and urgent clinical need, we propose to use induced pluripotent stem cell (iPSC) technology to produce a bankable and renewable source of LESC that could be used for transplantation in the affected people including Californians. Our goal is to produce such cells for the first time from the patient’s own tissue close in properties to the cornea, thus alleviating the need for lifelong use of immunosuppressive drugs. If successful, this exciting new approach would pave the way for human trials and clinical use of patient’s cells for transplantation in LSCD, a vision-threatening eye condition affecting many thousands of Californians.
Review Summary: 
This Development Candidate Feasibility (DCF) proposal intends to develop a therapy for bilateral limbal stem cell deficiency, a cause of vision loss shared by certain eye diseases and injuries. The proposed development candidate (DC) consists of human induced pluripotent stem cell-derived limbal epithelial stem cells (hiPSC-LESC) seeded on a matrix for autologous use. The applicant plans to derive hiPSC from human conjunctiva as s/he hypothesizes this cell source will more easily differentiate into LESC-like cells. The applicant will develop a protocol to differentiate hiPSC into LESC, identify a substrate, optimize the development candidate’s formulation and perform ex-vivo transplants on cultured human corneas to test for engraftment. Objective and Milestones - The panel did not find the proposed program to be scientifically or clinically reasonable. The proposal addresses a need most predominant in the developing world where the complexities and costs of an iPSC approach are prohibitive. - Some milestones are research, rather than translation, focused. Milestones lack clear success criteria. - The milestone dedicated to epigenetic studies is ill justified and does not accelerate achievement of a DC. Rationale and Significance - If successful, the DC will achieve only limited impact. Autologous limbal stem cells have already generated positive clinical results, but production costs have limited interest in commercial development. The rationale behind this more complex approach therefore appears flawed. - Finding a more cost efficient method to generate and bank LESC for transplants, perhaps in collaboration with those who are already performing this work, would have more clinical impact than the proposed study. - The rationale for using conjunctiva as the source for hiPSC was poorly developed. - Autologous hiPSC-LESC could address the small, but important, medical need imposed by bilateral limbal stem cell loss. Feasibility and Design - The omission of in vivo proof of concept testing is a major weakness of the proposal. - The application lacks preliminary data to support both the ability to reprogram and to differentiate conjunctival cells to LESC. This approach is underdeveloped. - Modification of the method to generate the scaffold introduces un-necessary regulatory complexity to the program. - Reviewers criticized the absence of any functional and morphological parameters to confirm the LESC phenotype, in addition to the proposed marker expression. Qualifications of the PI (Co-PI, Partner PI, if applicable) and Research Team - This is a strong research group with the necessary expertise to execute the project. - However, none of the team members will be focused upon the program full time. Collaborations Assets, Resources and Environment - Institutional support, environment and facilities are excellent. Responsiveness - The application is responsive to the RFA. - Reviewers noted that CIRM is already supporting the development of a limbal stem cell replacement approach (TR2-01768), which reviewers believe may have greater potential impact.
Conflicts: 
  • Richard Wade-Martins

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