Executive Summary
This application proposes the creation of a Disease Team whose goal is to cure corneal vision loss through the culture and implantation of stem-cell-derived full or partial thickness human corneal grafts. Currently corneal grafts are obtained from deceased donors, which can impose risk of disease transmission. Although systemic immunosuppression is not required, the topical immunosuppression regimens do not protect fully against rejection. The corneal tissue will be developed from human embryonic stem cells or parthenogenetic stem cells for which the applicants intend to optimize existing technology to produce them under GMP conditions.
Reviewers noted the importance of generating specific cell types that are suitable for transplantation in humans for diseases such as those that affect the eye. However, this proposal was found to have many weaknesses including that it was poorly written and offered poor rationale for the use of parthenogenetic stem cells. Although HLA homozygous cells can be produced through this method, reviewers felt its importance was overstated as the plan does not take into account the extensive HLA polymorphisms in the populace and the low likelihood of having a complete pool of human HLA homozygous parthenogenetic stem cells available.
Although this field is mature enough to consider therapeutic stem cell transplantation, the proposed project was found not convincing and unrealistic for translation to the clinic within 5 years.
The principal investigator (PI) was noted to have extensive experience in translational work with in vitro fertilization and parthenogenetic stem cell development, but reviewers found the productivity of the PI difficult to judge as many publications were in unfamiliar journals. The PI appears to have limited experience in disease team planning and with regulatory processes in the United States. However, the PI has identified some collaborators who will bring needed expertise
Overall, the proposed approach was viewed as vague, not sufficiently justified, and not coordinated into a coherent plan.
Reviewer Synopsis
This proposal aims to generate corneal tissue from human embryonic stem cells (hESCs). The overall goal of this application is to ultimately provide a cure for corneal vision loss from hESCs. The PI proposes to prepare a team of researchers and clinicians toward writing a research award application, starting by optimizing existing technology for differentiation of parthenogenetic human stem cells (phSCs). These cells must differentiate into different corneal structure produced under GMP procedures. This requires knowledge and experience in a broad set of scientific and clinical disciplines, including the fields of histology, corneal structure and function, molecular and genetic biology, immunology, corneal transplantation and clinical trial design and implementation.
Reviewer One Comments
Concept:
The formation of any specific cell types suitable to transplantation in humans represents a highly significant endeavor and is of the highest priority for this type of application. There are however several major shortcomings, for example using parthenogenic stem cells which are derived from abnormal embryos. Many other shortcomings highlight the poor quality of the proposal. It is very poorly written and very difficult to follow. Thus, despite strong significance, the quality of the proposed science is too poor to justify support at this stage
Five consultants include Dr. Hans Keirstead (UCI, stem cell researcher), Dr. Steinert (ophthalmologist from an unspecified institution), Dr. Chen (North County Laser Eye Assoc., San Diego), Mr. Requard, (VISION SHARE, Apex, NC, Managing Director), and Mr. Janus, (President of International Stem Cell Corp.) Each will receive $5,000 for their advice.
There seem to be nine specific aims.
Principal Investigator:
While I have little doubt about the qualifications of the PI and the eventual final team, I do not recognize any of the forums in which the author has published manuscripts. Examples include four references to the Russian Journal of Genetics. Certainly the caliber of these forums are not on par with the overly-ambitious aspect of the proposed work.
Planning Approach:
The planning approach remains vague, unjustified, and uncoordinated.
Reviewer Two Comments
Concept:
The application is of high significance as it deals with an approach to curing corneal vision loss through culture and implantation of stem cell-derived human corneal grafts. More than 34,000 corneal transplants are performed annually in the U.S. and concerns about donor to recipient disease transmission and the increasing use of Lasik treatment have reduced donor availability and increased cost. Meanwhile, demand for corneal tissue is growing based on advances in corneal transplant techniques. The investigators aim to optimize existing technologies to differentiate human parthenogenetic stem cells or embryonic stem cells into sterile, standardized, functional, FDA-approved human corneas and corneal tissue under GMP conditions. Constructs “comparable with cornea” tissue have been created, proving the concept that these can generate a non-keratinized stratified epithelium on a basal lamina that has characteristics of Bowman’s layer and has a fibrous layer underneath. Presented data suggest the existence of a cornea-like tissue structure, although the presence of an endothelial layer is not clearly demonstrated. The investigators propose to use human HLA homozygous parthenogenetic stem cells with common haplotypes to allow HLA matching to patients to reduce post-operative rejection. However, this plan does not take into account the extensive HLA polymorphism in the populace and the impossibility of having a complete pool of human HLA homozygous parthenogenetic stem cells with all possible haplotypes available. Another application from the investigator’s company proposes to generate these lines, but the most abundant HLA haplotypes they identify are found in only a few percent of people, and these haplotypes do not include HLA-DP, which is not in strong linkage disequilibrium with the loci that are included in these analyses. Thus, it seems likely that HLA-related rejection issues would affect this approach to allogeneic corneal transplantation. Moreover, the investigators seem to disregard the possibility that minor histocompatibility antigens could be a problem. If the lack of a role for the hundreds of human minor histocompatibility antigens has been established, which is possible, given the immune privilege of the anterior chamber, the investigators should cite evidence that HLA-identical corneas are not at risk of rejection. In summary, the idea is relatively mature, but the feasibility is somewhat questionable.
Principal Investigator:
Nikolay Turovets, Ph.D., is a senior Research Scientist at International Stem Cell Corporation. He has extensive experience in translational work with in vitro fertilization and parthenogenetic stem cell development in Russia. He has established a collaboration with Roger Steinert, MD, Vice Chair of Clinical Ophthalmology at UC Irvine. He also lists Dr. Hans Keirstead as a consultant, as well as Dr. Paul Chen and Jake Requard at Vision Share, as well as Jeffrey Janus, President of International Stem Cell Corporation. In summary, the Principal Investigator has limited experience in disease team planning and with regulatory processes in the United States. However, he has identified some collaborators who will bring needed expertise.
Planning Approach:
The planning is described in somewhat general terms, without detailed description of the outside expertise that will be needed.