Tools and Technologies I
Our goal is to build on existing research to perfect a stem-cell manufactured “model” of the front of the human eye (called the “cornea”) that can be used as a tool to improve the safety of chemicals and consumer products, as well as a tool for researchers to study eye injuries. Over 10 million people worldwide suffer from loss of sight due to their corneas becoming cloudy or opaque partly due to trauma and injury. Damage to the cornea by household products are involved in 125,000 eye injuries each year. Regulatory authorities in most countries require safety assessment of consumer products for potential eye injuries and commonly the “Draize” rabbit test their “gold standard” test. The Draize test determines the potential degree to which a substance damages the human eye by applying a substance in question directly in the eye of a rabbit. The Draize test is regarded by scientists as being flawed and by the public as cruel. Even with this limitation, alternative tests have not been effective as substitutes for the Draize test. Recently, top officials from the U.S. National Institutes of Health (NIH) and Environmental Protection Agency (EPA) announced an effort designed to expand the use of human cells to identify chemicals with toxic effects and therefore allow for non-animal-based laboratory models to gain a foothold towards becoming the new “gold standard.” Large economic and health benefits will accrue to California through the completion of a living stem-cell-based model of the cornea as a research tool to study eye injury. It will provide a safer environment for California consumers and workers through more accurate eye safety testing of chemical and household consumer products. It will provide a laboratory model for researchers to study healing of the eye for clinical research. World-wide demand for such a product will provide manufacturing and employment opportunities for Californians and added income to California. Our goal is to generate a corneal tissue model created from human parthenogenetic stem cells. Parthenogenetic stem cells are created from unfertilized human eggs and have the same characteristics as standard human embryonic stem cells, including the ability to become other human tissues, but don’t generate a viable human embryo in the process. We will build upon existing discoveries and develop a parthenogenetic stem cell-based corneal tissue model that can be provided as a standardized research tool allowing measurement of eye injury. We will achieve this goal by causing the stem cells to divide into corneal tissue and provide this tissue in a form that can be used to test chemicals and consumer products. The model will be manufactured and quality-tested so it is consistent. We will test the model using known chemicals and consumer products to prove that the model works. If successful, our efforts will result in a superior model to measure human eye damage.
Statement of Benefit to California:
Large economic and health benefits will accrue to California through the completion of a living stem-cell-based model of the human eye (the cornea) as a research tool to study eye injury. It will provide a safer environment for California consumers and workers through more accurate eye safety testing of chemical and consumer products. It will provide a laboratory model for researchers to study healing of the eye for clinical research. World-wide demand for such a product will provide manufacturing and employment opportunities for Californians and added income to California. Finally, this model will give tangible validation to the public of the benefits that proposition 71 is bringing to California. There is a world-wide demand for a product that models the human eye for safety testing of chemicals and consumer products. Damage to the cornea is estimated to affect over 10 million people worldwide and household products are involved in 125,000 eye injuries each year. In June of 2007 The European Union started its “REACH” regulation (Registration, Evaluation and Authorization of Chemicals) requiring approximately 3.9 million test animals be used to assess the safety of chemicals (18% for eye irritation) at a cost of over 1.5 billion EURO (data published by the European Commission, Institute for Health and Consumer Protection, Nov., 2004.) Current models use living animals (the “Draize” rabbit test) and are regarded by scientists as being flawed and by the public as cruel. Even with these flaws, alternative tests are not effective substitutes for the Draize. In the beginning of 2008, top officials from the U.S. National Institutes of Health (NIH) and Environmental Protection Agency (EPA) announced a five-year deal promising to share technology, information and other resources that will improve the toxicity testing of chemical compounds using current technologies rather than lab animals. This effort is designed to expand the use of human cells for testing and represents the "birth of a new approach to a crucial problem in public health." According to the Eye Bank Association of America’s 2006 Eye Banking Statistical Report, there are more than 34,000 corneal transplants performed annually in the US. An additional 150,000 transplants are performed in the rest of the world. Laboratory models of living human cornea will provide a valuable tool for California researchers to study corneal damage and will bypass the current and projected shortages of acceptable human adult corneal tissue for research due to the increased use of laser vision corrective surgery, the increased longevity of the general population, and the increase in incidence of transmissible diseases. Intellectual property is likely to be generated through this work, resulting in increased valuation for California research organizations involved. This will generate further growth and investment and result in increased employment for Californians and added tax re
This application focuses on the development of a parthenogenetic human embryonic stem cell (PSC)-derived model for testing ocular toxicity and injury in vitro. First, the Principal Investigator (PI) proposes to culture PSCs and subject them to a series of treatments and manipulations in order to optimize differentiation and stratification into corneal-like constructs. Next, these structures will be exposed to known ocular toxins and assessed for damage by microscopic and histological analyses. These results will be compared with those obtained from the standard Draize Eye Test in order to validate the relevance of the in vitro system. Finally, the PI proposes to develop methods for standardized production as well as packaging and delivery of the new model. The reviewers agreed that the proposed technology addresses an important need, but they commented that it is very unlikely to be successfully realized. The experiments were technically and temporally challenging, and the efficiency of the methods was impossible to judge. Finally, a substantially deficient validation strategy and a premature focus on end-point deliverables cast doubt on the relevance of the investigators’ experience. The proposed technology could offer a potential alternative to the Draize Eye Test for ocular toxicity. While this latter model system is currently the regulatory standard for industry, it is scientifically not optimal. The ability to predict ocular toxicity in an in vitro, more relevant human model would be highly desirable both for improved public safety as well as for reducing in vivo testing. The reviewers felt that this proposal was premature, and they were unsure about the overall feasibility of the work for a variety of practical and technical reasons. First, the PI did not scientifically justify the decision to use PSCs rather than corneal stem cells or progenitors to derive corneal-like constructs. The reviewers were uncertain of the overall efficiency of corneal construct derivation and expressed concern that the long periods of time required for construct generation, as well the challenges inherent to their handling and manipulation, would prevent this effort from being completed within the two year time constraint. Of greater concern, the PI did not include any biochemical or cell biological analyses to demonstrate the functional validity of the corneal constructs as surrogates for authentic cornea. Reviewers were also disappointed that the applicants proposed assessment of only one endpoint for in vitro toxicity testing (extent of injury) rather than the more thorough and definitive analyses that would be required for industry and regulatory acceptance. Given that the assay is so far from development, the reviewers felt that it was extremely premature to propose standardized methods for production, packaging and distribution of these models. The reviewers felt that, as a whole, the research team was well qualified to perform the described experiments. While the PI has no track record with leadership or corneas, the co-investigators would likely compensate for these shortcomings. The reviewers noted, however, that the team appeared to be inexperienced with in vitro toxicity tests. Reviewers also commented that the budget was inadequately justified. Overall, while the proposed technology addressees an important need, the reviewers were unconvinced of its feasibility and its potential to advance stem cell biology.