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RL1-00684-1: Generation of an Engineered Insulin Reporter hES Cell Line to Facilitate Cell-Based Assays for Diabetes Research

Recommendation: Not recommended for funding

Public Abstract (provided by applicant)

Diabetes mellitus is a disease that results from insufficient insulin production and affects approximately two million people in the state of California. Currently, the most widely-used therapy involves direct insulin injection to supplement the insulin that is naturally produced in the pancreas. This therapy diminishes the quality of life for diabetes patients, particularly because lifelong injections are required. Drugs that could either increase production of insulin-producing beta-islet cells or upregulate endogenous insulin would provide an alternative to current insulin injection therapy and dramatically decrease morbidity. In order to more accurately and quickly identify these candidate drugs, it would be very advantageous to have cells that reliably mimic a developing pancreas “in a dish” for drug screening. Human embryonic stem (hES) cells can provide a renewable source of normal cells that can be differentiated into pancreas-like cells, thus providing a good model for studying the effects of various compounds on insulin production. The applicant institution has significant expertise and intellectual property in engineering mouse embryonic stem cells to differentiate into pancreatic-like cells that strongly resemble cells in the body. We propose engineering a similar design in human ES cells to facilitate their differentiation into pancreas-like cells. This will allow for scaled production of large quantities of pancreatic-like cells, sufficient for screening drug screening. One key advance in the proposal is the ability to detect the effect of a given drug specifically on insulin production in these cells using fluorescence monitoring. Because small changes in fluorescence can be easily detected, drugs can be optimized to increased potency and reduce unwanted side effects. Another key element in this ES cell design is the ability to easily screen for developmental genes and growth factors that can stimulate beta-islet cell growth and insulin expression. The institution maintains a proprietary set of candidate genes that will be evaluated in this fashion to identify novel therapeutic molecules for treating diabetes.

Statement of Benefit to California (provided by applicant)

Diabetes and related diseases constitute a significant portion of healthcare expenditures in California. Direct and indirect costs are estimated to be approximately 16 billion USD a year based on population (http://www.cdc.gov/nccdphp/overview.htm). Furthermore, incidence in minority groups in California is disproportionately higher. Diabetes associated diseases such as stroke and cardiovascular disease are complicated and are often underestimated in cross-sectional assessments of State health. Tragically, the percentage of adults diagnosed with diabetes continues to rise. In 2005 seven percent were diagnosed with diabetes, compared to 6.1% in 2001 (Diamant et al, 2007). To address this alarming health issue, the pharmaceutical industry needs more efficient and clinically-relevant (i.e. human-based) drug discovery and development tools focused on the biology of beta-islet cell growth and response, and insulin regulation. The present proposal describes an engineered human cell line that will serve as a first-tier commercial drug discovery and screening platform that could yield many diabetes-relevant drug candidates. The proposal is by a California company that has many years of experience in commercializing human and mouse ES cell-based tools for drug discovery and development, and that has previously developed an analogous mouse insulin reporter ES cell line currently being used in commercial cell-based screening assays with a pharmaceutical partner, which is currently bringing revenue to California. Similar clinically relevant screening partnerships will be sought with the proposed hES line systems, bringing revenue and new jobs to California. In addition, commercialization of new diabetes drugs developed with the proposed hES cell line system will help relieve the burden on healthcare. Intellectual property gains for California are also potentially significant. Publication of the results derived from the described research project will continue to support the advancement of California and human embryonic stem cell technology and stimulate new academic and commercial collaborations for recruiting and job growth.

Review

The goal of this proposal is to characterize and engineer a human embryonic stem (hES) cell line that will efficiently differentiate into insulin-producing beta-islet cells. Such cells will be valuable tools for drug screening and the development of new therapies for diabetes. Three existing cell lines will be validated and characterized. These cells will be progressively engineered to promote more efficient differentiation into beta-islet cells and to monitor the differentiation process. A novel hES cell line appropriate for differentiation into pancreatic-like cells will be created and evaluated.

This proposal has a significant goal: the engineering of cell lines that efficiently differentiate into insulin-producing beta-islet cells. As diabetes mellitus is an important and increasing health concern, methods for production of pancreatic-like cells would be an important contribution to the development of new therapies.

Reviewers had serious reservations about the feasibility of the proposed study. The proposal suffers from a number of inconsistencies and does not present a clear or coherent experimental design for achieving the desired goal. Several aims lacked convincing rationale, and the logic of particular approaches was unclear. For instance, justification for the choice of the starting cell lines was not apparent. Furthermore, it is not clear that preliminary experiments presented for pancreatic differentiation of mouse ES cells are relevant or translatable to work with human ES cells. Many aspects of the proposal left reviewers with the impression that the applicant’s understanding of beta-islet cell biology was insufficient (e.g. reviewers questioned whether the proposed molecular manipulations would direct hES cells to a beta cell identity).

The application was viewed as not responsive to the RFA. The utility of any cell lines produced is unclear. Reviewers were not convinced that any new cell lines, if produced, would be made readily available to other researchers.

The following Working Group members had a conflict of interest with this application and were therefore recused from participating in review of, discussion of, and voting on the application:

• Evans, Todd