The retina is a thin layer of tissue lining the back of the eye. In humans, more than 80 percent of sensory information is acquired through vision. Many blinding diseases such as age-related macular degeneration (AMD) and glaucoma, involve the permanent loss of retinal cells, especially the light-sensing photoreceptors or the retinal ganglion cells, which connect the retina to the brain. Currently, there is no effective treatment to replenish these lost cells and to repair the damaged retinas. Recent advancements in stem cell technology have enabled scientists to propagate and coax pluripotent stem cells to develop into retinal cells that can potentially be used for this repair. However, despite the progress, major challenges remain to produce the desired cell types on demand, and to efficiently integrate these stem cell-derived neurons into a pre-existing retinal neural circuit. The proposed research will study how naïve, non-committed stem cells progressively develop into photoreceptor cells and ganglion cells, two of the most-often damaged retinal neuronal types. The investigation will combine advanced molecular genetic technologies and stem cell cultures to monitor retinal cell differentiation more effectively and to optimize conditions that promote photoreceptor and ganglion cell production. Knowledge gained from these studies will enhance our abilities to control the production of retinal cell types for integration and repair of diseased retinas.
Statement of Benefit to California:
Blinding eye diseases have devastating effects on human perception and daily activities. According to the Centers for Disease Control and Prevention (CDC), approximately 80 million people in the United States have eye diseases that could lead to vision loss. Thus, vision loss is among the top ten disabilities affecting the health and well being of Americans. The State of California is one of the most populated states in the United States and thus has vast patient population afflicted with various forms of vision loss. For example, over 215,00 people are afflicted with age-related retinal degeneration (AMD) in California now. The rising cost of healthy care and social services required to treat these and other blinding eye diseases thus creates an enormous burden to individual California citizens, as well as to the overall Californian economy. Stem cell therapies aimed at restoring vision in these patients would not only improve the patient care that California can offer its citizens, but also enhance and strengthen the leading position of California in ocular stem cell research and clinical therapy. The proposed research, with the help of CIRM funding, seeks to gain fundamental knowledge about stem cell-derived retinal precursor cells that will be crucial for developing these stem cell-based replacement and repair therapies.
The proposed research will study how naïve, non-committed stem cells progressively develop into photoreceptor cells and ganglion cells, two retinal neuronal types that often become damaged. The proposal combines advanced molecular genetic technologies and stem cell cultures to monitor retinal cell differentiation more effectively and to optimize conditions that promote photoreceptor and ganglion cell production. The first aim is to derive induced pluripotent stem cell (iPSC) lines from mice with genetically marked cell lineages. The second aim is to determine extrinsic and environmental cues that promote differentiation along specific retinal lineages. The third specific aim is to characterize molecular determinants that are required for stem cell-derived retinal cell lineage progression and specification. Knowledge gained from these studies could facilitate the production of retinal cell types for integration and repair of diseased retinas.
Significance and Innovation
- The proposal addresses an important problem, since the generation of retinal cell types could provide appropriate donor cells for therapeutic use.
- The predominant focus of the project on mouse cells greatly decreases the potential impact of the proposed research.
- Reviewers felt that the approach was not particularly innovative and were disappointed that strategies and opportunities to develop novel approaches for derivation of relevant human cells were not proposed.
- Reviewers were not convinced that the project would provide much new fundamental information about eye development.
Feasibility and Experimental Design
- The rationale for the mixed mouse and human cell cultures was not convincing, and reviewers considered this approach likely to create serious obstacles in both performing the experiments and interpreting the results.
- Preliminary data were mostly descriptive and phenomenological, with little quantitative data to support the project’s feasibility.
- Aim 1 appears to be completed already, since these cells were shown in the preliminary data section.
- Reviewers were concerned about significant differences between human and mouse stem cell populations and felt that working directly on human cells (and forgoing the mouse work) would have been a more promising approach.
- Reviewers considered the third experimental aim without focus, not based on a coherent hypothesis and of little apparent value.
Principle Investigator and Research Team
- The PI has expertise in the areas of retinal development, morphogenesis and neuronal fate in the mouse.
- The PI has displayed only modest recent productivity.
- The research team has limited experience in stem cell biology.
Responsiveness to the RFA
- The proposal is mostly unresponsive to the RFA, since much of the proposed work is focused on mouse iPSC lines. The experiments with mouse iPSCs were not considered groundbreaking, innovative or transformative.