Cells in the ciliary epithelium (CE) of the eye can clonally expand in culture to produce spheres of cells that differentiate into retinal neurons and glia. It is believed that these spheres are produced by retinal stem cells (RSCs) and hold promise for cell-based therapies to treat degenerative retinopathies. To improve our understanding of RSC expansion and differentiation, we have carried out a series of preliminary studies on human and mouse CE-derived spheres. Our data have led us to reconsider the current retinal stem cell model and to propose a new hypothesis on the expansion and differentiation of CE-derived cells. We propose that the pigmented CE cells rather than RSCs, expand to form spheres and subsequently transdifferentiate into rods, bipolar cells and M?ller glia. This proposal will test if CE-derived spheres form by proliferative expansion of pigmented CE cells or by an RSC mechanism (Aim 1). Culture experiments and in vivo transplantation studies will also be done to test whether pigmented CE cells transdifferentiate into retinal neurons and glia, or if those cells are produced from retinal stem/progenitor cells (Aim 2). Distinction between these 2 hypotheses must be made, because the pathways regulating proliferation and differentiation in retinal stem/progenitor cells differ from those in epithelial cells, and efforts to optimize expansion and differentiation of CE-derived cells must focus on the pathway that reflects that system's biology. The successful completion of these experiments may substantially affect future development of cell-based therapies for millions of people worldwide who suffer from retinal degeneration. This research proposal will also move the RSC field forward by resolving several outstanding questions regarding the proliferation and differentiation of CE-derived cells in culture and in vivo.

Public Health Relevance

Retinal degeneration affects millions of people worldwide each year. One approach that is being considered to treat degenerative retinopathies is the use of retinal stem cell-based therapy to repopulate the photoreceptors and other cells that are lost. Retinal degeneration is an ideal candidate for such cell-based therapy because the eye is easily accessible for therapeutic intervention and the immunoprivileged status of the eye makes rejection of grafted cells less likely than in other organs where stem cell-based therapies are being considered. However, one of the limitations of the retinal stem cell field compared to other areas of stem cell biology is that it is a relatively new area of research. Cells with properties of stem cells in the ciliary epithelium of the eye were first discovered just 7 years ago. As a result, there are still some important questions that must be answered before we can move forward with therapeutic intervention in humans using retinal stem cells. Specifically, we need to better understand the mechanism of retinal stem cell growth and differentiation in culture. The successful completion of the experiments proposed here will resolve whether there is a retinal stem cell in the ciliary epithelium of the mammalian eye or if pigmented ciliary epithelial cells simply expand and transdifferentiate into retinal neurons and glia. These data are essential for directing future studies on cell-based therapies for retinal degeneration and will have a major impact on moving the retinal stem cell field forward.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
3R01EY018599-02S1
Application #
7909831
Study Section
Biology and Diseases of the Posterior Eye Study Section (BDPE)
Program Officer
Mariani, Andrew P
Project Start
2008-08-01
Project End
2011-07-31
Budget Start
2009-08-01
Budget End
2010-07-31
Support Year
2
Fiscal Year
2009
Total Cost
$92,032
Indirect Cost
Name
St. Jude Children's Research Hospital
Department
Type
DUNS #
067717892
City
Memphis
State
TN
Country
United States
Zip Code
38105
Stewart, Elizabeth; McEvoy, Justina; Wang, Hong et al. (2018) Identification of Therapeutic Targets in Rhabdomyosarcoma through Integrated Genomic, Epigenomic, and Proteomic Analyses. Cancer Cell 34:411-426.e19
Wang, Lu; Hiler, Daniel; Xu, Beisi et al. (2018) Retinal Cell Type DNA Methylation and Histone Modifications Predict Reprogramming Efficiency and Retinogenesis in 3D Organoid Cultures. Cell Rep 22:2601-2614
Aldiri, Issam; Xu, Beisi; Wang, Lu et al. (2017) The Dynamic Epigenetic Landscape of the Retina During Development, Reprogramming, and Tumorigenesis. Neuron 94:550-568.e10
Stewart, Elizabeth; Federico, Sara M; Chen, Xiang et al. (2017) Orthotopic patient-derived xenografts of paediatric solid tumours. Nature 549:96-100
Hiler, Daniel J; Barabas, Marie E; Griffiths, Lyra M et al. (2016) Reprogramming of mouse retinal neurons and standardized quantification of their differentiation in 3D retinal cultures. Nat Protoc 11:1955-1976
Stewart, Elizabeth; Federico, Sara; Karlstrom, Asa et al. (2016) The Childhood Solid Tumor Network: A new resource for the developmental biology and oncology research communities. Dev Biol 411:287-293
Valle-GarcĂ­a, David; Qadeer, Zulekha A; McHugh, Domhnall S et al. (2016) ATRX binds to atypical chromatin domains at the 3' exons of zinc finger genes to preserve H3K9me3 enrichment. Epigenetics 11:398-414
Dyer, Michael A (2016) Lessons from Retinoblastoma: Implications for Cancer, Development, Evolution, and Regenerative Medicine. Trends Mol Med 22:863-876
Chen, X; Pappo, A; Dyer, M A (2015) Pediatric solid tumor genomics and developmental pliancy. Oncogene 34:5207-15
Stewart, Elizabeth; Shelat, Anang; Bradley, Cori et al. (2015) Development and characterization of a human orthotopic neuroblastoma xenograft. Dev Biol 407:344-55

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