Research Faculty

Address
Edward S. Harkness Eye Institute
160 Fort Washington Avenue,
Room 513
New York, NY

Phone: 212-342-1189
Fax: 212-305-4987

gene.targeting@gmail.com
Education and Training
MD, P&S 1998 and PhD. Columbia 1996
Jules Stein Eye Institute/UCLA 2003

Collaborations
Nikolai Artemyev Ph.D., University of Iowa
Gordon Fain Ph.D., UCLA
Criss Hartzell Ph.D., Emory
Randal Kaufman Ph.D., Sanford Burnham
Susanne Kohl, Ph.D., University of Tübingen
Vinit Mahajan M.D., Ph.D., Iowa
Marius Ueffing, Ph.D. (Dr. rer. nat.), University of Tübingen
Nicole Weisschuh, Ph.D., (Dr.rer. nat.) University of Tübingen
Bernd Wissinger, Ph.D., University of Tübingen
Lawrence Yannuzzi MD, Vitreous-Retina-Macula Consultants
King-Wai Yau Ph.D., Johns Hopkins
Eberhart Zrenner, M.D., Dr.h.c.mult., University of Tübingen

Internal Collaborations
Rando Allikmets, Ph.D. (Columbia University Medical Center)
Peter Gouras, M.D. (New York Presbyterian Hospital)
Donald Hood, Ph.D. (Columbia University)
Rudy Leibel, M.D. (Institute of Human Nutrition)
Janet Sparrow, Ph.D (Columbia University Medical Center)



Stephen Tsang, M.D. Ph.D.
Lazlo Z. Bito Associate Professor of Ophthalmology, Pathology and Cell Biology
Research Summary

Retinal degenerative diseases affect nine million Americans, including 6.5% of Americans older than 40 years of age. Other than cancer, blindness is the most feared of condition amongst Americans. Our New York State and NIH-R01EY018213 supported project investigates cell-based treatments for retinal diseases, and develops patient specific disease models relevant to drug development. The eye is an ideal testing ground for stem cell therapies because of its relative immune privilege and its ready accessibility for monitoring and imaging purposes. In the eye, various assays can be used to non-invasively quantify transplanted tissue at multiple time points. Furthermore, insight gained from the study of retinal disorders is applicable to other diseases and organ systems, thereby promoting the development of novel stem cell- and gene-based cures for a broad array of previously incurable maladies.

For example, in retinal gene therapy, the laboratory provided the preclinical feasibility data for an upcoming human trial. For cell therapy, laboratory was the first to restore visual function in mice using human induced pluripotent stem (iPS) cells – and to do so without inducing tumor formation. These achievements depended on novel preclinical models generated in the laboratory, including gene-targeted humanized mice and human iPS-derived cells – both with patient-specific mutations. The team also developed the first patient-specific model for an age-related retinal disease.

In addition to developing new therapeutics, the laboratory uses their models to study normal and disease physiology. For example, using a patient-specific cell model, they determined the function of risk factors identified by genome-wide-association studies – one of the first functional validations of GWAS. The laboratory’s genetically engineered mice provided a critical tool for studying phosphodiesterase (PDE6γ) metabolic pathways – a target in retinal degenerations. The team was the first to demonstrate in living neurons that GTPase regulation by PDE6 is rate limiting for the duration of the G-protein-coupled-receptor response, and light-induced post-translational modification of PDE6γ regulates light adaptation. Finally, the laboratory used non-invasive multi-modal imaging in patients and corresponding mouse models to identify new disease phenotypes, and correlated them with novel genes revealed by exome sequencing.


Research

We established a stem cell line engineered to express green fluorescent protein (GFP) under control of the rod photoreceptor-specific Pde6g promoter through an internal ribosome entry site (IRES), Pde6g-IRES-GFP. The Pde6g-IRES-GFP cassette was introduced into mouse stem cells. The GFP marker is transcribed as a bicistronic message in conjunction with Pde6g. The GFP marker will only be expressed when these stem cells differentiate into rod photoreceptors (Fig. 2). Control retina is shown in the left (Fig. 1); whereas GFP marked photoreceptors are derived from stem cells found in Fig. 2. The Pde6g-IRES-GFP retinas show specific GFP marker expression in the outer nuclear layer marked by white arrows (Fig. 2).

Research

A2E autofluorescence images (over 18 months, top to bottom) of non-exudate age-related macular degeneration, showing progressive retinal pigment epithelial (RPE) loss. Scattered, nonconfluent drusen are visible at the posterior pole, along with minor pigmentary alterations. Expanding spots of RPE loss can be seen in the area of increased autofluorescence nasal and superior to the large central spot of atrophy. A higher autofluorescence signal indicates excessive amounts of lipofuscin in the retinal sites that will continue to undergo RPE death, leading to absolute scotoma (areas of vision loss).

Research


The human induced pluripotent stem (iPS) cells have been produced by reprogramming somatic cells (skin fibroblast) with a set of 4 transcription factors. The human iPS-cells show striking similarities in their morphological, gene expression, and functional characteristics to human ES-cells, and seem to have acquired the critical ES-cell characteristics of unlimited growth and potential to differentiate to all cell types of human body. Fibroblasts and iPS Cells. Fibroblasts taken from patient skin. (right) () Fibroblasts after treatment with OCT4, SOX2, KLF4, and cMYC. iPS colonies after SB431542 and PD0325901 selection. (left)

Research


Retinal cells derived from human iPS (left) are morphologically similar to native human RPE cells (right).

Service Activities

Department and University Committees
2012-Present Member, Residency Selection Committee Harkness Eye Institute, Columbia
2011 Member, Review Committee for MS Program, Institute of Human
Nutrition, Columbia
2011-Present Member, Steering Committee for CME
2005-2011 Director, Basic Science Course in Ophthalmology
2005-Present Member, Basic Science Course in Ophthalmology Curriculum Committee

General Teaching Activities & Specific Courses
2005–Present Weekly Tuesday Retinal Degeneration Clinic, Columbia Ophthalmology
Consultants (3 trainees per year)
2005–Present Weekly Thursday Electrodiagnostic Clinic, NYPH
-Clinic provides consultations to Medicaid and NYPH private patients
with neuro-ophthalmic or retinal problems
2007–Present Nystagmus
-House-Staff Core Pediatrics Curriculum
2008-9 Age-Related Macular Degeneration and Macular Dystrophy Lecture, 2 hours
-Basic Science Course in Ophthalmology
2009–Present Morgan Stanley Children's Hospital Genetics Lectures Series, 4 hours
-Pediatric genetics residents attend this class yearly as a part of the Basic Science Course in Ophthalmology
2011–Present Medical Student Research Elective Coordinator (7 trainees per year)



Affiliations
Opthalmology
Stem Cell Consortium
Vision Science
Selected Publications

Tsang S.H., Gouras P., Yamashita C.K., Fisher J., Farber D.B., and Goff SP (1996). Retinal Degeneration in Mice Lacking the γ subunit of cGMP phosphodiesterase. Science 272: 1026-1029.

Tsang S.H., Burns, M. E., Calvert, P. D., Gouras, P., Baylor, D. A., Goff, S. P., and
Arshavsky, V. Y. (1998). Role of the Target Enzyme in Deactivation of Photoreceptor G
Protein in Vivo. Science. 282, 117-21.

Salchow, D.J., Gouras, P., Doi, K., Goff, S.P., Schwinger, E, Tsang S.H. (1999). A point mutation (W70A) in the rod PDE6γ gene desensitizing and delaying murine Rod photoreceptors. Invest Ophthal Vis Sci 40: 3262-3267.*

Tsang S.H., Woodruff, M. L., Chen, C. K., Yamashita, C. Y., Cilluffo, M. C., Rao, A. L., Farber, D. B., and Fain, G. L. (2006). Modulation of phosphodiesterase6 turnoff during background illumination in mouse rod photoreceptors J Neurosci 26, 4472-4480.

Davis, R., Tosi, J., Janisch, K., Kasanuki, J., Wang, N.K., Kong, J., Tsui, I., Cilluffo, M., Woodruff, M., Fain, G.L., Lin C.S., Tsang S.H. (2008). Functional rescue of degenerating photoreceptors in mice homozygous for a hypomorphic cGMP phosphodiesterase 6 allele (Pde6bH620Q). Invest Ophthalmol Vis Sci. 2008 Jul 24.*

Wang N.K., Tosi J., Kasanuki J.M., Chou C.L., Kong J., Parmalee N., Wert K.J., Allikmets R., Lai C.C., Chien C.L., Nagasaki T., Lin C.S., Tsang S.H.Transplantation of reprogrammed embryonic stem cells improves visual function in a mouse model for retinitis pigmentosa. Transplantation 89, 911-919.*

Braunstein, A.L., Trief, D., Wang, N., Chang, S., and Tsang S.H. (2010). Vitamin A deficiency in New York City.Lancet. 2010 Jul 24;376(9737):267*

Tosi J, Davis RJ, Wang N, Naumann M, Lin C, Tsang S.H. shRNA knockdown of guanylate cyclase 2e or cyclic nucleotide gated channel alpha 1 increases photoreceptor survival in a cGMP phosphodiesterase mouse model of retinitis pigmentosa. J Cell Mol Med. 2010 Oct 15. doi: 10.1111/j 1582-4934.2010.01201.x.*

Tsang, S.H., Woodruff, M.L., Lin, C.S., Jacobson, B.D., Naumann, M.C., Hsu, C.W., Davis, R.J., Cilluffo, M.C., Chen, J., Fain, G.L. (2012) Effect of the ILE86TER mutation in the γ subunit of cGMP phosphodiesterase (PDE6) on rod photoreceptor signaling. Cell Signal. 24:181-188.

Tsang S.H., Woodruff ML, Hsu CW, Naumann MC, Cilluffo M, Tosi J, Lin CS. (2011) Function of the asparagine 74 residue of the inhibitory -subunit of retinal rod cGMP-phophodiesterase (PDE) in vivo. Cell Signal. 23(10), 1584-9

Sancho-Pelluz, J., Tosi, J., Hsu, C.W., Lee, F., Wolpert, K., Tabacaru, M.R., Greenberg, J.P., Tsang, S.H., Lin, C.S. (2012) Mice with a D190N mutation in the gene encoding rhodopsin: a model for human autosomal dominant Retinitis Pigmentosa Mol Med. Jan 11. doi: 10.2119/molmed.2011.00475.

Tosi, J., Sancho-Pelluz, J., Davis, R.J., Hsu, C.W., Wolpert, K.V., Sengillo, J.D., Lin, C.S., Tsang, S.H. (2011). Lentivirus-mediated expression of cDNA and shRNA slows degeneration in retinitis pigmentosa. Exp Biol Med (Maywood). 236(10), 1211-7 (2011).*

Wert KJ, Davis RJ, Sancho-Pelluz J, Nishina PM, Tsang SH. (2013) Gene therapy provides long-term visual function in a pre-clinical model of retinitis pigmentosa. Human Molecular Genetics. 22:558-567.

Davis RJ, Hsu CW, Tsai Y, Wert KJ, Sancho-Pelluz J, Lin CS, Tsang SH. (2013) Therapeutic margins in a novel preclinical model of retinitis pigmentosa. Journal of Neuroscience. 33:13475-83.

Li Y, Tsai Y-T, Hsu C-W, Erol D, Yang J, Wu W-H, Davis RJ, Egli D, Tsang SH. (2012) Long-term safety and efficacy of human induced pluripotent stem cell (iPS) grafts in a preclinical model of retinitis pigmentosa. Molecular Medicine. 18:1312-9.

Wert, K.J., Sancho-Pelluz, and Tsang, S.H. (2014). Mid-stage intervention achieves similar efficacy as conventional early-stage treatment using gene therapy in a pre-clinical model of retinitis pigmentosa Hum Mol Genet. 2014 2014 Jan 15;23(2):514-23. doi: 10.1093/hmg/ddt452. Epub 2013 Sep 18. PMID: 24101599

Yang J, Li Y, Chan L, Tsai YT, Wu WH, Nguyen HV, Hsu CW, Li X, Brown LM, Egli D, Sparrow JR, Tsang SH. (2014) Validation of genome-wide association study (GWAS)-identified disease risk alleles with patient-specific stem cell lines. Human Molecular Genetics. Jan 31. PMID: 24497574.

Li Y, Wu W-H, Hsu C-W, Nguyen H-V, Tsai Y-T, Nagasaki T, Maumenee IH, Yannuzzi LA, Hoang QV, Hua H, Egli D, Tsang SH. (2014) Gene therapy in patient-specific stem cell lines and mice with membrane frizzled-related protein defects. Molecular Therapy. (2014) 0:00
Current Projects

Toward mechanism and gene based therapies for retinal degeneration. (Supported by R01)
The major goal of this project is to develop control of retinal gene expression by tamoxifen.

Functional Analyses of Embryonic Stem Cell Derived Retinal Cells (Supported by NYSTEM)
The goal of the ES cell-derived RPE graft is to prevent secondary degeneration of photoreceptor neurons. The project is focused on investigating the use of ES cell-derived RPE grafts to prevent secondary degeneration of photoreceptor neurons. In contrast, the current proposal seeks to investigate the safety and efficacy of iPS-derived RPE grafts to restore vision in mouse models of both retinal damage and retinal degeneration. The ES-derived aspect of the current proposal is merely an adjunct to the iPS-derived elements of the project.

Clinical Electrodiagnostic Module (Supported by Foundation Fighting Blindness)
The goal of this study is to assess genotype and phenotype correlations of retinitis pigmentosa and ABCA4 –retinopathies. Specifically, this study would involve studying PDE6A and PDE6B patients, and determining whether the rate of progression in these patients differs from those found in other forms of RP.


Honors and Awards

1989-1997
NIH-National Institute of General Medical Sciences Medical Scientist Training Program: MSTP fellowship PHS Grant # T32 GM 073667

1996
Dean's Award for Excellence in Research, Graduate School of Arts & Sciences, Columbia U.

1997
Dr. Alfred Steiner Award for Best Medical Student Research, College of Physicians and Surgeons, Columbia U.

2000
Jules Stein Eye Institute Research Award

2000
Research to Prevent Blindness-Association of University Professors in Ophthalmology (AUPO) Resident Award

2003
Burroughs-Wellcome Fund Career Award in Biomedical Sciences

2003
RPB Association of University Professors in Ophthalmology Resident Award

2003
Nesburn Resident Award

2004
Dennis W. Jahnigen Award, American Geriatrics Society

2005
Becker-AUPO-RPB Award

2005
The Irma T. Hirschl Trust Scholar

2006
ARVO/Alcon Early Career Clinician Scientist Award

2006
Dr. Isaac Bekhor Lecturer, Doheny Eye Institute at University of Southern California (Sept 29th)

2007
Charles E. Culpeper Prize

2008
Resident Teaching Award

2008
Listed as one of "America's Top Ophthalmologists" by Consumers' Research Council of America Consumer Research Council

2008
NIH-R01EY018213 awarded for five years

2009
Elected to Macular Society

2010
Keynote Speaker, GTCbio 2nd Annual Ocular Diseases & Drug Discovery conference (May 28, 2010)

2012
Invited Lecturer, University of Geneva

2013
Bradley Straastma Lecture, Resident Graduation, UCLA

2013
ARVO Foundation Carl Camras Award

Committees , Council, and Professional Society Memberships

Member:
2005–Present Member, The Harvey Society
2005–Present Member, Society for Neuroscience
1995–Present Member, ARVO
1989–Present Member, Society of Chinese Bioscientists in America
1988–Present Council Member, Association of Chinese Geneticists in America
1988–Present Member, American Society of Human Genetics (ASHG)

Federal and International Grant Review
2013 Ad Hoc Reviewer, Diseases and Pathophysiology of the Visual System Study Section, Center for Scientific Review, National Institutes of Health (NIH)
2013 Ad Hoc Reviewer, Biology of the Visual System Study Section,
Center for Scientific Review, National Institutes of Health (NIH)
2013 Reviewer, Israel Science Foundation
2012 Ad Hoc Reviewer, Biology of the Visual System Study Section,
Center for Scientific Review, National Institutes of Health (NIH)
2011 Ad Hoc Reviewer, Medical Research Council, UK
2011 Ad Hoc Reviewer, NIH Center for Scientific Review ZRG1 F05-A (20)
2009 Ad Hoc Reviewer, NIH Center for Scientific Review ZRG1 CB-N (58)

Federal-Advisory
2013 Member, Diabetic Retinopathy Clinical Research Network’s Genetics Advisory Committee, National Institutes of Health (NIH)
2011 Consultant, FDA Cellular, Tissue and Gene Therapies Advisory Committee

Private -Grant Review
2012-Present Reviewer, Burroughs Wellcome Fund Career Awards for Medical Scientists Internal Selection Committee for Columbia University

Keywords

Macular degenerations, Macular dystrophies, Stargardt disease, Best disease, Pattern Dystrophies, North Carolina macular dystrophy, Choroideremia, Retinitis pigmentosa, Leber congenital amaurosis, Cone dystrophies, Cone-rod dystrophies, Congenital Stationary night blindness, Bradyopsia, X-Linked Retinoschisis, Hereditary vitreoretinopathies, Refractive errors, Congenital nystagmus, Optic atrophies, Albinism, Foveal hypoplasia, Connective tissue disorders, and Inborn errors of metabolism, Stem cells, Regenerative medicine, Gene-targeting, Gene therapy, Molecular genetics

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