Physician’s Profile

Stephen H. Tsang, MD, PhD

Department of Ophthalmology
Department of Pathology & Cell Biology
Course co-director, BMENE6510 Stem Cells, Genome Engineering

Stephen H. Tsang, M.D, Ph.D. is an acclaimed clinical geneticist in the care of individuals with retinal degenerations, and is known worldwide for his pivotal research in reprogramming the metabolome as a therapeutic avenue.

Dr. Tsang graduated from Johns Hopkins University, where he began his medical genetics training under the tutelage of Professor Victor A. McKusick. He received his M.D.-Ph.D. degrees from the NIH-National Institute of General Medical Sciences Medical Scientist Training Program (MSTP) at Columbia University. Dr. Tsang then completed his residency at Jules Stein Eye Institute/UCLA, followed by studies with Professors Alan C. Bird and Graham E. Holder on improving the care of individuals with macular degenerations.

Dr. Tsang is a recognized pioneer in genome surgery in stem cells. Most recently, he has been invited to lecture at the genome surgery workshop during the annual Association for Research in Vision & Ophthalmology (ARVO) 2015, 16 & 18 Annual Meetings; and as a Moderator for Gene Editing/Rewriting the Genome: Moving from Association to Biology and Therapeutics session during the 65th American Society of Human Genetics (ASHG) Annual Meeting, and a lecturer at 2015 & 2016 CRISPR Revolution conferences at Cold Spring Harbor. 

In his New York State supported stem cell program (N09G-302), he is examining embryonic stem (ES) cells to model and replace diseased human retinal cells. His contributions were recognized by the 2005 Bernard Becker Association of University Professors in Ophthalmology's Research to Prevent Blindness Award. Dr. Tsang also participates in resident teaching and had been the Columbia ophthalmology basic science course director. He is a member of the American Society of Clinical Investigation.

Dr. Tsang is one of a handful of clinicians who can direct the full spectrum of bench-to-bedside research. PI’s research on cGMP-phosphodiesterase (PDE6) is a case in point. PDE6 defects lead to blindness in 72,000 people worldwide. PI generated the world’s first gene-targeted model of retinitis pigmentosa (a PDE6 mutant), and then used these mice to dissect the underlying pathophysiology. These studies led to novel and fundamental discoveries on PDE6 regulation of G-protein-coupled-receptor signaling and, eventually, preclinical testing in the same mice; of the different therapies tested, viral-gene therapy is slated for clinical trials. Many of his publications are in top rated general interest journals such as Science and Journal of Clinical Investigation, which attests to the broad impact that his work has had.


Board Certificates
Areas of Expertise:
  • Retinal Disorders
  • Eye Genetics
  • Electrophysiology
  • Stem Cell Transplantation
  • Retinitis pigmentosa
  • Precision Medicine
  • Skin Pigmentation Disorder
  • Retinal Disease
  • Macular Degeneration
  • Marfan's Syndrome
  • Retinopathy
  • Loss of Vision
  • Unexplained Vision Loss
  • Vitreoretinal Disorder
  • Retinal Vascular Disorders
  • Diabetic Retinopathy
  • Retina Degeneration
  • Retinal Bleeding
  • Retina Disorder
  • Pediatric Genetics
  • Genetic Testing
  • Genetic Disorders
  • Adult Genetics
  • Clinical Genetics
Honors & Awards:

Named Lectureships

2006                   Dr. Isaac Bekhor Lecturer, Doheny Eye Institute at University of Southern California (9/29)

2013                   Dr. Paul Stringer Memorial Lectureship, McMaster University

2013                   Dr. Bradley Straastma Lecturer, Resident Graduation, UCLA

2015                   Dr. Joginder Nath Lecturer, West Virginia U. School of Medicine

2016                   Lecturer, World Science Festival, CRISPR Technologies

1988 – 1989       Alpha Epsilon Delta, National Premedical Honor Society, Maryland Alpha (Historian)

1988 – 1989       Dean’s List, The Johns Hopkins University

1989                   Graduate with Departmental Honor

1989                   Recipient of Student Activities Award, The Johns Hopkins University

1989 – 1997       NIH-National Institute of General Medical Sciences Medical Scientist Training Program: MSTP fellowship PHS Grant #T32GM073667-14

1995                   ARVO/National Eye Institute Travel Fellowship Grant for the 1995 ARVO meeting

1996                   Dean’s Award for Excellence in Research, Graduate Sch of Arts & Sciences, Columbia U. Dr. Alfred Steiner Award for Best Medical Student Research, Columbia U.

1997                   Best Overall Presentation at Eastern Student Research Forum sponsored by American Medical Association and the University of Miami

1997                   Travel Grant, European Students’ Conference at the Charité in Berlin

1998                   Edith McKane Award in Ophthalmology, College of Physicians and Surgeons, Columbia U.

1998                   John Lattimer Award in Urology, College of Physicians and Surgeons, Columbia U.

2000                   Jules Stein Eye Institute Research Award

2000                   RPB-Association of University Professors in Ophthalmology (AUPO) Resident Award

2001 – present   Fight for Sight/Grant-In-Aid Review Panel Member

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

2006                   ARVO/Alcon Early Career Clinician Scientist Award

2007                   Charles E. Culpeper Award

2008                   Teacher Recognition Award, Columbia U.

2008 – 2009       Listed as one of “America’s Top Ophthalmologists” by Consumers’ Research Council of America                                                                                 

2009                   Patients' Choice Award for 2008

2009                   Elected to Macular Society

2010                   Keynote Speaker, GTCbio 2nd Annual Ocular Disease & Drug Discovery  conferen. May 28, 2010

2012                   Invited Lecturer, University of Geneva

2013, 14             Elected by his peers for inclusion in Best Doctors in America®

2013                   ARVO Foundation Carl Camras Award

2014                   Foundation Fighting Blindness Visionary Award Recipient and “Banking on a Cure” Honoree

2015                   ARVO 2015 Annual Meeting Gene Editing Symposium Invited Lecturer in Denver, Colorado

2015                   Elected to American Ophthalmological Society

2015                   Invited Lecturer,Deutsche Ophthalmologische Gesellschaft DOG

2015                   Plenary lecture, Rensselaer Center for Stem Cell Research (RCSCR) - Symposium

2015                   Chair,  Gene Editing/Rewriting the Genome Symposium American Society of Human Genetics Annual Meeting

2016                   Elected to American Society for Clinical Investigation

2018                   Young Investigator Award, Macular Society


H-index 42

Gene therapy and genome surgery in the retina. DiCarlo JE, Mahajan VB, Tsang SH.  Journal of Clinical Investigation.  2018 Jun 1;128(6):2177-2188.

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.

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.

Wert KJ, Mahajan VB, Zhang L, Yan Y, Li Y, Tosi J, Hsu CW, Nagasaki T, Janisch KM, Grant MB, Mahajan M, Bassuk AG, Tsang SH. Neuroretinal hypoxic signaling in a new preclinical murine model for proliferative diabetic retinopathy. Signal Transduct Target Ther. 2016;1. pii: 16005. Epub 2016 Apr 22. PubMed PMID: 27195131; PubMed Central PMCID: PMC4868361.

Petersen-Jones S.M., Occelli L.M., Winkler P.A., Lee W., Sparrow J.R., Tsukikawa M., Boye S.L., Chiodo V., Capasso J.E., Becirovic E., Schön C., Seeliger M.W., Levin A.V., Michalakis S., Hauswirth W.W., Tsang S.H. (2018). Patients and animal models of CNGβ1-deficient retinitis pigmentosa support gene augmentation approach. Journal of Clinical Investigation. 128(1):190-206. doi:10.1172/JCI95161.

1. Li, Y, Tsai, YT, Hsu, CW, Erol, D, Yang, J, Wu, WH, Davis, Richard, Egli, Dieter, TSANG, STEPHEN H. Long-term safety and efficacy of human induced pluripotent stem cell (iPS) grafts in a preclinical model of retinitis pigmentosa. Molecular Medicine18: 1312-1319. Cited 55 times.                                                      

Contribution: This high-impact study used a preclinical model for retinitis pigmentosa (RP) to provide the first evidence for human iPS-cell-mediated recovery of visual function. Therefore, this research provided critical feasibility data for therapies using autologous iPS-cell transplantation to treat retinal degenerations in humans. This study is also one of the first to provide strong in vivo preclinical evidence that this potential cell therapy does not induce tumor formation. This discovery was featured in numerous news outlets – including a Medscape Medical News article (1/7/13), and in two Columbia University Medical Center press releases (10/1/12 and 12/20/12).

2. Wert, K.J., Sancho-Pelluz, J., Davis, R.J., Nishina, P.M., and TSANG, S.H. Gene Therapy Provides Long-term Visual Function in a Pre-clinical Model of Retinitis Pigmentosa. (2013) Human Molecular Genetics. 22:558-567. Cited 18 times.

Contribution: This manuscript is unique in the field of gene therapy in that it demonstrates stable, sustained rescue – both functional and structural. These strong feasibility data provide a solid foundation for moving forward with gene-therapy in patients with a specific genetic form of retinitis pigmentosa (RP). In fact, we are currently recruiting patients for our upcoming gene-therapy trial, “Bringing Gene Supplementation Therapy for PDE6-associated Retinopathies into Clinical Practice” (funded by Tistou and Charlotte Kerstan Foundation).

3. 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, S.H. Gene therapy in patient-specific stem cell lines and a preclinical model of retinitis pigmentosa with membrane frizzled-related protein (MFRP) defects. (2014) Molecular Therapy. 2014 Sep;22(9):1688-97. Cited 15 times.

Contribution: This is the first demonstration that patient-specific induced pluripotent stem (iPS) cells can be used to model a disease phenotype, and study its etiology. This is also the first report of human iPS-derived cells being successfully used as a recipient for viral gene therapy.

4. Yang J, Li Y, Chan L, Tsai YT, Wu WH, Nguyen HV, Hsu CW, Li X, Brown LM, Egli D, Sparrow JR, TSANG, S.H. (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.  Cited 27 times.

Contribution: In vitro models for age-related diseases are invariably based on immortal cells, which are inherently unsuitable for modeling diseases of aging. In this study, we developed a novel human stem-cell-based model for age-related macular degeneration (AMD), an ocular disease with high incidence. We then used these cells to determine the function of two important, but poorly understood AMD risk factors. This is the first demonstration that patient-specific induced pluripotent stem (iPS) cells can be used to model a late onset disease phenotype, and study its etiology.

5. Koch SF, Tsai YT, Duong JK, Wu WH, Hsu CW, Wu WP, Bonet-Ponce L, Lin CS, TSANG SH. (2) Halting progressive neurodegeneration in advanced retinitis pigmentosa. 2015. Journal of Clinical Investigation. 2015 Sep;125(9):3704-13. doi: 10.1172/JCI82462. Epub 2015 Aug 24. PMID:26301813. Cited 5 times.

Koch SF, Duong JK, Hsu CW, Tsai YT, Lin CS, Wahl-Schott CA, Tsang SH. Genetic rescue models refute nonautonomous rod cell death in retinitis pigmentosa. Proc Natl Acad Sci U S A. 2017 May 16;114(20):5259-5264.

Contribution: Recent follow-up studies to the human RPE65 gene therapy trials demonstrated that the interventions failed to halt or even slow photoreceptor degeneration. As a means to explain this treatment failure, it was suggested that the diseased photoreceptors had reached a “point-of-no-return.” In this report, we tested this hypothesis in an RP mouse model, using a novel driver to deliver therapy to all rod photoreceptors at early, mid, and late disease stages. In these optimally treated retinas, not only was function rescued, but photoreceptor degeneration was also halted. Critically, we demonstrated significant sustained rescue, even at the late disease stage.

6. Wu WH, Tsai YT, Justus S, Lee TT, Zhang L, Lin CS, Bassuk AG, Mahajan VB, TSANG SH. CRISPR Repair Reveals Causative Mutation in a Preclinical Model of Retinitis Pigmentosa. Molecular Therapy 2016 Aug;24(8):1388-94. doi: 10.1038/mt.2016.107. Epub 2016 May 20. PMID:27203441. New publication (May 20), no citations yet.

Contribution: In the current era of next-generation sequencing, copious genetic variants are identified. This report illustrates how CRISPR can be used to validate sequence variants, distinguish between their pathogenicity, and elucidate disease pathophysiology. We applied CRISPR/Cas9 to resolve a century-long debate on the molecular origins of the Pde6brd1/Pde6brd1 (Rd1) mouse., Rd1 mice express two mutations – a murine leukemia virus (Xmv-28) insertion and a nonsense mutation (C to A transversion) in codon 347 – that still remain controversial. We sought to determine whether one or both of these mutations engenders the fast-progressing retinal deterioration typical of Rd1 mice.

7. Moshfegh Y, Velez G, Li Y, Bassuk AG, Mahajan VB, TSANG SH. BESTROPHIN1 mutations cause defective chloride conductance in patient stem cell-derived RPE. Hum Mol Genet. 2016 May 18. pii: ddw126. PMID: 27193166. New publication (May 18), no citations yet.

Contribution: Mutations in the BEST1 gene are clearly linked to eye disease in human RPE, including Best vitelliform macular dystrophy. The mechanism linking mutations in the gene to eye pathology is unknown, and the question of whether BEST1 is a bona fide chloride channel has been remaining in the field.  In this report we show that BEST1 encodes a predicted transmembrane anion channel that is calcium-activated and highly permeable to chloride ions. We have taken advantage of iPSC-RPE cell modeling of BEST1 disease, and developed a new approach for directly measuring chloride currents in live patient RPE with a biosensor.

8. Zhang L, Justus S, Xu Y, Pluchenik T, Hsu CW, Yang J, Duong JK, Lin CS, Jia Y, Bassuk AG, Mahajan VB, TSANG SH. Reprogramming towards anabolism impedes degeneration in a preclinical model of retinitis pigmentosa. Hum Mol Genet. 2016 Aug 11. pii: ddw256. PMID: 27516389. New publication (Aug 11), no citations yet.

Contribution: In RP, outer segment (OS) gets shortening which triggers photoreceptor death is mainly due to the imbalance between anabolic and catabolic processes. OS is shed and regenerated daily, but in disease photoreceptors, the rate of shedding exceeds the rate of renewal, leading to significantly shorter OS, excessive anabolic demands and subsequent death. Augmenting anabolism could theoretically fuel protein and lipid synthesis, thus encouraging OS regenesis.  Ablation of Tsc1, a transcriptional inhibitor of the mTOR pathway, preserved the structure and function of diseased rod and cone photoreceptors in a preclinical model of RP.

9. Yang J, Bassuk AG, Merl-Pham J, Hsu CW, Colgan DF, Li X, Au KS, Zhang L, Smemo S, Justus S, Nagahama Y, Grossbach AJ, Howard MA 3rd, Kawasaki H, Feldstein NA, Dobyns WB, Northrup H, Hauck SM, Ueffing M, Mahajan VB, TSANG SH. Catenin delta-1 (CTNND1) phosphorylation controls the mesenchymal to epithelial transition in astrocytic tumors. Hum Mol Genet. 2016 Aug 11. pii: ddw253. PMID:27516388. New publication (Aug 11), no citations yet.

Contribution: The tuberosclerosis complex (TSC) syndrome is due to mut