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Gene Therapy Lab

Gene therapy can modify mutations in genes or deliver an extra, healthy copy of an allele to treat inherited forms of blindness. Dr. Mahajan was a surgeon in the recent trial for gene therapy using a viral vector that successfully rescued vision loss in patients with Leber Congenital Amaurosis. The development of pre-clinical models to test gene therapy approaches for other forms of blindness, as well as testing gene therapy treatments in these pre-clinical animal models, is necessary and important to lead to clinical trials for human patients.

We are treating human patient stem cells and translational animal models with gene therapy approaches. We are also developing animal models for various inherited retinal degenerative diseases by introducing human genes or human mutations into the animals.

Pluripotent stem cells are made in the lab from patient volunteers with retinal degenerations. We then use gene editing (CRISPR) to correct the patient mutations in their own cells. Our lab was the first to correct a human blindness gene in human stem cells. These gene-corrected cells can then be used to test therapies and create transplants that replace diseased retinas.


Fixing faulty genes.
Direct modification of DNA in living cells.
Gene therapy correction in pre-clinical models of retinal disease.


Nov 23 2017 | Posted In: 20/20 Blog
Adeno-associated viral (AAV) gene therapy restores axial eye length in a mouse model for nanophthalmos.
Apr 22 2016 | Posted In: 20/20 Blog
A new pre-clinical mouse model to study blindness caused by diabetes.
Edited stem cells offer hope of precision therapy for blindness Findings raise the possibility of treating blinding eye diseases using a patient's own corrected cells as replacement tissue UNIVERSITY OF IOWA HEALTH CARE


CRISPR Repair Reveals Causative Mutation in a Preclinical Model of Retinitis Pigmentosa: A Brief Methodology, Wu, Wen-Hsuan, Tsai Yi-Ting, Justus Sally, Cho Galaxy Y., Sengillo Jesse D., Xu Yu, Cabral Thiago, Lin Chyuan-Sheng, Bassuk Alexander G., Mahajan Vinit B., et al. , Retinal Gene Therapy, p.191–205, (2018)
Autologous stem cell therapy for inherited and acquired retinal disease, Apatoff, Mary Ben L., Sengillo Jesse D., White Eugenia C., Bakhoum Mathieu F., Bassuk Alexander G., Mahajan Vinit B., and Tsang Stephen H. , Regenerative medicine, (2018)
CRISPR-Mediated Ophthalmic Genome Surgery, Cho, Galaxy Y., Abdulla Yazeed, Sengillo Jesse D., Justus Sally, Schaefer Kellie A., Bassuk Alexander G., Tsang Stephen H., and Mahajan Vinit B. , Current ophthalmology reports, Volume 5, p.199–206, (2017)
CRISPR-Cas Genome Surgery in Ophthalmology, DiCarlo, James E., Sengillo Jesse D., Justus Sally, Cabral Thiago, Tsang Stephen H., and Mahajan Vinit B. , Translational vision science & technology, Volume 6, p.13–13, (2017)
Retrospective Analysis of Structural Disease Progression in Retinitis Pigmentosa Utilizing Multimodal Imaging, Cabral, Thiago, Sengillo Jesse D., Duong Jimmy K., Justus Sally, Boudreault Katherine, Schuerch Kaspar, Belfort Rubens, Mahajan Vinit B., Sparrow Janet R., and Tsang Stephen H. , Scientific reports, Volume 7, Number 1, p.10347, (2017)
Unexpected mutations after CRISPR-Cas9 editing in vivo, Schaefer, Kellie A., Wu Wen-Hsuan, Colgan Diana F., Tsang Stephen H., Bassuk Alexander G., and Mahajan Vinit B. , Nature methods, Volume 14, Number 6, p.547–548, (2017)