Dr. Kang Zhang M.D. Ph.D. who is known for his breakthrough research in ophthalmic genetics released a manuscript in Nature highlighting a novel gene therapy that can be applied to degenerative conditions such as retinitis pigmentosa. In the paper, Dr. Kang Zhang and his research team from UC San Diego explain their strategy which revolves around using CRISPR/Cas9 gene-editing so that mutation-vulnerable cell types can be transformed into mutation-resistant cell types. CRISPR stands for clustered regularly interspaced short palindromic repeats and refers to DNA strands which the enzyme, Cas9, cleaves and can, therefore, alter the genetic makeup of an organism. Specifically, Zhang’s research team’s approach focused on deactivating the genes Nrl or Nr2e3. Deactivation of either individual gene alone was enough to result in transformation into cone cells. Nrl acts as a master switch gene between rod and cone cells whereas Nr2e3 is a downstream transcription factor. Both of these genes are responsible for controlling photoreceptor fate.
The team was able to successfully demonstrate the ability to reprogram mutated rod photoreceptor cells and transform them into functional cone photoreceptor cells in mouse models for retinitis pigmentosa. Dr. Kang Zhang explained that the rationale for transforming the mutated-rod cells into cone cells was because cone cells are less vulnerable to genetic mutations involved in causing retinitis pigmentosa.
The human retina consists of 120 million rod cells that provide vision in dim light and 6 million cone cells which function in providing color vision. Degenerative conditions such as retinitis pigmentosa often result in significant visual loss due to the degeneration of these photoreceptors. Dr. Zhang and his team were able to target specific genes responsible for the degeneration of these photoreceptors and the results illustrated an increase in cone-like cells which improved visual function in two mouse models. Currently, there is no treatment for retinitis pigmentosa and those affected by the condition are at serious risk of becoming legally blind.
Name: Kang Zhang