Delivery strategies for CRISPR/Cas genome editing tool for retinal dystrophies:challenges and opportunities

CRISPR/Cas,an adaptive immune system in bacteria,has been adopted as an efficient and precise tool for site-specific gene editing with potential therapeutic opportunities.It has been explored for a variety of applications,including gene modulation,epigenome editing,diagnosis,mRNA editing,etc.It has found applications in retinal dystrophic conditions including progressive cone and cone-rod dystrophies,congenital stationary night blindness,X-linked juvenile retinoschisis,retinitis pigmentosa,age-related macular degeneration,leber’s congenital amaurosis,etc.Most of the therapies for retinal dystrophic conditions work by regressing symptoms instead of reversing the genemutations.CRISPR/Cas9 through indel could impart beneficial effects in the reversal of gene mutations in dystrophic conditions.Recent research has also consolidated on the approaches of using CRISPR systems for retinal dystrophies but their delivery to the posterior part of the eye is a major concern due to high molecular weight,negative charge,and in vivo stability of CRISPR components.Recently,non-viral vectors have gained interest due to their potential in tissue-specific nucleic acid(miRNA/siRNA/CRISPR)delivery.This review highlights the opportunities of retinal dystrophies management using CRISPR/Cas nanomedicine.

Exploration and insights into the cellular internalization and intracellular fate of amphiphilic polymeric nanocarriers

The benefcial or deleterious effects of nanomedicines emerge from their complex interactions with intracellular pathways and their subcellular fate.Moreover,the dynamic nature of plasma membrane accounts for the movement of these nanocarriers within the cell towards different organelles thereby not only infuencing their pharmacokinetic and pharmacodynamic properties but also bioavailability,therapeutic effcacy and toxicity.Therefore,an in-depth understanding of underlying parameters controlling nanocarrier endocytosis and intracellular fate is essential.In order to direct nanoparticles towards specifc sub-cellular organelles the physicochemical attributes of nanocarriers can be manipulated.These include particle size,shape and surface charge/chemistry.Restricting the particle size of nanocarriers below 200 nm contributes to internalization via clathrin and caveolae mediated pathways.Similarly,a moderate negative surface potential confers endolysosomal escape and targeting towards mitochondria,endoplasmic reticulum(ER)and Golgi.This review aims to provide an insight into these physicochemical attributes of nanocarriers fabricated using amphiphilic graft copolymers affecting cellular internalization.Fundamental principles understood from experimental studies have been extrapolated to draw a general conclusion for the designing of optimized nanoparticulate drug delivery systems and enhanced intracellular uptake via specifc endocytic pathway.