Abstract
Purpose :
Lipid nanoparticles (LNPs) underpin the great success of mRNA vaccines for SARS-CoV-2 and are on the rise as a reliable tool for mRNA therapeutics. Nevertheless, the efficiency of LNPs for delivering mRNA has been reported to be too low to achieve a therapeutic effect in many tissues, and the transducing efficiency of and inflammation caused by LNPs in the ocular system need to be fully explored. Herein, we tested LNP-mRNA as ocular gene therapy vectors in mouse eyes.
Methods :
LNPs of different FDA-approved formulas encapsulating GFP or Cre mRNA were produced by microfluidic mixing. LNP vectors were injected into the eyes of the wildtype or Cre reporter mouse lines by two routes (i.e. subretinal and intravitreal injections). Immunohistochemistry (IHC) and confocal imaging were performed to examine the transgene expression and microglia activation in the retinal sections.
Results :
The LNPs enabled effective Cre expression in different subsets of retinal cells depending on the administration route. Intravitreal injection resulted in fluorescence expression in a few Müller glia (MGs), while the retinal pigment epithelium (RPE), photoreceptor (PR) and MG cells infection could be detected in the eye receiving a subretinal injection. LNP-GFP mRNA resulted in similar transgene expression patterns as LNP-Cre mRNA given by the same injection route. GFP expression could be detected as soon as 1 hour post injection and last at least 5 days. Interestingly, intravitreal injection of LNPs caused increased Iba1 signals distributing across different retinal layers, especially in the ganglion cell layer (GCL), compared to the uninjected eyes. On the other hand, the LNPs delivered by subretinal injection did not induce obvious microglia activation.
Conclusions :
LNP-mRNA resulted in potent and transient infection in the posterior segments of mouse eyes. Successful development of LNP-mRNA vectors could empower gene editing therapy for inherited blindness with improved safety and efficacy profiles.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.