Revolutionizing Retinal Therapeutics: How Peptide-Guided Lipid Nanoparticles Illuminate the Path for mRNA Delivery in Rodents and Nonhuman Primates

Posted on June 21, 2023

Retinal Therapeutics

In a groundbreaking study, researchers have pioneered an innovative technique for delivering mRNA to the neural retina, offering newfound hope in the quest to treat inherited retinal degenerations and combat blindness. By harnessing the power of peptide-guided lipid nanoparticles (LNPs), scientists have successfully honed in on photoreceptor cells within the eye and achieved the targeted delivery of mRNA to a diverse array of cell types residing in the retina.

To achieve this extraordinary feat, the researchers delved into the realm of peptide phage display libraries, unraveling the elusive secrets of specific peptide ligands that possess the remarkable ability to effectively target photoreceptor cells. These remarkable peptides were ingeniously incorporated into LNPs, acting as conduits for mRNA delivery to photoreceptor cells, retinal pigment epithelium, and Muller glia, both in mice and in non-human primates. The resultant protein expression yielded by this approach proved to be robust and brimming with promise.

The study further unfolded as the researchers embarked on an intriguing quest to pinpoint the precise peptide sequences that bestowed their targeting prowess upon the retina. Employing in vivo bacteriophage bio panning, the team injected a library of heptameric M13 bacteriophages into the eyes of mice, meticulously collecting the phage-peptide fusions that exhibited a binding affinity for the neural retina after undergoing multiple rounds of biopanning. Titer measurements confirmed the resounding success of this endeavor, and the subsequent Sanger sequencing of the amassed phage plaques unveiled an enriching motif emblematic of the sequences favoring retinal targeting. Ultimately, a grand total of 30 distinctive sequences emerged as the heralded retina-targeting peptides.

Yet, the journey of LNPs in effectively homing in on photoreceptor cells within the neural retina encountered its share of challenges. Undeterred, the scientists undertook a series of experiments to uncover peptides capable of enhancing the binding of LNPs to these crucial cells. Among the remarkable peptides discovered, one stood out—MH42—possessing favorable attributes, including a propensity for globular formation and a minimal binding affinity to serum albumin. Notably, the unique characteristics of MH42, characterized by a histidine residue and slightly basic amines, held the potential to fuel enhanced transfection of photoreceptor cells and amplify expression. However, further investigation is required to fully elucidate the intricate mechanisms at play.

While navigating the complexities of their research, the team also conducted an in-depth assessment of the immune response in both mice and non-human primates. Intriguingly, their observations uncovered retinal changes, with mice exhibiting a loss of PR cells, while non-human primates displayed immune cell activation. It is worth noting that these effects may be dose-dependent, and the mitigation of their impact may lie in dosage adjustments, the exploration of biodegradable systems, or the introduction of new materials.

Admittedly, the study faces certain limitations, including the necessity for PR-specific peptide elution and further refinements to enhance targeting efficiency. Crucially, identifying the receptors involved in the uptake and internalization of LNPs assumes paramount importance. Nevertheless, the study serves as a resounding testament to the immense potential held by peptide-conjugated LNPs as powerful instruments in mRNA-based therapies targeting the retina. The strides made in non-human primate models, specifically pertaining to inherited retinal diseases, inspire unwavering confidence in the future implications of this transformative approach.

In conclusion, this groundbreaking research advocates for the delivery of mRNA to the neural retina through the ingenious guidance of peptide-conjugated LNPs, thereby heralding a new era in the treatment of diverse retinal abnormalities and pathologies. The profound impact that this approach can have on improving our daily lives is nothing short of extraordinary.

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F. S. Alkuraya, Faculty opinions recommendation of peptide-guided lipid nanoparticles deliver mrna to the neural retina of rodents and nonhuman primates. Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature (2023), doi:10.3410/f.742489926.793597480.