Protamine-mediated efficient transcellular and transmucosal delivery of proteins

Proteins and peptides often require frequent needle-based administrations. Here, we report a non-parenteral delivery method for proteins through physical mixing with protamine, an FDA-approved peptide. Protamine was shown to promote tubulation and rearrangement of cellular actin, leading to enhanced intracellular delivery of proteins compared to poly(arginine)(8) (R8). While the R8-mediated delivery resulted in significant lysosomal accumulation of the cargo, protamine directed the proteins to the nuclei with little lysosomal uptake. Intranasal delivery of insulin mixed with protamine effectively reduced blood glucose levels in diabetic mice 0.5 h after administration and the effect lasted for similar to 6 h, comparable to subcutaneously injected insulin at the same dose. In mice, protamine was shown to overcome mucosal and epithelial barriers and modulate adherens junctions, promoting insulin penetration to the lamina propria layer for systemic absorption.

Automated summary

We propose a non-parenteral delivery method for proteins using protamine, an FDA-approved peptide. Protamine promotes actin tubulation and rearrangement, enhancing intracellular protein delivery compared to poly(arginine)(8) (R8). Protamine directs proteins to the nuclei with minimal lysosomal uptake, in contrast to R8-mediated delivery. Intranasal delivery of insulin mixed with protamine effectively reduces blood glucose levels in diabetic mice for up to 6 hours, similar to subcutaneously injected insulin.