Molecular pharmaceuticsApr 13, 2026

Polymer Micelles Targeting Iron Transport Receptors Improve mRNA Delivery to the Brain

mRNA Technology Weekly Brief ↗PubMed ↗DOI ↗OA ↗

Updated Jun 27, 2026

Abstract

Essence

A transferrin receptor 1-targeted ionizable polymeric micelle platform enhanced systemic mRNA delivery to the brain in preclinical testing.

Evidence

This formulation and delivery-platform experiment used TPP-containing PEG-polyaspartamide micelles with anti-transferrin receptor 1 antibody fragments and reported in situ brain protein production about 10-fold higher than the initial formulation with lower impact on off-target organ expression.

Caveat

The abstract presents a platform result rather than disease treatment outcomes, and the biological model, durability, safety, and clinical relevance remain bounded by preclinical delivery testing.

Simplified

mRNA-based therapies hold immense potential for treating a plethora of diseases. However, their application to central nervous system (CNS) disorders remains limited due to biological barriers, such as rapid degradation in circulation, restricted brain access, and endosomal entrapment within cells. To address these challenges, we developed a polymeric micelle-based nanocarrier capable of systemically delivering mRNA to the brain. This system employed triphenylphosphonium (TPP) as a cationic moiety to stably complex with mRNA and prolong its blood circulation. TPP was introduced into a PEG-polyaspartamide derivative bearing diethylenetriamines, whose pH-responsive ionizable amines facilitated endosomal escape. For brain targeting, antibody fragments against transferrin receptor 1 were conjugated to the PEG shell at a controlled density via click chemistry. This rational, multifaceted design enabled robust in situ protein production in the brain following systemic administration, achieving around a 10-fold increase compared to our initial formulation, while exerting lower impact on off-target expression in other organs. Our system offers a promising platform for systemic mRNA delivery to the brain, opening new avenues for treating CNS disorders.