Jul 2026· Journal of Controlled Release· Vol 397, pp.
115170
· 1 citation· 227 references
Medicine
TL;DR
This review critically examines recent progress in engineering delivery systems to access representative extrahepatic tissues, including the central nervous system (CNS), eye, lung, heart, spleen, inner ear, and bone marrow, and evaluates the rational design of viral vectors, polymeric and lipid-based nanocarriers, exosome platforms, hydrogel depot systems, and local administration strategies that bypass systemic clearance.
Abstract
Despite their transformative potential in treating genetic, neurological, and oncological disorders, the clinical application of RNA therapeutics remains largely confined to the liver. Current approved platforms rely on two fundamentally distinct hepatic delivery mechanisms. N-acetylgalactosamine (GalNAc) conjugation achieves liver targeting through designed, high-affinity binding to the asialoglycoprotein receptor on hepatocytes, while lipid nanoparticles (LNPs) accumulate in the liver through intrinsic physicochemical tropism driven by apolipoprotein adsorption and the fenestrated hepatic vasculature. Extending RNA delivery beyond the liver demands solutions to challenges that have no hepatic parallel, including formidable tissue-specific physiological barriers, critically low endosomal escape efficiencies, and the absence of any extrahepatic receptor-ligand system matching the efficiency and recyclability of the GalNAc-ASGPR axis. In this review, we critically examine recent progress in engineering delivery systems to access representative extrahepatic tissues, including the central nervous system(CNS), eye, lung, heart, spleen, inner ear, and bone marrow. We evaluate the rational design of viral vectors, polymeric and lipid-based nanocarriers, exosome platforms, hydrogel depot systems, and local administration strategies that bypass systemic clearance. By analyzing the molecular mechanisms, translational milestones, and persisting limitations of these approaches, this review identifies the key scientific and engineering bottlenecks that must be resolved to advance extrahepatic RNA therapeutics from preclinical promise toward broad clinical reality.
The success of mRNA vaccines has established lipid nanoparticles (LNPs) as a clinically validated delivery platform, yet their application to pulmonary therapeutics presents formidable challenges. This review systematically summarizes the mechanisms, delivery methods, key challenges, safety considerations, and translational gaps associated with mRNA-LNP therapeutics for pulmonary disorders. It surveys LNP-mediated delivery to pulmonary cell populations, distinguishing readily accessible targets (such as alveolar type II cells, bronchial epithelia, and macrophages) from refractory cell types (including T cells and rare fibroblast subsets). The evolution of LNPs is traced through three generations: from initial hepatic-optimized carriers, to lung-tropic selective organ targeting (SORT) formulations, and onward to contemporary precision-engineered aerosol systems. These advances have enabled diverse mRNA-based therapeutic modalities, encompassing protein replacement, gene editing, cell reprogramming, and cancer immunotherapy, each of which is examined with emphasis on their distinct mechanisms of action and safety profiles. Lung cancer represents a particularly intractable therapeutic challenge. Stromal barriers and tumor-associated macrophages render most lung-selective LNPs ineffective in orthotopic models, necessitating development strategies decoupled from those for non-malignant indications. Significant translational gaps persist, including a limited understanding of inhaled delivery barriers, insufficient long-term safety data for repeated dosing regimens, and the poor predictive value of healthy rodent models. While AI-guided lipid discovery, biodegradable formulations, and active targeting strategies offer considerable promise, clinical success will demand rigorous validation in disease-relevant preclinical models.
Fangru Jia, Linlin Ma, Yanan Li· International Journal of Pha...· 0 citations
Lipid nanoparticle (LNP)-mediated mRNA delivery has emerged as a powerful therapeutic modality, yet its clinical translation in oncology remains constrained by inherent hepatic tropism and inefficient endosomal escape. These limitations necessitate high-dose administration, which triggers lipid-associated toxicity and off-target protein expression in the liver. To overcome these barriers, we report a cleavable silyl-ether-based bioorthogonally activatable LNP platform, termed SiLNP, that enables tumor-specific activation and cytosolic mRNA release. We engineered ionizable lipids incorporating silyl ether structural fuses that respond to a phenylalanine trifluoroborate (Phe-BF3) trigger. This system leverages the upregulated transporter LAT-1 to actively import Phe-BF3 into tumor cells, where it triggers lipid desilylation and rapid cargo release. In vitro, SiLNPs demonstrated controllable external control over mRNA expression, achieving a 44-fold enhancement in mRNA expression compared to standard SM-102 LNPs with a 10-fold activation-to-silent ratio. In immunologically "cold" B16-F10 melanoma models, SiLNPs encoding the N-terminal domain of gasdermin D (GDNT) induced tumor-specific pyroptosis, resulting in tumor growth inhibition without detectable systemic toxicity. Furthermore, this platform demonstrated versatility by delivering immunomodulatory mRNAs, including IL-2 and Cxcl9. Taken together, this work presents a metabolically targeted, bioorthogonal-activated delivery strategy to address the selectivity and efficiency limitations of current mRNA medicines, providing a promising platform for precision oncology.
Mingzhe Zhang, Chunhong Wang, Xiaohan Xu et al.· Journal of the American Chem...· 0 citations
Abstract Messenger RNA (mRNA) therapeutics have revolutionized biomedicine by enabling direct in vivo programming of immune cells. This strategy bypasses the complex manufacturing and high costs associated with ex vivo cell therapies. However, efficient and specific systemic delivery of mRNA to target immune cell subsets remains a major translational hurdle. This review systematically examines engineering strategies that address this challenge. We first outline the key biological barriers to mRNA delivery, such as serum instability, nonspecific biodistribution, cellular uptake heterogeneity, and inefficient endosomal escape. Next, we comprehensively review advances in lipid nanoparticle (LNP) engineering, including discovering novel lipids, modulating compositions, conjugating targeting ligands, and incorporating stimuli-responsive elements, to enable enhanced tropism toward specific immune cells. Representative applications in oncology, protein replacement, autoimmune disease, and tissue regeneration are highlighted. Finally, we address translational challenges in safety, scalable manufacturing, and regulatory issues. The integration of rational material design, high-throughput screening, artificial intelligence, and interdisciplinary collaboration will be essential to advance next-generation targeted in vivo mRNA cell therapies toward clinical translation.
Danyang Wang, Yumin Li, Jinfeng Deng et al.· Drug Delivery· 0 citations
The blood-brain barrier (BBB) supporting the health of the central nervous system does this by limiting molecular exchange between circulation and brain tissue, although unfortunately this same restriction prevents therapeutically relevant macromolecules from entering the brain. Consequently, a number of protein-based therapies with success in peripheral tissues including enzymes, antibodies and biologics are unsuccessful in treating neurological disorders. The most recently described example is K16ApoE, a synthetic peptide that combines a polylysine-associated moiety with the receptor binding domain of apolipoprotein E (apoE), suggested to facilitate systemic delivery of large biomolecules across the BBB. Here, we show that co-administration of K16ApoE with therapeutic proteins can mediate high concentrations of this protein in brain tissue, which can yield significant substrate clearance (pathological storage) and profound neurologic improvement and survival benefits in animal models of late-infantile neuronal ceroid lipofuscinosis (LINCL; CLN2 disease). In addition to applications in lysosomal storage disorders, the peptide has shown efficacy in promoting delivery of chemotherapeutic agents, antibodies and biologics related to brain tumors and neurodegenerative diseases. However, broad limitations persist including dose-dependent toxicity or nonspecific BBB permeability and immunogenicity as well high levels of uncertainty in referencing animal findings to humans. This review provides the first integrated critical perspective on K16ApoE by connecting its proposed delivery mechanisms with therapeutic efficacy, toxicity, and translational barriers. In particular, we examine the unresolved balance between receptor-associated endothelial transport and transient BBB modulation and propose a mechanism-safety-translation framework to guide the rational development of K16ApoE and related peptide shuttles.
S. Amudha, Sivaraj Ramasamy, I. V. Enoch· Neuroscience· 0 citations
Systemic delivery of messenger RNA (mRNA) to target tissues and cells using lipid nanoparticles (LNPs) holds transformative potential for gene therapy. However, most clinically validated LNP exhibit strong liver tropism, and redirecting their organ specificity without redesigning entirely new chemistries remains challenging. Here we present a ligand-mediated lipid reprogramming approach that repurposes chemically defined, liver-tropic, ionizable lipids (lipidoids) for mRNA delivery beyond the liver. From a library of 90 degradable lipidoids, we identified 2-t6b as a potent liver-targeting platform. By site-specific displaying of small molecule ligands onto 2-t6b headgroup, we engineered a series of reconfigured lipidoids that achieve lung-specific targeting while retaining the parent delivery scaffold. Ligand7-2-t6b-lipid-functionalized LNP achieved over 200-fold higher mRNA translation in the lungs compared to the parent liver-tropic LNP. Proteomics and molecular docking analysis revealed enhanced binding of the modified lipid to vitronectin, a serum glycoprotein that improves integrin binding and thus promotes cellular uptake and translation efficiency. Ligand-mediated 2-t6b/ligand7 LNPs achieved outperformed efficacy and therapeutic potential in lung-specific genome editing relative to SORT-constructed 2-t6b LNP system. Our modular reprogramming strategy provides a generalizable framework to upgrade existing liver-biased LNPs into lung-selective mRNA carriers, advancing next-generation tissue-specific mRNA therapies for gene editing, protein replacement therapy, and regenerative medicine.
Messenger RNA (mRNA) therapeutics formulated in lipid nanoparticles (LNPs) have transformed vaccinology and enabled a versatile platform for protein-based therapy across a wide range of diseases. Despite their clinical success, LNP-encapsulated mRNA (LNP-mRNA) systems are still largely designed through empirical screening due to an incomplete understanding of their in vivo behavior. This review systematically examines how in vivo imaging modalities have been used in the recent literature to interrogate LNP biodistribution, cellular uptake, and functional mRNA expression. Across the studies reviewed, positron emission tomography (PET) and single-photon emission computed tomography (SPECT) tracers have demonstrated that LNP biodistribution, including organ tropism and size-dependent transport, is governed by formulation parameters and route of administration. Liver and spleen accumulation dominate current systemic delivery profiles. Particles in the 20-100 nm range generally favor efficient extravasation, cellular uptake, and lymphatic transport, while larger ones are gradually associated with reduced cellular internalization and increased reliance on cell-mediated transport to reach draining lymph nodes. Quantitative fluorescence and reporter-gene studies identified endosomal escape as the principal intracellular bottleneck, with less than 2% of internalized RNA typically reaching the cytosol. MRI results, although currently limited, have provided coherent evidence while offering a non-invasive approach for longitudinal monitoring of intracellular RNA trafficking. Imaging has also revealed a recurrent disconnect between LNP exposure and protein expression, demonstrating that LNP organ accumulation alone is an inadequate measure of productive delivery. Bioluminescent imaging approaches have enabled tracking of protein expression kinetics, showing that peak expression often occurs within hours post-administration, but varies significantly with ionizable lipid nature. Collectively, the recent literature indicates that in vivo imaging can help connect biodistribution and functional delivery with LNP designs. This review highlights that integrating quantitative in vivo imaging into the LNP-mRNA development pipeline enables mechanistic identification of delivery barriers and supports rational optimization of formulations.
Natacha Jugniot· European journal of medicina...· 0 citations