Trend AnalysisBiology & Life Sciences

RNA Interference Therapeutics: siRNA Delivery from Liver to Lung and Beyond

RNA interference (RNAi) — silencing specific genes by delivering small interfering RNA (siRNA) — has matured from a laboratory tool to FDA-approved therapeutics. Lin Xiong, Shuang Chen, Sihui Li et al...

By Sean K.S. Shin
This blog summarizes research trends based on published paper abstracts. Specific numbers or findings may contain inaccuracies. For scholarly rigor, always consult the original papers cited in each post.

The Question

RNA interference (RNAi) — silencing specific genes by delivering small interfering RNA (siRNA) — has matured from a laboratory tool to FDA-approved therapeutics. Lin Xiong, Shuang Chen, Sihui Li et al. (2025) and inclisiran (2021) established that liver-targeted siRNA can treat genetic and cardiovascular diseases. But liver targeting exploits a natural tropism of lipid nanoparticles (LNPs) for hepatocytes via ApoE-mediated uptake. The next frontier is extrahepatic delivery — lung, brain, tumour, muscle — where no such natural targeting mechanism exists. Can delivery technology extend RNAi's therapeutic reach beyond the liver?

Landscape

L. Xiong et al. (2025) developed ATP-responsive tumour-targeted LNPs for siRNA delivery in melanoma. The innovation: LNPs modified with phenylboronic acid (PBA) for tumour targeting via sialic acid interaction on tumour cell surfaces, with ATP-responsive intracellular siRNA release. This stimulus-responsive design addresses the challenge of premature siRNA release in blood and off-target delivery to healthy tissues.

Ooi et al. (2024) designed biodegradable hyperbranched poly(β-amino ester) carriers for siRNA delivery. Unlike LNPs (which persist in tissues for days), these polymers degrade rapidly after siRNA release, reducing potential toxicity from carrier accumulation. Their branched architecture provides more siRNA binding sites per molecule than linear polymers, improving loading efficiency.

Ahmed (2024) reviewed LNP-mediated siRNA delivery for Alzheimer's disease — a target requiring blood-brain barrier (BBB) crossing, the most challenging delivery barrier in medicine. Current approaches include receptor-mediated transcytosis (transferrin receptor-targeted LNPs), focused ultrasound BBB opening, and intranasal delivery that bypasses the BBB entirely.

Cabibbo et al. (2024) developed inhalable lipid-polymer hybrid nanoparticles for pulmonary siRNA delivery, demonstrating effective siRNA transfection in lung cancer cells as a proof of concept for respiratory applications.

Key Claims & Evidence

<
ClaimEvidenceVerdict
PBA-modified, ATP-responsive LNPs achieve tumour-targeted siRNA delivery and intracellular releaseEnhanced melanoma efficacy vs. non-responsive LNPs (L. Xiong et al. 2025)Demonstrated in preclinical models
Biodegradable polymers reduce carrier-related toxicityRapid degradation after siRNA release demonstrated (Ooi et al. 2024)Supported; long-term safety advantages likely
BBB-crossing siRNA delivery is feasible for neurodegenerative diseasesMultiple approaches reviewed; receptor-mediated transcytosis most advanced (Ahmed 2024)Early stage; clinical translation challenging
Inhalable siRNA reaches lung cellsNebulised lipid-polymer hybrids achieve pulmonary delivery in cancer cell models (Cabibbo et al. 2024)Demonstrated as proof of concept; dose uniformity across lung regions needs optimisation

Open Questions

  • Extrahepatic targeting: Can ionisable lipid chemistry be designed to preferentially target lung, brain, or muscle over liver? Selective organ targeting (SORT) LNPs are emerging but not yet clinically validated.
  • Durability: siRNA silencing is transient (~3–6 months per dose for liver targets). Can self-amplifying RNA or repeated dosing achieve sustained silencing without immune response?
  • Off-target effects: siRNA can silence unintended genes through partial sequence complementarity. Can chemical modifications (2'-OMe, phosphorothioate) minimise off-targets while maintaining potency?
  • Manufacturing scale: Can GMP-grade siRNA-LNP production scale to support chronic disease indications requiring millions of doses annually?
  • Referenced Papers

    • [1] Xiong, L. et al. (2025). ATP-responsive tumor-targeted LNP for siRNA delivery in melanoma. J. Controlled Release. DOI: 10.1016/j.jconrel.2025.113622
    • [2] Ooi, Y.J. et al. (2024). Biodegradable Hyperbranched pBAEs for siRNA Delivery. ACS Appl. Mater. Interfaces. DOI: 10.1021/acsami.3c10620
    • [3] Ahmed, T. (2024). LNP-mediated siRNA delivery for Alzheimer's disease. European J. Neuroscience. DOI: 10.1111/ejn.16336
    • [4] Lin, S. et al. (2025). Guanidinium-siRNA nanoparticles for long-distance gene silencing. Plant Biotechnology Journal. DOI: 10.1111/pbi.14575
    • [5] Cabibbo, M. et al. (2024). Inhalable Lipid-Polymer Hybrids for Pulmonary siRNA Delivery. Biomacromolecules. DOI: 10.1021/acs.biomac.4c00387

    References (5)

    Xiong, L., Chen, S., Li, S., He, D., Wang, Y., Zhang, Q., et al. (2025). ATP-responsive tumor targeted lipid nanoparticle for enhanced siRNA delivery and improved treatment efficacy in melanoma. Journal of Controlled Release, 382, 113622.
    Ooi, Y. J., Huang, C., Lau, K., Chew, S. Y., Park, J. G., & Chan-Park, M. B. (2024). Nontoxic, Biodegradable Hyperbranched Poly(β-amino ester)s for Efficient siRNA Delivery and Gene Silencing. ACS Applied Materials & Interfaces, 16(11), 14093-14112.
    Ahmed, T. (2024). Lipid nanoparticle mediated small interfering RNA delivery as a potential therapy for Alzheimer's disease. European Journal of Neuroscience, 59(11), 2915-2954.
    Lin, S., Zhang, Q., Bai, S., Yang, L., Qin, G., Wang, L., et al. (2025). Beyond species and spatial boundaries: Enabling long‐distance gene silencing in plants via guanidinium‐siRNA nanoparticles. Plant Biotechnology Journal, 23(4), 1165-1177.
    Cabibbo, M., Scialabba, C., Craparo, E. F., Carneiro, S. P., Merkel, O. M., & Cavallaro, G. (2025). Diving into RNAi Therapy: An Inhalable Formulation Based on Lipid–Polymer Hybrid Systems for Pulmonary Delivery of siRNA. Biomacromolecules, 26(1), 163-177.

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