What this is
- This rapid review evaluates nanoparticle-mediated mRNA delivery for therapeutic applications beyond infectious diseases.
- It focuses on advancements in delivery platforms, therapeutic applications in cancer, autoimmunity, and genetic diseases, and identifies translational barriers.
- The review synthesizes findings from 15 studies published between January 2020 and October 2025.
Essence
- Nanoparticle-mediated mRNA therapy is advancing in oncology, autoimmunity, and genetic medicine. Key findings include a 49% reduction in melanoma recurrence with mRNA-4157/V940 plus pembrolizumab.
Key takeaways
- () are the leading platform for mRNA delivery, but alternatives like polymeric and hybrid nanoparticles are emerging. These alternatives may enhance targeting and therapeutic durability.
- Inhaled CFTR mRNA (ARCT-032) has progressed to phase 2 trials, indicating potential for treating cystic fibrosis, though efficacy needs further validation.
- Challenges include extrahepatic targeting and endosomal escape, which limit the effectiveness of mRNA delivery systems. Ongoing innovations aim to address these issues.
Caveats
- The review's findings are based on a limited number of studies (15), which may not fully represent the breadth of ongoing research in this area.
- Single-reviewer data extraction may introduce bias, potentially affecting the reliability of the synthesized results.
Definitions
- mRNA therapeutics: Therapeutics that use messenger RNA to instruct cells to produce proteins that can prevent or treat diseases.
- Lipid nanoparticles (LNPs): Nanoparticles made of lipids that encapsulate mRNA, facilitating its delivery into cells while protecting it from degradation.
Simplified
Highlights
Platform: LNPs lead clinical translation; polymeric, peptide, hybrid, and exosome-inspired carriers provide complementary approaches. Clinical signal: mRNA-4157/V940 plus pembrolizumab reduced melanoma recurrence or death by approximately 49% in phase 2b; phase-3 trials are underway. Autoimmunity: Tolerogenic LNP-mRNA induces antigen-specific tolerance in EAE; splenic targeting is a key design axis. Genetic disease: Inhaled CFTR mRNA has advanced to phase 2; efficacy requires confirmation in sustained, appropriately powered studies. Evidence gaps: Extrahepatic targeting, endosomal escape, repeat-dose safety, and thermostability remain limiting but addressable engineering challenges.
Introduction
Messenger RNA (mRNA) therapeutics have evolved from a conceptual tool for studying gene expression into a clinically validated modality, as illustrated in Figure 1 (Fei et al., 2024; Simonsen, 2024). The rapid development and high effectiveness of LNP-formulated mRNA vaccines during the COVID-19 pandemic demonstrated the feasibility of scalable nucleic-acid medicine manufacture and clarified key regulatory considerations (Zhang et al., 2024; Chatterjee et al., 2024). These advances established mRNA as a broadly applicable therapeutic approach characterised by rapid design, versatile payload encoding, and transient expression without genomic integration (Wang X. et al., 2025).
The field is now expanding beyond prophylaxis to therapeutics, including tumour-specific mRNA vaccines encoding personalised neoantigens in combination with immune checkpoint inhibitors; tolerogenic mRNA programmes that reprogramme immune responses in autoimmune disease; and transient mRNA delivery for protein replacement or genome editing in inherited disorders (Casmil et al., 2025; Vallet and Vignuzzi, 2025). This shift reframes mRNA delivery from pathogen-directed immune stimulation towards disease-context-specific immune modulation and restoration of physiological function (Wang Y. et al., 2025).
Delivery remains the principal determinant of therapeutic performance. Naked mRNA is intrinsically unstable, susceptible to enzymatic degradation, and inefficiently internalised by cells (Shen et al., 2023). Non-viral nanoparticles particularly LNPs have therefore become the leading clinical delivery strategy because they encapsulate and protect mRNA and support cytosolic delivery with negligible risk of insertional mutagenesis (Gabelmann et al., 2025). Their modularity enables optimisation of lipid composition, surface chemistry, charge, and size to tune biodistribution, cellular uptake, endosomal escape, and immunostimulatory profile.
Despite these advances, major obstacles remain to extending mRNA nanotherapeutics beyond hepatotropic delivery and vaccine use (Yu et al., 2025). Most conventional LNPs accumulate in the liver, in part due to adsorption of apolipoprotein E and subsequent uptake pathways, which limits access to extrahepatic targets. Addressing this constraint requires rational lipid design, control of biomolecular corona formation, ligand conjugation, and route optimisation to enhance delivery to tissues such as lung, spleen, and the tumour microenvironment (Pastre et al., 2025). Endosomal escape is an additional bottleneck: only a small proportion of internalised mRNA typically reaches the cytosol, limiting efficiency and therapeutic index. Emerging approaches including self-amplifying RNA (saRNA), circular RNA (circRNA), and biodegradable or organ-selective ionisable lipids aim to improve durability, safety, and biodistribution (Paroor et al., 2025). Collectively, these developments support mRNA as a programmable platform for oncology, autoimmunity, and genetic medicine (Wu et al., 2024).
Key design dimensions for next-generation RNA therapeutics. Schematic overview of four interdependent modules that govern RNA therapeutic performance: (i) RNA design, including 5′cap and untranslated regions (UTRs), nucleoside modification, and alternative RNA modalities such as self-amplifying RNA (saRNA) and circular RNA (circRNA); (ii) formulation, encompassing lipid nanoparticles (LNPs), polymeric or hybrid nanoparticles, biodegradable lipid components, and polyethylene glycol (PEG) alternatives to optimise stability and biocompatibility; (iii) delivery and intracellular trafficking, highlighting organ-selective targeting and cellular entry/processing steps; and (iv) therapeutic modules, illustrating representative applications including cancer immunotherapy, antigen-specific immune tolerance, and protein replacement or genome/protein editing. Abbreviations: UTR, untranslated region; saRNA, self-amplifying RNA; circRNA, circular RNA; LNP, lipid nanoparticle; PEG, polyethylene glycol.
AIM/objective
This rapid review synthesises preclinical and clinical evidence (2020–2025) on nanoparticle-mediated mRNA delivery beyond infectious-disease prophylactic vaccines, focusing on (i) delivery platform advances and mechanistic enablers (biodistribution, cellular uptake, endosomal escape, and stability), (ii) therapeutic applications in oncology, autoimmunity, and genetic disease, and (iii) translational barriers relevant to clinical development, manufacturing, and regulation.
Methods
Search strategy and databases
A rapid, scoping-style review was conducted in line with PRISMA 2020 and PRISMA-ScR guidance (Tricco et al., 2018), adapted for expedited synthesis. PubMed, Scopus, Web of Science Core Collection, and ClinicalTrials.gov↗ were searched for records published or registered between 1 January 2020 and 30 October 2025.
Search strings combined controlled vocabulary and free-text terms using Boolean operators: (“messenger RNA” OR mRNA OR “self-amplifying RNA” OR saRNA OR “circular RNA” OR circRNA) AND (“nanoparticle” OR “lipid nanoparticle” OR LNP OR “non-viral vector”) AND (“cancer” OR “autoimmunity” OR “genetic disease” OR “protein replacement” OR “gene editing”).
Searches were restricted to English-language peer-reviewed articles and completed or active clinical trials. Reference lists of eligible papers were screened to identify additional studies.
Inclusion and exclusion criteria
Inclusion criteria
Experimental or clinical studies describing nanoparticle-mediated mRNA delivery for therapeutic (non-infectious) indications.Reports addressing mechanistic, formulation, or translational aspects (e.g., endosomal escape, tissue targeting, stability).Preclinical animal studies, in vitro mechanistic studies, and early-phase clinical trials (phases 1–3).Systematic reviews/meta-analyses (2020–2025) providing aggregated data relevant to therapeutics.
Exclusion criteria
Vaccine studies limited to infectious-disease prophylaxis without a therapeutic intent. Non-mRNA nucleic acids (e.g., siRNA, DNA, ASOs) unless used as comparators. Conference abstracts, editorials, and commentaries lacking primary data. Non-English literature or inaccessible full texts.
Study selection and screening flow
The database search identified 1,126 records. After removal of 245 duplicates, 881 unique records were screened by title and abstract. Of these, 756 were excluded as irrelevant or non-mRNA-based; 125 full texts were assessed; and 15 studies met inclusion criteria and were included in the qualitative synthesis (Figure 2).
PRISMA flow diagram of study selection. Records were identified through database searching (n = 1,126). After removal of duplicates (n = 245) and non–peer-reviewed records (n = 0), 881 records were screened, of which 756 were excluded. Full-text reports were sought for retrieval (n = 125) and all were retrieved (n = 0 not retrieved). Reports were assessed for eligibility (n = 125), with 110 full-text reports excluded, resulting in 15 studies included in the final review. Abbreviations: PRISMA, Preferred Reporting Items for Systematic Reviews and Meta-Analyses.
Composition of included studies (n = 15)
Seven preclinical studies (LNP optimisation, organ-selective delivery, saRNA/circRNA formats). Four translational studies (oncology and autoimmunity applications). Three early-phase clinical trials (therapeutic safety/dosing). One systematic review/meta-analysis providing mechanistic/regulatory context.
Data extraction and synthesis
Data were extracted into a structured matrix capturing study design, nanoparticle composition, RNA format, indication, outcomes, and translational status. Given rapid-review constraints, extraction was conducted by a single reviewer with an independent cross-check against indexed abstracts. Findings were synthesised narratively by theme (platform design, oncology, autoimmunity, genetic diseases, and translational barriers). Meta-analysis was not undertaken due to heterogeneity in designs and endpoints.
Limitations
This review was not registered in PROSPERO due to its cross-indication scope, but reporting was aligned with PRISMA-P principles for transparency. Single-reviewer screening and extraction may increase selection bias. Search documentation and structured extraction were used to support reproducibility.
Main findings/Thematic overview
Platforms and mechanistic enablers
LNPs dominate clinical translation, and the composition of ionisable lipids, helper lipids, and cholesterol analogues influences colloidal stability, apparent pKa, tissue tropism, and endosomal escape (Pastre et al., 2025; Paroor et al., 2025; Wu et al., 2024). In most settings, unmodified LNPs exhibit predominant hepatic accumulation; extrahepatic delivery is being pursued using organ-selective formulations and targeting strategies designed to alter protein corona composition, cellular uptake pathways, and biodistribution (Asthana et al., 2025; Alshehry et al., 2025; Han et al., 2026). These approaches should be described with mechanistic precision: passive uptake driven by biodistribution and biomolecular corona effects differs from receptor-mediated targeting achieved through ligand decoration and cell-specific binding.
Beyond LNPs, polymeric and hybrid nanoparticles (including lipopolyplexes) and exosome-inspired systems have been explored to improve targeting and to modulate immunostimulatory properties; however, endosomal escape remains a principal efficiency bottleneck, with low cytosolic release prompting lipid-phase engineering, fusogenic additives, and pH-responsive designs (Younis et al., 2025; Yang et al., 2025; Prazeres et al., 2025; Zwolsman et al., 2025). RNA formats also shape dose and durability: saRNA can reduce dose while sustaining expression, whereas circRNA may provide enhanced nuclease resistance and prolonged translation (Shahsavandi et al., 2024; Ren et al., 2025; Li et al., 2025; Mrksich et al., 2024; Ge et al., 2025). Materials innovation increasingly emphasises biodegradability; ester- or disulphide-containing ionisable lipids may accelerate clearance and reduce tissue retention while maintaining activity (Simonsen and Larsson, 2025; Lee et al., 2025; Alasmari et al., 2025). Thermostability and deployability remain central: lyophilised or solid-state formulations aim to reduce cold-chain dependence and improve access, although comparative stability data across platforms remain limited in the included evidence base (Gomi et al., 2023).
Oncology: immunostimulatory mRNA nanomedicines
Personalised neoantigen mRNA vaccination represents the most clinically mature therapeutic application. In KEYNOTE-942 (phase 2b), mRNA-4157/V940 plus pembrolizumab improved recurrence-free and distant metastasis-free survival compared with pembrolizumab alone (approximately 49% reduction in recurrence or death), supporting phase-3 programmes (Weber et al., 2024). In parallel, tumour-directed delivery strategies seek to enhance intratumoural mRNA expression and immune activation, including constructs encoding cytokines (e.g., IL-12, GM-CSF) and dendritic-cell–targeted formulations to improve antigen presentation and CD8+ T-cell expansion; most supporting evidence remains preclinical or early clinical (Floudas et al., 2025). Key barriers include efficient extrahepatic and tumour delivery, stromal penetration, and durability of response. Formulation strategies must balance potency with innate immune sensing to avoid excessive inflammation that may reduce efficacy or tolerability (Alasmari et al., 2025).
Autoimmunity: antigen-specific tolerance with mRNA nanoparticles
Tolerogenic mRNA delivery aims to induce antigen-specific immune regulation without global immunosuppression. Krienke et al. showed that nucleoside-modified mRNA-LNPs encoding autoantigens induced antigen-specific tolerance and ameliorated disease in experimental autoimmune encephalomyelitis (EAE) without systemic immunosuppression (Krienke et al., 2021). Related work supports engineering of spleen-targeted or tolerogenic LNPs, including formulations enriched with immunomodulatory lipids, to bias immune processing towards regulatory phenotypes (Gomi et al., 2023; Krienke et al., 2021). Design variables that influence tolerogenic outcomes include lipid pKa, nucleoside chemistry, and splenic tropism, which together determine innate activation and downstream immune programming. Translational priorities include clarifying durability under repeat dosing and defining clinically relevant endpoints for human autoimmune disease trials (Younis et al., 2025).
Genetic diseases: transient protein replacement and genome editing applications
Therapeutic mRNA can support transient protein replacement, with delivery route and tissue access determining feasibility. In cystic fibrosis, inhaled CFTR mRNA (ARCT-032) was reported as safe and well tolerated in phase 1 and has progressed to phase 2; early efficacy signals were described as mixed and dose-dependent, underscoring the need for adequately powered and sustained studies (Geller et al., 2024). For metabolic or hepatic indications, preclinical biodegradable LNPs have enabled in vivo expression of missing enzymes, indicating potential as an adjunct or alternative to enzyme replacement approaches (Richard et al., 2024). In cardiovascular or ischaemia models, circRNA-LNPs have been reported to prolong VEGF expression and support angiogenesis in preclinical settings, illustrating the potential of alternative RNA modalities where prolonged translation is desirable (Chai et al., 2025; Sayed et al., 2025).
Table 1 summarizes the evidence maturity (2020–2025) for nanoparticle-mediated therapeutic mRNA (non-vaccine) applications, highlighting where clinical translation is most advanced and where progress remains predominantly preclinical.
This table summarises the studies included in the qualitative synthesis, categorised by study type (preclinical, mechanistic, review, perspective, clinical), therapeutic indication, nanoparticle platform or formulation variable, administration route (where reported), primary biological or clinical endpoints, and specific translational contribution.The dataset spans oncology (including phase 2b clinical validation in melanoma), autoimmunity (antigen-specific tolerance in EAE models), genetic/protein replacement (early clinical inhaled CFTR mRNA), and platform-enabling mechanistic and structure–activity relationship (SAR) studies. Collectively, the studies define key translational determinants, including organ-selective targeting, route-dependent pharmacokinetics/biodistribution (PK/BD), ionisable lipid chemistry (tail length, unsaturation, apparent pKa), potency-immunogenicity balance, and endosomal escape efficiency (Table 2).
Table 3 provides a concise clinical translation snapshot of the therapeutic mRNA-nanoparticle programs highlighted in this review, emphasizing route feasibility, endpoint alignment, and near-term translational implications.
| Domain (therapeutic focus) | What the evidence mostly contains | Maturity (2020–2025) | Anchor examples |
|---|---|---|---|
| Oncology (immunostimulatory mRNA-NPs) | Personalised neoantigen vaccines; tumour immune reprogramming; delivery/tropism optimisation | Highest clinical maturity (phase 2b signal; phase-3 programmes initiated) | KEYNOTE-942 neoantigen mRNA + pembrolizumab (); delivery for precision tumour therapy (); antigen-based IO synthesis () [Weber et al., 2024] [Fei et al., 2024] [Floudas et al., 2025] |
| Autoimmunity (tolerogenic mRNA-NPs) | Antigen-specific tolerance using nucleoside-modified mRNA-LNPs; splenic/immune targeting strategies | Strong preclinical, limited clinical | Non-inflammatory/tolerogenic mRNA-LNP in EAE (); tolerogenic LNP self-antigen delivery () [Krienke et al., 2021] [Gomi et al., 2023] |
| Genetic/protein replacement (incl. lung) | Protein expression restoration (e.g., CFTR); biodistribution and route effects | Early clinical (signals emerging) plus enabling preclinical | Inhaled CFTR mRNA (phase 1 safety/tolerability; phase 2 ongoing) (); PK/BD by lipid type and route () [Geller et al., 2024] [Ren et al., 2025] |
| Platform/mechanistic enablers | Organ-selective delivery, lipid SAR, endosomal escape mechanisms, formulation stability considerations | Rapidly expanding; key bottlenecks persist | Organ-selective LNP delivery(); endosomal escape bottleneck (); extrahepatic delivery challenges/opportunities (); lipid pKa perspective () in vivo [Zhang et al., 2024] [Chatterjee et al., 2024] [Simonsen, 2024] [Simonsen and Larsson, 2025] |
| Ref. | Study type | Indication/Use-case | Platform/Variable | Route (as reported) | Primary readout(s) | Why it matters for this review |
|---|---|---|---|---|---|---|
| [Fei et al. (2024)] | Preclinical | Precision tumour therapy (lung metastasis model) | Tissue/cell-targeted LNP strategy | (reported)In vivo | Tumour/therapeutic response | Demonstrates extrahepatic/tumour-oriented delivery design |
| [Simonsen (2024)] | Review | Extrahepatic delivery | LNP strategies and constraints | — | — | Frames liver-tropism constraints and solution space |
| [Zhang et al. (2024)] | Preclinical | Organ-selective NA delivery | Organ-selective LNPs | In vivo | Organ-level delivery | Supports organ-selective targeting claims |
| [Chatterjee et al. (2024)] | Mechanistic perspective | Endosomal escape | LNP-mediated escape bottleneck | — | — | Establishes escape as a central efficiency limiter |
| [Wang et al. (2025a)] | Review | Endosomal escape control | Lipid-raft/phase concepts | — | — | Summarises formulation–escape design levers |
| [Ren et al. (2025)] | Preclinical PK/BD | Route dependence | Ionisable lipid type vs. PK/BD | IV, SC | PK/BD | Supports route selection and lipid chemistry effects |
| [Li et al. (2025)] | Preclinical | Efficacy vs. immunogenicity | mRNA vs. saRNA in LNPs | Intravitreal | Expression and immunogenicity | Demonstrates modality trade-offs (potency vs. innate sensing) |
| [Mrksich et al. (2024)] | Preclinical | Formulation SAR | Ionisable lipid tail length | (reported)In vivo | Delivery efficiency | Identifies SAR lever for potency/robustness |
| [Ge et al. (2025)] | Preclinical | Formulation SAR | Tail unsaturation in ionisable lipids | (reported)In vivo | Delivery and immunogenicity | Links lipid chemistry to potency–immunogenicity coupling |
| [Simonsen and Larsson (2025)] | Perspective | Formulation principle | Apparent pKa of ionisable lipids | — | — | Connects pKa to efficacy/escape |
| [Lee et al. (2025)] | Review/SAR | Design rules | Ionisable lipid SAR (siRNA/mRNA) | — | — | Extends transferable design principles |
| [Gomi et al. (2023)] | Preclinical | Autoimmunity (EAE) | Tolerogenic LNP self-antigen mRNA | (reported)In vivo | Disease scores/tolerance | Demonstrates antigen-specific tolerance |
| [Krienke et al. (2021)] | Preclinical (landmark) | Autoimmunity (EAE) | Non-inflammatory nucleoside-modified mRNA-LNP | In vivo | Tolerance | Proof-of-concept for tolerogenic mRNA therapeutics |
| [Weber et al. (2024)] | Clinical (phase 2b) | Melanoma (adjuvant) | Individualised neoantigen LNP-mRNA + pembrolizumab | Clinical | RFS/DMFS | Highest-level therapeutic clinical signal in this review |
| [Geela et al. (2024)] | Early clinical (phase 1 report) | Cystic fibrosis | Inhaled CFTR mRNA (ARCT-032) | Inhaled | Safety/tolerability | Anchors feasibility of lung delivery |
| Program (ref.) | Indication | Platform/Cargo | Route | Phase (as cited) | Trial ID | Status | Key endpoint(s) | Key takeaway for clinicians/Researchers |
|---|---|---|---|---|---|---|---|---|
| mRNA-4157/V940 + pembrolizumab () [Weber et al., 2024] | Resected high-risk melanoma (adjuvant) | Individualised neoantigen LNP-mRNA + anti-PD-1 | Systemic | Phase 2b | NCT03897881 | Active, not recruiting | RFS, DMFS | Clinically meaningful ↓ recurrence risk; supports phase-3 advancement |
| ARCT-032 (LUNAR®-CFTR mRNA) () [Geller et al., 2024] | Cystic fibrosis | Nebulised LNP-mRNA (CFTR) | Inhaled | Phase 1 (reported) → Phase 2 (noted) | NCT06747858 | Recruiting | Safety/tolerability (early); lung function/biomarkers (as available) | Feasibility of repeat-dose, non-invasive airway delivery; efficacy still consolidating |
| VX-522 (Vertex/Moderna) | Cystic fibrosis (non-modulator eligible genotypes) | Inhaled mRNA-LNP (CFTR) | Inhaled | Phase 1/2 | NCT05668741 | Recruiting | Safety/tolerability; exploratory efficacy | Confirms field move toward inhaled LNP-mRNA CFTR replacement; watch for dose-limiting tolerability signals |
| mRNA-3927 | Propionic acidemia | Systemic LNP-mRNA (enzyme replacement) | IV | Phase 1/2 | NCT04159103 | Recruiting | Safety; PK/PD biomarkers; metabolic decompensation (as applicable) | “Intracellular protein replacement” via LNP-mRNA is clinically testable; endpoints rely heavily on PD/biomarkers early |
| mRNA-3705 | Isolated methylmalonic acidemia (MUT deficiency) | Systemic LNP-mRNA (enzyme replacement) | IV | Phase 1/2 | NCT04899310 | Active, not recruiting | Safety; plasma MMA reduction (PD/efficacy) | Shows how rare-disease mRNA-LNP trials anchor on biomarker efficacy + tolerability over repeated IV dosing |
| ARCT-810 (LUNAR®-OTC) | Ornithine transcarbamylase deficiency | Systemic LNP-mRNA (OTC) | IV | Phase 2a | NCT06488313 | Recruiting | Safety/PD; ammonia control (as applicable) | Tests whether repeated LNP-mRNA dosing can achieve clinically meaningful metabolic control in urea-cycle disorders |
| mRNA-2752 (triplet cytokine/ligand) ± durvalumab | Advanced solid tumours/lymphoma (IT) | LNP-mRNA encoding OX40L/IL-23/IL-36γ | Intratumoral | Phase 1 | NCT03739931 | Completed (study completion listed) | Safety; immune PD markers; response (exploratory) | Illustrates IT mRNA-LNP as an “in situ immune-engineering” approach; translational readouts hinge on tumour immune modulation |
| BNT111 (FixVac) ± cemiplimab | Advanced melanoma (PD-1/PD-L1 refractory/relapsed) | RNA-lipoplex cancer immunotherapy | Systemic | Phase 2 | NCT04526899 | Completed | ORR/PFS (trial-specific) | Provides comparator “non-LNP RNA nanoparticle” oncology experience; useful for contextualising delivery platform vs. clinical activity |
Challenges and Open Questions
Therapeutic mRNA delivery beyond vaccinology is constrained by a recurring set of translational barriers that are incompletely resolved in current evidence. Extrahepatic targeting remains difficult because biodistribution is dominated by liver uptake for many conventional LNP designs (Simonsen, 2024; Zhang et al., 2024). The relative contribution of passive biodistribution, biomolecular corona formation, and ligand-driven receptor targeting should be specified when interpreting ‘targeting’ claims to avoid conflating mechanisms.
Endosomal escape is widely recognised as a limiting step for functional delivery, motivating lipid design strategies that modify membrane interactions and phase behaviour (Chatterjee et al., 2024), (Wang X. et al., 2025), (Simonsen and Larsson, 2025). For chronic indications requiring repeat dosing, innate immune sensing and anti-carrier immune responses may reduce durability and tolerability; nucleoside modification and immunologically ‘silent’ designs are relevant levers, but comparative human data remain sparse (Krienke et al., 2021), (Gomi et al., 2023), (Ge et al., 2025). PEG-associated hypersensitivity has been reported in LNP contexts and supports interest in PEG-sparing alternatives; however, prevalence and risk factors should be described cautiously and anchored to cited evidence.
Manufacturing and stability remain decisive for clinical translation and equitable access. Thermostable and lyophilised presentations may reduce cold-chain dependence, but formulation-dependent changes in particle size distribution, encapsulation efficiency, potency, and impurity profiles require standardised reporting and quality-by-design control (Mrksich et al., 2024), (Gomi et al., 2023). Regulatory pathways must also align with therapeutic endpoints, long-term monitoring, and repeat-dose considerations, particularly for genetic disease applications and any programmes involving genome editing.
Table 4 consolidates the shared translational bottlenecks that repeatedly constrain therapeutic mRNA nanoparticle development beyond vaccines, and links each barrier to actionable engineering solution classes and a minimum reporting set needed for reproducibility and interpretability.
| Barrier (cross-cutting) | Why it limits translation | Practical solution classes (examples) | Minimum reporting for Q1 rigour | Key supporting refs |
|---|---|---|---|---|
| Extrahepatic targeting | Default liver tropism limits disease breadth | Organ-selective LNPs; composition/charge tuning; route optimisation | Quantitative tissue BD and target-cell identification | ,, [Fei et al. (2024)] [Simonsen (2024)] [Zhang et al. (2024)] |
| Endosomal escape | Major efficiency bottleneck for cytosolic delivery | Ionisable lipid tuning; membrane/phase engineering; raft-focused strategies | Escape assay linked to functional protein output | ,, [Chatterjee et al. (2024)] [Wang et al. (2025a)] [Simonsen and Larsson (2025)] |
| Repeat-dose immunogenicity | Chronic indications require re-dosing; innate sensing may erode efficacy | Nucleoside modification; immunologically ‘silent’ designs; lipid SAR optimisation | Cytokines, complement activation, anti-component antibodies; durability | ,, [Ge et al. (2025)] [Gomi et al. (2023)] [Krienke et al. (2021)] |
| Potency–immunogenicity trade-off | Higher expression may coincide with stronger innate activation | Format selection (mRNA vs. saRNA); lipid tail/SAR tuning | Head-to-head potency and immune markers under matched dosing | ,, [Li et al. (2025)] [Mrksich et al. (2024)] [Ge et al. (2025)] |
| Route dependence | Route alters PK/BD and immune exposure | IV vs. SC vs. local vs. inhaled route selection driven by target organ | PK/BD by route and exposure–response relationship | , [Ren et al. (2025)] [Geller et al. (2024)] |
| Design rationalisation (pKa/SAR) | Empirical design limits reproducibility and scale-up | Apparent pKa targeting; SAR frameworks | Full formulation disclosure; pKa/ionisation rationale; CQAs | [27], [28] |
Solid lipid nanoparticles (SLN) for mRNA delivery: opportunities beyond immunization, and persistent hurdles
Solid lipid nanoparticles (SLNs) are colloidal carriers built from physiologically tolerated solid lipids (often triglycerides/waxes) stabilized by surfactants, offering high physical stability and established manufacturing routes (e.g., high-pressure homogenization) that are familiar to pharmaceutical development (Sayed et al., 2025; Müller et al., 2000; Mehnert and Mäder, 2001; Schwarz et al., 1994). Their appeal for therapeutic mRNA extends from (i) a solid lipid matrix that can protect labile cargo during handling/storage and (ii) the prospect of PEGylation/surface engineering to tune circulation and tissue exposure. However, translating SLNs from small-molecule encapsulation to large, polyanionic mRNA places stringent constraints on loading, structural stability, and endosomal escape issues that differ materially from conventional ionizable LNPs used in vaccines (Sayed et al., 2025; Müller et al., 2000; Mehnert and Mäder, 2001; Schwarz et al., 1994).
Recent advances that may enable therapeutic use beyond immunization
Ionizable-lipid incorporated SLNs (iSLNs/PEG-iSLNs). A key step-change has been the move from “neutral” SLNs toward SLNs doped with ionizable/cationic lipids to improve electrostatic complexation, cellular uptake, and critically endosomal escape, while maintaining the formulation’s solid-lipid stability features (Müller et al., 2000; Mehnert and Mäder, 2001; Schwarz et al., 1994). Recent work describing PEGylated, ionizable-lipid–incorporated SLNs for mRNA and pDNA delivery supports the concept that SLN-like matrices can be engineered into functional gene delivery systems rather than passive depots. “Second-generation” solid lipid systems: nanostructured lipid carriers (NLCs) and defect-engineered matrices (Gómez-Aguado et al., 2020). A recurring limitation of classical SLNs is the tendency of highly crystalline matrices to exclude (“squeeze out”) payload on storage (Joshi et al., 2025). NLCs (solid + liquid lipid blends) intentionally introduce lattice imperfections to increase loading capacity and reduce expulsion risk, and are increasingly discussed as a pragmatic evolution path for nucleic acid cargo where the “solid core” concept is retained but crystallinity is moderated (Schwarz et al., 1994). Process innovation for tighter control (microfluidics, continuous processing) (Gómez-Aguado et al., 2020). Advanced preparation approaches (including microfluidic strategies) are being explored to reduce batch-to-batch variability, control size/PDI, and potentially enable continuous manufacture important if SLN-mRNA is to compete with LNPs on reproducibility (Joshi et al., 2025). Collectively, these advances suggest a plausible route for SLN-type carriers into repeat-dose therapeutic domains (protein replacement, local delivery, chronic indications) provided that loading/release and tolerability barriers can be solved at clinically relevant dose intensities.
Critical appraisal: challenges and open questions (aligned to “challenges and open questions”)
Encapsulation constraints for large RNAs (loading vs. functionality trade-off): Unlike hydrophobic small molecules that partition readily into solid lipid matrices, mRNA’s size and polyanionic character complicate true “encapsulation” in a crystalline core. Practically, many SLN formulations rely on (a) surface adsorption/complexation using cationic components or (b) incorporation of ionizable lipids to form electrostatic complexes (Sayed et al., 2025; Müller et al., 2000). This can constrain achievable mRNA payload, increase sensitivity to ionic strength/serum proteins, and may raise cationic-lipid linked tolerability concerns at therapeutic dosing. The field still lacks consensus on what constitutes robust, scalable, high-EE mRNA loading in an SLN architecture without reverting to conventional LNP designs (Mehnert and Mäder, 2001).
Polymorphic transitions and their impact on release and stability: A central SLN-specific risk is lipid polymorphism: many triglycerides transition from metastable α/β′ forms to the more stable β form during storage, which can alter lattice packing, promote payload expulsion, and change release kinetics (often unpredictably) (Schwarz et al., 1994). For mRNA (where both integrity and timing of cytosolic availability matter), such transitions could shift performance between batches or over shelf-life unless tightly controlled (lipid selection, stabilizers, NLC-type matrices, and robust QC for polymorphic state) (Gómez-Aguado et al., 2020).
Scalability, sterilization, and “GMP reality: While high-pressure homogenization is attractive for scale-up, mRNA adds sensitivity to heat/shear, and SLN size distributions can drift with process parameters raising comparability risks across development stages (Müller et al., 2000). Sterility is also non-trivial: terminal sterilization (heat, irradiation) may perturb lipid matrices, while sterile filtration can be challenged by nanoparticle size, filter fouling, and adsorption losses (Mehnert and Mäder, 2001). These issues are increasingly recognized across lipid-based nanomedicines and should be explicitly considered early for SLN-mRNA CMC plans (aseptic processing strategy, validated hold times, container/closure interactions) (Schwarz et al., 1994).
Repeat-dose tolerability and immunological liabilities (especially surface chemistries): Chronic or repeat-dose therapeutic use places higher emphasis on innate immune activation, complement activation, and accelerated blood clearance phenomena (Mehnert and Mäder, 2001). PEGylation can stabilize dispersions and prolong circulation, but PEG is also linked to anti-PEG antibodies, complement activation, and hypersensitivity signals in lipid nanoparticle settingsri sks that may be amplified under repeated exposure (Schwarz et al., 1994). For SLN-mRNA (which is often positioned for chronic indications), the immunology of both the surface polymer and any cationic/ionizable lipids used to bind mRNA becomes a primary “open question,” and may motivate alternative stealth coatings (or dosing regimens) in later-stage development (Gómez-Aguado et al., 2020).
Bottom line for the “Challenges and Open Questions” section. SLNs/NLCs represent a credible “adjacent” platform to LNPs with potential advantages in physical stability and manufacturing familiarity, and recent ionizable-lipid-enabled SLN designs strengthen the case for therapeutic (non-vaccine) use. Yet, the platform remains gated by (1) true high-capacity mRNA loading, (2) control of polymorphism-driven instability and release variability, (3) sterile GMP manufacture without damaging the lipid matrix or RNA, and (4) repeat-dose tolerability under clinically relevant dosing schedules (Schwarz et al., 1994; Gómez-Aguado et al., 2020; Joshi et al., 2025; Tricco et al., 2018).
Discussion
Programmable mRNA cargoes combined with nanoparticle delivery have demonstrated scalability and acceptable safety in population-scale vaccination, and therapeutic development is extending to individualised cancer vaccination, antigen-specific immune tolerance, and transient protein replacement without genomic integration (Fei et al., 2024; Wang X. et al., 2025; Wang Y. et al., 2025; Yu et al., 2025). Across the included evidence, preclinical support is substantial, early clinical evidence is emerging most clearly in oncology and cystic fibrosis while late-stage therapeutic trials remain limited. Statements regarding overall evidence levels should be interpreted in the context of the small number of included studies and the heterogeneity of endpoints.
Biodistribution remains constrained by hepatic sequestration for many LNP designs, despite progress in lipid chemistry, ligand decoration, route optimisation, and strategies intended to modulate corona formation and cellular uptake (Asthana et al., 2025). Endosomal escape remains a major barrier, and reported cytosolic release efficiencies are typically low, motivating rational lipid design and modulation of membrane phase behaviour (Prazeres et al., 2025). Safety and immunogenicity considerations are central for therapeutic, repeat-dose applications. Claims regarding post-vaccine myocarditis and PEG-related hypersensitivity should be supported by appropriate clinical safety literature; such evidence is not clearly represented within the current reference set and therefore requires careful citation alignment.
Access and stability remain practical constraints. Lyophilised or solid formulations and control of lipid impurities may improve long-term stability and reduce cold-chain dependence, but reproducible manufacturing depends on robust characterisation and reporting of critical quality attributes and performance metrics (Mrksich et al., 2024). The field is also adopting data-driven formulation and process optimisation (including microfluidic production and computational design), and near-term milestones include phase-3 neoantigen programmes and broader exploration of organ-selective delivery for lung and liver disease (Simonsen and Larsson, 2025).
For clinicians, key implications include awareness of emerging adjuvant melanoma mRNA programmes and the expansion of early trials in cystic fibrosis and metabolic disorders, coupled with careful monitoring for immune-mediated adverse events in settings where repeat dosing is required. For researchers and developers, priorities include organ-selective and biodegradable lipid systems, standardised assays for endosomal escape linked to functional expression, transparent PK/PD reporting, and stability-focused formulations compatible with low-resource settings under quality-by-design control (Gomi et al., 2023; Weber et al., 2024; Floudas et al., 2025; Krienke et al., 2021; Geller et al., 2024; Richard et al., 2024; Chai et al., 2025; Sayed et al., 2025).
Conclusion
Nanoparticle-mediated mRNA therapy is progressing beyond infectious-disease vaccines into oncology, autoimmunity, and genetic medicine. Platform maturation including biodegradable and organ-selective lipids, saRNA/circRNA modalities, and stability-oriented formulations addresses longstanding delivery and storage constraints. To support durable therapeutic impact, the field now requires disease-specific trials, standardised reporting of biodistribution and endosomal escape, and regulatory pathways aligned with chronic use and repeat dosing. Achieving these objectives would strengthen the evidence base for mRNA-nanoparticle therapeutics across precision immunotherapy and molecular medicine.
Table 5 collates representative, high-signal examples (2020–2025) showing how nanoparticle-enabled mRNA has moved beyond infectious-disease vaccines into (i) clinically anchored oncology, (ii) mechanistically compelling immune tolerance, and (iii) organ/CMC innovations that expand feasible targets, dosing strategies, and global deployability.
| Year | Indication | Platform/Cargo | Model/Phase | Key finding | Source |
|---|---|---|---|---|---|
| 2023–2024 | Melanoma (adjuvant) | LNP-mRNA individualised neoantigen vaccine (mRNA-4157/V940) + pembrolizumab | Phase 2b | ∼49% lower risk of recurrence or death vs. pembrolizumab alone; improved DMFS | ,, [Pastre et al. (2025)] [Alshehry et al. (2025)] [Yang et al. (2025)] |
| 2021 | Autoimmune neuroinflammation | Tolerogenic LNP-mRNA encoding myelin antigens | EAE (mouse) | Antigen-specific tolerance without systemic immunosuppression | ,, [Yang et al. (2025)] [Zwolsman et al. (2025)] [Li et al. (2025)] |
| 2024–2025 | Cystic fibrosis | Inhaled LNP-CFTR mRNA (ARCT-032) | Phase 1 → Phase 2 | Acceptable safety/tolerability; phase-2 evaluation ongoing | ,, [Mrksich et al. (2024)] [Ge et al. (2025)] [Lee et al. (2025)] |
| 2023 | Extrahepatic targeting (lung) | Charged-helper-lipid LNPs | Multi-cell lung models | Altered tropism and transcriptional response enabling lung delivery | ,, [Alasmari et al. (2025)] [Gomi et al. (2023)] [Weber et al. (2024)] |
| 2024–2025 | Endosomal escape | LNP design/raft engineering | Reviews/mechanistic | Endosomal escape remains limiting; strategies aim to improve cytosolic release | ,, [Prazeres et al. (2025)] [Shahsavandi et al. (2024)] [Li et al. (2025)] |
| 2024–2025 | Stability | Lyophilised/solid mRNA-LNPs; impurity-controlled lipids | Formulation studies | Extended stability towards room temperature | ,, [Gomi et al. (2023)] [Krienke et al. (2021)] [Geller et al. (2024)] |
| 2023–2025 | Biodegradable lipids | Disulphide/ester-linked ionisable lipids | Libraries/preclinical | Faster clearance with maintained activity | ,, [Weber et al. (2024)] [Geller et al. (2024)] [Richard et al. (2024)] |