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    • Transdermal HA-Lipid Nanoparticle Delivery of PTEN mRNA in M

    2026-06-02

    Transdermal HA-Lipid Nanoparticle Delivery of PTEN mRNA in Melanoma

    Study Background and Research Question

    Melanoma represents one of the most aggressive forms of skin cancer, often characterized by high metastatic risk and poor response to conventional therapies when diagnosed at advanced stages. Immune checkpoint inhibitors (ICIs) have improved outcomes for many patients, yet a significant proportion experience resistance, partially attributable to loss or mutation of the phosphatase and tensin homolog (PTEN) tumor suppressor gene. PTEN plays a pivotal role in regulating the PI3K/Akt signaling pathway, acting as a brake on cell proliferation and survival. Loss of PTEN is linked to unchecked tumor growth, reduced apoptosis, immune evasion, and poor infiltration of cytotoxic T cells, thereby promoting resistance to ICIs and facilitating tumor progression. The central research question of the study by Kim et al. (Journal of Controlled Release) is whether a novel, non-viral, transdermal delivery system can efficiently restore PTEN expression in melanoma, thereby reactivating antitumor immune responses and enhancing therapeutic outcomes.

    Key Innovation from the Reference Study

    The reference study introduces hyaluronate-conjugated lipid nanoparticles (HA-LNPs) as a platform for transdermal delivery of PTEN mRNA. Unlike traditional lipid nanoparticles that rely on PEGylation to confer stability and colloidal uniformity, the HA-LNPs in this work utilize a hyaluronate-dimyristoyl glycerol (HA-DMG) conjugate. This design replaces PEG with HA, a biocompatible glycosaminoglycan, providing several advantages:

    • Stable HA Integration: HA-DMG directly incorporates into the LNP bilayer during self-assembly, ensuring uniform HA display on the nanoparticle surface and eliminating the need for post-formulation surface modifications.
    • Enhanced Biocompatibility: By avoiding PEG, the risk of immunogenicity and anaphylactic reactions is reduced, which is particularly relevant for repeated or topical administration.
    • CD44-Mediated Targeting: HA on the nanoparticle surface enables selective binding to CD44, a receptor highly expressed on melanoma cells and skin-resident antigen-presenting cells, thus promoting both tumor cell targeting and immune system engagement.
    • Optimized Skin Penetration: The HA moiety facilitates skin penetration through receptor-mediated uptake and hydration effects, overcoming a key barrier in transdermal delivery.

    This combination of features positions HA-LNPs as a versatile and clinically relevant vehicle for localized, mRNA-based cancer immunotherapy.

    Methods and Experimental Design Insights

    To realize targeted restoration of tumor suppressor function, the authors synthesized PTEN mRNA and encapsulated it within HA-LNPs using ethanol injection and microfluidic mixing. The resulting nanoparticles were characterized for size, surface charge (zeta potential), and encapsulation efficiency. Key methodological highlights include:

    • HA-DMG Synthesis: HA was covalently linked to dimyristoyl glycerol, generating an amphiphilic molecule capable of self-assembly with other lipid components.
    • Nanoparticle Characterization: Dynamic light scattering and electron microscopy revealed nanoscale particle uniformity and efficient HA surface coverage.
    • CD44 Targeting Validation: Flow cytometry and confocal microscopy confirmed enhanced uptake of HA-LNPs by CD44-positive melanoma cells compared to PEG-LNP controls.
    • In Vitro Transfection: Melanoma cell lines were treated with PTEN mRNA-loaded HA-LNPs, and restoration of PTEN protein expression was assessed by Western blot and immunofluorescence.
    • Functional Assays: Induction of immunogenic cell death (ICD) and reduction in cell viability were quantified, providing evidence of restored tumor suppressor activity.
    • In Vivo Application: A topical application protocol was employed in melanoma-bearing mouse models, evaluating skin penetration, tumor uptake, immune activation (by flow cytometry of tumor-infiltrating lymphocytes), and antitumor efficacy.

    Protocol Parameters

    • HA-LNP formulation: Incorporate HA-DMG during initial lipid mixing to ensure uniform HA surface display.
    • mRNA encapsulation: Use microfluidic mixing at controlled flow rates to maximize encapsulation efficiency and maintain mRNA integrity.
    • Topical application: Apply HA-LNPs to shaved skin directly above the tumor site; optimize contact time for maximal penetration (e.g., 1–2 hours under occlusion).
    • In vitro transfection: Incubate melanoma cells with PTEN mRNA@HA-LNP for 4–6 hours before replacing media; monitor PTEN expression 24–48 hours post-transfection.
    • Immune activation assessment: Harvest tumors and draining lymph nodes 2–5 days post-treatment to assess T cell infiltration and activation.

    Core Findings and Why They Matter

    The study demonstrates that HA-LNPs deliver PTEN mRNA efficiently across the skin barrier, restoring PTEN expression in melanoma cells both in vitro and in vivo. Key findings include:

    • Efficient Transdermal Delivery: HA-LNPs penetrate deep skin layers and accumulate in tumor tissue after topical application, outperforming PEG-LNPs.
    • Restoration of Tumor Suppressor Function: Delivered PTEN mRNA is robustly translated, resulting in increased PTEN protein levels and suppression of the PI3K/Akt signaling pathway, as shown by reduced phosphorylation of downstream effectors.
    • Induction of Immunogenic Cell Death: Treated melanoma cells exhibit hallmarks of ICD, including surface calreticulin exposure and HMGB1 release, which are signals for immune activation.
    • Enhanced Antitumor Immunity: In vivo, topical HA-LNP-mediated PTEN mRNA delivery leads to increased infiltration of CD8+ T cells and dendritic cells in the tumor microenvironment, promoting immune-mediated tumor clearance.
    • Significant Tumor Growth Inhibition: Mice receiving transdermal PTEN mRNA@HA-LNP therapy exhibit reduced tumor burden and improved survival compared to controls, with minimal systemic toxicity (reference study).

    Together, these results validate the premise that restoring PTEN function via transdermal mRNA delivery can sensitize melanoma to immune attack and suppress tumor growth, addressing a critical barrier in current cancer immunotherapy.

    Comparison with Existing Internal Articles

    This reference study advances the field beyond prior reports by integrating HA-mediated targeting and transdermal delivery. Related internal articles provide complementary insights:

    Compared to these articles, the reference study uniquely demonstrates the preclinical feasibility and therapeutic impact of combining HA-mediated targeting with non-viral, localized mRNA delivery in vivo.

    Limitations and Transferability

    While the findings are promising, several limitations should be noted:

    • Species Differences: Preclinical data are based on murine models; human skin structure and immune responses may differ.
    • Tumor Model Specificity: The therapeutic benefit is demonstrated in melanoma; generalizability to other CD44-expressing solid tumors requires further validation.
    • Delivery System Scalability: Large-scale manufacturing and standardization of HA-LNPs for clinical use remain to be addressed.
    • Long-Term Safety: Although minimal toxicity was observed in short-term studies, chronic or repeated topical application effects need assessment.

    The study provides a strong proof-of-concept for transdermal mRNA-based gene therapy in localized cancer settings but highlights the need for additional studies to support clinical translation and broader application.

    Research Support Resources

    For researchers interested in replicating or extending these findings, high-quality tumor suppressor gene mRNA reagents are critical. EZ Cap™ Human PTEN mRNA (SKU R1025) from APExBIO is a rigorously characterized, Cap 1-modified mRNA with poly(A) tail, optimized for enhanced stability and translational efficiency. This reagent can be readily incorporated into HA-LNP-based or other non-viral delivery platforms to support workflows in cancer research, gene therapy research, and studies on the PI3K/Akt signaling pathway. For detailed protocol recommendations and troubleshooting strategies related to mRNA transfection and expression, refer to the aforementioned internal articles and the product information provided by APExBIO.