# Synergistic Enhancement of Non-viral SIRT1 Gene Delivery to Human Skin Equivalents Using Microneedling and Liposomal Vectors

## TL;DR

This study shows that combining microneedling and liposomal vectors can greatly enhance the delivery of the SIRT1 gene to human skin, potentially improving anti-aging treatments.

## Contribution

The study introduces a novel combination of microneedling and liposomal vectors for efficient non-viral SIRT1 gene delivery to human skin equivalents.

## Key findings

- Liposomal plasmid delivery with microneedling increased SIRT1 mRNA expression by ~357-fold.
- Topical naked plasmid application achieved a ~70-fold increase in SIRT1 expression without invasion.
- Non-invasive plasmid delivery outperformed other methods like liposomal topical application.

## Abstract

Introduction: The "longevity gene" sirtuin 1 (SIRT1) is a critical regulator of oxidative stress and cellular senescence, making it a high-value target for anti-aging dermatological interventions. However, the stratum corneum poses a formidable barrier to the transdermal delivery of therapeutic genes. This study systematically evaluated the efficacy of non-viral SIRT1 plasmid delivery to a full-thickness 3D human skin equivalent (T-Skin™) using distinct vector formulations and physical enhancement methods.

Materials and methods: We compared the delivery efficiency of naked plasmid DNA and a cationic liposomal formulation using two delivery methods: (1) simple topical application and (2) automated microneedling (Dermapen, 0.2 mm diameter). SIRT1 expression was quantified 24 hours post-delivery using quantitative reverse transcription polymerase chain reaction (RT-qPCR) and validated by immunohistochemistry (IHC).

Results: The results demonstrated a pronounced synergistic effect: the combination of a liposomal plasmid with Dermapen (Lipo-Dermapen) yielded the highest efficiency, with a ~357-fold increase in SIRT1 mRNA expression compared with the control. Notably, the second-highest efficiency was achieved by the simple, non-invasive, and topical application of naked plasmids (Plasmid-Direct), which achieved a remarkable ~70-fold increase in expression. This non-invasive approach unexpectedly outperformed other delivery groups, including liposomal topical application (Lipo-Direct, ~27-fold) and naked plasmid with Dermapen (Plasmid-Dermapen, ~10-fold).

Conclusions: The Lipo-Dermapen platform provides robust proof of concept for the development of high-efficacy, minimally invasive clinical gene therapies. Furthermore, the unexpected efficacy of non-invasive naked plasmid delivery suggests a novel potential for accessible, self-administered dermatological interventions.