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Published on: July 30, 2018
Inhibition of Smad3 expression in radiation-induced fibrosis using a novel method for topical transcutaneous gene
Judy W Lee1, John P Tutela, Richard A Zoumalan
1Department of Otolaryngology-Neck Surgery, New York University School of Medicine, 550 First Ave, NBV 5E5, New York, NY 10016, USA. judy.lee@nyumc.org
Objective:
To attempt to mitigate the effects of irradiation on murine skin after high-dose radiation using a novel transcutaneous topical delivery system to locally inhibit gene expression with small interfering RNA (siRNA) against Smad3.
Design:
Laboratory investigation.
Setting:
University laboratory.
Subjects:
Twenty-five wild-type C57 mice.
Intervention:
In an isolated skin irradiation model, the dorsal skin of C57 wild-type mice was irradiated (45 Gy). Just before irradiation, Smad3 and nonsense siRNA were applied to 2 separate dorsal skin areas and then reapplied weekly. Skin was harvested after 1 and 4 weeks. Smad3 expression were assessed by immunohistochemistry, and collagen deposition and architecture was examined using picrosirius red collagen staining.
Main Outcome Measures:
Epidermal thickness was measured semiquantitatively at 4 weeks. Radiation-induced fibrosis was measured quantitatively via tensiometry. The Young modulus, a measure of cutaneous rigidity inversely related to elasticity, was determined, with normal irradiated skin serving as a control specimen.
Results:
Murine skin treated with topical Smad3 siRNA demonstrated effective Smad3 inhibition at 1 week and persistent suppression at 4 weeks. Collagen deposition and epidermal thickness were significantly decreased in skin treated with Smad3 siRNA compared with control irradiated skin. Tensiometry demonstrated decreased tension in Smad3 siRNA-treated skin, with a Young modulus of 9.29 MPa (nonirradiated normal skin, 7.78 MPa) compared with nonsense (control) siRNA-treated skin (14.68 MPa).
Conclusions:
Smad3 expression can be effectively silenced in vivo using a novel topical delivery system. Moreover, cutaneous Smad3 inhibition mitigates radiation-induced changes in tissue elasticity, restoring a near-normal phenotype.
Insights
Topical small interfering RNA (siRNA) against Smad3 effectively reduced radiation-induced skin fibrosis and restored elasticity in mice. This novel delivery system offers a promising approach for mitigating radiation damage.
Area of Science:
- Dermatology
- Molecular Biology
- Biotechnology
Background:
- High-dose irradiation causes significant skin damage, including fibrosis and altered elasticity.
- Current treatments for radiation-induced skin damage are limited.
- Smad3 signaling pathway plays a crucial role in fibrosis development.
Purpose of the Study:
- To evaluate the efficacy of a novel topical delivery system for small interfering RNA (siRNA) targeting Smad3.
- To mitigate radiation-induced effects on murine skin.
- To assess the impact of Smad3 inhibition on skin elasticity and collagen deposition.
Main Methods:
- A laboratory investigation using a murine skin irradiation model.
- Irradiated dorsal skin received topical application of Smad3 siRNA or nonsense siRNA.
- Assessed Smad3 expression, collagen deposition, epidermal thickness, and tissue elasticity (Young modulus) at 1 and 4 weeks post-irradiation.
Main Results:
- Topical Smad3 siRNA effectively inhibited Smad3 expression in murine skin.
- Significantly reduced collagen deposition and epidermal thickness in Smad3 siRNA-treated skin compared to controls.
- Smad3 inhibition improved tissue elasticity, with a Young modulus closer to normal skin.
Conclusions:
- Novel topical delivery of Smad3 siRNA effectively silences gene expression in vivo.
- Cutaneous Smad3 inhibition mitigates radiation-induced changes in tissue elasticity and fibrosis.
- This approach shows potential for restoring a near-normal skin phenotype after radiation exposure.
