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Updated: Jun 28, 2026
An In-House-Built and Light-Emitting-Diode-Based Photodynamic Therapy Device for Enhancing Verteporfin Cytotoxicity in a 2D Cell Culture Model
Published on: January 13, 2023
Molecular effects of photodynamic therapy for photoaging
Jeffrey S Orringer1, Craig Hammerberg, Ted Hamilton
1Department of Dermatology, University of Michigan Medical School, 1500 E Medical Center Dr, 1910 Taubman Center, Ann Arbor, MI 48109-0314, USA. jorringe@umich.edu
Objective:
To quantitatively examine the epidermal and dermal cellular and molecular changes that occur after photodynamic therapy of photodamaged human skin.
Design:
Serial in vivo biochemical and immunohistochemical analyses after photodynamic therapy using topical 5-aminolevulinic acid (5-ALA) and pulsed-dye laser treatment.
Setting:
Academic referral center, Department of Dermatology, University of Michigan, Ann Arbor.
Patients:
A volunteer sample of 25 adults, 54 to 83 years old, with clinically apparent photodamage of the forearm skin.
Interventions:
Three-hour application of 5-ALA followed by pulsed-dye laser therapy using non-purpura-inducing settings to focal areas of photodamaged forearms and serial biopsy specimens taken at baseline and various times after treatment.
Main Outcome Measures:
Immunohistochemical analysis was used to assess levels of markers of epidermal proliferation (Ki67), epidermal injury (cytokeratin 16), and photodamage (p53), as well as various markers of dermal collagen production (including prolyl 4-hydroxylase and heat shock protein 47, and type I procollagen). Real-time reverse transcriptase-polymerase chain reaction technology was used to quantify type I and type III collagen. Type I procollagen protein was quantified with enzyme-linked immunosorbent assay.
Results:
Epidermal proliferation was stimulated as demonstrated by increases in Ki67 (more than a 5-fold increase; P < .05) and epidermal thickness (more than a 1.4-fold increase; P < .05). Epidermal injury was produced with increased cytokeratin 16 levels demonstrated (to nearly 70-fold of baseline levels; P < .05). Upregulation of collagen production was demonstrated with increases in procollagen I messenger RNA (2.65-fold; P < .05), procollagen III messenger RNA (3.32-fold; P < .05), and procollagen I protein (2.42-fold; P < .05) levels detected. The baseline epidermal p53 level correlated with cytokeratin 16 levels at acute time points, and the latter were found to correlate with peak collagen production.
Conclusions:
Photodynamic therapy with the specific treatment regimen employed produces statistically significant quantitative cutaneous molecular changes (eg, production of types I and III collagen) that are associated with improved appearance of the skin. Baseline epidermal p53 immunostaining levels may be predictive of dermal responses to this therapy. Comparison with historical data using pulsed-dye laser therapy alone suggests that use of the photosensitizer may enhance dermal remodeling. The quantitative in vivo molecular data presented herein are in keeping with an evolving model to potentially predict the efficacy of new techniques for the treatment of photoaging.
Insights
Photodynamic therapy with 5-aminolevulinic acid (5-ALA) and pulsed-dye laser significantly increases collagen production and epidermal thickness in photodamaged skin. This treatment promotes skin repair and may improve appearance, with p53 levels potentially predicting outcomes.
Area of Science:
- Dermatology
- Molecular Biology
- Aesthetic Medicine
Background:
- Photodamaged skin exhibits cellular and molecular alterations.
- Photodynamic therapy (PDT) is a potential treatment for skin aging.
Purpose of the Study:
- Quantitatively assess epidermal and dermal changes after PDT in photodamaged human skin.
- Evaluate molecular markers of skin repair and collagen production post-treatment.
Main Methods:
- Serial in vivo biochemical and immunohistochemical analyses were performed.
- 25 adults with photodamaged skin received topical 5-aminolevulinic acid (5-ALA) followed by pulsed-dye laser therapy.
- Biopsy specimens were analyzed for proliferation (Ki67), injury (cytokeratin 16), photodamage (p53), and collagen markers (prolyl 4-hydroxylase, HSP47, type I procollagen).
- Real-time RT-PCR and ELISA quantified collagen types I and III mRNA and protein.
Main Results:
- PDT significantly increased epidermal proliferation (Ki67, thickness) and injury (cytokeratin 16).
- Collagen production was upregulated, with significant increases in type I and III procollagen mRNA and type I procollagen protein.
- Baseline p53 levels correlated with acute cytokeratin 16 levels, which in turn correlated with peak collagen production.
Conclusions:
- PDT with 5-ALA and pulsed-dye laser induces significant molecular changes, including collagen synthesis, associated with improved skin appearance.
- Baseline epidermal p53 levels may predict dermal response to PDT.
- PDT may enhance dermal remodeling compared to laser therapy alone, supporting its use in photoaging treatment.
