Infrared Photobiomodulation Modulates PpIX Production After Topical Methyl Aminolevulinate in Normal Human Skin: An
Letícia Palombo Martinelli1, Natasha Ferreira Mezzacappo1, Ana Paula Silva2
1São Carlos Institute of Physics, University of São Paulo, São Carlos, Brazil.
Journal of Biophotonics
|March 27, 2026
Summary
Photobiomodulation (PBM) may influence photosensitizer accumulation for photodynamic therapy (PDT). This study found PBM showed a trend but high variability in protoporphyrin IX (PpIX) levels in human skin.
Area of Science:
- Dermatology
- Photomedicine
- Biophysics
Background:
- Optimizing photosensitizer accumulation is crucial for effective photodynamic therapy (PDT) in treating skin lesions.
- Protoporphyrin IX (PpIX) synthesis is intrinsically linked to mitochondrial activity, suggesting a potential role for photobiomodulation (PBM) in its regulation.
Purpose of the Study:
- To investigate the effects of photobiomodulation (PBM) at specific wavelengths (780 nm or 808 nm) on the accumulation of methyl aminolevulinate (MAL)-induced protoporphyrin IX (PpIX) in normal human skin.
- To assess the influence of varying PBM fluences (5, 10, 15 J/cm²) on PpIX levels.
Main Methods:
- An exploratory study involving eleven healthy volunteers.
- Paired-arm treatments were administered, with MAL incubation followed by PBM application.
- PpIX levels were quantified using spectroscopy and widefield imaging after a total incubation period of 210 minutes.
Main Results:
- While mean ratios of PpIX with PBM versus without PBM were nominally greater than 1, no statistically significant differences were observed across different fluences or compared to a baseline of no PBM.
- High interindividual variability, with coefficients of variation up to 35%, was identified as a primary factor limiting statistical significance.
Conclusions:
- Photobiomodulation (PBM) demonstrates a potential trend towards modulating photosensitizer (PpIX) accumulation in human skin.
- The significant interindividual variability observed suggests that a personalized approach to PBM-assisted photodynamic therapy (PDT) is necessary to optimize clinical outcomes.
- Further research is warranted to explore tailored PBM protocols to manage biological heterogeneity and enhance PDT efficacy.
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