Evaluation of the effectiveness and safety of photodynamic skin therapy

BACKGROUND: Photodynamic therapy is an innovative technique for non-invasive skin rejuvenation by stimulating neocollagenogenesis.

AIMS: The aim of our study was to assess the safety and efficacy of photodynamic therapy on the skin using a wavelength of 660 nm, as a photosensitizer (PS) – Spherometallochlorin™.

MATERIALS AND METHODS: The study was divided into 2 stages. The first stage of the study involved 5 female laboratory rats. The first stage was divided into 2 substages: 1A – the oral mucosa of 5 rats were irradiated for 30 minutes with 5 wavelengths of 660 nm (energy 100 J/cm², power 100 mW/cm²). 1B – FS Spherometallochlorin™ was applied to the skin of the back of rats after preliminary shaving in the form of 0.4% gel. Before applying the topical agent, after 15 minutes of exposure, after 30 minutes of exposure, after 45 minutes of exposure, in order to assess the penetration of the PS, a punch biopsy was taken in the area of application of the gel. The second stage of the study involved 15 female volunteers aged 21 to 65 years. At stage 2A, the skin behind the ear of 5 women was irradiated for 30 minutes at a wavelength of 660 nm (energy 100 J/cm², power 100 mW/cm²) using a PS 0.4% gel containing Spherometallochlorin™. Stage 2B evaluated the effectiveness of the effect of PDT procedures on the skin of 15 women. Skin condition was assessed using cutometry, corneometry, measurement of transepidermal water loss, and punch biopsy samples of the parotid skin (before and after the course of procedures), photographing and assessment of unwanted effects were also carried out.

RESULTS: The histological picture before and after the study was similar. The preparation usually contained small fragments of the oral mucosa. The superficial squamous non-keratinizing epithelium was of normal morphology. On the surface of some fragments, hemorrhages (artifact of material sampling) were present. No inflammation, edema or hyperemia was observed in the underlying mucosa. Thus, no signs of inflammation or burns were found.

CONCLUSION: The used radiation with a wavelength of 660 nm is completely safe, does not cause pathological changes in the skin. The course of PDT procedures is a safe, effective method causing remodeling of the dermis. PDT using 660 nm radiation and Spherometallochlorin™ as a PS can be recommended for use in practical health care.