Can red-light 5-aminolevulinic photodynamic therapy cure port wine stains on comb animal model?

•Topical and systemic ALA was firstly used to study the curative effect of ALA-PDT to PWS on comb animal model.•There is no curative effect of the topical red-light ALA-PDT on comb dermal capillaries.•Systemic ALA-PDT could damage the dermal blood vessels, but it also has severe effect on the epidermis and other non-targeted parts.•Either topical or systemic red-light ALA-PDT is not suitable treatment methods for PWS. To study the curative effect of red-light 5-Aminolevulinic photodynamic therapy(ALA-PDT) to port wine stains(PWS) on comb animal model. 160 male cocks were randomly divided into 16 groups. The ALA only group was given ALA only topical or systemic application. Light only groups were only given 630 nm red light irradiation with different light density. ALA-PDT groups were given red light after the application of topical or systemic ALA. PDL group was given PDL irradiation. The distribution of fluorescence in tissue after topical or systemic application of ALA was detected. The morphological changes, the pathological changes and the capillary reduction rate of the comb were observed after treatment for 0, 1, 3, 5, 7, 14 days. The PpIX fluorescence generated after topical and systemic application of ALA. In the topical ALA-PDT group at low light density 80 J/cm2, the morphology and the histopathology had no obvious change. While under 160 J/cm2 and 200 J/cm2 light density, severe erosion and thick scab appeared. The histopathology showed epidermal necrosis and loss. The immunohistochemistry showed that there was no significant change in the number of capillaries under different light density (P > 0.05). In the systemic ALA-PDT group under low light density 80 J/cm2, only partial erosion and thin scab was observed on the treatment side. With the increase of light density, thick charred crust and even scar was observed. The histopathology showed that there were different degrees of damage to dermal and epidermal tissues. And the immunohistochemistry showed the capillary reduced significantly in the treatment side (P