Single Cell Transcriptome Profiling reveals Cutaneous Immune Microenvironment Remodeling by Photodynamic Therapy in Photoaged Skin

Two volunteers were recruited (2 females, 54 and 56 years old, Fitzpatrick skin type III or IV) who demonstrated photoaging phenotype on extensor side of forearms and the back of hands according to the Glogau scale. After informed consent, 20 percent ALA cream with a thickness of 1 mm was applied to the skin of left forearm extensor and the back of left hand. And after 30 min of incubation, the ALA-applied area was irradiated by a red LED light (630 nm, 144 J cm-2, 40 mW cm-2, Philips, Netherlands) for 1 h. The identical 5-aminolevulinic acid photodynamic therapy (ALA-PDT) was performed every two weeks for a total of 5 times. The skin samples (3 mm x 3 mm) on the extensor skin of two subjects left forearm were taken for scRNA-seq after final ALA-PDT.