ALA-PDT exerts beneficial effects on chronic venous ulcers by inducing changes in inflammatory microenvironment, especially through increased TGF-beta release: A pilot clinical and translational study

A cohort of 19 patients affected by chronic venous ulcers was recruited from our centre. A 4-mm punch biopsy from wound bed was taken before application of ALA 20% gel and repeated one hour after the first PDT irradiation. We observed a significant and progressive reduction of wounds mean volumes right after three ALA-PDT sessions (once per week; 4479.9 +/− 345.5 mm3 vs 34599 +/− 190.3 mm3, p < .01). On immunofluorescence staining from biopsy specimens, we observed a change in all tested stains of post treatment specimens compared to pre-treatment ones. An increase of plasmacytoid dendritic cells (from 699 +/− 22 cells/0.018 mm2 to 1369 +/− 27 cells/0.018 mm2, p < .0001); MHC-II expression (260.39 +/− 99.7 Red, Green, Blue [RGB 0-255] to 370.2 +/− 162.6 RGB (0-255), p < .01), TNF-alpha positive mast cells expression (49 +/− 0.3 cells/0.018 mm2 to 69 +/− 0.4 cells/0.018 mm2, p < .001), TGF-beta expression (59.89 +/− 23.2 RGB (0-255)/cell vs 137.39 +/− 56.6 RGB (0-255)/cell, p < .01) and CD4+/CD25+ Treg cells (39 +/− 1 cells/0.018 mm2 vs 209 +/− 10 cells/0.018 mm2, p < .001) was observed. An increase of TGF-beta was correlated in a statistical significant manner with a reduction of wounds' mean volumes.