OBJECTIVETo investigate the effect of 8-aminolevulinic acid (ALA) photodynamic therapy (PDT) on the cell proliferation, apoptosis and collagen secretion in keloid fibroblasts and to provide the theoretical base for ALA-PDT treatment of keloids.

METHODSFibroblasts from keloid patients were cultured to the third generation in vitro and incubated in 0, 1, 3, 6, 9 mmol/L of δ-aminolevulinic acid for 3 h in the darkness. Then they were exposed to 635 nm wavelength red light ( 30 J/cm2 ) and continued incubation 24 h after irradiation. CCK-8 assay was used to detect proliferation inhibition rate of fibroblasts. The content of hydroxyproline was measured by colorimetric method. The expression of p-Akt and programmed cell death 4 ( PDCD4) were detected by Western blot.

RESULTSThe inhibition rate of keloid fibroblasts were respectively 0, (8.30 ± 1.01)%, (29.48 ± 3.27)%, (52.01 ± 5.34)%, (79.99 ± 5.85)% with the presence of difference concentrations (0, 1, 3, 6, 9 mmol/L) of ALA. The content of hydroxyproline were respectively (9.540 0 ± 0.352 42), (6.242 5 ± 0.224 85 ), (5.107 5 ± 0.534 88), (3.490 0 ± 0.623 48), (2.945 0 ± 0.514 10) μg/mg. The relative expression of p-Akt were respectively 1, 0.75 ± 0.12, 0.52 ± 0.14, 0.41 ± 0.18, 0.32 ± 0.09. The relative expression of PDCD4 were respectively 1, 1.18 ± 0.19, 1.51 ± 0.22, 0.15 ± 0.30, 2.44 ± 0.22. The difference was statistically significant when compared the group of 1, 3, 6, 9 mmol/L with 0 mmol/L (P < 0.05).

CONCLUSIONSIn concentration within the range of 1-9 mmol/L, ALA could inhibit the proliferation of fibroblasts significantly, promote fibroblasts apoptosis and reduce the content of hydroxyproline in a dose-dependent manner, indicating that 8-aminolevulinic acid photodynamic therapy may be a potential treatment for keloid.