To evaluate the effect of diammonium glycyrrhizinate extracted from the Chinese traditional medicine licorice root on the growth of human hair follicles cultured in vitro, and to detect the expression of wnt/β-catenin signaling pathway-related molecules.

Isolated hair follicles were cultured with diammonium glycyrrhizinate at different concentrations of 0.1, 0.01, 0.001 and 0.000 1 μmol/L for 10 days, and the hair follicles cultured in Williams′ E medium without diammonium glycyrrhizinate served as a control group. The length of hair follicles was measured under a microscope every day, the morphologic changes of hair follicles were observed, and photos were taken. Immunofluorescence assay was performed to assess the proliferation of hair matrix cells, as well as to determine the expression of β-catenin, glycogen synthase kinase 3β (GSK3β) , phosphorylated GSK3β (p-GSK3β) and lymphoid enhancer factor-1 (Lef1) in the Wnt/β-catenin signaling pathway. Statistical analysis was carried out by repeated-measures analysis of variance and one-way analysis of variance.

As repeated-measures analysis of variance showed, only 0.01 μmol/L diammonium glycyrrhetate showed significantly promotive effect on the growth of hair follicles compared with the medium alone ( P < 0.05) , and there were no significant differences in the length of hair follicles between the other concen-tration groups and the control group. Compared with the control group, the transition to the catagen phase of human hair cycle was delayed in the 0.01-μmol/L diammonium glycyrrhetate group, while it did not change in the other diammonium glycyrrhetate groups and control group. Immunofluorescence assay showed that the number of ki67-positive hair matrix cells was obviously increased in the 0.1-, 0.01-, 0.001-μmol/L diammonium glycyrrhizinate groups compared with the control group, while there was no difference between the 0.000 1-μmol/L diammonium glycyrrhizinate group and the control group. One-way analysis of variance revealed that the expression of β-catenin, p-GSK3β and Lef1 significantly differed among all the groups ( F=12.604, 16.65, 15.266 respectively, P < 0.05) , while no significant difference in the expression of GSK3β was found among these groups ( F=1.472, P > 0.05) . Least significant difference (LSD) - t test revealed that the expre-ssion of β-catenin, p-GSK3β and Lef1 in the hair matrix cells was significantly higher in the 0.1-, 0.01-, 0.001-μmol/L diammonium glycyrrhizinate groups than in the control group (all P < 0.05) , but there was no significant difference between the 0.000 1-μmol/L diammonium glycyrrhizinate group and the control group ( P > 0.05) .

Diammonium glycyrrhetate at the concentration of 0.01 μmol/L shows markedly promotive effect on the in vitro growth of hair follicles, and can increase the proliferative activity of hair matrix cells and delay the transition to the catagen phase, which may be associated with the activation of Wnt/β-catenin signaling pathway.

Hair follicle; Organ culture techniques; Wnt signaling pathway; Fluoroimmunoassay; Diammonium glycyrrhizinate