Lagerstroemia indica extract regulates human hair dermal papilla cell growth and degeneration via modulation of β-catenin, Stat6, and TGF-β signaling pathway.

Background: Lagerstroemia indica (L. indica) is reported to have diverse biological activities including anti-inflammatory, anti-cancer, neuro-regulatory, antidiabetic, and antioxidant activity.

Aims: The purpose of this study is to examine the potential of hair growth promotion and/or hair loss prevention by L. indica extract.

Patients/methods: The effects of L. indica on hair growth have been studied in human hair follicle dermal papillary (hHFDP) cells and follicular organ culture ex vivo by cell proliferation assay, PCR, western blot analysis, and reporter gene activity assay. Moreover, a clinical trial was conducted in healthy volunteers.

Results: Lagerstroemia indica significantly promoted the proliferation of hHFDP cells, which was associated with increased expression of TCF/LEF, VEGF, and Gli1 mRNA, and inhibition of STAT6 and Smad2 mRNA. Treatment with L. indica also increased the TCF/LEF reporter gene activity but downregulated the SBE- and STAT6-luciferase activities. The expression of total β-catenin, CDK4, and CDK2 were elevated, while that of STAT6 and SMAD2/3 was suppressed upon treatment with L. indica. In human hair follicles organ culture, L. indica significantly inhibited hair follicular degeneration. The clinical trial showed a statistically significant rise in total hair count in test group (n = 24) after 24 weeks of applying the hair tonic enriched with L. indica (141.46 ± 21.27 number/cm , p < 0.05).

Conclusion: We suggest that L. indica extract prevents hair loss as well as stimulate hair growth by regulating the Wnt-β-catenin, JAK3-STAT6, and TGF-β1-Smad signaling pathways, and may be further developed as a novel functional cosmetic for preventing hair loss.