Melanogenesis Markers Expression in Premature Graying of Hair: A Cross-Sectional Study

Abstract

Background: Studies on mice and aging human hair follicles provide compelling evidence that graying of hair results from premature differentiation of melanocyte stem cells in the niche/bulge.

Objective: The aim of this study was to analyze whether differentiation of melanocyte stem cells is responsible for premature graying of hair (PGH).

Methods: Twenty-five patients with PGH (n = 25) attending the dermatology department were recruited. Five unpigmented and 5 pigmented hairs were obtained per patient by separating individual follicles after 1 mm punch biopsies. The hairs were dissected at a distance of 2 mm from the bulb to separate the stem cells (upper segment - US) from the melanocytes (lower segment - LS). RNA was extracted from hair follicle US and LS, and expression of GP100, tyrosinase (TYR), and tyrosinase-related protein-1 (TYRP1) genes was quantified using Qiagen one-step RT-PCR kit.

Results: We found melanogenesis gene expression in both temporary (US) and permanent (LS) segments of unpigmented and pigmented hair follicles. When compared between the US and LS of white hair, the expression of TYR and GP100 was much higher in US than LS, suggestive of melanogenesis in the bulge. Similarly, when compared between white and black US, the expression of all 3 genes was higher in white US than black US, although not statistically significant.

Limitations: Low samples size and lack of data pertaining to the expression of genes at protein level are the limitations of current study.

Conclusion: Even though this pilot study data yielded key information about the expression of GP100, TYR, and TYRP-1 at the mRNA level, further studies quantifying the expression of these genes at protein level are needed to provide additional clues to further address the results in detail.

Keywords: Hair graying; Melanocyte stem cells; Melanogenesis markers; Premature graying; Tyrosinase; Tyrosinase-related protein.