Promotive effects of adenosine on human hair follicle growth and angiogenin expression

Abstract

Objective To evaluate the promotive effects of adenosine on human hair follicle growth and angiogenin expression. Methods Intact human hair follicles in the anagen phase were isolated from the scalp, and then divided into 6 groups to be treated with adenosine at different concentrations of 0, 0.1, 1, 10, 100 and 1 000 μmol/L respectively. Each adenosine group was further divided into 2 subgroups to be treated either with or without 0.8 mg/L anti-human angiogenin antibody, and hair follicles receiving no treatment served as the control group. The growth length of hair follicles during 6-day culture was measured by using a microscope. Human dermal papilla cells were isolated by a two-step enzyme digestion method, and then classified into the same groups as above. After 48-hour culture, methyl thiazolyl tetrazolium (MTT) assay was performed to evaluate cellular proliferative activity, flow cytometry to analyze cell cycle, reverse transcription (RT)-PCR to measure the mRNA expression of angiogenin in dermal papilla cells, and enzyme-linked immunosorbent assay (ELISA) to measure the protein expression of angiogenin in the culture supernatant of dermal papilla cells. Results Compared with the control group, the 10-1 000 μmol/L adenosine-treated groups showed significantly increased growth of hair follicles in vitro (F = 377.776, P < 0.05), and 100 μmol/L adenosine had the strongest promotive effect (P < 0.05). However, anti-human angiogenin antibody could partly antagonize the promotive effect. Compared with the control group, the proliferative activity of human dermal papilla cells was significantly enhanced in the 0.1-1 000 μmol/L adenosine-treated groups (F = 230.067, P < 0.05), and adenosine at 10 and 100 μmol/L had the strongest enhancing effects (both P < 0.05). Similarly, anti-human angiogenin antibody could partly antagonize the enhancing effects of adenosine on cell proliferation. As flow cytometry showed, compared with the control group, the 10-1 000 μmol/L adenosine-treated groups showed significantly lower proportions of dermal papilla cells in G1 phase (F = 75.5, P < 0.05), but higher proportions of cells in G2 phase (F = 15.7, P < 0.05) and S phase (F = 81.8, P < 0.05). In addition, the mRNA and protein expressions of angiogenin were significantly up-regulated in human dermal papilla cells treated by 10 and 100 μmol/L adenosine compared with the control group (F = 942.630, 148.544, respectively, both P < 0.05). Conclusion Adenosine can promote the growth of human hair follicles and proliferation of dermal papilla cells, likely by up-regulating angiogenin expression. Key words: Adenosine; Angiogenins; Hair follicle; Cell proliferation; Cell cycle; Dermal papilla cells