Stimulation of hair regrowth in an animal model of androgenic alopecia using 2-deoxy-D-ribose

Abstract

Androgenic alopecia (AGA) affects both men and women worldwide. New blood vessel formation can restore blood supply and stimulate the hair regrowth cycle. Recently, our group reported that 2-deoxy-D-ribose (2dDR) is 80%-90% as effective as VEGF in the stimulation of neovascularization in in vitro models and in a chick bioassay. In this study, we aimed to assess the effect of 2dDR on hair growth. We prepared an alginate gel containing 2dDR, polypropylene glycol, and phenoxyethanol. AGA was developed in C57BL6 mice by intraperitoneally injecting testosterone (TE). A dihydrotestosterone (DHT)-treated group was used as a negative control, a minoxidil group was used as a positive control, and we included groups treated with 2dDR gel and a combination of 2dDR and minoxidil. Each treatment was applied for 20 days. Both groups treated with 2dDR gel and minoxidil stimulated the morphogenesis of hair follicles. H&E-stained skin sections of C57BL/6 mice demonstrated an increase in length, diameter, hair follicle density, anagen/telogen ratio, diameter of hair follicles, area of the hair bulb covered in melanin, and an increase in the number of blood vessels. Masson's trichrome staining showed an increase in the area of the hair bulb covered in melanin. The effects of the FDA-approved drug (minoxidil) on hair growth were similar to those of 2dDR (80%-90%). No significant benefit were observed by applying a combination of minoxidil with 2dDR. We conclude that 2dDR gel has potential for the treatment of androgenic alopecia and possibly other alopecia conditions where stimulation of hair regrowth is desirable, such as after chemotherapy. The mechanism of activity of 2dDR remains to be established.

Keywords: 2-deoxy-D-ribose; C57BL6 mice; androgenic alopecia; chemotherapy; hair regrowth; minoxidil; testosterone.

FIGURE 1

(A) FTIR spectra of blank-SA and 2dDR-SA hydrogels; (B) release and colorimetric detection of 2dDR at different time intervals (4 h and 1, 2, 3, 4, and 7 days) of drug release analysis.

FIGURE 2

(A) Schematic illustration of the in vivo experiment. (B) Comparison of dorsal hair regeneration of C57BL/6 mice without any treatment (NC), testosterone (T-1), blank-SA (T-2), 2dDR-SA (T-3), minoxidil (T-4), synergistic 2dDR, and minoxidil (T-5) (n = 04) at different time intervals (days 0, 7, 14, and 21 of the experiment). (C) Mouse skin color score index. (D) Graphical representation of skin color scored by different treatment groups at various time intervals (days 0, 4, 8, 12, 16, and 20 of the experiment).

FIGURE 3

Gross analysis of hair: (A) digital photographs of hair length, (B) hair length analysis of skin sections from different treatment groups. Results are presented as n = 60 + SD; ****p ≤ 0.0001 denotes NC versus T-1 and T-2; ns p > 0.05. (C) Photographs of hair shafts from different treatment groups. (D) Hair shaft analysis of skin sections from different treatment groups. Results are presented as n = 60 + SD; ****p ≤ 0.0001 denotes NC versus T-1; ***p ≤ 0.001 NC versus T-2; **p ≤ 0.01 denotes NC versus T-5; and ns p > 0.05 denoted NC versus T-3 and T-4.

FIGURE 4

Microscopic analysis of skin sections retrieved on day 21 of experiment after H&E staining: (A) length of hair follicles in skin sections from different treatment groups (arrows representing the length of the hair follicles). (B) Comparison of the length of hair follicles in skin sections from different treatment groups. Results are presented as n = 4 + SD; *p ≤ 0.1 denotes NC versus T-1 and T-2; ns p > 0.05. (C) Hair follicle density in skin sections from different treatment groups (arrows representing the density of the hair follicles). (D) Comparison of hair follicle density in skin sections from different treatment groups. Results are presented as n = 4 + SD; ****p ≤ 0.0001 denotes NC versus T-1; ***p ≤ 0.001 NC versus T-2 and T-4; **p ≤ 0.01 denotes NC versus T-3 and T-5.

FIGURE 5

Microscopic analysis of skin sections retrieved on day 21 of experiment after H&E staining: (A) diameter of hair follicles in skin sections from different treatment groups (arrows representing the diameter of the hair follicles); (B) Comparison of the diameter of hair follicles in skin sections from different treatment groups. Results are presented as n = 4 + SD; ****p ≤ 0.0001 denotes NC versus T-1; ***p ≤ 0.001 NC versus T-2; **p ≤ 0.01 denotes NC versus T-5, *p ≤ 0.1 denotes NC versus T-5, and ns p > 0.05. (C) Hair follicle structures of terminal anagen and terminal telogen phases from different treatment groups (black and orange arrows representing anagen and telogen phases, respectively). (D) Comparison of hair follicle structures of terminal anagen and terminal telogen from different treatment groups. Results are presented as n = 4 + SD; ****p ≤ 0.0001 denotes NC versus T-1, T-2, T-3, T-4, and T-5. (E) The difference between the anagen and telogen hair bulb: (E1) Hair bulb in the anagen stage: black, orange, and red arrows indicating the outer root sheath, inner root sheath, and medulla, respectively, (E2) hair bulb in the telogen stage: black and red arrows indicating the desiccated outer root sheath and medulla, respectively, with no inner root sheath.

FIGURE 6

Microscopic analysis in skin sections retrieved on day 21 of experiment after H&E staining: (A) morphology of the area of the hair bulb covered in melanin in skin sections from different treatment groups (arrows representing the area covered by the hair bulb in melanin). (B) Comparison of the morphology of the area of the hair bulb covered in melanin in skin sections from different treatment groups. Results are presented as n = 4 + SD; ****p ≤ 0.0001 denotes NC versus T-1 and T-2; **p ≤ 0.01 denotes NC versus T-5, *p ≤ 0.1 denotes NC versus T-4, and ns p > 0.05 denotes NC versus T3. (C) The number of blood vessels from different treatment groups (arrows representing no. of blood vessels per view). (D) Comparison of the number of blood vessels from different treatment groups. Results are presented as n = 4 + SD; ***p ≤ 0.0001 denotes NC versus T-1 and T-2; **p ≤ 0.01 denotes NC versus T-4, *p ≤ 0.1 denotes NC versus T-5, and ns p > 0.05 denotes NC versus T3.