Hair growth stimulated by allogenic adipose-derived stem cells supplemented with ATP in a mouse model of dihydrotestosterone-induced androgenetic alopecia

Abstract

Background: Androgenetic alopecia (AGA), also known as male or female pattern hair loss, is the most prevalent form of alopecia worldwide. Current treatments are based on hormone drugs, topical vasodilators and hair transplants. Newer options include stem cell therapy targeted at recovering the capacity for hair follicle regeneration. This study examines the effects of intradermally administering allogenic adipose-derived stem cells (ASCs) per se or supplemented with ATP in a mouse model of dihydrotestosterone (DHT)-induced AGA.

Methods: Male and female C57BL6-strain mice were treated with DHT to induce AGA and then given injections of treatment solution in a defined area of the depilated back skin, and the same injections three days later. The treatments tested were several concentrations of ASCs combined with two ATP formulations. Photographs of the treated zones were taken on days 7, 10, 14, 17 and 21 and subjected to Image J analysis. On day 21, skin samples were also obtained for histological analysis. The main outcome measure was percentage treated surface area showing hair regrowth on treatment days 17 and 21 expressed as five categories: null, poor, moderate, intense and complete (20, 40, 60, 80 and 100% respectively).

Results: The experimental groups found to show the highest number of male individuals with intense/complete hair regrowth on day 21 were those in which mice received low dose ASCs (1 ∙ 10⁶) combined either with liposomal ATP or non-liposomal ATP. Both these groups showed significant differences compared to controls. In females, while low dose ASC treatments and the high dose ASC + liposomal ATP treatment led to no hair regrowth improvement over the control treatment, medium dose ASC (2 × 10⁶) + non-liposomal ATP gave rise to greater regrowth scores.

Conclusions: Hair regrowth was improved in all experimental groups in which male mice were administered stem cell solutions supplemented with ATP. In female mice, the highest hair regrowth scores were observed for the medium dose ASC + liposomal ATP treatment.

Keywords: ATP; Adipose derived stem cells; Androgenetic alopecia; Hair growth; Mouse model.

Fig. 1

AGA model groups

Fig. 2

Experimental treatment groups

Fig. 3

Immunophenotype of 2x10⁶ ASCs incubated in HTS + liposomal ATP solution. Through flow cytometry, the immunophenotype of the stem cells was assessed according to several markers (CD90; CD73; CD166; CD105 and CD44) 24 h after incubation of the ASCs with ATP [100 μM] in refrigerated conditions. Representative image

Fig. 4

Male AGA model assessment. Hair regrowth photographs taken on days 0, 4, 7, 11, 14, 18 and 21 after depilation in male C57BL6 mice

Fig. 5

Female AGA model assessment. Hair regrowth on days 0, 4, 7, 14 and 21 recorded in female C57BL6 mice after depilation

Fig. 6

Male mice experimental groups. a Pictures of hair regrowth taken on day 17. b Visual classification into 5  levels of hair regrowth on day 17. c Pictures of hair regrowth taken on day 21. d Visual classification into 5 levels of hair regrowth on day 21 (AGA model groups included)

Fig. 6

Male mice experimental groups. a Pictures of hair regrowth taken on day 17. b Visual classification into 5  levels of hair regrowth on day 17. c Pictures of hair regrowth taken on day 21. d Visual classification into 5 levels of hair regrowth on day 21 (AGA model groups included)

Fig. 7

Female mice experimental groups. a Pictures of hair regrowth taken on day 17. b Visual classification into 5 levels of hair regrowth on day 17. c Pictures of hair regrowth taken on day 21. d Visual classification into 5 levels of hair regrowth on day 21 (AGA model groups included)

Fig. 7

Female mice experimental groups. a Pictures of hair regrowth taken on day 17. b Visual classification into 5 levels of hair regrowth on day 17. c Pictures of hair regrowth taken on day 21. d Visual classification into 5 levels of hair regrowth on day 21 (AGA model groups included)

Fig. 8

Box-and-whisker plots of modal grey values on day 7 (a) and day 10 (b) recorded in the experimental treatment groups of female and male mice

Fig. 9

Box-and-whisker plots of raw integrated density on days 14 (a), 17 (b) and 21 (c) recorded in the experimental treatment groups of female and male mice

Fig. 9

Box-and-whisker plots of raw integrated density on days 14 (a), 17 (b) and 21 (c) recorded in the experimental treatment groups of female and male mice

Fig. 10

Box-and-whisker plots of hair growth rates on days 14 (a), 17 (b) and 21 (c) recorded in the experimental groups of male and female mice

Fig. 10

Box-and-whisker plots of hair growth rates on days 14 (a), 17 (b) and 21 (c) recorded in the experimental groups of male and female mice

Fig. 11

Representative images of histological findings in the skin of male mice in the control (a) and experimental (b) treatment groups. The experimental group showed greater hair follicle density and bulb diameter

Fig. 12

Representative images of histological findings in the skin of female mice in the control (a) and experimental (b) treatment groups. The experimental group showed a higher hair follicle density