Establishment of vitiligo model and treatment regimen
C57BL/6 mice (age 4-7 weeks; body weight 18-38 g;) with black dorsal skin were supplied by Vital River Laboratory Animal Technology Co. Ltd., Beijing (Approval ID: SCXK-(jing) 2014-0013). Four to six mice were housed in clear plastic cages (225 × 340 × 155 mm) containing bedding made of paper/cellulose with ad libitum access to standard chow diet and water. All animals were housed at 22 ± 4 °C and 50 ± 10% humidity. The experiments were approved by the Institutional Ethical Committee for Laboratory of Xinjiang Medical University (Approval ID: SYXK-(xin) 2016-0002) and conducted in accordance with relevant guidelines and regulations. The dorsal side of the animals was shaved a day before the experiment using electric clippers. Dorsal hypopigmentation in mice was induced by hydroquinone (HQ) as previously described. Briefly, a 2 cm × 2 cm depilated region of each mouse was smeared with 0.5 mL of 5% HQ (CAS:23-31-9) once a day for 50 days. The animals were acclimatized for 1 week and randomly divided into six groups (n = 12 per group): (1) the control group, in which distilled water was administered and smeared; (2) the vitiligo model group, which received 5% HQ (Jiang lai) on the 2 × 2 cm shaved dorsum for 50 days and distilled water for 30 days; (3) the 8-MOP group, which received 5% HQ for 50 days and 8-MOP (4.25 mg/kg) for 30 days; (4)–(6) the HCJA121 group, which received 5% HQ for 50 days and HCJA121 at various concentrations (0.0425 mg/kg (n = 12), 0.425 mg/kg (n = 12), 4.25 mg/kg (n = 12)) for 30 days; and (7)–(9) the HCJA404 group, which received 5% HQ for 50 days and HCJA121 at the same doses specified above. At the end of the 30-day treatment, the blood samples were collected retro-orbitally from the mice. In addition, dorsal skin samples were isolated from the animals.