Stem cell‐derived exosomes in the treatment of melasma and its percutaneous penetration

Background and Objectives Melasma is a refractory skin disease due to its complex pathogenesis and difficult treatment. Studies have found that human umbilical cord mesenchymal stem cell‐derived exosomes (hUCMSC‐Exos) could serve as a novel cell‐free therapeutic strategy in regenerative and esthetic medicine. It could potentially treat melasma, but the skin barrier is a challenge. In this study, we aim to explore the safety and efficacy of hUCMSC‐Exos in the treatment of melasma and the means to promote its percutaneous penetration. Materials and Methods In the animal study about the effect of penetration, percutaneous penetration of PKH67‐labeled hUCMSC‐Exos was studied under microneedles, 1565 nm nonablative fractional laser (NAFL), and a plasma named Peninsula Blue Aurora Shumin Master (PBASM) treatments, observed by confocal laser scanning microscopy. In the clinical application study, 60 patients with melasma treated in our department were divided into four groups. NAFL combined with normal saline treatment was used for Group A. Microneedles, NAFL, and PBASM combined with hUCMSC‐Exos treatments were used for Groups B, C, and D, respectively. Each patient received four treatments at 1‐month intervals. Assessments were done using the degree of pain posttreatment, melasma area and severity score, improvement rate, physician global assessment score, satisfaction, and complications. Results In the animal study about the effect of penetration, hUCMSC‐Exos can penetrate the deep dermis under microneedles, NAFL, and PBASM treatments. In the clinical application study, compared with Group A, Groups B, C, and D showed significantly improved therapeutic effect and patient satisfaction (p 0.05). Patients in Group B reported higher pain levels than those in the other three groups (p