Hair follicle stem cells in dermis have multiple differentiation potential, and can differentiate into hair shaft, internal myelin sheath, external myelin sheath, skin epithelial keratinocytes and sebaceous glands. Hair follicle stem cells can maintain the cycle of hair follicle, but also plays an important role in epidermis wound healing. Studies on hair follicle cells participate in epidermal healing following wound are early, but studies on hair follicle stem cells appear recently. The signal pathways related may be Wnt, BMP, FGF, Notch, SHH and so on. In order to understanding the role of micro-wound healing in plastics and cosmetic medicine and skin issue-engineering, how hair follicle stem cells participate in epidermal healing and signaling pathways related were reviewed in this study.

Objective To investigate the histological changes of normal human skin after fixed irradiation with multiple-pulse fractional Er:YAG laser.Methods After hair removal,the upper arms of 7 healthy volunteers were consecutively irradiated with multiple-pulse fractional Er:YAG laser.Tissue samples were resected from the irradiated skin at 1,24,48,72 hours,on day 5,7,15,and 30 after the irradiation.Hematoxylin and eosin(HE)staining and Masson staining were performed to observe the histological changes and collagen proliferation respectively.Immunohistochemical staining was used to detect the expression of heat shock protein(HSP)70 and 47.Results The consecutive irradiation with multi-pulse fractional Er:YAG laser generated an array of tapering microscopic treatment zones(MTZs)of gasification and ablation in the upper arm skin.After the irradiation,inflammation developed in the microscopic lesions with the epithelization of epidermal cells within 7 days; local dermal collagen was renewed and remodelled during the 7th to 30th day.HSP70 expression peaked as early as 48 hours after the treatment and maintained until the 7th day,while the high expression of HSP47 persisted from the 15th to 30th day after irradiation.Conclusion The fixed,multiplepulse and fractional Er:YAG laser irradiation can reach the deep dermis,and induce the local proliferation of dermal collagen.

Objective To evaluate the combined treatment effect of intensive pulsed light (IPL,420 nm and 540 nm,by mode of 4+3) on acne vulgaris and acne erythem.Methods A total of 80 patients with acne vulgaris were divided randomly into the treatment and the control group.The treatment group including forty cases were first treated by 420 nm IPL for 4 times,and the interval was one week; and then treated by IPL 420 nm combined with 540 nm for 3 times,the interval was four weeks.The control group was just treated by Adapalene at every night for 16 weeks.Results The treatment efficiency of inflammatory lesion after 4 weeks showed that the effective rate in the treatment group was 65.0 ％ compared to 47.5 ％ in the control group,and the difference was statistically significant (P＜0.05).The treatment results of inflammatory lesion after 16 weeks showed that efficiency was 85％ in the treatment group,while 62.5％ in the control group,and difference was statistically significant (P＜0.05).The treatment results of acne erythem showed that the effective rate was 90 ％ in the treatment group,but 37.5 ％ in control group,there was statistically significant (P＜ 0.01) between the two groups.Conclusions Combined use of 420 nm and 540nm IPL by protocol of4+3 is an effective method for treatment of acne vulgaris and acne erythem.

Objective To evaluate the effect of fractional Er:YAG laser therapy on collagen and elastic fibers in photoaged skin of ultraviolet-irradiated Guinea pigs.Methods Sixty Guinea pigs were randomly divided into the non-intervention group (n =10) and model group (n =50) by a random number table.To establish a model of photoaging,the 50 Guinea pigs were irradiated by ultraviolet A (UVA) and ultraviolet B (UVB) on the back every other day for two months.Subsequently,the 50 mice were equally classified into five groups:photoaging group receiving no laser therapy,as well as 2-week,4-week,8-week and 12-week group receiving one,one,two and three sessions of successive multi-pulsed fractional Er:YAG laser therapy,respectively,on the left side (treatment side) of the back,with the right side as the control side.The interval of laser therapy was four weeks.Skin biopsies were obtained from the right and left side of the back of Guinea pigs after the laser therapy,and subjected to haematoxylin and eosin (HE) staining,Masson staining and Weigert-van Gieson staining.The content of hydroxyproline was measured by using an alkaline-hydrolysis method.Results The minimal erythema dose for UVA and UVB was 4224 mJ/cm2 and 504 mJ/cm2 respectively on Guinea pig skin.The model for photoaging was successfully established in 50 Guinea pigs after two months of irradiation with the cumulative dose of UVA and UVB being 459.36 J/cm2 and 54.81 J/cm2 respectively.HE staining revealed an obvious increase in newly-growing collagen and elastic fibers,which were arranged densely,in the treatment side compared with the control side of the back of Guinea pigs after laser therapy.The area ratio of collagen fibers stained positive for Masson's trichrome and content of hydroxyproline were significantly higher in the treatment side than in the control side of the 12-week group (0.70 ± 0.12 vs.0.63 ± 0.08,t =1.18,P ＜ 0.05;(4.73 ± 0.39) mg/g vs.(3.66 ± 0.85) mg/g,t =3.40,P ＜ 0.05).Conclusion Successive multi-pulsed fractional Er:YAG laser irradiation can result in an increase in collagen fibers and renewal of elastic fibers in superficial dermis of photoaged skin of Guinea pigs.

Objective Based on the theory of"lung governs the skin and hair"in"Yellow Emperor's Inner Classic",this paper analyzes the medication rules of whitening and freckle-removing.The aim of this study is to provide reference for the clinical practice of traditional Chinese medicine(TCM)theory and the medication in TCM cosmetics.Methods"Chinese Medical Classics"was used to search the records of whitening and freckle-related drugs.The frequency,nature,flavor,meridian tropism and compatibility laws of TCM for whitening and freckle-removal were analyzed by statistics and association rules.The network pharmacology research was used to analyze the whitening and freckle-removing effects and mechanisms of high-frequency drugs.Then,the potential active ingredients were analyzed.The whitening and anti-freckle effect was verified through cytotoxicity experiments and melanin content detection.Results A total of 171 external prescriptions were selected in eligible articles,including 261 Chinese medicinals,most of which were pungent and belong to the lung meridian.The most frequently used Chinese medicinals was"Erbai Yixin"(EBYX,Angelicae Dahuricae Radix,Typhonii Rhizoma,Asari Radix et Rhizoma).Network pharmacological analysis showed that the core targets of EBYX for whitening and removing freckles are TP53,EGFR,ALB,etc.,which are mainly involved in oxygen perception and response,skin immune regulation,skin cell growth,differentiation,stress,inflammatory response,and other biological processes.Based on the results of molecular docking,biological analysis proved that the active ingredients of EBYX are chrysophanol,gallic acid and caffeic acid,which have inhibitory effects on the proliferation of melanoma cells and melanin production.Conclusion Most of the ancient prescriptions for whitening and removing freckles are pungent and belong to the lung meridian,which embodies the theory of"lung governs the skin and hair".The high-frequency drug EBYX may play a role by regulating skin redox,immunity and inflammation.The active ingredients of EBYX have an inhibitory effect on melanin formation.This study enriches the scientific connotation of TCM whitening and freckle-removing prescriptions based on the theory of"lung governs the skin and hair",realizes interdisciplinary integration and provides support for the modernization of TCM.