Scarless healing is considered as the most ideal mode of wound repair. This ability generally exists in the early period of mammalian embryos, however it gradually turns to scar healing with the development of the embryos. This phenomenon is the result of the interaction of multiple biological functions, and the mechanism is still uncertain. This article deals with a systematical review of literature concerning the mechanism of scarless healing based on the recent experimental studies, hoping to provide evidence for the treatment of wounds to realize scarless healing in adult.
Adult ; Animals ; Cicatrix ; prevention & control ; Fetus ; physiology ; Humans ; Wound Healing ; physiology

Objective: To preliminarily observe the effects of application of micro-negative pressure in children with small-area deep partial-thickness burn. Methods: From January 2016 to August 2018, 64 children with small-area deep partial-thickness burn who were admitted to the Department of Burn Surgery of the First Affiliated Hospital of Naval Medical University were recruited in this prospective randomized controlled study. According to the random number table, they were divided into negative pressure group [18 boys and 14 girls, aged (3.9±1.6) years with total burn area of (5.5±2.2)% total body surface area (TBSA)] and conventional group [20 boys and 12 girls, aged (3.8±1.7) years with total burn area of (5.8±1.6)% TBSA], with 32 patients in each group. After admission, simple debridement was performed in the patients of 2 groups. After that, the children in negative pressure group were treated with micro-negative pressure with negative pressure material replaced every 3 to 5 days. Children in conventional group were treated with silver sulfadiazine cream with dressing change every other day. On post injury day (PID) 14 and 21, general wound observation was performed, the wound healing rate was calculated, the exudates from the wounds were cultured and the positive detection rate was calculated. The number of patients requiring surgical skin grafting was recorded and the rate of surgical skin grafting was calculated, and the complete wound healing time was recorded in the patients of 2 groups. Scar formation was evaluated by the Vancouver Scar Scale (VSS) in 3, 6, and 12 months after wound healing. Data were processed with chi-square test, t test, Bonferroni correction, and analysis of variance for repeated measurement. Results: (1) On PID 14, all the necrotic tissue in the wounds of patients in negative pressure group was removed, with few exudates, and most of the wounds had been epithelialized; most of necrotic tissue in the wounds of patients in conventional group was removed, with more exudates and smaller wound healing area than those in negative pressure group. On PID 21, most of the wounds of patients in negative pressure group were healed, and the exudates were rare, while the wound healing area of patients in conventional group was significantly smaller than that in negative pressure group with more exudates. (2) On PID 14 and 21, the wound healing rates [(49.8±3.3)% and (95.8±2.4)%] of patients in negative pressure group were significantly higher than those in conventional group [(40.0±3.2)% and (75.3±2.5)%, t=11.899, 33.461, P<0.01]. (3) On PID 14 and 21, the positive detection rates of wound bacteria of patients in negative pressure group were significantly lower than those in conventional group (χ²=6.275, 5.741, P<0.05). (4) The rate of surgical skin grafting of patients in negative pressure group was significantly lower than that in conventional group (χ²=5.333, P<0.05). (5) The complete wound healing time of patients in negative pressure group [(23.9±2.3) d] was significantly shorter than that in conventional group [(27.9±1.8) d, t=-7.806, P<0.01]. (6) In 3, 6, and 12 months after wound healing, the VSS scores [(6.9±1.8), (5.6±1.4), (3.4±1.5) points] of patients in negative pressure group were significantly lower than those in conventional group [(9.0±1.5), (7.4±2.0), (5.7±1.6) points, t=-4.987, -4.127, -5.988, P<0.01]. Conclusions In comparison with routine dressing change, the treatment of application of micro-negative pressure in children with small-area deep partial-thickness burn can significantly improve the wound healing rate and rate of surgical skin grafting, decrease the wound infection rate, shorten the wound healing time, and improve the wound healing quality.