Identification of differentially expressed proteins involved in fetal scarless wound healing using a rat model of cleft lip.

In early pregnancy, fetal skin wounds can heal quickly and undergo a transition period from scarless healing to scar formation. The aim of the present study was to identify potential biomarkers associated with scarless repair of cleft lips, in order to determine the intrinsic factors leading to scar formation in embryonic tissue. A stable model of cleft lip was established using microsurgery by constructing a wedge‑shaped cleft lip‑like defect in fetal rats at gestational age (GA) 16.5 and GA18.5. The GA16.5 and GA18.5 groups were used to model scarless healing and scar formation, respectively. The fetuses were returned to the uterus following surgery, then removed 72 h after the procedure. Macroscopic observation of the cleft defect and histological examination were carried out. Reverse transcription‑quantitative (RT‑q) PCR and parallel reaction monitoring (PRM) were used to detect mRNA and protein expression levels, respectively. The upper‑left lip completely healed 72 h after surgery in the GA16.5 group of fetal rats. However, this was not the case in the GA18.5 group. Histological examination indicated new follicles visible under the epidermis of the scarless group (GA16.5). Scarring was visible on the upper‑left cleft lip wound of the fetal rats in the GA18.5 group. The expression of some growth and pro‑inflammatory factors, including TNF‑α, were also different between two groups. Label‑free quantification was used to identified differentially expressed proteins and five differentially expressed proteins (Smad4, Fabp5, S100a4, S100a8 and S100a9) were identified. The relative expression of these molecules at the mRNA and protein levels were measured using RT‑qPCR and PRM. These molecules may represent potential biomarkers for the scarless repair of fetal rat cleft lip wounds.