Introduction: This study aimed to evaluate the amount of orbicularis oris muscle formation and function after using scaffold-free cells and mesenchymal stem cells scaffold in repaired cleft lip of rats. Methods: Forty male Wistar rats were used. A triangular cut (774mm) was made on the upper lip of 30 rats and then divided into 3 equal groups. In the first group (control), the defected cuts were closed by routine surgical procedures. The second group consisted of cell scaffold and the third scaffold-free cells (553) in the area of the incision.Two months after restoration, muscle electromyography activity was examined alongside 10 normal rats and tissue samples were histologically examined. Data were analyzed statistically by SPSS software and ANOVA and the Kruskal–Wallis test. The significance level was considered at P<0.05. Results: Electromyography activity in second and third groups was not significantly different from each other and with normal muscle. The control group had, however, higher activity than normal muscle (P<0.001). The amount of newly formed muscle tissue in the scaffold group had a clear statistical difference with the cell scaffold (P¼0.018) and control group (P<0.001). Furthermore, the inflammatory reaction showed a significant statistical difference in the control and scaffold group (P¼0.001) and the scaffold and cell-scaffold groups (P¼0.007). There was no significant difference in the number of formed fibroblast cells and collagen tissue in the area between the 3 groups. Conclusions: The results of this study show that extracellular matrix scaffold can reduce tension in the repaired cleft lip area by increasing muscle formation and decreasing scar tissue contraction, confirming the benefits of this type of scaffold.

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