The miR‐21‐5p + PFD group demonstrated an increase in the expressions of TNF‐α, TGF‐β1, and COL1A1 mRNA and proteins and a down‐regulation in the expression of Smad7 mRNA and protein but a lesser extent of down‐regulation than the miR‐21‐5p mimic one. This evidence concerns the gene COL1A1 and polyostotic fibrous dysplasia.