MiR‐141‐3p‐Functionalized Exosomes Loaded in Dissolvable Microneedle Arrays for Hypertrophic Scar Treatment

Abstract Hypertrophic scar (HS) is a common fibroproliferative disease caused by abnormal wound healing after deep skin injury. However, the existing approaches have unsatisfactory therapeutic effects, which promote the exploration of newer and more effective strategies. MiRNA‐modified functional exosomes delivered by dissolvable microneedle arrays (DMNAs) are expected to provide new hope for HS treatment. In this study, a miRNA, miR‐141‐3p, which is downregulated in skin scar tissues and in hypertrophic scar fibroblasts (HSFs), is identified. MiR‐141‐3p mimics inhibit the proliferation, migration, and myofibroblast transdifferentiation of HSFs in vitro by targeting TGF‐β2 to suppress the TGF‐β2/Smad pathway. Subsequently, the engineered exosomes encapsulating miR‐141‐3p (miR‐141‐3p OE ‐Exos) are isolated from adipose‐derived mesenchymal stem cells transfected with Lv‐miR‐141‐3p. MiR‐141‐3p OE ‐Exos show the same inhibitive effects as miR‐141‐3p mimics on the pathological behaviors of HSFs in vitro. The DMNAs for sustained release of miR‐141‐3p OE ‐Exos are further fabricated in vivo. MiR‐141 OE ‐Exos@DMNAs effectively decrease the thickness of HS and improve fibroblast distribution and collagen fiber arrangement, and downregulate the expression of α‐SMA, COL‐1, FN, TGF‐β2, and p‐Smad2/3 in the HS tissue. Overall, a promising, effective, and convenient exosome@DMNA‐based miRNA delivery strategy for HS treatment is provided.