Engineered exosomes for targeted delivery of miR-187-3p suppress the viability of hemangioma stem cells by targeting Notch signaling.

Background: Infantile hemangioma (IH) is the most common benign vascular tumor of infancy and is proposed to arise from hemangioma stem cells (HemSCs). Therapies for IH include oral beta-blockers, surgery, and the delivery of novel therapeutic agents, such as bioactive microRNAs (miRNAs). However, in the extracellular environment, miRNA is easily hydrolyzed by RNase. miR-187-3p has previously been confirmed to promote or inhibit various malignancies, but its role in the development and progression of IH remains unclear.

Methods: In this study, engineered exosomes (E-exos) were exploited to deliver miR-187-3p into HemSCs. The E-exos were generated by introducing miR-187-3p mimics into human adipose mesenchymal stem cell-derived exosomes (hAMSC-exos) via electroporation. The expression and secretion of miR-187-3p were examined by quantitative reverse transcription-polymerase chain reaction (qRT-PCR). Western blot analysis, transmission electron microscopy (TEM), and dynamic light scattering (DLS) were used to characterize the exosomes. The effects of the E-exos on HemSC viability were examined using the tube formation assay and the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide assay. Western blot analysis was used to evaluate the effects of E-exos on Notch-1, Notch-4, and Jagged-1 expression in HemSCs.

Results: E-exos did not differ significantly from hAMSC-exos in terms of morphology, particle size, or surface markers. E-exos could be internalized by HemSCs, and the course of cellular uptake of E-exos was time dependent. After 12 hours of treatment, E-exos significant inhibited tube formation. Notch signaling was also inhibited by miR-187-3p loading by E-exos. E-exos showed excellent inhibitory effects against HemSC proliferation via Notch signaling.

Conclusions: This study provides a foundation for using hAMSC-exos to optimize current clinical options to facilitate IH treatment and deliver therapeutic agents in the future.