Lineage-specific exosomes promote the odontogenic differentiation of human dental pulp stem cells (DPSCs) through TGFβ1/smads signaling pathway via transfer of microRNAs

Abstract

Background Exosomes derived from dental pulp stem cells (DPSCs) can be used as biomimetic tools to induce odontogenic differentiation of stem cells, but the regulatory mechanisms and functions of exosome-encapsulated microRNAs are still unknown. The present study aimed to clarify the role of microRNAs contained in the exosomes derived from human DPSCs and their potential signaling cascade in odontogenic differentiation. Methods Exosomes were isolated from human DPSCs cultured undergrowth and odontogenic differentiation conditions, named UN-Exo and OD-Exo, respectively. The microRNA sequencing was performed to explore the microRNA profile contained in UN-Exo and OD-Exo. Pathway analysis was taken to detect enriched pathways associated with the predicted target genes of microRNAs. The regulatory roles of a highly expressed microRNA in OD-Exo were investigated through its inhibition or overexpression (miRNA inhibitors and miRNA mimics). Automated western blot was used to identify the function of exosomal microRNA and the roles of TGFβ1/smads pathway in odontogenic differentiation of DPSCs. A luciferase reporter gene assay was used to verify the direct target gene of exosomal miR-27a-5p. Results Endocytosis of OD-Exo triggered odontogenic differentiation of DPSCs by upregulating DSP, DMP-1, ALP, and RUNX2 proteins. MicroRNA sequencing showed that 28 microRNAs significantly changed in OD-Exo, of which 7 increased and 21 decreased. Pathway analysis showed genes targeted by differentially expressed microRNAs were involved in multiple signal transductions, including TGFβ pathway. 16 genes targeted by 15 differentially expressed microRNAs were involved in TGFβ signaling. Consistently, automated western blot found that OD-Exo activated TGFβ1 pathway by upregulating TGFβ1, TGFR1, p-Smad2/3, and Smad4 in DPSCs. Accordingly, once the TGFβ1 signaling pathway was inhibited by SB525334, protein levels of p-Smad2/3, DSP, and DMP-1 were significantly decreased in DPSCs treated with OD-Exo. MiR-27a-5p was expressed 11 times higher in OD-Exo, while miR-27a-5p promoted odontogenic differentiation of DPSCs and significantly upregulated TGFβ1, TGFR1, p-Smad2/3, and Smad4 by downregulating the inhibitory molecule LTBP1. Conclusions The microRNA expression profiles of exosomes derived from DPSCs were identified. OD-Exo isolated under odontogenic conditions were better inducers of DPSC differentiation. Exosomal microRNAs promoted odontogenic differentiation via TGFβ1/smads signaling pathway by downregulating LTBP1. Electronic supplementary material The online version of this article (10.1186/s13287-019-1278-x) contains supplementary material, which is available to authorized users.

Exosomal microRNAs derived from mesenchymal stem cells: cell-to-cell messages

“…By analysis of the effects of MSC-exomiRNAs, some targeted genes were identified which contribute to specific pathways related to cell death and cell growth, and pathways related to fibrosis such as Wnt signaling, PDGF, and TGF-β [ 63 ]. In another study it was found that lineage-specific exosomes could promote the odontogenic differentiation of human dental pulp stem cells (DPSCs) through the TGFβ1/Smad signaling pathway via transfer of miRNAs such as miR-27a-5p [ 64 ].…”

Insight into the Role of Dental Pulp Stem Cells in Regenerative Therapy

“…Although the main substance contained in conditioned medium and exerting therapeutic effects has not been clarified, exosomes might play an important role in regenerative processes. Exosomes derived from DPSCs increased the odontogenic differentiation of DPSCs [ 146 ] and promoted the regeneration of dental pulp-like tissue [ 147 ]. In addition, Li et al demonstrated that exosomes derived from SHEDs suppressed neuroinflammation when they were transplanted into a rat brain injury model [ 148 ].…”

Exosomes From LPS-stimulated hDPSCs Promote the Angiogenesis of HUVECs

“…The cell signaling pathways by which hDPSC-EXOs regulate angiogenesis in an in ammatory environment remain unclear. Exosomal microRNAs negatively regulate the expression of their target genes by binding to the 3'UTRs of the target genes, causing translational repression [29,30]. By conducting microRNA sequencing, we found that the expression of certain microRNAs was downregulated/upregulated in the LPS-hDPSC-EXOs.…”