Inhibition of the Notch1 Pathway Promotes the Effects of Nucleus Pulposus Cell-Derived Exosomes on the Differentiation of Mesenchymal Stem Cells into Nucleus Pulposus-Like Cells in Rats

Abstract

Stem cell therapies for intervertebral disc degeneration have been demonstrated as a promising strategy. Previous studies have shown that human nucleus pulposus cell- (NPC-) derived exosomes can induce the differentiation of mesenchymal stem cells (MSCs) into NP-like cells in vitro. However, the mechanism of MSC differentiation into NP-like cells with the induction of NPC exosomes is still unclear. Here, we verified the induction effects of NPC exosomes on the differentiation of MSCs into NP-like cells. In addition, the Notch1 pathway was downregulated in this process. Then, DAPT and soluble Jagged1 (SJAG) were applied to inhibit or enhance the expression of the Notch1 pathway, respectively, resulting in the upregulation or downregulation of collagen II, aggrecan, and Sox9 in MSCs. Knocking down of Notch1 protein facilitated the effects of NPC exosomes on the differentiation of MSCs into NP-like cells. NPC exosomes were more effective than an indirect coculture system in terms of the differentiation of MSCs into NP-like cells. Inhibition of NPC exosome secretion with Rab27a siRNA prevented the induction effects of an indirect coculture system on the differentiation of MSCs into NP-like cells. Transwell migration assays revealed that NPC exosomes could promote the migration of MSCs. Taken together, the Notch1 pathway was negatively associated with the differentiation of MSCs into NP-like cells with the treatments of NPC exosomes. Inhibition of the Notch1 pathway facilitates NPC exosome-induced differentiation of MSCs into NP-like cells in vitro. NPC exosomes play a key role in the differentiation of MSCs into NP-like cells in an indirect coculture system of NPCs and MSCs.

Therapeutic Potential of Extracellular Vesicles in Degenerative Diseases of the Intervertebral Disc

“…Notochordal cell-derived EVs increased DNA and glycosaminoglycan content in human NP cell micro-aggregates compared to untreated control medium, although the underlying mechanism or the associated EV content was not analyzed in this study by the Tryfonidou Lab (Bach et al, 2017). EVs harvested from human NP cells derived from patients with lumbar degenerative disease were able to promote MSC migration and differentiation into an NP-like phenotype (Lu et al, 2017) through the Notch1 pathway (Lan et al, 2019), although the EV content responsible for this action (e.g., specific miRNAs) remains unknown at this time. However, a delicate interplay between different miRNAs and components of Notch signaling pathway has been identified in cancer, pointing toward miR-146a, miR-19, miR-100, miR-21, miR-181a-1/b-1, miR-375, and miR-483-5p as potentially interesting candidates for further investigation in the IVD field (Majidinia et al, 2018).…”

Mesenchymal stem cells regulate inflammatory milieu within degenerative nucleus pulposus cells via p38 MAPK pathway

“…Not until recently have MSCs been introduced into the therapeutic managements of IDD, emerging as a promising strategy from bench (11)(12)(13) to bedside (14). MCSs are probably implicated in the degenerative disc repair in the following aspects: i) complement damaged cells through regeneration of disc-specific cells that have the ability to produce ECM components; ii) control the inflammatory response and (III) promote tissue regeneration by virtue of paracrine signaling factors (15).…”

Biomaterials-Induced Stem Cells Specific Differentiation Into Intervertebral Disc Lineage Cells

“…Numerous signaling pathways, including the Notch1, the Sonic Hedgehog (Shh) and NF-κB signaling pathways, have been shown to be related to IVD-like cell differentiation (Dahia et al, 2012;Cao et al, 2015;Lan et al, 2019). Identifying the key pathway that is most closely associated with biomaterials-induced IVD differentiation could provide novel perspectives for the future research and development of materials (Figure 6).…”