Mesenchymal stem cell exosomes inhibit nucleus pulposus cell apoptosis via the miR-125b-5p/TRAF6/NF-κB pathway axis

Abstract

Intervertebral disc degeneration (IVDD) is the pathological basis of a range of degenerative spinal diseases and is the primary cause of lower back pain. Mesenchymal stem cell (MSC) transplantation inhibits IVDD progression. However, the specific mechanisms that underlie these effects remain unclear. In this study, candidate microRNAs (miRNAs) are screened using bioinformatics and high-throughput sequencing. TNF-α is used to induce nucleus pulposus cell (NPC) degeneration. MSC-derived exosomes (MSC-exosomes) are obtained using high-speed centrifugation and identified by transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA) and western blot analysis. Cell viability is determined by CCK-8 assay. Flow cytometry and TUNEL assays are used to detect cell apoptosis. The expression levels of miR-125b-5p are detected by RT-qPCR, and a dual-luciferase gene reporter assay confirms the downstream target genes of miR-125b-5p. Protein expression is determined by western blot analysis. Rat models are used to validate the function of miR-125b-5p in MSC-exosomes. The results show that miR-125b-5p is expressed at low levels in degenerated disc tissues compared with that in normal disc tissues; however, it is highly expressed in MSC-exosomes. Furthermore, MSC-exosomes are efficiently taken up by NPCs while miR-125b-5p is delivered into NPCs; thus, MSC-exosomes act as inhibitors of apoptosis in NPCs. Overexpression of miR-125b-5p downregulates TRAF6 expression and inhibits NF-κB activation. However, TRAF6 overexpression reverses these effects of miR-125b-5p. We demonstrate that MSC-exosomes attenuate IVDD in vivo by delivering miR-125b-5p. MSC-exosomes can deliver miR-125b-5p to target TRAF6, inhibit NF-κB activation, and attenuate the progression of IVDD.

From drugs to biomaterials: a review of emerging therapeutic strategies for intervertebral disc inflammation

“…Additionally, the regulatory measures and ethical concerns associated with cell therapy products derived from human sources pose significant challenges, consuming a substantial amount of time. Numerous studies have suggested that cell therapy achieves therapeutic effects by activating pathways through paracrine signaling molecules ( Duan et al., 2023 ; Zhou et al., 2023 ). Consequently, extracellular vesicles (EVs) have emerged as a new focal point of research.…”

Maslinic acid alleviates intervertebral disc degeneration by inhibiting the PI3K/AKT and NF-κB signaling pathways

“…Several reports on reversing IDD have been published, such as related studies on exosomes [ 15 ‒ 17 ] and some examples of new classical drugs, including metformin [18] and dexamethasone [19] . However, at present, the main treatment for IDD is still limited to relieving symptoms, which cannot solve the fundamental problem of disc degeneration [20] .…”