Amelioration of ligamentum flavum hypertrophy using umbilical cord mesenchymal stromal cell-derived extracellular vesicles

Ligamentum flavum(LF)hypertrophy(LFH)has been recognised as one of the key contributors to lumbar spinal stenosis.Currently,no effective methods are available to ameliorate this hypertrophy.In this study,human umbilical cord mesenchymal stromal cell-derived extracellular vesicles(hUCMSC-EVs)were introduced for the first time as promising vehicles for drug delivery to treat LFH.The downregulation of miR-146a-5p and miR-221-3p expressions in human LF tissues negatively correlated with increased LF thickness.The hUCMSC-EVs enriched with these two miRNAs significantly suppressed LFH in vivo and notably ameliorated the progression of transforming growth factorβ1(TGF-β1)-induced fibrosis in vitro after delivering these two miRNAs to mouse LF cells.The results further demonstrated that miR-146a-5p and miR-221-3p directly bonded to the 3′-UTR regions of SMAD4 mRNA,thereby inhibiting the TGF-β/SMAD4 signalling pathway.Therefore,this translational study determined the effectiveness of a hUCMSC-EVs-based approach for the treatment of LFH and revealed the critical target of miR-146a-5p and miR-221-3p.Our findings provide new insights into promising therapeutics using a hUCMSC-EVs-based delivery system for patients with lumbar spinal stenosis.

Circular RNA circ_0003609 ameliorates hypertrophied ligamentum flavum by regulating the miR-155/SIRT1 axis

Background:Hypertrophy of the ligamentumflavum(HLF)is a common contributor to spinal stenosis which results in significant neurological impairments.Circular RNA(circRNA)circ_0003609 has been linked to HLF;however,the exact mechanism by which it causes this disease is unclear.Methods:Circ_0003609 expressions were regulated in HLF cells by overexpression vectors and RNA interference.Cell proliferation andfibrosis-related gene expression were checked by the Cell Counting Kit-8(CCK-8)assay and western blotting.CircBank’s prediction of the association between miR-155 and circ_0003609 was supported by a dual-luciferase reporter experiment.The function of the miR-155/sirtuin 1(SIRT1)axis in controlling HLFfibrosis was further examined.Results:Overexpression of circ_0003609 suppressed HLF cell propagation andfibrosis compared to its silencing.It was found that circ_0003609 served as the sponge for miR-155 and that the circ_0003609/miR-155 axis controlled thefibrosis of HLF cells.It was found that circ_0003609 acted as a sponge for miR-155,regulating thefibrosis of HLF cells.Further,miR-155 targets SIRT1,and the miR-155/SIRT1 axis promotes HLF cellfibrosis.Conclusion:Circ_0003609 ameliorates hypertrophied ligamentumflavum(LF)by modulating the miR-155/SIRT1 axis,indicating a potential treatment approach for HLF.