Effect of exosomes derived from rabbit bone marrow mesenchymal stem cells on the expression of collagen, aggrecan, and tumor necrosis factor-alpha genes in nucleus pulposus cells

Low back pain (LBP) is one of the most common musculoskeletal diseases in the world. Apoptosis of nucleus pulposus (NP) cells and structural changes in the intervertebral disc (IVD) matrix cause its degeneration and are directly related to LBP. Because of exosomes derived from mesenchymal stem cells (MSC-Exo) are high therapeutic potential and may be valuable options for decreasing intervertebral disc degeneration (IDD). 
The present study evaluates changes in the expression level of genes responsible for repairing NP cells (collagen and aggrecan) and tumor necrosis factor-alpha (TNF-α) gene and the effectiveness of exosomes in inhibiting excessive apoptosis of NP cells under inflammation.

Exosomes were separated by ultracentrifuge. They were identified with the help of transmission electron microscopy (TEM), atomic force microscope (AFM), and dynamic light scattering (DLS). Cell viability was evaluated by MTT assay and DAPI staining. Real-time PCR measured the expression of collagen, aggrecan, and TNF-α genes.

Exosomes are vesicles with a diameter of about 35.5 to 100 nm. Based on the findings of the MTT assay, the survival rate of the inflammatory cells treated with exosomes was significantly different from the inflammation group without treatment (*P<0.05 at the dose of 100 μg/ml, **P<0.01 at the doses of 25 and 50 μg/ml). DAPI results showed a decrease in cell death in the exosome-treated group. Real-time PCR results showed increased expression of collagen (*P<0.05) and aggrecan (***P<0.001) genes and decreased the TNF-α (**P<0.01) gene in inflammatory cells treated with exosomes.

Exosomes derived from mesenchymal stem cells can increase collagen and aggrecan gene expression and decrease TNF-α gene expression in treated cells.