To investigate the effect of human umbilical cord mesenchymal stem cell derived exosomes (huc-MSCs-exo) on cartilage apoptosis in osteoarthritis (OA) rats.

Huc-MSCs-exo was isolated and extracted from the umbilical cord of healthy and full-term cesarean section newborns. Thirty Wistar rats were randomly divided into sham operation group, model group and treatment group (10 rats in each group). OA model rats were prepared in the model group and treatment group. Huc-MSCs-exo 100μg was injected into the articular cavity after treatment. After eight weeks of treatment, the gait disorder score, cartilage histomorphological changes, chondrocyte apoptosis and nitric oxide (NO) expression were compared. Detection of tumor necrosis factor -α(TNF- α) in cartilage by real time PCR、interleukin(IL)-1β、IL-4, B-cell lymphoma gene-2 (Bcl-2) and Bcl-2 related X protein (Bax) mRNA expression. Another 12 rats were chosen, among which sixratswere normalfed and the other six rats were used for knee OA modeling. After the models were succeeded, OA chondrocytes were isolated, cultured and stained. The normal chondrocytes were used as the control group, and the OA chondrocytes were also cultured and divided into the OA group and the experimental group. The experimental group were cultured with 1g/L huc-MSCs-exo 0.2 ml, while the control group and the OA group were cultured with phosphate buffer. The three groups of cells were cultured for 24 h. The inhibition rate of cell proliferation, apoptosis and NO expression were compared by LSD t test.

Compared with the model group, in the treatment group, the gait disorder score decreased (t =5.49, P<0.001), the content of no decreased (t=15.69, P<0.001), the value of apoptosis index (AI) decreased (t=7.42, P<0.001). The expression of TNF- α and IL-1β decreased (t =5.74, P <0.001) (t=17.22, P<0.001), the expression of IL-4 decreased (t=11.33, P<0.001), the expression of Bax mRNA decreased (t=19.51, P<0.001), while the expression of bcl-2 mRNA increased (t=10.12, P<0.001).

Huc-MSCs-exocan effectively improve chondrocyte apoptosis in knee OA rats, and its mechanism may be related to improving inflammatory response.