Synovial mesenchymal stem cells effectively alleviate osteoarthritis through promoting the proliferation and differentiation of meniscus chondrocytes

OBJECTIVE

To investigate the relationship between the meniscal defect area and OA progression and explore the effect and mechanism of SMSCs cell therapy in knee osteoarthritis (OA) rat model.

MATERIALS AND METHODS

For animal experiments, knee osteoarthritis (OA) model was constructed in Sprague Dawley (SD) rats by removing the medial meniscus of the right knee. Synovial mesenchymal stem cells (SMSCs) were engrafted by injecting into the right knee cavity. For in vitro experiments, CCK-8 assay was performed to evaluate the proliferation and differentiation of BMSCs and ATDC5 cells after co-cultured with SMSCs. qRT-PCR analysis was performed to detect the expressions of chondrogenic genes in BMSCs and ATDC5 cells after co-cultured with SMSCs. Western blot analysis was conducted to detect the phosphorylations of c-Jun N-terminal kinase (JNK) and extracellular regulated protein kinases (ERK) in MAPK signaling of BMSCs and ATDC5 cells. Enzyme-linked immunosorbent assay (ELISA) was performed to detect the serum levels of interleukin (IL)-1β, IL-1β, IL-6, IL-18 and C-reactive protein (CRP).

RESULTS

Results showed that meniscus damaged area is positively correlated to serum inflammatory factor levels. In vitro study showed that the proliferation and differentiation of BMSCs and ATDC5 cells were promoted after co-cultured with SMSCs. By co-culturing with SMSCs, the MAPK signaling pathway was activated and the expression of chondrogenic markers such as aggrecan (acan), SRY-related high mobility group-box gene 9 (sox9) and Type II collagen a1 (col2a1), was up-regulated both in BMSCs and ATDC5 cells. In vivo study showed SMSCs cell therapy significantly decreased serum inflammatory factor levels and protected cartilage by upregulating the expression of chondrogenic genes of meniscus chondrocytes derived from OA rats.

CONCLUSIONS

For the first time, we found the positive correlation between meniscal defect area and OA progression and demonstrated the effect and mechanism of SMSCs cell therapy in knee osteoarthritis (OA) treatment.

Synthesis of poly (3-hydroxybutyrate-co-3-hydroxyoctanoate) by a Sinorhizobium fredii strain

AIMS

The potential of a Sinorhizobium fredii strain to produce a copolymer from glucose and sodium dodecanoate substrates was investigated.

METHODS AND RESULTS

Using an orthogonal design in a flask-shaker culture system, the vital regulation conditions for copolymer synthesis were optimized. These optimal results were applied to further studies in a two-stage fed-batch fermentation with a 10-l fermentor. When the biomass approached 33.5 g l(-1) dry cells at 35 h, 7 mmol l(-1) sodium dodecanoate was added into the broth to trigger the copolymer synthesis. After further culturing for 3 h, the copolymer product could be 17.14 g l(-1). The molecular structure of the copolymer was determined to be a poly (3-hydroxybutyrate-co-3-hydroxyoctanoate) [P (HB-HO)] by nuclear magnetic resonance. The content of HB and HO in P (HB-HO) was 79.2% (w/w) and 20.8% (w/w) respectively. The molecular weight of the P (HB-HO) was measured as 1.85 x 10(5) Da by a viscosity method.

CONCLUSION

The results demonstrated that the S. fredii strain used could be a potential candidate for the industrial production of the copolymer.

SIGNIFICANCE AND IMPACT OF THE STUDY

Some basic fermentation parameters were acquired through the fed-batch culturing experiments and they should be applicable in developing large-scale fermentation technologies for producing the P (HB-HO) copolymers.