BMP-2 promotes osteogenic differentiation of mesenchymal stem cells by enhancing mitochondrial activity.

OBJECTIVES: Mesenchymal stem cells (MSCs) have become seed cells and basic elements for bone regeneration and bone tissue engineering. The aim of the present study was to investigate the roles and mechanisms of bone morphogenetic protein 2 (BMP-2) on osteogenic differentiation of MSCs. METHODS: Primary MSCs were isolated from the femur and tibia bone of rats and then transfected with BMP-2 and PGC-1α adenovirus vectors. Alkaline phosphatase (ALP) activity and alizarin red staining were used to measure osteogenic differentiation of MSCs. Real-time PCR and western blot assays were performed to assess osteogenic differentiation-related proteins levels. The activities of mitochondrial respiratory chain complexes I and II and mitochondrial fluorescence intensity were used to explore mitochondria status during osteogenic differentiation of MSCs. RESULTS: We found that the ability of BMP-2 overexpressed (OE) group osteogenic differentiation was significantly improved, compared with the negative control (NC) group. The results also indicated that BMP-2 can promote the activity of mitochondria. We further used the gain- and loss-of-function approaches to demonstrate that BMP-2 promotes mitochondrial activity by up-regulating PGC-1α to promote osteogenic differentiation of MSCs. CONCLUSIONS: These results explored the important role of BMP-2 in the osteoblast differentiation of MSCs from a new perspective, providing a theoretical and experimental basis for bone defect and repair.

Comparison of the effects of minimally invasive percutaneous pedicle screws osteosynthesis and open surgery on repairing the pain, inflammation and recovery of thoracolumbar vertebra fracture.

We compared the clinical effects of minimally invasive percutaneous pedicle screws osteosynthesis (MIPPSO) and open surgery on the repair of thoracolumbar vertebra fracture. Seventy patients, who suffered from thoracolumbar vertebra fracture and received treatment at our hospital, were selected and randomly divided into either the minimally invasive percutaneous pedicle screws osteosynthesis group (MIPPSO group) and the traditional open pedicle screws osteosynthesis group (TOPSO group) with 35 cases in each group. The perioperative parameters including length of incision, duration of operation, bleeding during operation, length of hospital stay, the changes of pre-operative and post-operative VAS pain scores, inflammatory indexes including serum C-reactive protein (CRP) and creatine kinase (CK), and imaging indexes including Cobb's angle and anterior margin height of vertebral body of both groups were compared. The length of incision, duration of operation, bleeding volume during operation and length of hospital stay in the MIPPSO group were significantly lower than those in the TOPSO group (P<0.05). Both minimally invasive surgery and traditional surgery effectively alleviated the pain (P<0.05), which was more significant in MIPPSO group (P<0.05). The post-operative inflammatory indexes, CRP and CK levels, of both groups were higher compared to the pre-operation (P<0.05), which was more significant in TOPSO group (P<0.05). The differences of imaging indexes, including Cobb's angle and anterior margin height of injured vertebra, were statistically significant between pre-operation and post-operation for each group (P<0.05); however, there were no statistically significant differences between two groups at either pre-operation or post-operation (P>0.05). The effect of minimally invasive percutaneous pedicle screws osteosynthesis is similar to the traditional open surgery, however, the MIPPSO technique has the advantages of small trauma, less bleeding, short duration of operation, rapid post-operative recovery, light pain, less economic cost, and better aesthetic effect and is therefore worthy of clinical promotion.