Experimental study on the long-term conversion of fresh and cryopreserved osteochondral allografts after transplantation / 中国矫形外科杂志

[Objective]To compare long-term conversion between fresh and cryopreserved osteochondral allografts in order to further provide theoretical foundation for treatment of articular cartilage defect using osteochondral allografts. [Methods]Articular cartilage defect models of 5 mm in diameter and depth were established for 32 New Zealand rabbit’s knees and treated by fresh and cryopreserved osteochondral allografts. Allografts were harvested and assessed by observing and analysing proteoglycan content,chondrocyte viability and ultrastructure of articular cartilage using Alcianblue staining and BCECF-AM /PI fluorescent staining,respectively,at 12 and 18 months postoperatively.[Results]Proteoglycan content and percentage of viable chondrocytes of osteochondral allografts were obviously decreased.Results of fresh osteochondral allografts were significantly better than those of cryopreserved osteochondral allografts at different time points. Ultrastructure of chondrocytes demonstrated degenerative changes.[Conclusion]In treatment of artificial articular cartilage defect ,serious degenerative changes were found for both fresh and cryopreserved osteochondral allografts at a long period,suggesting that fresh,especially cryopreserved osteochondral allografts are not feasible to treat articular cartilage defect.

Fluid stress with multiple mechanisms to enhance the cell cycle progression of osteoblastic cells from G1 to S phase / 中国矫形外科杂志

[Objective] To investigate into the cellular mechanism of growth promotion due to shear stress by studying G1-phase events responsible for the suppression of cell transition from the G1 to S phase of the cell cycle,and to establish the most suitable physiological stress to stimulate bone formation.[Methods]The osteoblasts derived from Kunming murine's calvaria were exposed to Fliud shear stress(FSS:12 dyn/cm2)for 0,0.25,0.5,1,2,4 h,respectively.In the flow chamber,its impact on cell proliferation,differentiation and the effection of cell cycle's G1/S checkpoint were recorded.The cell proliferation was studied by MTT assay.The cell differentiation was assessed through alkaline phosphatase(ALP)activity assay.Flow-cytometry,immunofluorescence and RT-PCR techniques were used to evaluate the proportion of S phase in cell cycle,the activity of CDK2,CDK4 and the expression of E2F-1,p27mRNA,which demonstrate how FSS underlying multiple mechanisms to enhance the cell cycle progression from G1 to S phase.[Results]FSS increased proliferation and advanced the time in cell growth curve,but after 1,2,4 h,the proliferation was inhibited.The FSS also increased the ALP activity,which were significantly stimulated at 0.25 and 0.5 h after shear stress(128% and 158 % of control);but the FSS decreased ALP activity at 1,2,and 4 hs.The proportion of S phase in cell cycle raised within the early period.The S phase rate significantly increased at 0.5 h(P

Two-way Regulation of Apoptosis-inducing Factor SIVA-1 in the Proliferation and Differentiation of Osteoblasts under Fluid Shear Stress / 中国微创外科杂志

Objective To investigate the regulatory effect of fluid shear stress(FSS) on the proliferation and differentiation of osteoblasts,as well as the expression of apoptosis-inducing factor,SIVA-1.Methods The third-passage osteoblasts were divided into five experiment groups and one control group.In the experiment groups,1.2 Pa FSS were given to the osteoblasts for 0.25,0.5,1,2,and 4 hours respectively,while the control group received no FSS.Afterwards,the cells were harvested to measure MTT value and ALP activity;mRNA level of SIVA-1 were determined by RT-PCR.Results MTT revealed that the cells proliferation markedly increased in the 0.25 h and 0.5 h experiment groups with advanced cell growth curve;whereas significantly inhibited in 1,2,and 4 h groups.The FSS also increased the ALP activity at 0.25 and 0.5 hour,especially in the 0.5 h group(2.4320?0.205 S unit/100ml,158% of the control;P