Objective To gain purified platelets for further research of the immune function of platelet.Methods Platelets were purified by positive(MS) and negative(LD) magnetic cell sorting(MACS) separation.The percentage of activated platelets was detected by flow cytometry and nucleated cell clearance was evaluated by white cell count.Results The percentage of activated platelets before separation was(2.39?1.10)%,and increased to(2.56?1.08)% and(16.76?4.04)%,respectively,after MS and LD MACS.The clearances of nucleated cells after MACS MS and LD were(98.44?0.24)% and(98.47?0.18)%,respectively.The recovery rate of purified platelet after MS and LD was(76.50?1.49)% and(79.20?2.61)%.Conclusion MACS LD method was more suitable for the platelet purification.

Objective To analyze the change of phosphotidyl serine(PS) in apheresis platelets(plts) during storage process,and to evaluate the quality of the plts during the storage period.Methods The apoptosis ligand Fas(CD95) was used to induce plts as apoptosis model,and by which the method to detect plts PS by flow cytometry(FCM) was established.Subsequently the resting PS expressive rate and the induced PS expressive rate of 30 apheresis plts,which induced by CD95,were determined using the FCM method established in storage process.Results At the 1st,5th,7th,8th day of storage process,the PS expression of plts kept on increasing.The PS expressive rate of plts were 2.03%?0.91%,3.26%?1.86%,8.98%?4.60%,26.68%?21.28%,and 38.85%?26.43%,respectively,and there were significant differences among groups respectively(P0.05).Conclusion The PS expression of apheresis plts increase significantly with the prolongation of storage time;Fresh plts has the ability of anti-apoptosis;Apheresis plts could keep normal function until storage 7 d.

Objective To analyze and compare pore characteristics and mechanical properties of models with solid and sheet triply periodic minimal surface (TPMS) structures, and build a porous structure with high specific surface area, low stiffness and high strength. Methods The solid TPMS and sheet TPMS models of D, G, and P units with the same porosity were established, and pore characteristics of the model such as pore diameter, rod diameter and specific surface area were compared; mechanical properties of the model were analyzed by finite element method. The porous titanium samples were made by additive manufacturing technology, pore characteristics of porous titanium were observed by microscope and scanning electron microscope, and mechanical properties of porous titanium were detected by compression test. Results The specific surface area of the sheet structure with the same unit was significantly higher than that of the solid structure; mechanical properties of the sheet structure with the same were significantly better than those of the solid structure. Among them, the D unit sheet TPMS model had the most significant advantages, with the specific surface area of 13.00 mm-1, and the elastic modulus, yield strength and compressive strength of the sheet porous titanium sample were (5.65±0.08) GPa, (181.03±1.30) MPa and (239.83±0.45) MPa, respectively, which were 43.87%, 55.08% and 67.21% higher than those of the solid porous titanium sample. Conclusions While retaining low rigidity of the porous structure, the sheet TPMS model of the same unit has a larger specific surface area, which is beneficial for cell adhesion and growth, and its low stiffness and high strength mechanical properties can effectively reduce stress shielding and provide sufficient mechanical support. It is an ideal pore structure model for bone defect repair substitutes.