BACKGROUND:At present,there are two main methods of isolating and purifying bone marrow mesenchymal stem cells(BMSCs):density gradient centrifugation and the whole bone marrow adherent method.The former has complicated procedures,and the latter has simple operation,but the purified outcomes are not ideal.OBJECTIVE:To establish a rat BMSCs isolated and cultured in vitro purification methods on the basis of the whole bone marrowadherence and isolation of BMSCs in combination of differential passage digestion method.METHODS:By whole bone marrow adherent culturing to isolate and differential digestion and passage of rat BMSCs,the speed ofMSCs in the process of digestion and passage was quicker than other bone marrow cells,as well as the characteristics of adherentspeed,instead of density gradient centrifugation to separate and purify MSCs,and their morphological characteristics wereobserved.Cell growth and proliferation of two kinds of culture method were compared with the density gradient centdfugationseparation.Alkaline phosphatase and oil red staining results were observed to verify BMSC differentiation capacity,to detect thecall surface markers,to validate immune properties and to test its purity.RESULTS AND CONCLUSION:The whole bone marrow adherent culture method isolated and differentially subcultured ratBMSCs.Flow cytometry and osteogenic and adipogenic culture results displayed cytoirnmunity property,purity and differentialcapacity,which have no significant difference compared with density gradient centrifugation.However,cell viability andreproductive activity are obviously elevated.

Objective:To analyze the stress distribution in the fixed denture of edentulous maxilla supported by 6 implants at different implant position.Methods:The skull of a volunteer with total anodontia and moderate alveolar bone absorption was scanned by CBCT.Computer software,Abaqus 6.9,Geomagic Studio 12,and Mimics10.01,were applied for data processing and reconstruction of a 3D finite element model of implant-supported fixed denture with 6 implants in different location;and then,the stress distribution was analisized.Results:3D finite element model of edentulous maxillary implant-supported fixed bridge with good geometric similarity was established.The implant neck bone interface stress value of the distal of the implant fixed bridge at the molar area,the stress concentration area,was the maximum.The main stresses were compressive in the cortical bone adjacent to the mesial or the distal implants.The shift of the denture decreased from anterior to posterior.In model Ⅰ (implants at 13,15,17,23,25 and 27) distal cantilever was not used and the stress distribution was the evenest.Conclusion:The implant position at 13,15,17,23,25 and 27 of edentulous maxillary 6-implants-supported fixed bridge was the best for the stress distribution among the 8 models.

BACKGROUND:The preliminary findings confirm that bone marrow mesenchymal stem celltransplantation is safe and effective in the treatment of acute myocardial infarction, but its exact mechanism is unclear. There are few studies addressing the survival status of transplanted stem cells and its acting timing.
OBJECTIVE:To study the survival of rat bone marrow mesenchymal stem cells transplanted into the infracted myocardium. METHODS:Bone marrow mesenchymal stem cells were cultured using density gradient centrifugation. Eighty rat models of myocardial infarction were prepared. Bone marrow mesenchymal stem cells were injected via a microsyringe at four sites around the infarcted region at 14 days after modeling. Then, 70 rats with living cells were selected for detecting the survival of bone marrow mesenchymal stem cells at days 3, 5, 7, 10, 20, 28 after transplantation. RESULTS AND CONCLUSION:Under ×400 visual field, the number of Brdu-positive bone marrow mesenchymal stem cells was (36±12) at 3 days posttranplantation, (33±13) at 5 days, (28±9) at 7 days, (15±5) at 10 days, (5±3) at 14 days, 0 at 20 days, and 0 at 28 days, showing a overal downward trend after transplantation. The number of bone marrow mesenchymal stem cells was negatively correlated with transplant days (P<0.01, r=-0.47). The number of cells decreased most significantly within 1 week after transplantation, and then decreased to 0 at 20 days. These findings indicate that transplanted bone marrow mesenchymal stem cells in the myocardium cannot survive for a long term and also cannot be transformed into myocardial tissue.

Objective To investigate the value of blood oxygenation level dependent(BOLD)fMRI in assessing the functional changes of the lumbar dorsal extensor muscles before and after exercise in healthy young people.Methods The changes of the R2*value of lumbar dorsal extensor group in 30 healthy young volunteers(15 males and 15 females)before and after exercise was prospectively studied.BOLD-fMRI scans were performed on healthy young volunteers before and after exercise, the exercise mode was to perform the upper body flexion and extension movement with a simple Rome stool.The scanned images were processed and analyzed, the cross-sectional area and R2* value of the lumbar dorsal extensor muscles (including the multifidus,the longissimus and the iliocostalis)were measured at the upper margin of the L3 and L4 vertebral body before and after exercise.The paired t test was used to compare CSA and R2*values of muscles before and after loading. The CSA and R2* value of different muscles in different sides were compared by independent sample t test. Pearson correlation analysis was used to analyze the relevance between CSA and R2* in muscle before and after exercise. Results After exercise, the R2* values of multifidus,longissimus and iliocostalis at the upper margin of the L4 vertebral body were[(39.2±8.6),(38.9± 7.7),(41.6±7.8)]Hz,significantly lower than before exercise[(46.1±6.9),(45.3±6.2),(46.0±6.7)]Hz(P<0.01);the changes of R2*values of the muscles between the left and right sides before and after the movements were not statistically significant(P>0.05).The R2*values of longissimus and iliocostalis at the upper margin of the L3 vertebral body were[(44.2±9.1),(46.6±9.3)]Hz,significantly lower than before exercise[(48.6±7.2),(49.7± 6.8)]Hz (P<0.01), but the R2* values of multifidus after loading was (43.9 ± 9.0)Hz, there was no statistical difference compared with before exercise (46.8 ± 6.6)Hz (P>0.05);there was a significant difference in the changes of R2*value before and after the movement between the left and right side of iliocostalis(P<0.05).A significant negative correlation between CSA and R2*value was found in the iliocostalis on the right side at the upper margin of L3 vertebral body and in the multifidus on the left side at the upper margin of L4 vertebral body,and the correlation coefficients were (-0.697,-0.616).Conclusion BOLD-fMRI can be a new way to assess the functional changes of the lumbar dorsal extensor group before and after exercise.