ABSTRACT
Objective To investigate the effects of transplantation with different amount of bone marrow mesenchymal stem cells(BMSCs)on osteoporosis in ovariectomized rats.Methods The rat model of osteoporosis was prepared by ovariectom(OVX)and verified after 3 months.A total of 60 female Sprague-Dawley rats were randomly divided into 6 groups(n=10 each).The rats with shamed operation served as a sham-injured control group(sham control group).The 5 ovariectom (OVX) groups with osteoporosis were study groups as follows:(1)the negative therapy group(simple OVX group);(2)the positive therapy group(OVX+ estrogen,E2 group) by intramuscular injection;others were treated with transplantation of BMSCs by tail vein injection in low dose(LS group),middle dose (MS group)and high dose(HS group).At 8,12 and 16 weeks after intervention,body mineral density (BMD)were detected by dual-energy x-ray absorptiometry scans.After 16 weeks of intervention,rat shinbone was obtained and stained by hematoxylin-eosin(HE) staining.Results Compared with the sham control group,simple OVX group showed a reduced total body BMD and the decreased proportion of trabecular bone to bone marrow cavity area (P ＜0.05).The total body BMD and the proportion of trabecular bone to bone marrow cavity area were higher in each BMSCs transplantation groups than in simple OVX group at 8,12,16 weeks after intervention(P ＜0.05),which showed a increased trend in the total body BMD and the proportion with the increased dose of transplantation BMSCs(P＜0.05).Rats in the HS group had highest BMD and best proportion of trabecular bone to bone marrow cavity area among three doses of transplantation BMSCs.Conclusions BMSCs transplantation can significantly improve osteoporosis of ovariectomized rats with an increased total body BMD and higher proportion of trabecular bone to bone marrow cavity area,and better and longer outcomes can be achieved.
ABSTRACT
Objective Based on structure of animal trabecular bone, implants with porous structure were designed to describe mechanical properties of trabecular structure and explain significance of bionic trabecular porous implants in clinical treatment. Methods Based on anisotropic mechanical properties of animal trabecular bone, a porous structure was designed using the topology optimization method. The principles of partition and block reconstruction were first proposed according to bone function theory. The trabecular structure was then reconstructed based on micro-CT images. The boundary constraint and external load were applied on this model according to the respective-volume-element (RVE) method. Taking the solved mechanical properties as objective functions of optimization, the porous structure design and optimization were conducted using the variable density method and the homogenization method. Results The trabecular bone possessed the anisotropic mechanical properties. It was found that the volume fraction showed an increasing trend from the edge to the middle across the same section of trabecular bone. But there was no obvious regular pattern in Poisson’s ratio, which was evenly distributed in the range between 0.17 and 0.30. As to the values of elastic modulus and shear modulus, they were both significantly higher in the main pressure position compared with those in the other positions. After topography optimization based on these mechanical properties, the Poisson’s ratio of the optimized model was in the same range as the animal trabecular bone. The elastic modulus error was less than 14%， with the minimum being only 3%. In addition, the shear modulus error was below 8%， which ultimately complied with criteria of the original goal. Conclusions The designed porous structure based on topology optimization had the same anisotropic characteristics as animal trabecular bone, while reducing the stress concentration phenomenon, which could achieve the specific design for porous structure, thus providing a reasonable and effective method for clinical porous implants.