Objective To explore the effect of rolling compression loading bioreactor on chondrogenesis of rabbit bone marrow mesenchymal stem cells (BMSCs) with different loading parameters. Methods BMSCs were isolated from New Zealand rabbits, aged 2.5 months. BMSCs at passage 3 were used to prepare BMSCs-agarose gels (4 mm in diameter and height, respectively). Samples were divided into 8 groups: 10% (group A1), 20% (group A2), and 30% (group A3) compression groups (0.4 Hz, 3 h/ d) and 20 minutes (group B1), 3 hours (group B2), and 12 hours (group B3) rolling time groups and static culture (control groups). The living cell rate, the collagen type II and Aggrecan gene expressions, and glycosaminoglycan (GAG) content were determined, and histological staining was done at 24 hours, 7 days, 14 days, and 21 days after culture. Results At 14 and 21 days, the living cell rates of groups A1 and A2 were significantly higher than that of group A3 (P lt; 0.05), groups B1 and B2 were significantly higher than group B3 (P lt; 0.05). Collagen type II and Aggrecan gene expressions of the experimental groups at each time point were significantly higher than those of the control groups (P lt; 0.05); at 14 and 21 days, collagen type II and Aggrecan gene expressions of groups A1 and A2 were significantly higher than those of group A3, and groups B1 and B2 were also significantly higher than group B3 (P lt; 0.05). At 14 and 21 days, the GAG contents of groups A1 and A2 were significantly higher than those of group A3 (P lt; 0.05); groups B1 and B2 were also significantly higher than group B3 (P lt; 0.05). At 21 days, toluidine blue staining showed that obvious blue-staining and even cartilage lacunae were seen in groups A2 and B2, but light and quite rare blue-staining in groups A1, A3, B1, and B3. Conclusion The rolling compression loading bioreactor has great promotion effect on chondrogenesis of rabbit BMSCs with rolling parameters of 0.4 Hz, 3 hours, and 20% compression.
目的 总结肾动脉下腹主动脉瘤腔内修复术的初步经验。 方法 对我院2006年8月至2009年3月期间收治的10例肾动脉下腹主动脉瘤患者在全麻下采用单侧或双侧股动脉入路置入带膜支架行腔内修复术。 结果 10例肾动脉下腹主动脉瘤采用腔内修复治疗，带膜支架置入顺利，立即DSA 7例动脉瘤体消失，Ⅰ型内瘘2例，经支架附着点球囊扩张后内瘘即刻消失。随访3～30个月(平均10个月)，2例术后切口淋巴瘘，经换药痊愈。全部患者肢体血运正常。1例发生Ⅱ型内瘘，未经治疗，随访2个月后消失。 结论 腔内修复术对肾动脉下腹主动脉瘤是一种创伤小、恢复快及效果好的治疗方法。
目的 探讨捆绑式胰肠吻合术在预防胰十二指肠切除术后胰肠吻合口漏的可行性及临床应用价值。 方法 我院在2002年3月至2006年10月期间对32例胰十二指肠切除术患者采用捆绑式胰肠吻合术。结果 32例患者手术均顺利，无一例发生胰瘘，无手术死亡病例。 术后发生胆瘘2例，经腹腔引流治愈。结论 捆绑式胰肠吻合术操作简便，预防胰瘘效果可靠，值得推广。
Cartilage surface fibrosis is an early sign of osteoarthritis and cartilage surface damage is closely related to load. The purpose of this study was to study the relationship between cartilage surface roughness and load. By applying impact, compression and fatigue loads on fresh porcine articular cartilage, the rough value of cartilage surface was measured at an interval of 10 min each time and the change rule of roughness before and after loading was obtained. It was found that the load increased the roughness of cartilage surface and the increased value was related to the load size. The time of roughness returning to the initial condition was related to the load type and the load size. The impact load had the greatest influence on the roughness of cartilage surface, followed by the severe fatigue load, compression load and mild fatigue load. This article provides reference data for revealing the pathogenesis of early osteoarthritis and preventing and treating articular cartilage diseases.
Based on transversely isotropic theory, a finite element model for three-dimensional solid-liquid coupling defect repair of articular cartilage was established. By studying stress state of host cartilage near the restoration interface, we identified deformation type of cartilage and discussed the cause of restoration interface cracking. The results showed that the host cartilage surface node near the restoration interface underwent compression deformation in the condition of surface layer defect repair. When the middle layer, deep layer or full-thickness defect were repaired, the node underwent tensile deformation. At this point, the radial dimension of cartilage increased, which might cause restoration interface cracking. If elastic modulus of the tissue engineered cartilage (TEC) was lower (0.1 MPa, 0.3 MPa), the host cartilage surface layer and middle layer mainly underwent tensile deformation. While elastic modulus of TEC was higher (0.6 MPa, 0.9 MPa), each layer of host cartilage underwent compression deformation. Therefore, the elastic modulus of TEC could be increased properly for full-thickness defect repair. This article provides a new idea for evaluating the effect of cartilage tissue engineering repair, and has a certain guiding significance for clinical practice.
In order to study the mechanical behavior of degeneration and nucleotomy of lumbar intervertebral disc, compression experiments with porcine lumbar intervertebral discs were carried out. The lumbar intervertebral discs with trypsin-treated and nucleus nucleotomy served as the experimental group and the normal discs as the control group. Considering the effects of load magnitude and loading rate, the relationship between stress and strain, instantaneous elastic modulus and creep property of intervertebral disc were obtained. The creep constitutive model was established. The results show that the strain and creep strain of the experimental group increase significantly with the increase of compression load and loading rate, whereas the instantaneous elastic modulus decreases obviously, compared with the control group. It indicates that the effect of load magnitude and loading rate on load-bearing capacity of intervertebral disc after nucleotomy is larger obviously than that of normal disc. The creep behavior of the experimental group can be still predicted by the Kelvin three-parameter solid model. The results will provide theoretical foundation for clinical treatment and postoperative rehabilitation of intervertebral disc disease.
Based on the current study of the influence of mechanical factors on cell behavior which relies heavily on experiments in vivo, a culture chamber with a large uniform strain area containing a linear motor-powered, up-to-20-Hz cell stretch loading device was developed to exert mechanical effects on cells. In this paper, using the strain uniformity as the target and the substrate thickness as the variable, the substrate bottom of the conventional incubation chamber is optimized by using finite element technique, and finally a new three-dimensional model of the incubation chamber with “M” type structure in the section is constructed, and the distribution of strain and displacement fields are detected by 3D-DIC to verify the numerical simulation results. The experimental results showed that the new cell culture chamber increased the accuracy and homogeneous area of strain loading by 49.13% to 52.45% compared with that before optimization. In addition, the morphological changes of tongue squamous carcinoma cells under the same strain and different loading times were initially studied using this novel culture chamber. In conclusion, the novel cell culture chamber constructed in this paper combines the advantages of previous techniques to deliver uniform and accurate strains for a wide range of cell mechanobiology studies.
Triply periodic minimal surface (TPMS) is widely used because it can be used to control the shape of porous scaffolds precisely by formula. In this paper, an I-wrapped package (I-WP) type porous scaffolds were constructed. The finite element method was used to study the relationship between the wall thickness and period, the morphology and mechanical properties of the scaffolds, as well as to study the compression and fluid properties. It was found that the porosity of I-WP type scaffolds with different wall thicknesses (0.1 ~ 0.2 mm) and periods (I-WP 1 ~ I-WP 5) ranged from 68.01% ~ 96.48%, and the equivalent elastic modulus ranged from 0.655 ~ 18.602 GPa; the stress distribution of the scaffolds tended to be uniform with the increase of periods and wall thicknesses; the equivalent elastic modulus of the I-WP type scaffolds was basically unchanged after the topology optimization, and the permeability was improved by 52.3%. In conclusion, for the I-WP type scaffolds, the period parameter can be adjusted first, then the wall thickness parameter can be controlled. Topology optimization can be combined to meet the design requirements. The I-WP scaffolds constructed in this paper have good mechanical properties and meet the requirements of repairing human bone tissue, which may provide a new choice for the design of artificial bone trabecular scaffolds.