Biomechanical characteristics of ankle joint in volleyball players during stop-jump / 中国组织工程研究

BACKGROUND: The biomechanical studies of ankle joint focus on methodology, and the biomechanical characteristics of the ankle joint under combined modes are little reported. OBJECTIVE: To analyze the kinematics and dynamics characteristics of the ankle joints in the movement of stop-jump of volleyball players. METHODS: Twenty male and 20 female volleyball players at Tianjin University of Sport were selected. The three-dimensional motion capture system (Vicon) and the three-dimensional force plate (Kistler) were mainly used to synchronously collect the kinematics and dynamics parameters of the ankle joint when the subjects were taking off and landing. Statistical methods were used to conduct comparative analysis of the data. The study was in accordance with the ethical requirements of Tianjin University of Sport, and the subjects signed the informed consents. RESULTS AND CONCLUSION: (1) Under this mode, the plantar flexion angle of the ankle joint in males was less than that in females. During the take-off phase, the ankle joint was in an inversion and internal rotation state, during the landing buffer phase, the ankle joint was in an inversion and external rotation state, and the angle in males was slightly larger than in the females, which was likely to cause ankle injury. (2) The three-dimensional peak torque and force value when stop-jump in males were higher than those in females. The appearing time of peak torque and force value in different directions in males was later than that in females, and imbalances between two legs and landing at different time occurred.

Perfluorooctanoic acid stimulates ovarian cancer cell migration, invasion via ERK/NF-κB/MMP-2/-9 pathway.

As widely used in consumer products, perfluorooctanoic acid (PFOA) has become a common environmental pollutant, which has been detected in human serum and associated with cancers. Our previous study showed that PFOA is a carcinogen that promotes endometrial cancer cell migration and invasion through activation of ERK/mTOR signaling. Here, we showed that PFOA (≥100 nM) treatment also stimulated A2780 ovarian cancer cell invasion and migration, which correlated with increased matrix metalloproteinases MMP-2/-9 expression, important proteases associated with tumor invasion and migration. Notably, PFOA treatment induced activation of ERK1/2/ NF-κB signaling. Pre-treatment with U0126, an ERK1/2inhibitor；or JSH-23, a NF-kB inhibitor, can reverse the PFOA-induced cell migration and invasion. Consistent with these results, inhibiting ERK1/2 or NF-κB signaling abolished PFOA-induced up-regulation of MMP-2/-9 expression. These results indicate that PFOA can stimulate ovarian cancer cell migration, invasion and MMP-2/-9 expression by up-regulating ERK/NF-κB pathway.

Combining conformational sampling and selection to identify the binding mode of zinc-bound amyloid peptides with bifunctional molecules.

The pathogenesis of Alzheimer's disease (AD) has been suggested to be related with the aggregation of amyloid ß (Aß) peptides. Metal ions (e.g. Cu, Fe, and Zn) are supposed to induce the aggregation of Aß. Recent development of bifunctional molecules that are capable of interacting with Aß and chelating biometal ions provides promising therapeutics to AD. However, the molecular mechanism for how Aß, metal ions, and bifunctional molecules interact with each other is still elusive. In this study, the binding mode of Zn(2+)-bound Aß with bifunctional molecules was investigated by the combination of conformational sampling of full-length Aß peptides using replica exchange molecular dynamics simulations (REMD) and conformational selection using molecular docking and classical MD simulations. We demonstrate that Zn(2+)-bound Aß((1-40)) and Aß((1-42)) exhibit different conformational ensemble. Both Aß peptides can adopt various conformations to recognize typical bifunctional molecules with different binding affinities. The bifunctional molecules exhibit their dual functions by first preferentially interfering with hydrophobic residues 17-21 and/or 30-35 of Zn(2+)-bound Aß. Additional interactions with residues surrounding Zn(2+) could possibly disrupt interactions between Zn(2+) and Aß, which then facilitate these small molecules to chelate Zn(2+). The binding free energy calculations further demonstrate that the association of Aß with bifunctional molecules is driven by enthalpy. Our results provide a feasible approach to understand the recognition mechanism of disordered proteins with small molecules, which could be helpful to the design of novel AD drugs.

Ex vitro expansion of human placenta-derived mesenchymal stem cells in stirred bioreactor.

The high demand of human placenta-derived mesenchymal stem cells (hPDMSCs) for therapeutic applications requires reproducible production of large numbers of well-characterized cells under well-controlled conditions. However, no method for fast hPDMSCs proliferation has yet been reported. In the present study, the feasibility of using a stirred bioreactor system to expand hPDMSCs was examined. hPDMSCs were cultured either in stirred bioreactors or in tissue culture flasks (T-flasks) for 5 days. Total cell density and several parameters of physical microenvironments were monitored in the two culture systems every 24 h. The maintenance of the antigenic phenotype of hPDMSCs before and after culturing in the stirred bioreactor system was cytometrically assessed. Data suggested that the physical microenvironment in the stirred bioreactors was much more favorable than that of the T-flasks. At the end of 144 h culturing, the total cell number was increased 1.73 times from the T-flasks to the stirred bioreactors. In addition, hPDMSCs could maintain their antigenic phenotype when cultured in stirred bioreactors. These results provide the initial assessment for large-scale hPDMSCs production using suspension culture bioreactors.

Effects of encapsulated rabbit mesenchymal stem cells on ex vivo expansion of human umbilical cord blood hematopoietic stem/progenitor cells.

The expansion of umbilical cord blood mononuclear cells (UCB MNCs) was investigated in a novel co-culture system by means of encapsulation of rabbit bone marrow (BM) mesenchymal stem cells (MSCs) in alginate beads (Alg beads). Three kinds of media were applied and the experiments lasted for 7 days. The total nucleated cell density was measured every 24 h. Flow cytometric assay for CD34(+) cells and methylcellulose colony assays were carried out at 0, 72 and 168 h. It was found that the encapsulated MSCs illustrated remarkable effects on UCB MNCs expansion regardless of whether serum is present in culture media or not. At the end of 168 h co-culture, the total nucleated cell number was multiplied by 15 +/- 2.9 times, and CD34(+) cells 5.3 +/- 0.3 times and colony-forming units in culture (CFU-Cs) 5.6 +/- 1.2 times in the serum-free media supplemented with conventional dose of cytokines, which was very similar to the results in the containing 20% serum media. While in the control, i.e. MNC expansion without encapsulated MSCs, however, total nucleated cells density changed mildly, CD34(+) cells and CFU-Cs showed little effective expansion. It is demonstrated that the encapsulated stromal cells can support the expansion of UCB MNCs effectively under the experimental condition.

[The investigation of ex-vivo expansion of hematopoietic stem/progenitor cells].

Rotating wall vessel (RWV) was used for the ex-vivo expansion of umbilical cord blood stem cells to meet the requirement of clinical application in the aspect of quantity and quality of the stem cells. The mononuclear cells (MNCs) from umbilical cord blood were cultured in T-flasks for 24 h, and then inoculated in RWV to culture for 200 h. The nucleated-cell numbers, pH and osmolality of the culture medium were determined every 24 h. The CD34+ cells content was measured and CFU-GM culture was carried out at 144 h and 197 h. Nucleated cells (NC) and CD34+ cells had a 435.5 +/- 87.6 fold expansion and a 32.7 +/- 15.6 fold expansion respectively in 197 h, and CFU-GM (colony-forming unit-granulocyte/macrophage) cells had a 21.7 +/- 4.9 fold expansion. In the whole course of culture, the pH and osmolality of the medium in the RWV were kept in the optimal hematopoietic stem cells' expansion conditions. pH was kept from 7.2 to 7.4, and the osmolality was kept from 290 mmol/kg to 310 mmol/kg. Owing to its structural particularity, the RWV could ensure cells to grow in the suspension state, could simulate the micro-environment of umbilical cord blood, and thus could make the hematopoietic stem cells expand largely in the RWV in short time.

Culture of neural stem cells in calcium alginate beads.

Neural stem cells (NSCs) with the capacity of extensive self-renewal and multilineage differentiation have attracted more and more attention in research as NSCs will play an important role in the nerve disease treatment and nerve injury repair. The shortage of NSCs, both their sources and their numbers, however, is the biggest challenge for their clinic application, and hence, in vitro culture and expansion of NSCs is vitally important to realize their potentials. In this work, mouse-derived NSCs were cultured in three-dimensional calcium alginate beads (Ca-Alg-Bs). Gelling conditions, cell density, and cell harvest were determined by the exploration of formation and dissociation parameters for Ca-Alg-Bs. Additionally, the recovered and the subsequent induced cells were identified by immunofluorescence staining of Nestin, beta-tubulin, and GFAP. The results show that the 2-mm diameter Ca-Alg-Bs, prepared with 1.5% sodium alginate solution and 3.5% CaCl2 solution and with gelling for 10 min, is suitable for the NSCs culture. The seeding density of 0.8 x 10(5) cells x mL-1 for the encapsulation of NSCs resulted in the most expansion, and the NSCs almost doubled during the experiment. The average cell recovery rate is over 88.5%, with the Ca-Alg-Bs dissolving in 55 mM sodium citrate solution for 10 min. The recovered cells cultured in the Ca-Alg-Bs still expressed Nestin and had the capacity of multilineage differentiation into neurons and glial cells and, thus, remained to be NSCs. These results demonstrate that NSC expansion within Ca-Alg-Bs is feasible and provides further possibilities for NSC expansion in bioreactors of the scale of clinical relevance.