Investigation on disturbing of adipocytic differentiation of rBMSCs by loaded titanium particles / 生物医学工程学杂志

Our previous investigations demonstrated that varying sizes of loaded titanium particles could inhibit proliferaion, adhension and osteoblastic differentiation of rat bone marrow mesenchymal stem cells (rBMSCs). The present study aims to validate the hypothesis that particled-shaped wear debris from prosthetic implants influence the adipocytic differentiation of rBMSCs. The effects of different sizes of loaded titanium particles (6.9 microm, 2.7 microm and 0.9 microm) on the adipocytic differentiation of rBMSCs were studied by observing lipid droplet formation, assaying the expression of lipoprotein lipase (LPL) mRNA by RT-PCR and Triglycerides (TG) secretion. The loaded titanium particles were found to influence adipogenesis of rBMSCs, but had different effects, depending upon particle size, concentration and loading time duration. 2.7 microm and 0.9 microm titanium particles promoted lipid droplet formation, LPL mRNA expression and TG secretion, while at a higher concentration of titanium particles and a longer loading duration, 6.9 microm titanium particles gradually inhibited adipogenic differentiation of rBMSCs. Three sizes of loading titanium particles obviously disturbed the adipocytic differentiation capability of rBMSCs: the smaller particles promoted but the larger inhibited the adipogenic differentiation of rBMSCs.

Static magnetic fields and its biomedical effects / 生物医学工程学杂志

Nowadays, health care products based on static magnetic fields (SMF) and merchandise of magnetic therapy are popular around the world. But the biomedical effects of SMF to animals or human beings remain a widely concerned controversy. In this paper, the recent researches in China and abroad about the biomedical effects of SMF were reviewed in three levels: the cellular, animal and human levels. Nevertheless, these data were not consistent with each other and even some contradicts others' researches. So, it is necessary to do more and further studies on SMF dosing regiman, sham control magnetic device and blinding procedures to obtain the optimal magnetic intensity, the desired therapeutic effects in practical cases and prepare for applying the SMF in biomedical fields more effectively in the future.

Pancreas transplantation for diabetes mellitus / 中华内分泌代谢杂志

Diabetes mellitus impacts patient survival and quality of life mainly due to its acute and chronic complications.Pancreas transplantation may restore normoglycemia and reduce the complication of insulin-dependent diabetes,thus improving the quality of life and prolonging patient's survival.Although pancreas transplantation requires major surgery and life-long immunosuppression therapy,it currently remains the gold stand for patients with type 1 diabetes mellitus,who do not respond to conventional therapy.Meanwhile,potential of the islet transplantation,insulin-producing cells replacement therapy,and artificial pancreas as the alternative to pancreas transplantation are under investigation.

Influence of titanium particles loading on releases of cytokines of osteoblasts / 生物医学工程学杂志

Aseptic loosening is mainly mediated by bone resorption cytokines in the surrounding area of orthopaedic implants. Our previous investigation demonstrtated that different-sized titanium particles loading can inbibit the osteoblastic differentiation and mineraliztion. In order to investigate the hypothesis that particulate wear debris derived from prosthetic biomaterials affects the release of bone resorption related cytokines, we studied the influence of different-sized titanium particles loading on the osteoblastic cytokines by assaying the secretion of IL-6, IL-10 with use of ABC-quantitative sandwich enzyme-linked immunosorbent assay, and on the expression of osteoclast differentiation factors (ODF) by RT-PCR. The results showed that the 0.9 microm titanium particles promoted osteoblasts producing bone resorption cytokines (IL-6, ODF), and simultaneously secreted bone absorption restraining factor (IL-10) quickly and transitorily. In comparison, the 2.7 microm and 6.9 microm titanium particles,especially the latter primarily promoted osteoblasts secreting bone absorption promoting factors powerfully and slowly. The results suggested that there was a biphasic response appearing in titanium particles loaded-osteoblastic cultures, the level of which varied according to the different size and the loading time of titanium particles. This in vitro experimental result showed that attentaion to the inhibition of bone resorption cytokines stimulated by wear debris and to the screen potential favourable biomaterials for implants must be taken.

Potential of cell transplantation as an alternative to liver transplantation / 生物医学工程学杂志

Human hepatocyte transplantation to treat liver-based metabolic deficiencies and acute liver failure has shown promising early improvement in liver function; however, long-term success has not been achieved. Stem cell transplantation to restore liver function as an alternative to whole liver transplantation has not been successful in humans. As alternative sources of cells for human hepatocyte transplantation, stem cells are under investigation. The liver extracellular matrix presents an ideal scaffold for stem cell differentiation into hepatocytes, as well as cell transplantation. The innovative technique of the decellularized liver matrix presents great potential as the scaffold for hepatocyte maturation and transplantation, and allows the development of engineered recellularized liver graft for transplantation.

Stimulative and regulative functions of osteoblasts loaded under the titanium particles on osteoclasts / 生物医学工程学杂志

Our previous studies on the function of the osteoblasts (OBs) have shown that worn titanium particles decrease osteoblast function and promot secretion of bone resorption cytokines of OBs surrounding the synovium-like interface membrane of loosening implants. The current study was aimed to test the hypothesis that osteoclasts (OCs) bone absorption function is induced by conditioned media (CM) prepared from OBs loaded in the presence or absence of titanium particles (with three mean diameters 6.9 microm, 2.7 microm, and 0.9 microm, respectively). The effects of CM on OCs function were examined using a combination of the morphological characteristics tests, i.e., TRAP dyeing, scanning electron microscopy, F-actin immunofluorescence protocol for confocal microscopy, bone resorption lacunae assay, osteoclastic calcium tracking, with biochemical evaluation, i.e., C-terminal cross-linked telopeptides of type I collagen evaluated with ABC-ELISA method. The results showed that CM from 0.9 microm titanium particles could induce osteoclastic differentiation and formation, could partially influence the survival of the OCs; while CM of 2.7 microm and 6.9 microm titanium particles, especially the latter, could obviously augmented osteoclastic activity, survival, or differentiation. The stimulation of osteoclast function may be due to a parallel increase in the intracellular free calcium concentration. The present study provides strong support for the hypothesis that osteoclastic activity, survival, or differentiation are very important in the development of aseptic loosening. The development of therapeutic interventions to reduce osteoclastic function and optimization of biomaterials may be useful approaches for improving the performance of orthopaedic implants.

Construction and selection of effective mouse Smad6 recombinant lenti-virus interference vectors / 生物医学工程学杂志

This experiment was designed to construct mouse Smad6 recombinant RNA interference vectors and determine their interference effects on bone marrow mesenchymal stem cells (BMSCs). Three recombinant Smad6 RNA interference vectors were constructed by molecular clone techniques with a lenti-virus vector expressing green fluorescent protein (GFP), and the correctness of recombinant vectors was verified by DNA sequencing. Mouse BMSCs were used for transfection experiments and BMP-2 was in use for osteogenic induction of MSCs. The transfection efficiency of recombinant vectors was examined by Laser confocal scanning microscope and the interference effect of recombinant vectors on Smad6 gene expression was determined by real-time RT-PCR and Western blot, respectively. Three Smad6 recombinant RNA interference vectors were successfully constructed and their correctness was proved by DNA sequencing. After transfection, GFPs were effectively expressed in MSCs and all of three recombinant vectors gained high transfection efficiency (> 95%). Both real-time PCR and Western blot examination indicated that among three recombinant vectors, No. 2 Svector had the best interference effect and the interference effect was nearly 91% at protein level. In conclusion, Mouse recombinant Smad6 RNA interference (RNAi) vector was successfully constructed and it provided an effective tool for further studies on BMP signal pathways.

Effects of M-CSF concentration, RANKL concentration and M-CSF preinduction on osteoclastogenesis / 生物医学工程学杂志

This study was directed to the effects of macrophage-colony stimulating factors (M-CSF) concentration, recerptor activator of nuclear factor kappaB ligand (RANKL) concentration and M-CSF preinduction on osteoclastogenesis and the related resorption function. Bone marrow mononuclear cells were isolated and were divided into 4 groups. Group A underwent osteoclastogenic induction with the use of 30 ng/ml M-CSF and 50 ng/ml RANKL, while Group B received 50 ng/ml M-CSF and 100 ng/ml RANKL treatment. Both C and D Group underwent preinduction with the use of 30 ng/ml M-CSF for 3days, and then they were treated with 30 ng/ml M-CSF and 50 ng/ml RANKL, 50 ng/ml M-CSF and 100 ng/ml RANKL, respectively. Osteoclastogenesis was examined by TRAP staining 6 days after induction, and dentin resorption lacunae were detected by Scanning Electron Microscope 9 days after induction. TRAP positive multinuclear cells were observed in all groups of cells, and resorption lacunae were formed in all of them. However, more TRAP positive multinuclear cells were observed and more large resorption lacunae were detected in groups B and D than in groups A and C, respectively. The number of TRAP positive cells, number of resorption lacunae and lacuna areas in groups C and D were also greater than those in groups A and B, respectively. Higher concentration of M-CSF and RANKL and preinduction with M-CSF may benefit osteoclastogenesis and increase resorption function of osteoclast.

Mechanism of AMPK regulating GLUT4 gene expression in skeletal muscle cells / 生物医学工程学杂志

AMP-activated protein kinase, AMPK, is responsible for regulation of exercise-induced GLUT4 gene expression in skeletal muscle. But the molecular mechanisms for this regulation and key protein in this signaling pathway are obscure. There has been growing recognition that histone acetylation probably represents a central mechanism for regulation of gene transcription, and recent studies showed that numerous gene expressions are regulated by nucleosomal histone acetylation, which is modulated through histone acetyltransferases (HATs) and histone deacetylases (HDACs). So we have a hypothesis that the AMPK regulates GLUT4 gene through recruiting HDACs. Skeletal muscle cells cultured with normal (5 mmol/L) and high (20 mmol/L) glucose concentration were incubated with AICAR, and then total and nuclear AMPKalpha2, HDAC5 protein and GLUT4 mRNA were measured. The results show that the AICAR activated AMPKalpha2, reduced nuclear HDAC5,and increased GLUT4 mRNA in skeletal muscle cells; in contrast, the effect evoked by AICAR was blunted in cultured skeletal muscle cells with high glucose. Therefore, the changes of GLUT4 gene expression under different glucose concentration are closely related to the changes of AMPKalpha2 and HDAC5 protein in skeletal muscle cells. This result demonstrates that HDAC5 plays an important role in regulating GLUT4 gene transcription by AMPK signaling pathway skeletal muscle cells.

A new three-point bending test for bone biomechanical properties of rat's tibia / 生物医学工程学杂志

In this study, we compared the three-point bending test of the metaphyseal tibia versus the three-point bending test of the diaphysial tibia in rats. Twenty 6-month-old female Sprague-Dawley rats were randomly divided into the ovariectomized (OVX) group and the sham-operated (Sham) group. All rats were housed in standard environmental conditions. Five months after operation, all rats were sacrificed by depletion method. All left tibia were removed for the three-point bending test. The changes of mechanical parameters were examined by the three-point bending test of the metaphyseal tibia and by that of the diaphysial tibia. Elastic, Maximum Load, Maximum Stress, Failure Load, and Failure Stress of the metaphyseal tibia were much lower in OVX rats than in Sham rats. However, there was no statistically significant difference in all of the mechanical parameters of the diaphysial tibia between the OVX group and the Sham group. The new three-point bending test of the metaphyseal tibia is much more sensitive and useful as compared with the test of the diaphysial tibia in evaluating the changes of mechanical properties of tibia in osteoporotic rats.

Effects of CTGF gene silencing on the proliferation and myofibroblast differentiation of human lung fibroblasts / 生物医学工程学杂志

Connective tissue growth factor (CTGF) is involved in the differentiation of lung fibroblast into myofibroblast and is considered as an important mediator in the pathogenesis of pulmonary fibrosis. In the present study, a CTGF small interference RNA (siRNA) expressing plasmid (CTGF-siRNA) was constructed and stably transfected into human lung fibroblast cell line, MRC-5. Stable clones with CTGF gene silencing (CTGF-siRNA/MRC-5) were successfully established by G418 screening and further confirmed by real-time quantitative PCR and Western blot. Cell proliferation was investigated by growth curve analysis, and cell doubling time of the CTGF-siRNA/MRC-5 cells was markedly longer than that of the control cells (P < 0.05). Compared with control cells, the expression of alpha-smooth muscle actin (alpha-SMA), the marker of myofibroblast differentiation, was decreased in CTGF-siRNA/MRC-5 cells. Moreover, the deposition of extracellular matrix (ECM) proteins (such as collagen type I and fibronectin) in CTGF-siRNA/MRC-5 cells was also declined. Our data suggest that CTGF may play an important role in the differentiation of lung fibroblast into myofibroblast, and that siRNA targeting CTGF gene might provide a new strategy for gene therapy of pulmonary fibrosis.

The influence of the pulsed electrical stimulation on the morphology and the functions of the endothelial cells / 生物医学工程学杂志

The aim of this study is to explore the effects of the pulsed electrical stimulation (PES) on the morphology, the proliferation and the values of NO and ET-1 of the endothelial cells (ECs). We chose the different frequency PES (1, 5, 10, 20, 50, 100 Hz) with 25 mV to stimulate the ECs for 6 hours. We observed the cell's morphous by the scanning electron microscope (SEM) and detected the values of MTT, NO and ET-1. The proliferation of the ECs was obviously rose up under the PES from 10 to 100 Hz. But the PES inhibited the proliferation with the frequency lower than 10 Hz. After stimulated with PES (20 - 100 Hz), the NO expression of ECs were increased obviously, and the peak value was appeared at 50 Hz. The peak value of ET-1 was appeared at 100 Hz. The PES has significant effects on the ECs' morphology, proliferation and expression of NO and ET-1. Particularly, the 50 Hz PES plays a positive role to enhance the ECs' function and to maintain the vascular biology.

Pressure shift mediated changes of vascular endothelial cell morphology and adhesive function in the flow field in vitro / 生物医学工程学杂志

In mankind, the circulation system is a closed pressure-loaded system; the pressure in circulation flow field would change with the variation of natural or pathological geometry of the local bloodvessel, and the pressure shift induced by the variation of vascular geometry would lead to a series of physiological and pathological changes in the endothelial cells (ECs). This experiment is designed to elucidate the effects of different pressure shift on F-actin alignment and expression in cultured endothelial cells in vitro, and to investigate the relationship between the altered pressure shift and the expression intensity of Vascular adhesion molecule (VCAM) and Integrin alphaVbeta3. Non-activated cultured ECs and single shear stress loaded ECs as control group were set, the double-immuno-fluoro-cytochemistry, laser confocal scanning microscopy and image analysis system were used to observe the expression of VCAM, Integrin alphaVbeta3 and F-actin in endothelial cells which were exposed to levels of pressure shift in an improved parallel plate flow chamber. When exposed to different decreased pressure shift, the expression intensity of VCAM, Integrin alphaVbeta3 and F-actin showed regular changes. The decreased pressure shift resulted in changes in cell alignment and cytoskeleton F-actin, and also affected ECs adhesion function and transmembrane mechanotransduction function which were represented by VCAM and Integrin alphaVbeta3 respectively.

Advances and trends in the researches on meridians / 生物医学工程学杂志

This review summarizes the newest advances in recent researches on meridian. Firstly, fascia, connective tissue, mast cells, fibroglia fibrils and interstitial fluid are found accumulated under the deeper layer tissue of the acupoints and channels, thus giving indications of their important role in the propagated sensation along meridian. Secondly, the supplementary data involve the characteristics and the neurobiological basis of propagated sensation along meridian, which suggest that the function of the meridian is of integrity, i.e. the points on different segments of the same channel produce a uniform clinical effect. The effect of Luomai (collateral, branch of the large channel) and the mechanism of long distance of transmission across spinal segments are introduced. Thirdly, the objective evidence of channel-viscera bi-directional correlativity. Lastly, the application of the gene chip technique to meridian research. As for the main trends in the researches of meridian, the emphases are laid on the function of acupoints and channels, on the correlation between the channel and internal organs, on the rational distribution of proportion as well as on the coordination of meridian research between laboratory experiments and clinical practices. Recently, faced to international competition, Chinese physicians and researchers feel an unshrinkable duty and are making a greater effort to carry out researches on the meridian.

A sharp rise in portal vein pressure, not arterial constriction, initiates bile salt-induced pancreatic microcirculatory disturbance / 生物医学工程学杂志

It was reported that pancreatic arteries constricted during the early phase of bile salt-induced acute pancreatitis (AP), leading to pancreatic microcirculatory disturbance. We conducted this experiment to verify whether the above-mentioned finding was true. AP was induced with intraductal injection of taurodeoxyholate. Small pancreatic artery pressure in dogs was recorded. Functional capillaries were counted and calibrated by multiplying wet weight of pancreas. Pancreatic perfusion was measured with Laser Doppler flowmeter. Pancreatic arterioles of rats dilated during the initial 20 min of AP, and pancreatic arterial pressure declined during the early phase of AP in dogs (from 104.5 +/- 4.8 mmHg to 54.6 +/- 5.6 mmHg). The hematocrit of blood from inferior vena cava was significantly lower than that of portal vein at 5 min after pancreatitis induction. The "true" pancreatic functional capillary density increased. The early pancreatic microcirculatory disturbance coincided with a marked increase of portal vein pressure (PVP) as high as 9.18 +/- 0.78 mmHg. Reduction of PVP to baseline level was followed by a marked increase of pancreatic perfusion (by 1.4-fold). Arterial dilatation, but not constriction, occurred during the early phase of bile salt-induced AP. The pancreatic microcirculatory disturbance was due to a marked rise in PVP that greatly reduced the pressure difference in the pancreatic blood vessels and increased plasma extravasation which led. to local hemoconcentration.

Expressions of type I and type III collagens and tenascin-C in rat bone mesenchymal stem cells co-cultured with ligament fibroblasts / 生物医学工程学杂志

Bone marrow mesenchymal stem cells (BMSCs) can be directed to differentiate into a variety of cell types depending on their micro-environment. In this study, rat BMSCs were co-cultured with rat ligament fibroblasts during different time courses. The mRNA expressions of type I, type III collagens and tenascin-C were measured by real time RT-PCR, and the corresponding protein levels of type I and type III collagens by radioimmunoassay. Results show that the mRNA expressions of type I and type III collagens in the BMSCs were 2 times up-regulated after a 6-day co-culture, and the relative mRNA expressions of type I and type III collagens were 3.9 +/- 0.2 and 1.9 +/- 0.2, while they were 1.9 +/- 0.3 and 0.8 +/- 0.1 in the control groups, respectively. The protein syntheses of these two collagens were also increased after a 12-day co-culture; the type I and type III collagens synthesis were 13.6 +/- 1.3 ng/microg and 5.9 +/- 0.5 ng/microg in co-culture groups and 12.4 +/- 0.8 ng/microg and 5.0 +/- 0.4 ng/microg in their control groups, respectively. Likewise, there was a 2 times enhancement in tenascin-C mRNA expression after the 12-day co-culture (0.07 +/- 0.02 by control group and 0.14 +/- 0.02 by co-culture group, P < 0. 05). These data suggest that the presence of the ligament fibroblast promotes the syntheses of type I and the III collagens and tenascin-C in the rat BMSC.

Particle image velocimetry in measuring the flow fields distribution in carotid artery bifurcation model / 生物医学工程学杂志

To understand the local hemodynamics of modified TF-AHCB carotid bifurcation model, using particle image velocimetry technique to measure the instantaneous velocity distribution of the model attatched to a circuit. The velocity was controlled by regulating the height of the reservoir. The working fluid consists of glycerine and water mixture with viscosity of 3.75 mPa.s similar to human blood. Instantaneous velocity fields were obtained by PIV and the shear stresses were calculated according to the velocity. The results showed that inside the model, there were a large flow separation and an anticlockwise rotating vortex on the lateral wall of ICA, The location and distance of the vortex changed with the flow velocity. The higher the flow velocity, the smaller the vortex distance, and the farther the location. The shear stresses on the lateral wall were significantly lower in all work condition. And there a low shear stress kernel when the velocity was lower than 0.839 m/s. The location of the low shear stress was just the position of atherosclerosis. The flow pattern inside the model consists of large flow separation and vortex zones. And there are low shear stress zones at the lateral wall of ICA, Where are thought to be associated with the genesis of atherosclerosis.

Fabrication and evaluation of a new decellularized tissue engineered blood vessel scaffold / 生物医学工程学杂志

The aim of this study was to fabricate an ideal nature-based tissue engineered blood vessel (TEBV) scaffold. It should have several special characteristics such as little immunogenicity and good biocompatibility, and it should be similar in mechanical property to fresh tissue. New-got canine aortas were dipped in ion-free water for 12 h under 4 degrees C to make the cells disrupted, then fixed in a kind of polyepoxy compounds solution (EX-810) for 72 h, and finally treated with sonication to remove the cell debris. Histological slices of the TEBV scaffold were stained with H&E. The results showed that our method could effectively remove the cells in fresh tissues because there was no visible nuclear stain. A series of biomechanical analyses revealed that these TEBV scaffold had nearly the same mechanical properties as fresh tissues. Also, these TEBV scaffolds showed good cell-compatibility, and their surfaces were suitable for endothelial cells and smooth muscle cells to grow on.

Study of color blood image segmentation based on two-stage-improved FCM algorithm / 生物医学工程学杂志

This paper introduces a new method for color blood cell image segmentation based on FCM algorithm. By transforming the original blood microscopic image to indexed image, and by doing the colormap, a fuzzy apparoach to obviating the direct clustering of image pixel values, the quantity of data processing and analysis is enormously compressed. In accordance to the inherent features of color blood cell image, the segmentation process is divided into two stages. (1)confirming the number of clusters and initial cluster centers; (2) altering the distance measuring method by the distance weighting matrix in order to improve the clustering veracity. In this way, the problem of difficult convergence of FCM algorithm is solved, the iteration time of iterative convergence is reduced, the execution time of algarithm is decreased, and the correct segmentation of the components of color blood cell image is implemented.

Mechanical environment of rotating bioreactor and its effect on cell growth / 生物医学工程学杂志

In this paper is presented an analysis of the mechanical effect of horizontal rotating bioreactor on cell culture. Getting the microgravity of the bioreactor and the shear stress on canine mesenchymal stem cells (cMSCs) with theoretic calculating model and differential equations, we have validated the density,growth rate and modality of cultured cell by scanning electron microscopy. The horizontal rotating bioreactor which we developed could create the mechanic environment of microgravity (K<8.38 X 10(-2))and low shear stress(r<1.62 dyn/cm2) in theory. The results of scanning electron microscopy indicated that the cells' growth-speed, quantity and modality in bioreactor were better than those of cells cultured in static 24-well plate. The mechanical environment of the rotating bioreactor is propitious for keeping better modality and more rapid proliferation of cMSCs. The rotating bioreactor is a novel approach and technique it is superior to static culture.