Neuroprotective effects of tetrandrine against vascular dementia.

Tetrandrine is one of the major active ingredients in Menispermaceae Stephania tetrandra S. Moore, and has specific therapeutic effects in ischemic cerebrovascular disease. Its use in vascular dementia has not been studied fully. Here, we investigated whether tetrandrine would improve behavioral and cellular impairments in a two-vessel occlusion rat model of chronic vascular dementia. Eight weeks after model establishment, rats were injected intraperitoneally with 10 or 30 mg/kg tetrandrine every other day for 4 weeks. Behavioral assessment in the Morris water maze showed that model rats had longer escape latencies in training trials, and spent less time swimming in the target quadrant in probe trials, than sham-operated rats. However, rats that had received tetrandrine showed shorter escape latencies and longer target quadrant swimming time than untreated model rats. Hematoxylin-eosin and Nissl staining revealed less neuronal necrosis and pathological damage, and more living cells, in the hippocampus of rats treated with tetrandrine than in untreated model rats. Western blot assay showed that interleukin-1ß expression, and phosphorylation of the N-methyl-D-aspartate 2B receptor at tyrosine 1472, were lower in model rats that received tetrandrine than in those that did not. The present findings suggest that tetrandrine may be neuroprotective in chronic vascular dementia by reducing interleukin-1ß expression, N-methyl-D-aspartate receptor 2B phosphorylation at tyrosine 1472, and neuronal necrosis.

A microwell pattern for C17.2 cell aggregate formation with concave cylindrical surface induced cell peeling.

We have developed a polydimethylsiloxane (PDMS) pattern with arrays of microwells for the formation of multicellular aggregates by C17.2 neural stem cells. Upon interfacing with the patterns, the neural stem cells would firstly attach to the microwell sidewalls, forming cellular strips on day 1 after plating. For channel connected microwells, cellular strips on the concave semi-cylindrical sidewall surfaces continued among wells and through channels, followed by strip peeling due to prestress arising from actin filaments and assembly of suspending cellular aggregates within the microwells in the following 1-2 days. Our results also suggested that a small microwell diameter of 80 and 100 µm and a narrow channel width of 20 µm would facilitate the aggregate formation among the structural dimensions tested. Finite element method (FEM) simulation revealed that cellular strips on the semi-cylindrical sidewall surfaces peeled under significantly smaller prestresses (critical peeling prestress, CPP), than cells on flat substrates. However, the CPP by itself failed to fully account for the difference in aggregate inducing capability among the patterns addressed, suggesting cell growth behaviors might play a role. This study thus justified the current patterning method as a unique and practical approach for establishing 3D neural stem cell-based assay platforms.

Electrical field manipulation of cancer cell behavior monitored by whole cell biosensing device.

All living cells possess electrical characteristics and are thus responsive to, and even generate electric fields and currents. It has been shown that the electrical properties of cancer cells differ from normal proliferating cells, thus electric fields may induce differential effects in normal and cancer cells. Manipulation of these electrical properties may provide a powerful direct and/or adjuvant therapeutic option for cancer. A whole cell impedance-based biosensor to monitor the effects of a range of different frequencies (50 kHz-2 MHz) at low-intensity (<2 V/cm) on the growth rate of human SKOV3 ovarian cancer cells versus non-cancerous HUVECs is reported. Rapid real-time monitoring of the SKOV3 behavior was observed as the alternating electric fields were applied and the impedimetric response of the cells was recorded. The cells were also labeled with propidium iodide to examine morphological changes and cell viability with fluorescence microscopy with trypan blue for comparison. A noticeable decrease in the growth profile of the SKOV3 was observed with the application of 200 kHz alternating electric fields indicating specific inhibitory effects on dividing cells in culture in contrast to the HUVECs. The outcome of this research will improve our fundamental understanding of the behavior of cancer cells when exposed to alternating electric fields at specific frequencies and foster the development strategies and optimal parameters for alternating electric field therapies for clinical and drug delivery applications.

Responsiveness of voltage-gated calcium channels in SH-SY5Y human neuroblastoma cells on quasi-three-dimensional micropatterns formed with poly (l-lactic acid).

INTRODUCTION: In this study, quasi-three-dimensional (3D) microwell patterns were fabricated with poly (l-lactic acid) for the development of cell-based assays, targeting voltage-gated calcium channels (VGCCs). METHODS AND MATERIALS: SH-SY5Y human neuroblastoma cells were interfaced with the microwell patterns and found to grow as two dimensional (2D), 3D, and near two dimensional (N2D), categorized on the basis of the cells' location in the pattern. The capability of the microwell patterns to support 3D cell growth was evaluated in terms of the percentage of the cells in each growth category. Cell spreading was analyzed in terms of projection areas under light microscopy. SH-SY5Y cells' VGCC responsiveness was evaluated with confocal microscopy and a calcium fluorescent indicator, Calcium Green™-1. The expression of L-type calcium channels was evaluated using immunofluorescence staining with DM-BODIPY. RESULTS: It was found that cells within the microwells, either N2D or 3D, showed more rounded shapes and less projection areas than 2D cells on flat poly (l-lactic acid) substrates. Also, cells in microwells showed a significantly lower VGCC responsiveness than cells on flat substrates, in terms of both response magnitudes and percentages of responsive cells, upon depolarization with 50 mM K(+). This lower VGCC responsiveness could not be explained by the difference in L-type calcium channel expression. For the two patterns addressed in this study, N2D cells consistently exhibited an intermediate value of either projection areas or VGCC responsiveness between those for 2D and 3D cells, suggesting a correlative relation between cell morphology and VGCC responsiveness. CONCLUSION: These results suggest that the pattern structure and therefore the cell growth characteristics were critical factors in determining cell VGCC responsiveness and thus provide an approach for engineering cell functionality in cell-based assay systems and tissue engineering scaffolds.

Microbiosensor for Alzheimer's disease diagnostics: detection of amyloid beta biomarkers.

Alzheimer's disease (AD) affects about 35.6 million people worldwide, and if current trends continue with no medical advancement, one in 85 people will be affected by 2050. Thus, there is an urgent need to develop a cost-effective, easy to use, sensor platform to diagnose and study AD. The measurement of peptide amyloid beta (Aß) found in CSF has been assessed as an avenue to diagnose and study the disease. The quantification of the ratio of Aß1-40/42 (or Aß ratio) has been established as a reliable test to diagnose AD through human clinical trials. Therefore, we have developed a multiplexed, implantable immunosensor to detect amyloid beta (Aß) isoforms using triple barrel carbon fiber microelectrodes as the sensor platform. Antibodies act as the biorecognition element of the sensor and selectively capture and bind Aß1-40 and Aß1-42 to the electrode surface. Electrochemistry was used to measure the intrinsic oxidation signal of Aß at 0.65 V (vs. Ag/AgCl), originating from a single tyrosine residue found at position 10 in its amino acid sequence. Using the proposed immunosensor Aß1-40 and Aß1-42 could be specifically detected in CSF from mice within a detection range of 20-50 nM and 20-140 nM respectively. The immunosensor enables real-time, highly sensitive detection of Aß and opens up the possibilities for diagnostic ex vivo applications and research-based in vivo studies.

Effects of integrin α6ß1 on migration of hepatocellular carcinoma cells.

In this study, we applied specific blocking antibodies for integrin α6 or ß1 subunit, and evaluated the in vitro effects of integrins α6ß1 on the adhesion, chemotaxis and migration of hepatocellular carcinoma (HCC) cell line SMMC-7721 to type IV collagen. The adhesion force and cell migration, as measured by a micropipette aspiration system and Boyden chamber assay respectively, was dramatically reduced when either integrin subunits was blocked. The chemotaxis, as determined using a dual-micropipette system, was only affected by the antibody against ß1 subunit. This study suggests that integrin α6ß1 is an important cell surface receptor that mediates the adhesion of SMMC-7721 to type IV collagen. But the α6 subunit has minimal effect on pseudopod formation in response to type IV collagen. Therefore, the integrin α6ß1-mediated cell migration is, at least in part, through the regulation on the cell adhesion step.

Effects of topography on the functional development of human neural progenitor cells.

We have fabricated a topographical substrate with a packed polystyrene bead array for the development of cell-based assay systems targeting voltage-gated calcium channels (VGCCs). Human neural progenitor cells (H945RB.3) cultured on both flat and topographical substrates were analyzed in terms of morphological spreading, neuronal commitment, resting membrane potential (V(m)) establishment and VGCC function development. We found, by SEM imaging, that arrayed substrates, formed with both sub-micrometer (of 0.51 microm in mean diameter) and micrometer (of 1.98 microm in mean diameter) beads, were capable of promoting the spreading of the progenitor cells as compared with the flat polystyrene surfaces. With the micrometer beads, it was found that arrayed substrates facilitated the neural progenitor cells' maintenance of less negative V(m) values upon differentiation with bFGF starvation, which favored predominant neuronal commitment. Almost all the progenitor cells were responsive to 50 mM K(+) depolarization with an increase in [Ca(2+)](i) either before or upon differentiation, suggesting the expression of functional VGCCs. Compared to the flat polystyrene surfaces, microbead arrayed substrates facilitated the development of higher VGCC responsiveness by the progenitor cells upon differentiation. The enhancement of both VGCC responsiveness and cell spreading by arrays of micrometer beads was most significant on day 14 into differentiation, which was the latest time point of measurement in this study. This study thus rationalized the possibility for future substrate topography engineering to manipulate ion channel function and to meet the challenge of low VGCC responsiveness found in early drug discovery.

Effects of integrins on laminin chemotaxis by hepatocellular carcinoma cells.

To quantitatively evaluate the effects of integrins alpha1beta1, alpha2beta1, alpha3beta1, alpha4beta1, alpha5beta1, and alpha6beta1 on the chemotaxis of hepatocelluar carcinoma (HCC) cell line SMMC-7721 to laminin (LN). A modified dual-micropipette system was used to dynamically and quantitatively monitor the formation of pseudopod protrusion of HCC cells toward LN in the presence or absence of specific antibodies against integrins alpha1, alpha2, alpha3, alpha4, alpha5, alpha6, and beta1. Additionally, the expression levels of different integrin subunits on the surface of the cells were determined via flow cytometry analysis. In response to equal concentrations of LN in both micropipettes, HCC cells form symmetrical pseudopod protrusions on both sides. Addition of antibodies against alpha3, alpha6, or beta1 into one micropipette leads to significant reduction of pseudopod formation on that side, while antibodies against alpha1, alpha2, alpha4, and alpha5 do not affect the symmetrical formation of pseudopods in either micropipette. The percentages of HCC cells positive for expression of integrins alpha1, alpha2, alpha3, alpha4, alpha5, alpha6, and beta1 were 95.07, 23.17, 95.55, 2.47, 34, 14.29, and 95.78%, respectively. Integrins alpha3beta1 and alpha6beta1 are important cell surface receptors that mediate the chemotaxis of HCC cells toward LN.

Interfacing SH-SY5Y human neuroblastoma cells with SU-8 microstructures.

Microwell structures were fabricated using SU-8 photoresist for engineering a quasi-three-dimensional (quasi-3D) microenvironment for cultured neuronal cells. SH-SY5Y human neuroblastoma cells were successfully integrated into microwells of a nominal diameter of 100 microm, with or without 10-microm wide microchannels connecting neighboring microwells, in an aspect ratio (ratio of structure depth over width) of approximately 1. With the help of polyethylene glycol stamping and laminin coating, a neuronal-like network was achieved by integrating populations of SH-SY5Y cells with a microwell network pattern. Resting membrane potential establishment was evaluated with confocal microscopy and the potentiometric fluorescent dye tetramethylrhodamine methyl ester. It was found that the intra/extracellular fluorescent intensity ratio (R) was 2.4+/-1.4 [n (number of cells measured)=112] for SH-SY5Y cells on flat SU-8 substrates on day 5 into differentiation, which was not significantly different from the ratio on day 13 into differentiation, 2.0+/-1.8 (n=104) (P>0.05). For cells in the microwell network structures, R was 4.8+/-4.7 (n=51) and 3.9+/-3.2 (n=62) on days 5 and 13 into differentiation, respectively (P>0.5). Cells within the network structures had higher R ratios than on flat substrates, for either day 5 or 13 into differentiation (P<0.01). These results demonstrated that the well network structures, or topographically patterned substrates, were more suitable formats for promoting SH-SY5Y cell resting membrane potential establishment than flat substrates, suggesting the potential to control cellular function through substrate topography engineering.

Adhesion strength of human tenocytes to extracellular matrix component-modified poly(DL-lactide-co-glycolide) substrates.

We report a direct measurement of the adhesion strength of human embryonic tenocytes (HETCs) and transformed human embryonic tenocytes (THETCs) to fibronectin (FN)- and type I collagen (CNI)- modified poly(DL-lactide-co-glycolide) (PLGA) substrates with a micropipette aspiration technique. PLGA substrates were first coated with poly-D-lysine (PDL), and then with various concentrations (1 microg/ml, 2 microg/ml, 5 microg/ml, and 10 microg/ml) of FN and CNI in serum-free F12 media. Anti-FN and Anti-CNI antibodies were used to inhibit attachment of tenocytes to FN- and CNI- modified substrates in a dilution range of 1:5000-1:500 and 1:1500-1:250, respectively. The substrates were employed for incubation of HETCs and THETCs for 30 min at 37 degrees C before the adhesion strength measurements. We found that the adhesion strengths showed a strong dependence on the seeding time and FN or CNI concentrations. Anti-FN and Anti-CNI antibodies significantly compromised adhesion of HETCs and THETCs to the corresponding modified substrates (P < 0.05). These findings show that FN- or CNI-modified polymer substrates offer significant advantages for tissue engineering tendon scaffolds concerning tenocyte adhesion. In addition, HETCs and THETCs bear similar biological behaviors in terms of adhesion, indicating the possibility of using THETCs in place of HETCs in tissue engineering construction of human tendons.

Integrin beta1 mediates hepatocellular carcinoma cells chemotaxis to laminin.

BACKGROUND: Chemotaxis is an important step during the invasion of carcinoma cells. And integrins are most important receptors mediating interaction between cells and extracellular matrix (ECM). This study was designed to study integrin beta1 mediating chemotaxis of hepatocellular carcinoma (HCC) cells to laminin(LN). METHODS: A micropipette technique was adopted to investigate the effect of blockade of integrin beta1 on pseudopod protrusion of HCC cells in response to LN stimulation. Chemotactic pseudopod protrusion of a HCC cell was evaluated using a dual-pipette set-up, in which two pipettes filled with LN solution were positioned in close contact with the same cell, and pseudopod protrusion into each pipette was viewed dynamically and recorded with a tape recorder. The lengths of pseudopods were measured and plotted against time to obtain a pseudopod growth curve. The integrin beta1 subunit on the surfaces of HCC cells were analyzed by flow cytometry. RESULTS: In dual pipette chemotaxis experiment, when the two pipettes were filled with LN(50 microg/ml, 200 microg/ml), pseudopods extended from the HCC cell into each of the pipettes nearly symmetrically, ie, with nearly identical maximum pseudopod length and similar pseudopod growth curves. Upon addition of anti-CD29 (20 microg/ml) to one of the pipettes, pseudopod protrusion was blocked nearly completely while protrusion into the opposite pipette became more evidently, with a larger maximum length. Expression of integrin beta1 was up to 95.78% to cells chosen in the experiment. CONCLUSION: Integrin beta1 subunit was an important constituent receptor subunit for mediating chemotactic pseudopod protrusion of HCC cell to LN.

[Integrin beta1 mediates hepatocellular carcinoma cells chemotaxis to laminin].

OBJECTIVE: To study the effects of integrin beta1 on the chemotaxis of hepatocellular carcinoma (HCC) cells to laminin (LN). METHODS: A micropipette technique was adopted to investigate the effect of integrin beta1 blockade on pseudopod protrusion of HCC cells in response to LN stimulation. Chemotactic pseudopod protrusion of a HCC cell was evaluated using a dual-pipette set-up, in which two pipettes filled with LN solution were positional in close contact with the same cell, and pseudopod protrusion into each pipette was viewed dynamically and recorded with a tape recorder. The lengths of pseudopods were measured, then plotted against time to obtain a pseudopod growth curve. The integrin beta1 subunit on the surfaces of HCC cells was analyzed by flow cytometry. RESULTS: In dual pipette chemotaxis experiment, when the two pipettes were filled with LN (50microg/ml, 200microg/ml), pseudopods extended from the HCC cells into each of the pipettes nearly symmetrically. Upon addition of anti-CD29 (20microg/ml) to one of the pipettes, the pseudopod protrusion was blocked almost completely, while the pseudopod protrusion into the opposite pipette became more evidently, with larger maximum length. The expression rate of integrin beta1 on the cells was up to 95.78%. CONCLUSION: Integrin beta1 subunit is the important receptor for mediating HCC cells chemotaxis to laminin.

[Integrin alpha3beta1 mediates hepatocellular carcinoma cell adhesion and chemotaxis to type IV collagen].

OBJECTIVE: To investigate the effects of Integrin alpha(3)beta(1) on the adhesion and chemotaxis of hepatocellular carcinoma (HCC) cells to type IV collagen (Col IV). METHODS: (1) HCC cells were culture and suspension of HCC cells was made. Anti-alpha(3) and Anti-beta(1) were added into the HCC cell suspension. Flow cytometry was used to determine the expression of integrin alpha(3)beta(1) on the surface of HCC. (2) 5 micro g/ml Col IV was used to coat a cell with the diameter of 25 mm. Digested HCC cells were added. Anti-alpha(3) and Anti-beta(1) of the concentrations of 5 micro g/ml and 10 micro g/ml respectively were added into the cell suspension. Before and after the addition of Anti-alpha(3) and Anti-beta(1), micropipette technique was used to measure the adhesion force of HCC on Col IV-coated surface, as function of the square of internal radius of micropipette and the critical negative pressure needed to detach a single HCC cell away from the substrate. (3) Col IV of the concentration of 600 micro g/ml was added into the dual micropipettes. Then the dual micropipettes were led towards the HCC cells. A HCC cell was made to seal the openings of the 2 micropipettes with different parts of the cell contacting Col IV in different micropipettes. The pseudopod protrusion was observed dynamically and recorded with tape recorder. The length of pseudopod was measured and plotted against the chemotactic time so as to obtain a pseudopod growth curve. RESULTS: (1) The expression rates of integrin subunit alpha(3) and beta(1) on the surface of HCC cells were 95.55% and 95.78% respectively. (2) The adhesion force of HCC cells to the 5 micro g/ml Col IV-coated surface was 932 +/- 134 (x 10(-10) N, n = 60). Upon treatment of the HCC cells with Anti-alpha(3) of the concentrations of 5 micro g/ml and 10 micro g/ml, the adhesion force decreased by 42% and 49%, to 536 +/- 122 (x 10(-10) N, n = 60) and 476 +/- 63 (x 10(-10) N, n = 60) respectively. Upon treatment of the HCC cells with Anti-beta(1) of the concentrations of 5 micro g/ml and 10 micro g/ml, the adhesion force decreased by 52% and 76%, to 449 +/- 119 (x 10(-10) N, n = 60) and 220 +/- 78 (x 10(-10) N, n = 60) respectively. (3) The length of pseudopod increased along with the chemotactic time. The pseudopod length and growth curve were almost identical in the dual micropipettes when they were filled with Col IV. When Anti-alpha(3) or Anti-beta(1) was added into one of the dual micropipettes, the HCC cell pseudopod protrusion was almost blocked completely, while the HCC cell pseudopod in the opposite micropipette became more evident. CONCLUSION: Integrin alpha(3)beta(1) is an important constituent receptor in mediating HCC cell adhesion and chemotactic pseudopod protrusion to Col IV.

Inhibition of adhesion of hepatocellular carcinoma cells to basement membrane components by receptor competition with RGD- or YIGSR-containing synthetic peptides.

A micropipette technique was used to investigate the effects of four synthetic peptides, YIGSR, CDPGYIGSR, RGDS and GRGDTP, on the adhesion of hepatocellular carcinoma (HCC) cells onto type IV collagen/laminin/fibronectin coated surfaces. Adhesion of HCC cells to laminin was found to be YIGSR- or CDPGYIGSR-dependent while that to fibronectin and type IV collagen was RGDS- or GRGDTP-dependent. The reduction in adhesion strengths of HCC cells was slight to moderate (up to 55%), and was dependent on the peptide concentration. The decrease in adhesion strengths was reversed by an increase in ligand coating concentration and was compromised by prolonged interaction of the cells with the surfaces. These results suggested that the inhibition was due to competitive retardation rather than to a blockade of adhesion strengthening. A simple asymptotic function was adopted to fit the correlation between the mean of cell adhesion strengths and peptide concentration within defined concentration ranges. Regression analysis showed that cell adhesion strengths appeared to approach a plateau with increasing concentration of the inhibitory peptides, which was not always uniform over the entire concentration range tested. Further reduction in adhesion strengths was observed at higher peptide concentrations. It is suggested that the constants obtained by fitting over a low peptide concentration range might be kinetically representative of the inhibition during early events of adhesion or attachment.

[Effects of burn serum on the viscoelasticity and the structure of rat intestinal epithelial cells].

OBJECTIVE: To investigate the effects of burn serum on the viscoelasticity and the structure of rat intestinal epithelial cells. METHODS: The rat intestinal epithelial cell strain (IEC-6) was cultured and stimulated by burn serum. The changes of IECs before and after the stimulation were dynamically observed by cytoskeleton immunohistochemistry, ELISA and the measurement of cytomembranous viscoelasticity. RESULTS: During the early stage of burn serum stimulation, the skeleton protein expression in IEC decreased obviously with weakened positive signals of microfilaments and microtubules and with decreased cellular elasticity. CONCLUSION: The cytoskeleton injury could cause the increase of cellular fragility and the decrease of the viscoelasticity, which ultimately lead to the change of cellular biodynamics. These changes might directly participate the development of postburn intestinal epithelial injury.