Analysis methods of human cell migration

Induction of Migration and Collagen Synthesis in Human Gingival Fibroblasts Using Periodontal Ligament Stem Cell Conditioned Medium

OBJECTIVE

 This study aimed to examine the effect of periodontal ligament stem cell conditioned medium (PDLSC-CM) on human gingival fibroblast (HGF) migration and collagen synthesis.

MATERIALS AND METHODS

 To assess cell viability, we extracted PDLSC-CM, and the total derived protein concentration was adjusted to 12.5 to 200 µg/mL, followed by treatment with HGFs. The viability of HGFs was observed for 24 hours using the MTT assay. Cell migration was monitored for 24 to 48 hours by wound healing and Boyden chamber assays. Collagen synthesis from HGFs was examined by picrosirius red dye and real-time polymerase chain reaction (PCR) to measure collagen type I and III gene expression for 7 to 10 days. A comparison among the groups was assessed using a one-way analysis of variance (ANOVA) and Bonferroni post hoc test, with the exception of the cell viability assay, which was subjected to Welch's test and Dunnett's T3 post hoc test.

RESULTS

 HGF viability was significantly enhanced by 12.5, 25, and 50 µg/mL PDLSC-CM. The HGFs treated with 50 µg/mL PDLSC-CM promoted cell migration as shown by wound healing and Boyden chamber assays. At this concentration, collagen synthesis increased at 10 days. Collagen type I gene expression increased by 1.6-fold (p < 0.001) and 4.96-fold (p < 0.001) at 7 and 10 days, respectively. Collagen type III gene expression showed an increase of 1.76-fold (p < 0.001) and 6.67-fold (p < 0.001) at the same time points.

CONCLUSION

 Our study suggested that a low concentration of PDLSC-CM at 50 µg/mL has given an amelioration of HGFs providing for periodontal wound healing and periodontal regeneration, particularly migration and collagen synthesis.

MACC1-induced migration in tumors: Current state and perspective

Malignant tumors are still a global, heavy health burden. Many tumor types cannot be treated curatively, underlining the need for new treatment targets. In recent years, metastasis associated in colon cancer 1 (MACC1) was identified as a promising biomarker and drug target, as it is promoting tumor migration, initiation, proliferation, and others in a multitude of solid cancers. Here, we will summarize the current knowledge about MACC1-induced tumor cell migration with a special focus on the cytoskeletal and adhesive systems. In addition, a brief overview of several in vitro models used for the analysis of cell migration is given. In this context, we will point to issues with the currently most prevalent models used to study MACC1-dependent migration. Lastly, open questions about MACC1-dependent effects on tumor cell migration will be addressed.

Insight into Factors Influencing Wound Healing Using Phosphorylated Cellulose-Filled-Chitosan Nanocomposite Films

Marine polysaccharides are believed to be promising wound-dressing nanomaterials because of their biocompatibility, antibacterial and hemostatic activity, and ability to easily shape into transparent films, hydrogels, and porous foams that can provide a moist micro-environment and adsorb exudates. Current efforts are firmly focused on the preparation of novel polysaccharide-derived nanomaterials functionalized with chemical objects to meet the mechanical and biological requirements of ideal wound healing systems. In this contribution, we investigated the characteristics of six different cellulose-filled chitosan transparent films as potential factors that could help to accelerate wound healing. Both microcrystalline and nano-sized cellulose, as well as native and phosphorylated cellulose, were used as fillers to simultaneously elucidate the roles of size and functionalization. The assessment of their influences on hemostatic properties indicated that the tested nanocomposites shorten clotting times by affecting both the extrinsic and intrinsic pathways of the blood coagulation system. We also showed that all biocomposites have antioxidant capacity. Moreover, the cytotoxicity and genotoxicity of the materials against two cell lines, human BJ fibroblasts and human KERTr keratinocytes, was investigated. The nature of the cellulose used as a filler was found to influence their cytotoxicity at a relatively low level. Potential mechanisms of cytotoxicity were also investigated; only one (phosphorylated microcellulose-filled chitosan films) of the compounds tested produced reactive oxygen species (ROS) to a small extent, and some films reduced the level of ROS, probably due to their antioxidant properties. The transmembrane mitochondrial potential was very slightly lowered. These biocompatible films showed no genotoxicity, and very importantly for wound healing, most of them significantly accelerated migration of both fibroblasts and keratinocytes.

Possible roles for the hominoid-specific DSCR4 gene in human cells

Down syndrome in humans is caused by trisomy of chromosome 21. DSCR4 (Down syndrome critical region 4) is a de novo-originated protein-coding gene present only in human chromosome 21 and its homologous chromosomes in apes. Despite being located in a medically critical genomic region and an abundance of evidence indicating its functionality, the roles of DSCR4 in human cells are unknown. We used a bioinformatic approach to infer the biological importance and cellular roles of this gene. Our analysis indicates that DSCR4 is likely involved in the regulation of interconnected biological pathways related to cell migration, coagulation and the immune system. We also showed that these predicted biological functions are consistent with tissue-specific expression of DSCR4 in migratory immune system leukocyte cells and neural crest cells (NCCs) that shape facial morphology in the human embryo. The immune system and NCCs are known to be affected in Down syndrome individuals, who suffer from DSCR4 misregulation, which further supports our findings. Providing evidence for the critical roles of DSCR4 in human cells, our findings establish the basis for further experimental investigations that will be necessary to confirm the roles of DSCR4 in the etiology of Down syndrome.

Guide Cells Support Muscle Regeneration and Affect Neuro-Muscular Junction Organization

Muscular regeneration is a complex biological process that occurs during acute injury and chronic degeneration, implicating several cell types. One of the earliest events of muscle regeneration is the inflammatory response, followed by the activation and differentiation of muscle progenitor cells. However, the process of novel neuromuscular junction formation during muscle regeneration is still largely unexplored. Here, we identify by single-cell RNA sequencing and isolate a subset of vessel-associated cells able to improve myogenic differentiation. We termed them 'guide' cells because of their remarkable ability to improve myogenesis without fusing with the newly formed fibers. In vitro, these cells showed a marked mobility and ability to contact the forming myotubes. We found that these cells are characterized by CD44 and CD34 surface markers and the expression of Ng2 and Ncam2. In addition, in a murine model of acute muscle injury and regeneration, injection of guide cells correlated with increased numbers of newly formed neuromuscular junctions. Thus, we propose that guide cells modulate de novo generation of neuromuscular junctions in regenerating myofibers. Further studies are necessary to investigate the origin of those cells and the extent to which they are required for terminal specification of regenerating myofibers.

Establishment and Characterization of Canine Mammary Gland Carcinoma Cell Lines With Vasculogenic Mimicry Ability in vitro and in vivo

Mammary tumors affect intact and elderly female dogs, and almost 50% of these cases are malignant. Cell culture offers a promising preclinical model to study this disease and creates the opportunity to deposit cell lines at a cell bank to allow greater assay reproducibility and more reliable validation of the results. Another important aspect is the possibility of establishing models and improving our understanding of tumor characteristics, such as vasculogenic mimicry. Because of the importance of cancer cell lines in preclinical models, the present study established and characterized primary cell lines from canine mammary gland tumors. Cell cultures were evaluated for morphology, phenotype, vasculogenic mimicry (VM), and tumorigenicity abilities. We collected 17 primary mammary carcinoma and three metastases and obtained satisfactory results from 10 samples. The cells were transplanted to a xenograft model. All cell lines exhibited a spindle-shaped or polygonal morphology and expressed concomitant pancytokeratin and cytokeratin 8/18. Four cell lines had vasculogenic mimicry ability in vitro, and two cell lines showed in vivo tumorigenicity and VM in the xenotransplanted tumor. Cellular characterization will help create a database to increase our knowledge of mammary carcinomas in dogs, including studies of tumor behavior and the identification of new therapeutic targets.

Gamma ray-induced in vitro cell migration via EGFR/ERK/Akt/p38 activation is prevented by olaparib pretreatment

Purpose: Radiotherapy using gamma ray is still the main therapeutic modality for the treatment of various cancers. However, local recurrence and increase of metastasis after radiotherapy is still a major therapeutic challenge. Aim of this work was to check cell migration along with activity and expression of some marker proteins involved in epithelial-mesenchymal transition (EMT) pathway in three different human cancer cells after exposure with gamma radiation in combination with PARP inhibitor olaparib.Materials and methods: Here, we presented cell viability, in vitro cell migration, activity of MMPs by gelatin zymography, expression of few EMT marker proteins and the signaling cascade involved in transcriptional regulation of MMPs after gamma irradiation with and without olaparib pretreatment in highly metastatic three human cancer cell lines-A549, HeLa and U2OS.Results: We observed that gamma irradiation alone increased in vitro cell migration, MMP-2,-9 activity, expression of N-cadherin, vimentin and the signaling molecules EGFR, ERK1/2, Akt, p38 that enhanced NF-kB expression in all three cell types. Olaparib treatment alone reduced in vitro cell migration along with reduction of expression of all the above-mentioned marker proteins of the EMT pathway. However, 4 h olaparib pretreatment prevented gamma ray induced activation of all these marker proteins in all three cell types.Conclusions: This data implicates that olaparib treatment in combination with gamma therapy could be promising in protecting patients from gamma-induced metastasis.

Neutrophil-endothelial interactions of murine cells is not a good predictor of their interactions in human cells

All drugs recently developed in rodent models to treat inflammatory disease have failed in clinical trials. We therefore used our novel biomimetic microfluidic assay (bMFA) to determine whether the response of murine cells to inflammatory activation or anti-inflammatory treatment is predictive of the response in human cells. Under physiologically relevant flow conditions, permeability and transendothelial electrical resistance (TEER) of human or mouse lung microvascular endothelial cells (HLMVEC or MLMVEC), and neutrophil-endothelial cell interaction was measured. The differential impact of a protein kinase C-delta TAT peptide inhibitor (PKCδ-i) was also quantified. Permeability of HLMVEC and MLMVEC was similar under control conditions but tumor necrosis factor α (TNF-α) and PKCδ-i had a significantly higher impact on permeability of HLMVEC. TEER across HLMVEC was significantly higher than MLMVEC, but PKCδ-i returned TEER to background levels only in human cells. The kinetics of N-formylmethionyl-leucyl-phenylalanine (fMLP)-mediated neutrophil migration was significantly different between the two species and PKCδ-i was significantly more effective in attenuating human neutrophil migration. However, human and mouse neutrophil adhesion patterns to microvascular endothelium were not significantly different. Surprisingly, while intercellular adhesion molecule 1 (ICAM-1) was significantly upregulated on activated HLMVEC, it was not significantly upregulated on activated MLMVEC. Responses to activation and anti-inflammatory treatment in mice may not always be predictive of their response in humans.

Recapitulation of molecular regulators of nuclear motion during cell migration

Cell migration is a highly orchestrated cellular event that involves physical interactions of diverse subcellular components. The nucleus as the largest and stiffest organelle in the cell not only maintains genetic functionality, but also actively changes its morphology and translocates through dynamic formation of nucleus-bound contractile stress fibers. Nuclear motion is an active and essential process for successful cell migration and nucleus self-repairs in response to compression and extension forces in complex cell microenvironment. This review recapitulates molecular regulators that are crucial for nuclear motility during cell migration and highlights recent advances in nuclear deformation-mediated rupture and repair processes in a migrating cell.

Reduction of metastatic potential by inhibiting EGFR/Akt/p38/ERK signaling pathway and epithelial-mesenchymal transition after carbon ion exposure is potentiated by PARP-1 inhibition in non-small-cell lung cancer

BACKGROUND

Carbon ion (¹²C) radiotherapy is becoming very promising to kill highly metastatic cancer cells keeping adjacent normal cells least affected. Our previous study shows that combined PARP-1 inhibition with ¹²C ion reduces MMP-2,-9 synergistically in HeLa cells but detailed mechanism are not clear. To understand this mechanism and the rationale of using PARP-1 inhibitor with ¹²C ion radiotherapy for better outcome in controlling metastasis, we investigated metastatic potential in two non-small cell lung cancer (NSCLC) A549 and H1299 (p53-deficient) cells exposed with ¹²C ion in presence and absence of PARP-1 inhibition using siRNA or olaparib.

METHODS

We monitored cell proliferation, in-vitro cell migration, wound healing, expression and activity of MMP-2, - 9 in A549 and p53-deficient H1299 cell lines exposed with ¹²C ion with and without PARP-1 inhibitor olaparib/DPQ. Expression and phosphorylation of NF-kB, EGFR, Akt, p38, ERK was also observed in A549 and H1299 cells exposed with ¹²C ion with and without PARP-1 inhibition using siRNA or olaparib. We also checked expression of few marker genes involved in epithelial-mesenchymal transition (EMT) pathways like N-cadherin, vimentin, anillin, claudin-1, - 2 in both NSCLC. To determine the generalized effect of ¹²C ion and olaparib in inhibition of cell's metastatic potential, wound healing and activity of MMP-2, - 9 was also studied in HeLa and MCF7 cell lines after ¹²C ion exposure and in combination with PARP-1 inhibitor olaparib.

RESULTS

Our experiments show that ¹²C ion and PARP-1 inhibition separately reduces cell proliferation, cell migration, wound healing, phosphorylation of EGFR, Akt, p38, ERK resulting inactivation of NF-kB. Combined treatment abolishes NF-kB expression and hence synergistically reduces MMP-2, - 9 expressions. Each single treatment reduces N-cadherin, vimentin, anillin but increases claudin-1, - 2 leading to suppression of EMT process. However, combined treatment synergistically alters these proteins to suppress EMT pathways significantly.

CONCLUSION

The activation pathways of transcription of MMP-2,-9 via NF-kB and key marker proteins in EMT pathways are targeted by both ¹²C ion and olaparib/siRNA. Hence, ¹²C ion radiotherapy could potentially be combined with olaparib as chemotherapeutic agent for better control of cancer metastasis.

Continuous, label-free, 96-well-based determination of cell migration using confluence measurement

Cellular migration is essential in diverse physiological and pathophysiological processes. Here, we present a protocol for quantitative analysis of migration using confluence detection allowing continuous, non-endpoint measurement with minimal hands-on time under cell incubator conditions. Applicability was tested using substances which enhance (EGF) or inhibit (cytochalasin D, ouabain) migration. Using a gap-closure assay we demonstrate that automated confluence detection monitors cellular migration in the 96-well microplate format. Quantification by % confluence, % cell free-area or % confluence in cell-free area against time, allows detailed analysis of cellular migration. The study describes a practicable approach for continuous, non-endpoint measurement of migration in 96-well microplates and for detailed data analysis, which allows for medium/high-throughput analysis of cellular migration in vitro.

Light-sheet Microscopy for Three-dimensional Visualization of Human Immune Cells

In vivo, activation, proliferation, and function of immune cells all occur in a three-dimensional (3D) environment, for instance in lymph nodes or tissues. Up to date, most in vitro systems rely on two-dimensional (2D) surfaces, such as cell-culture plates or coverslips. To optimally mimic physiological conditions in vitro, we utilize a simple 3D collagen matrix. Collagen is one of the major components of extracellular matrix (ECM) and has been widely used to constitute 3D matrices. For 3D imaging, the recently developed light-sheet microscopy technology (also referred to as single plane illumination microscopy) is featured with high acquisition speed, large penetration depth, low bleaching, and photocytotoxicity. Furthermore, light-sheet microscopy is particularly advantageous for long-term measurement. Here we describe an optimized protocol how to set up and handle human immune cells, e.g. primary human cytotoxic T lymphocytes (CTL) and natural killer (NK) cells in the 3D collagen matrix for usage with the light-sheet microscopy for live cell imaging and fixed samples. The procedure for image acquisition and analysis of cell migration are presented. A particular focus is given to highlight critical steps and factors for sample preparation and data analysis. This protocol can be employed for other types of suspension cells in a 3D collagen matrix and is not limited to immune cells.

Hepatitis B virus X induces inflammation and cancer in mice liver through dysregulation of cytoskeletal remodeling and lipid metabolism

Hepatitis B virus X protein (HBx) participates in the occurrence and development processes of hepatocellular carcinoma (HCC) as a multifunctional regulation factor. However, the underlying molecular mechanism remains obscure. Here, we describe the use of p21^HBx/+ mouse and SILAM (Stable Isotope Labeling in Mammals) strategy to define the pathological mechanisms for the occurrence and development of HBx induced liver cancer. We systematically compared a series of proteome samples from regular mice, 12- and 24-month old p21^HBx/+ mice representing the inflammation and HCC stages of liver disease respectively and their nontransgenic wild-type (WT) littermates. Totally we identified 22 and 97 differentially expressed proteins out of a total of 2473 quantified proteins. Bioinformatics analysis suggested that the lipid metabolism and CDC42-induced cytoskeleton remodeling pathways were strongly activated by the HBx transgene. Interestingly, the protein-protein interaction MS study revealed that HBx directly interacted with multiple proteins in these two pathways. The same effect of up-regulation of cytoskeleton and lipid metabolism related proteins, including CDC42, CFL1, PPARγ and ADFP, was also observed in the Huh-7 cells transfected with HBx. More importantly, CFL1 and ADFP were specifically accumulated in HBV-associated HCC (HBV-HCC) patient samples, and their expression levels were positively correlated with the severity of HBV-related liver disease. These results provide evidence that HBx induces the dysregulation of cytoskeleton remodeling and lipid metabolism and leads to the occurrence and development of liver cancer. The CFL1 and ADFP might be served as potential biomarkers for prognosis and diagnosis of HBV-HCC.

Technical Advance: New in vitro method for assaying the migration of primary B cells using an endothelial monolayer as substrate

Migration of B cells supports their development and recruitment into functional niches. Therefore, defining factors that control B cell migration will lead to a better understanding of adaptive immunity. In vitro cell migration assays with B cells have been limited by poor adhesion of cells to glass coated with adhesion molecules. We have developed a technique using monolayers of endothelial cells as the substrate for B cell migration and used this technique to establish a robust in vitro assay for B cell migration. We use TNF-α to up-regulate surface expression of the adhesion molecule VCAM-1 on endothelial cells. The ligand VLA-4 is expressed on B cells, allowing them to interact with the endothelial monolayer and migrate on its surface. We tested our new method by examining the role of L-plastin (LPL), an F-actin-bundling protein, in B cell migration. LPL-deficient (LPL^-/-) B cells displayed decreased speed and increased arrest coefficient compared with wild-type (WT) B cells, following chemokine stimulation. However, the confinement ratios for WT and LPL^-/- B cells were similar. Thus, we demonstrate how the use of endothelial monolayers as a substrate will support future interrogation of molecular pathways essential to B cell migration.

A Modular and Affordable Time-Lapse Imaging and Incubation System Based on 3D-Printed Parts, a Smartphone, and Off-The-Shelf Electronics

Time-lapse imaging is a powerful tool for studying cellular dynamics and cell behavior over long periods of time to acquire detailed functional information. However, commercially available time-lapse imaging systems are expensive and this has limited a broader implementation of this technique in low-resource environments. Further, the availability of time-lapse imaging systems often present workflow bottlenecks in well-funded institutions. To address these limitations we have designed a modular and affordable time-lapse imaging and incubation system (ATLIS). The ATLIS enables the transformation of simple inverted microscopes into live cell imaging systems using custom-designed 3D-printed parts, a smartphone, and off-the-shelf electronic components. We demonstrate that the ATLIS provides stable environmental conditions to support normal cell behavior during live imaging experiments in both traditional and evaporation-sensitive microfluidic cell culture systems. Thus, the system presented here has the potential to increase the accessibility of time-lapse microscopy of living cells for the wider research community.

Synergistic effect of atorvastatin and cyanidin-3-glucoside against angiotensin II-mediated vascular smooth muscle cell proliferation and migration through MAPK and PI3K/Akt pathways

This study aimed to investigate the mechanism of cyanidin-3-glucoside (C3G) in synergy with atorvastatin, even when it is used in low concentrations. Human aortic smooth muscle cells (HASMCs) were used to verify the synergistic mechanism of atorvastatin and C3G against angiotensin II-induced proliferation and migration. BrdU incorporation assay was used to evaluate cell proliferation. Wound healing and Boyden chamber assays were used to investigate cell migration. The cell cycle was examined using flow cytometry. The results revealed that atorvastatin and C3G exhibit a synergistic effect in ameliorating HASMC proliferation and migration by enhancing cell cycle arrest. In addition, these effects also decreased mitogen-activated protein kinase (MAPK) activity by attenuating the expression of phospho-p38, phospho-extracellular signaling-regulated kinase 1/2, and phospho-c-Jun N-terminal kinase. Furthermore, the combination of atorvastatin and C3G modulated the PI3K/Akt pathway and upregulated p21Cip1, which was associated with decreases in cyclin D1 and phospho-retinoblastoma expressions. The synergistic effect of atorvastatin and C3G induced anti-proliferation and anti-migration through MAPK and PI3K/Akt pathways mediated by AT1R. These results suggest that the synergistic effect of atorvastatin and C3G may be an alternative therapy for atherosclerosis patients.

Comparison between fibroblast wound healing and cell random migration assays in vitro

Cell migration plays a key role in many biological processes, including cancer growth and invasion, embryogenesis, angiogenesis, inflammatory response, and tissue repair. In this work, we compare two well-established experimental approaches for the investigation of cell motility in vitro: the cell random migration (CRM) and the wound healing (WH) assay. In the former, extensive tracking of individual live cells trajectories by time-lapse microscopy and elaborate data processing are used to calculate two intrinsic motility parameters of the cell population under investigation, i.e. the diffusion coefficient and the persistence time. In the WH assay, a scratch is made in a confluent cell monolayer and the closure time of the exposed area is taken as an easy-to-measure, empirical estimate of cell migration. To compare WH and CRM we applied the two assays to investigate the motility of skin fibroblasts isolated from wild type and transgenic mice (TgPED) overexpressing the protein PED/PEA-15, which is highly expressed in patients with type 2 diabetes. Our main result is that the cell motility parameters derived from CRM can be also estimated from a time-resolved analysis of the WH assay, thus showing that the latter is also amenable to a quantitative analysis for the characterization of cell migration. To our knowledge this is the first quantitative comparison of these two widely used techniques.

Substance-specific importance of EGFR for vascular smooth muscle cells motility in primary culture

Besides their importance for the vascular tone, vascular smooth muscle cells (VSMC) also contribute to pathophysiological vessel alterations. Various G-protein coupled receptor ligands involved in vascular dysfunction and remodeling can transactivate the epidermal growth factor receptor (EGFR) of VSMC, yet the importance of EGFR transactivation for the VSMC phenotype is incompletely understood. The aims of this study were (i) to characterize further the importance of the VSMC-EGFR for proliferation, migration and marker gene expression for inflammation, fibrosis and reactive oxygen species (ROS) homeostasis and (ii) to test the hypothesis that vasoactive substances (endothelin-1, phenylephrine, thrombin, vasopressin and ATP) rely differentially on the EGFR with respect to the abovementioned phenotypic alterations. In primary, aortic VSMC from mice without conditional deletion of the EGFR, proliferation, migration, marker gene expression (inflammation, fibrosis and ROS homeostasis) and cell signaling (ERK 1/2, intracellular calcium) were analyzed. VSMC-EGFR loss reduced collective cell migration and single cell migration probability, while no difference between the genotypes in single cell velocity, chemotaxis or marker gene expression could be observed under control conditions. EGF promoted proliferation, collective cell migration, chemokinesis and chemotaxis and leads to a proinflammatory gene expression profile in wildtype but not in knockout VSMC. Comparing the impact of five vasoactive substances (all reported to transactivate EGFR and all leading to an EGFR dependent increase in ERK1/2 phosphorylation), we demonstrate that the importance of EGFR for their action is substance-dependent and most apparent for crowd migration but plays a minor role for gene expression regulation.

Fibroblasts Enhance Migration of Human Lung Cancer Cells in a Paper-Based Coculture System

A multilayered paper-based platform is used to investigate the interactions between human lung tumor cells and fibroblasts that are isolated from primary patient tumor samples.

Xenopus: An in vivo model for imaging the inflammatory response following injury and bacterial infection

A major goal in regenerative medicine is to identify therapies to facilitate our body׳s innate abilities to repair and regenerate following injury, disease or aging. In the past decade it has become apparent that the innate immune system is able to affect the speed and quality of the regenerative response through mechanisms that are not entirely clear. For this reason there has been a resurgent interest in investigating the role of inflammation during tissue repair and regeneration. Remarkably, there have only been a handful of such studies using organisms with high regenerative capacity. Here we perform a study of the inflammatory response following injury in Xenopus larvae, which are able to achieve scarless wound healing and to regenerate appendages, as a preamble into understanding the role that inflammation plays during tissue repair and regeneration in this organism. We characterized the morphology and migratory behavior of granulocytes and macrophages following sterile and infected wounding regimes, using various transgenic lines that labeled different types of myeloid lineages, including granulocytes and macrophages. Using this approach we found that the inflammatory response following injury and infection in Xenopus larvae is very similar to that seen in humans, suggesting that this model provides an easily tractable and medically relevant system to investigate inflammation following injury and infection in vivo.

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Xenopus larvae is an ideal model to study injury-induced inflammation in vivo.

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Xenopus larvae provides an easily tractable model of human inflammation.

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Xenopus larvae provides a powerful model for investigating cell migration in vivo.

Combretastatin A-4 derived imidazoles show cytotoxic, antivascular, and antimetastatic effects based on cytoskeletal reorganisation

INTRODUCTION

Combretastatin A-4 (CA-4) is a natural cis-stilbene which interferes with the cellular tubulin dynamics and which selectively destroys tumour blood vessels. Its pharmacological shortcomings such as insufficient chemical stability, water solubility, and cytotoxicity can be remedied by employing its imidazole derivatives.

METHODS

We studied 11 halogenated imidazole derivatives of CA-4 for their effects on the microtubule and actin cytoskeletons of cancer and endothelial cells and on the propensity of these cells to migrate across tissue barriers or to form blood vessel-like tubular structures.

RESULTS

A series of N-methyl-4-aryl-5-(4-ethoxyphenyl)-imidazoles proved far more efficacious than the lead CA-4 in growth inhibition assays against CA-4-resistant HT-29 colon carcinoma cells and generally more selective for cancer over nonmalignant cells. Et-brimamin (6), the most active compound, inhibited the growth of various cancer cell lines with IC50 (72 h) values in the low nanomolar range. Active imidazoles such as 6 reduced the motility and invasiveness of cancer cells by initiating the formation of actin stress fibres and focal adhesions as a response to the extensive microtubule disruption. The antimetastatic properties were ascertained in 3D-transwell migration assays which simulated the transgression of highly invasive melanoma cells through the extracellular matrix of solid tumours and through the endothelium of blood vessels. The studied imidazoles exhibited vascular-disrupting effects also against tumour xenografts that are refractory to CA-4. They were also less toxic and better tolerated by mice.

CONCLUSIONS

We deem the new imidazoles promising drug candidates for combination regimens with antiangiogenic VEGFR inhibitors.

Biological evaluation of 4,5-diarylimidazoles with hydroxamic acid appendages as novel dual mode anticancer agents

PURPOSE

New (4-aryl-1-methylimidazol-5-yl)cinnamoylhydroxamic acids were prepared as potential dual mode anticancer agents combining the antivascular effect of the 4,5-diarylimidazole moiety and the histone deacetylases (HDAC) inhibition by the cinnamoyl hydroxamate.

METHODS

Their antiproliferative activity against a panel of primary cells and cancer cell lines was determined by MTT assays and their apoptosis induction by caspase-3 activation. Their ability to reduce the activity of HDAC was measured by enzymatic assays and Western blot analyses of cellular HDAC substrates. Additional effects on cancer cell migration were ascertained via immunofluorescence staining of cytoskeleton components and three-dimensional migration assays. The chorioallantoic membrane assay was used as an in vivo model to assess their antiangiogenic properties.

RESULTS

The 4-phenyl- and 4-(p-methoxyphenyl)-imidazole derivatives had a greater antiproliferative and apoptosis inducing effect in a variety of cancer cell lines when compared with the approved HDAC inhibitor SAHA, and most distinctly so in non-malignant human umbilical vein endothelial cells. Like SAHA, both compounds acted as pan-HDAC inhibitors. In 518A2 melanoma cells, they led to hyperacetylation of histones and of the cytoplasmic HDAC6 substrate alpha-tubulin. As a consequence, they inhibited the migration and invasion of these cells in transwell invasion assays. In keeping with its pronounced impact on endothelial cells, the 4-phenyl-imidazole derivative also inhibited the growth and sprouting of blood vessels in the chorioallantoic membrane of fertilized hen eggs.

CONCLUSIONS

The 4-phenyl- and 4-(p-methoxyphenyl)-imidazole compounds combine the antivascular effects of 4,5-diarylimidazoles with HDAC inhibition by cinnamoyl hydroxamates and show additional antimetastatic activity. They are promising candidates for pleiotropic HDAC inhibitors.

Real-time monitoring of cell migration, phagocytosis and cell surface receptor dynamics using a novel, live-cell opto-microfluidic technique

We report an opto-microfluidic method for continuous and non-interfering monitoring of cell movement and dynamic molecular processes in living cells enabled by the microfluidic "Lab-in-a-Trench" (LiaT) platform. To demonstrate real-time monitoring of heterogeneous cell-cell interactions, cell tracking and agent-induced cell activation dynamics, we observe phagocytosis of Escherichia coli by murine macrophages, migration of active macrophages and LPS-induced CD86 expression in macrophages. The visualization of phagocytosis is facilitated through the loading of green fluorescent protein (GFP) expressing E. coli to the array of cell capture modules before the introduction of macrophages. Simple migration tracking of active macrophages is enabled by a spatio-temporal control of the environment conditions within the LiaT platform. Furthermore, we report an interference-free monitoring of non-modified, endogenous changes in protein expression on the surface of living cells using traditional, antibody immuno-reagents. Throughout the experiment, murine macrophages were captured in the LiaT device and exposed to sub-background levels of fluorescently labeled anti-CD86 antibody. Upon lipopolysaccharide (LPS) stimulation, CD86 changes were visualized in real-time by time-lapse microscopy. This novel opto-microfluidic effect is controlled by the equilibrium of convective-diffusive replenishment of fluorescently labeled antibodies and antibody affinity. Overall, our non-interfering analysis method allows the studying of active cellular processes and endogenous protein dynamics in live cells in a simple and cost-efficient manner.

In vitro cell motility as a potential mesenchymal stem cell marker for multipotency

Mesenchymal stem cells (MSCs) are expected to have a fundamental role in future cell-based therapies because of their high proliferative ability, multilineage potential, and immunomodulatory properties. Autologous transplantations have the "elephant in the room" problem of wide donor variability, reflected by variability in MSC quality and characteristics, leading to uncertain outcomes in the use of these cells. We propose life imaging as a tool to characterize populations of human MSCs. Bone marrow MSCs from various donors and in vitro passages were evaluated for their in vitro motility, and the distances were correlated to the adipogenic, chondrogenic, and osteogenic differentiation potentials and the levels of senescence and cell size. Using life-image measuring of track lengths of 70 cells per population for a period of 24 hours, we observed that slow-moving cells had the higher proportion of senescent cells compared with fast ones. Larger cells moved less than smaller ones, and spindle-shaped cells had an average speed. Both fast cells and slow cells were characterized by a low differentiation potential, and average-moving cells were more effective in undergoing all three lineage differentiations. Furthermore, heterogeneity in single cell motility within a population correlated with the average-moving cells, and fast- and slow-moving cells tended toward homogeneity (i.e., a monotonous moving pattern). In conclusion, in vitro cell motility might be a useful tool to quickly characterize and distinguish the MSC population's differentiation potential before additional use.

Agent-based model of human alveoli predicts chemotactic signaling by epithelial cells during early Aspergillus fumigatus infection

Aspergillus fumigatus is one of the most important human fungal pathogens, causing life-threatening diseases. Since humans inhale hundreds to thousands of fungal conidia every day, the lower respiratory tract is the primary site of infection. Current interaction networks of the innate immune response attribute fungal recognition and detection to alveolar macrophages, which are thought to be the first cells to get in contact with the fungus. At present, these networks are derived from in vitro or in situ assays, as the peculiar physiology of the human lung makes in vivo experiments, including imaging on the cell-level, hard to realize. We implemented a spatio-temporal agent-based model of a human alveolus in order to perform in silico experiments of a virtual infection scenario, for an alveolus infected with A. fumigatus under physiological conditions. The virtual analog captures the three-dimensional alveolar morphology consisting of the two major alveolar epithelial cell types and the pores of Kohn as well as the dynamic process of respiration. To the best of our knowledge this is the first agent-based model of a dynamic human alveolus in the presence of respiration. A key readout of our simulations is the first-passage-time of alveolar macrophages, which is the period of time that elapses until the first physical macrophage-conidium contact is established. We tested for random and chemotactic migration modes of alveolar macrophages and varied their corresponding parameter sets. The resulting first-passage-time distributions imply that randomly migrating macrophages fail to find the conidium before the start of germination, whereas guidance by chemotactic signals derived from the alveolar epithelial cell associated with the fungus enables a secure and successful discovery of the pathogen in time.

Rapamycin promotes Schwann cell migration and nerve growth factor secretion

Rapamycin, similar to FK506, can promote neural regeneration in vitro. We assumed that the mechanisms of action of rapamycin and FK506 in promoting peripheral nerve regeneration were similar. This study compared the effects of different concentrations of rapamycin and FK506 on Schwann cells and investigated effects and mechanisms of rapamycin on improving peripheral nerve regeneration. Results demonstrated that the lowest rapamycin concentration (1.53 nmol/L) more significantly promoted Schwann cell migration than the highest FK506 concentration (100μmol/L). Rapamycin promoted the secretion of nerve growth factors and upregulated growth-associated protein 43 expression in Schwann cells, but did not significantly affect Schwann cell proliferation. Therefore, rapamycin has potential application in peripheral nerve regeneration therapy.

Bioinspired microfluidic assay for in vitro modeling of leukocyte-endothelium interactions

Current in vitro models of the leukocyte adhesion cascade cannot be used for real-time studies of the entire leukocyte adhesion cascade, including rolling, adhesion, and migration in a single assay. In this study, we have developed and validated a novel bioinspired microfluidic assay (bMFA) and used it to test the hypothesis that blocking of specific steps in the adhesion/migration cascade significantly affects other steps of the cascade. The bMFA consists of an endothelialized microvascular network in communication with a tissue compartment via a 3 μm porous barrier. Human neutrophils in bMFA preferentially adhered to activated human endothelial cells near bifurcations with rolling and adhesion patterns in close agreement with in vivo observations. Treating endothelial cells with monoclonal antibodies to E-selectin or ICAM-1 or treating neutrophils with wortmannin reduced rolling, adhesion, and migration of neutrophils to 60%, 20%, and 18% of their respective control values. Antibody blocking of specific steps in the adhesion/migration cascade (e.g., mAb to E-selectin) significantly downregulated other steps of the cascade (e.g., migration). This novel in vitro assay provides a realistic human cell based model for basic science studies, identification of new treatment targets, selection of pathways to target validation, and rapid screening of candidate agents.

Tracking migration during human T cell development

Specialized microenvironments within the thymus are comprised of unique cell types with distinct roles in directing the development of a diverse, functional, and self-tolerant T cell repertoire. As they differentiate, thymocytes transit through a number of developmental intermediates that are associated with unique localization and migration patterns. For example, during one particular developmental transition, immature thymocytes more than double in speed as they become mature T cells that are among the fastest cells in the body. This transition is associated with dramatic changes in the expression of chemokine receptors and their antagonists, cell adhesion molecules, and cytoskeletal components to direct the maturing thymocyte population from the cortex to medulla. Here we discuss the dynamic changes in behavior that occur throughout thymocyte development, and provide an overview of the cell-intrinsic and extrinsic mechanisms that regulate human thymocyte migration.

Chemical analysis, antioxidant, antichemotactic and monoamine oxidase inhibition effects of some pteridophytes from Brazil

Background:

Ferns are a group of plants that have been little explored from a chemical and biological perspective but that have interesting potential, occurring in various parts of the world.

Objective:

This work investigates the chemical profile and the biological effects of ferns from Brazil.

Materials and Methods:

Analyses were performed using rapid performance liquid chromatography (RP-LC) with a diode array detector (DAD). Extracts were tested for their in vitro antioxidant activity, by the total reactive antioxidant potential method and for their antichemotactic potential, by the Boyden chamber method. Cytotoxic effects were assessed by lactate dehydrogenase levels, while the monoamine oxidase (MAO) assay was carried out using a fluorescence-based method.

Results:

Different chemical compositions were found for the studied ferns, such as Asplenium gastonis, in which hesperidin was identified in its extract, while A. serra showed the presence of xanthone mangiferin. The most samples with highest antioxidant activity were the Asplenium serra, Lastreopsis amplissima and Cyathea dichromatolepis extracts, at 10 μg/mL. High antichemotactic activity was found for A. serra (94.06%) and Didymochlaena truncatula (93.41%), at 10 μg/mL. The extracts showed no cytotoxicity at the highest concentration. Against MAO-A, D. truncatula (82.61%), Alsophila setosa (82.21%), Cyathea phalerata (74.07%) and C. delgadii (70.32%) were the most active extracts (100 μg/mL).

Conclusion:

The hypothesis was considered that phenolics and triterpenes are responsible for these pronounced activities.

Tissue engineering concept in the research of the tumor biology

Tumor is a heterogeneous complex, which lives in a three-dimensional environment flush with biopathophysiological and biomechanical signals. This signaling abundant extracellular milieu co-evolving from cell-cell and cell-host interaction guides the development and the generation of the tumor. There has been a recent surge of interest in studying the tumor biology that more closely mirror what happens in living organisms, especially in cancer research. Incorporating cancer cells in the 3D mimicking environment instead of monolayers is reasonable for maintaining in vivo cancer behaviors in spatial and temporal context. However, 3D culture for cancer still presents a challenge for researchers in this field. Tissue engineering, originally aiming at designing the artificial organs, provided a feasible approach to recreate such complex mechanical and biochemical interplay. Aside from reproducing bionic environment, tissue engineering has been routinely introduced into cancer study to build three dimensional structures not only to develop molecular therapeutics, but also to screen for toxic effects of drugs or radiotherapy sensitivity. In this article, we focused on the recent advances of the well-defined tissue-engineering biomaterials in the application in tumor biology. We also discussed the fabrications of the scaffolds from different materials, which might contribute to future cancer research.

Norepinephrine inhibits the migratory activity of pancreatic cancer cells

We have shown previously that norepinephrine induces migratory activity of tumour cells from breast, colon and prostate tissue via activation of beta-2 adrenergic receptors. Consequently, this effect can be inhibited pharmacologically by clinically established beta-blockers. Tumour cell migration is a prerequisite for metastasis formation, and accordingly we and others have shown that breast cancer patients, which take beta-blockers due to hypertension, have reduced metastasis formation and increased survival probability as compared to patients without hypertension or using other anti-hypertensive medication. Unlike the aforementioned tumour cells, pancreatic cancer cells show a reduced migratory activity upon norepinephrine treatment. By means of our three-dimensional, collagen-based cell migration assay, we have investigated the signal transduction pathways involved in this phenomenon. We have found that this conflicting effect of norepinephrine on pancreatic cancer cells is due to an imbalanced activation of the two pathways that usually mediate a pro-migratory effect of norepinephrine in other tumour cell types. Firstly, the inhibitory effect results from activation of a pathway which causes a strong increase of the secondary cell signalling molecule, cAMP. In addition, activation of phospholipase C gamma and the downstream protein kinase C alpha were shown to be already activated in pancreatic cancer cells and cannot be further activated by norepinephrine. We hypothesize that this constitutive activation of the phospholipase C gamma pathway is due to a cross-talk with receptor tyrosine kinase signalling, and this might also deliver an explanation for the unusual high spontaneous migratory activity of pancreatic cancer cells.

A novel application for a 3-dimensional timelapse assay that distinguishes chemotactic from chemokinetic responses of hematopoietic CD133(+) stem/progenitor cells

Efficient homing/mobilization of human hematopoietic stem/progenitor cells to/from bone marrow niches enhances their therapeutic efficacy. Additionally, homing is dependent on cell source and may be modulated by prior ex vivo cell expansion. Here, we describe a novel application of a 3-dimensional time-lapse method for assessing trafficking of individual human cord blood CD133⁺ hematopoietic stem/progenitor cells in vitro, using the key chemokine CXCL12 as a paradigm. This new methodology allows distinction between chemotactic responses (displacement of center of mass and the forward migration index of the cells), and chemokinetic responses such as total cell path traveled in any direction (accumulated distance) and cell velocity in a 3-dimensional matrix. Other key advantages of this novel assay over existing assays include the ability to assess individual cell migration over times comparable to in vivo homing and rapid mobilization assays (18–24 h) and to directly compare the strength or response of individual hematopoietic progenitor cells to different or competing stimuli and small molecule inhibitors in a single assay prior to analyses in vivo. Importantly, using this method, our results demonstrate definitively that CXCL12 regulates the chemotactic responses of human cord blood CD133⁺ cells, but not their random migration or chemokinesis.

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Development of a novel 3-dimensional timelapse chemotaxis assay application.

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Measuring individual CD133+ HSPC trafficking towards chemokines in a 3D matrix.

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Chemotactic and chemokinetic responses reflecting homin kinetics in vivo.

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Comparative analysis of inhibitors or expansion on HSPC chemotaxis and chemokinesis.

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Definitive proof that CXCL12 regulates CD133+ HSPC chemotaxis but not chemokinesis.

Myopodin isoforms alter the chemokinetic response of PC3 cells in response to different migration stimuli via differential effects on Rho-ROCK signaling pathways

The gene encoding myopodin, an actin binding protein, is commonly deleted in invasive, but not in indolent, prostate cancers. There are conflicting reports on the effects of myopodin expression on prostate cancer cell migration and invasion. The recent recognition that myopodin is expressed as four different isoforms further complicates our understanding of how this potentially important invasive prostate cancer biomarker affects tumor cell migration and invasion. We now show that myopodin affects the chemokinetic, rather than the chemotactic, properties of PC3 prostate cancer cells. Furthermore, all myopodin isoforms can either increase or decrease PC3 cell migration in response to different chemokinetic stimuli. These migration properties were reflected by differences in cell morphology and the relative dependence on Rho-ROCK signaling pathways induced by the environmental stimuli. Truncation analysis determined that a unique 9-residue C-terminal sequence in the shortest isoform and the conserved, PDZ domain-containing N-terminal region of the long isoforms both contribute to the ability of myopodin to alter the response of PC3 cells to chemokinetic stimuli. Matrigel invasion assays also indicated that myopodin primarily affects the migration, rather than the invasion, properties of PC3 cells. The correlation between loss of myopodin expression and invasive prostate cancer therefore reflects complex myopodin interactions with pathways that regulate the cellular migration response to diverse signals that may be present in a tumor microenvironment.

MICROFLUIDIC DEVICE FOR EXAMINING DIRECTIONAL SENSING IN DENDRITIC CELL CHEMOTAXIS

Dendritic cell chemotaxis is an important process involved in the acquisition of adaptive immunity. Despite several studies, our understanding of this process remains limited. One of the reasons for this is the lack of experimental models that give us real-time information on dendritic cell locomotion. Here, using tools in microfluidics, we have fabricated a microdevice that allows us to monitor dendritic cell migration in a chemokine gradient in real time. We successfully observed the migration of dendritic cells derived from a myeloid leukemia cell line (MUTZ-3) in a soluble chemokine (CCL-19) gradient. Our experiments suggest the utility of microdevices in monitoring dendritic cell chemotaxis in real time and getting important information regarding migration speeds and distances previously not available from conventional chemotaxis assays. This kind of data is useful for building mechanistic mathematical models of dendritic cell chemotaxis that may give us novel insights to the process of dendritic cell chemotaxis.

Combined experimental and mathematical approach for development of microfabrication-based cancer migration assay

Migration of cancer cells is a key determinant of metastasis, which is correlated with poor prognosis in patients. Evidence shows that cancer cell motility is regulated by stromal cell interactions. To quantify the role of homotypic and heterotypic cell-cell interaction in migration, a two-dimensional migration assay has been developed by microfabrication techniques. Two breast cancer cell lines, MDA-MB-231 and MDA-MB-453, were used to develop micropatterns of cancer cells (cell islands) that revealed distinct migration profiles in this assay. Although the individual migration rates of these cells showed only a sevenfold difference, MDA-MB-453 islands migrated significantly lower than MDA-MB-231 islands, indicating differential regulation of migration in isolated cells vs. islands. Island size had the greatest impact on migration, primarily for MDA-MB-231 cells. Migration of MDA-MB-231 islands was decreased by interaction with homotypic cells, and significantly more by heterotypic non-cancer-associated fibroblasts. In addition, a mathematical model of island migration in multi-cellular population has been developed using Stefan-Maxwell's equation. The model showed qualitative agreement with experimental results and predicted a biphasic relation between cell densities and island sizes. The combined experimental and mathematical model can be used to quantitatively study the impact of cell-cell interactions on migration.

A semi-automated programme for tracking myoblast migration following mechanical damage: manipulation by chemical inhibitors

BACKGROUND

Potential roles for undifferentiated skeletal muscle stem cells or satellite cells in muscle hypertrophy and repair have been reported, however, the capacity, the mode and the mechanisms underpinning migration have not been investigated. We hypothesised that damaged skeletal myoblasts would elicit a mesenchymal-like migratory response, which could be precisely tracked and subsequently manipulated.

METHODS

We therefore established a model of mechanical damage and developed a MATLAB(TM) tool to measure the migratory capacity of myoblasts in a non-subjective manner.

RESULTS

Basal migration following damage was highly directional, with total migration distances of 948μm ± 239μm being recorded (average 0-24 hour distances: 491μm ± 113μm and 24-48 hour distances: 460μm ± 218μm). Pharmacological inhibition of MEK or PI3-K using PD98059 (20μM) or LY294002 (5μm), resulted in significant reduction of overall cell migration distances of 38% (p<0.001) and 39.5% (p<0.0004), respectively. Using the semi-automated cell tracking using MATLAB(TM) program we validated that not only was migration distance reduced as a consequence of reduced cell velocity, but critically also as a result of altered directionality of migration.

CONCLUSION

These studies demonstrate that murine myoblasts in culture migrate and provide a good model for studying responsiveness to damage in vitro. They illustrate for the first time the powerful tool that MATLAB(TM) provides in determining that both velocity and directional capacity influence the migratory potential of cellular movement with obvious implications for homing and for metastases.

Diabetogenic glucose and insulin concentrations modulate transcriptome and protein levels involved in tumour cell migration, adhesion and proliferation

Background:

During the last decade, epidemiological studies uncovered the tremendous impact of metabolic syndrome/diabetes mellitus type 2 (DM T2) as risk factors of the progression of cancer. Therefore, we studied the impact of diabetogenic glucose and insulin concentrations on the activities of tumour cells, because little is known about how high glucose and insulin levels are influencing gene activities causing changes in the signal cascade activities with respect to kinases involved in the proliferation and migration of cancer cells.

Methods:

To address this question we analysed the activity of more than 400 gene signatures related to (i) cell cycle, (ii) cell movement as well as (iii) signal transduction. We examined transcriptoms of kinases (PKCα, PI3K), cadherins (E-, N- VE-), integrins and cyclins by comparing physiological (5.5 mM) vs diabetogenic (11 mM) glucose concentrations (without and with insulin).

Results:

Proliferation assays revealed that high levels of glucose (11 mM) and insulin (100 ng ml⁻¹) did promote the proliferation of the tumour cell lines HT29, SW480, MCF-7, MDA MB468, PC3 and T24. Using a 3D-migration assay, we have shown that high glucose concentrations caused increased motility rates of the tumour cells. The increase in migratory activity at high glucose and insulin concentrations was mediated by an activation of PI3K, PKCα and MLCK, as figured out by the pharmacological inhibitors wortmannin, Go6976 and ML-7.

Conclusion:

We present molecular and functional data, which could help to understand how hyperglycaemia and hyperinsulinemia might trigger tumour cell proliferation and motility in patients, too.

Systems microscopy approaches to understand cancer cell migration and metastasis

Cell migration is essential in a number of processes, including wound healing, angiogenesis and cancer metastasis. Especially, invasion of cancer cells in the surrounding tissue is a crucial step that requires increased cell motility. Cell migration is a well-orchestrated process that involves the continuous formation and disassembly of matrix adhesions. Those structural anchor points interact with the extra-cellular matrix and also participate in adhesion-dependent signalling. Although these processes are essential for cancer metastasis, little is known about the molecular mechanisms that regulate adhesion dynamics during tumour cell migration. In this review, we provide an overview of recent advanced imaging strategies together with quantitative image analysis that can be implemented to understand the dynamics of matrix adhesions and its molecular components in relation to tumour cell migration. This dynamic cell imaging together with multiparametric image analysis will help in understanding the molecular mechanisms that define cancer cell migration.

Effect of NRG1, GDNF, EGF and NGF in the migration of a Schwann cell precursor line

The Schwann cells are the myelinating glia of the peripheral nervous system that originated during development from the highly motile neural crest. However, we do not know what the guidance signals for the Schwann cell precursors are. Therefore, we set to test some of the known neurotrophins that are expressed early in developing embryos and have been shown to be critical for the survival and patterning of developing glia and neurons. The goal of this study was to determine more specifically if GDNF, NRG1 and NGF are chemoattractants and/or chemokinetic molecules for a Schwann cell precursor line, the Spl201. We performed live chemoattraction assays, with imaging and also presented these molecules as part of their growing substrate. Our results show for the first time that GDNF and NRG1 are potent chemoattractive and chemokinetic molecules for these cells while NGF is a chemokinetic molecule stimulating their motility.

Significantly improved precision of cell migration analysis in time-lapse video microscopy through use of a fully automated tracking system

Background

Cell motility is a critical parameter in many physiological as well as pathophysiological processes. In time-lapse video microscopy, manual cell tracking remains the most common method of analyzing migratory behavior of cell populations. In addition to being labor-intensive, this method is susceptible to user-dependent errors regarding the selection of "representative" subsets of cells and manual determination of precise cell positions.

Results

We have quantitatively analyzed these error sources, demonstrating that manual cell tracking of pancreatic cancer cells lead to mis-calculation of migration rates of up to 410%. In order to provide for objective measurements of cell migration rates, we have employed multi-target tracking technologies commonly used in radar applications to develop fully automated cell identification and tracking system suitable for high throughput screening of video sequences of unstained living cells.

Conclusion

We demonstrate that our automatic multi target tracking system identifies cell objects, follows individual cells and computes migration rates with high precision, clearly outperforming manual procedures.

Coagulation Factor Xa inhibits cancer cell migration via LIMK1-mediated cofilin inactivation

Previously, we showed that activated coagulation factor X (FXa) inhibits migration of breast, lung and colon cancer cells. We showed that the effect of FXa on migration was protease-activated receptor (PAR)-1-dependent, but the subsequent cellular signaling routes remained elusive. In the current manuscript, we show that both the Rho/ROCK and Src/FAK/paxillin pathways are required for FXa-mediated inhibition of breast cancer cell migration. FXa induced pronounced stress fiber formation that was partially inhibited by pre-treatment with specific ROCK or Src inhibitors. Downstream of Rho/ROCK and Src/FAK/paxillin, FXa induced myosin light chain phosphorylation and LIMK1 activation resulting in cofilin inactivation. Knocking-down LIMK1 expression abolished FXa-induced inhibition of cell invasion. Our results reveal that FXa-mediated sustained cofilin inactivation leads to stabilization of actin filaments incompatible with migration. Overall we confirm that, beyond its role in blood coagulation, FXa plays a key role in cell migration and we unravel a new mechanism of PAR-1-mediated inhibition of migration via Rho and Src dependent pathways.

Neutrophil granulocytes promote the migratory activity of MDA-MB-468 human breast carcinoma cells via ICAM-1

Tumor infiltrating neutrophil granulocytes do not only exhibit tumor eliminating functions but also promote tumor progression. We have recently shown that neutrophil granulocytes can serve as linking cells for the adhesion of MDA-MB-468 breast carcinoma cells to pulmonary endothelium. Neutrophil granulocytes but not MDA-MB-468 cells express beta(2)-integrins, the ligands of the intercellular adhesion molecule (ICAM)-1, whereas ICAM-1 is strongly expressed on MDA-MB-468 cells. Consequently, the herein presented study was performed to investigate if this interaction has also an influence on the migratory activity of the tumor cells and whether ICAM-1 signaling plays a role in this process, too. We found that the continuous release of interleukin-8 (IL-8) and GRO-alpha by MDA-MB-468 cells increases the migratory activity of neutrophil granulocytes and attracts these cells towards the tumor cells which enables direct cell-cell interactions. These interactions in turn increase the migratory activity of the tumor cells in an ICAM-1 clustering-dependent mechanism since transfection of the tumor cells with specific siRNA against ICAM-1 abolished the effect. Moreover, ICAM-1 cross-linking on tumor cells induces the phosphorylation of focal adhesion components such as focal adhesion kinase and paxillin via src kinase as well as the activation of the p38 MAPK pathway via Rho kinase in a time-dependent manner. Our results provide evidence that ICAM-1 is coupled to intracellular signaling pathways involved in tumor cell migration. Thus, neutrophil granulocytes can act as modulators of the metastatic capability of tumor cells by ligation of ICAM-1.

Cadherin and integrin regulation of epithelial cell migration

These studies quantified the relative effects of E-cadherin expression and homophilic ligation on the integrin-mediated motility of epithelial cells. Micropatterned proteins were used to quantitatively titrate the ligation of E-cadherin and integrin receptors in order to assess their coordinate influence on the migration velocities of MDA-MB-231 breast tumor epithelial cells. Fibronectin, E-cadherin, and mixtures of fibronectin and E-cadherin were covalently patterned on solid surfaces at defined compositions and mass coverages. The migration velocities of parental epithelial cells and of cells engineered to express E-cadherin under tetracycline control show that E-cadherin expression reduces cell motility by both adhesion-dependent and adhesion-independent mechanisms. Increasing E-cadherin expression levels also suppresses the dependence of cell velocity on the fibronectin coverage. On E-cadherin-containing substrata, the cell velocity decreases both with the E-cadherin expression level and with the immobilized E-cadherin surface density. These studies thus identified conditions under which E-cadherin preferentially suppresses cell migration by adhesion-independent versus adhesion-dependent mechanisms.