Flow cytometric assay for quantitative and qualitative evaluation of adhesive interactions of tumor cells with endothelial cells

Insights in Cell Biomechanics through Atomic Force Microscopy

We review the advances obtained by using Atomic Force Microscopy (AFM)-based approaches in the field of cell/tissue mechanics and adhesion, comparing the solutions proposed and critically discussing them. AFM offers a wide range of detectable forces with a high force sensitivity, thus allowing a broad class of biological issues to be addressed. Furthermore, it allows for the accurate control of the probe position during the experiments, providing spatially resolved mechanical maps of the biological samples with subcellular resolution. Nowadays, mechanobiology is recognized as a subject of great relevance in biotechnological and biomedical fields. Focusing on the past decade, we discuss the intriguing issues of cellular mechanosensing, i.e., how cells sense and adapt to their mechanical environment. Next, we examine the relationship between cell mechanical properties and pathological states, focusing on cancer and neurodegenerative diseases. We show how AFM has contributed to the characterization of pathological mechanisms and discuss its role in the development of a new class of diagnostic tools that consider cell mechanics as new tumor biomarkers. Finally, we describe the unique ability of AFM to study cell adhesion, working quantitatively and at the single-cell level. Again, we relate cell adhesion experiments to the study of mechanisms directly or secondarily involved in pathologies.

"Endothelial Antibody Factory" at the Blood Brain Barrier: Novel Approach to Therapy of Neurodegenerative Diseases

The failures of anti-β-amyloid immunotherapies suggested that the very low fraction of injected antibodies reaching the brain parenchyma due to the filtering effect of the BBB may be a reason for the lack of therapeutic effect. However, there is no treatment, as yet, for the amyotrophic lateral sclerosis (ALS) despite substantial evidence existing of the involvement of TDP-43 protein in the evolution of ALS. To circumvent this filtering effect, we have developed a novel approach to facilitate the penetration of antibody fragments (Fabs) into the brain parenchyma. Leveraging the homing properties of endothelial progenitor cells (EPCs), we transfected, ex vivo, such cells with vectors encoding anti-β-amyloid and anti-TDP43 Fabs turning them into an “antibody fragment factory”. When injected these cells integrate into the BBB, where they secrete anti-TDP43 Fabs. The results showed the formation of tight junctions between the injected engineered EPCs and the unlabeled resident endothelial cells. When the EPCs were further modified to express the anti-TDP43 Fab, we could observe integration of these cells into the vasculature and the secretion of Fabs. Results confirm that production and secretion of Fabs at the BBB level leads to their migration to the brain parenchyma where they might exert a therapeutic effect.

Endothelial Cells as Tools to Model Tissue Microenvironment in Hypoxia-Dependent Pathologies

Endothelial cells (ECs) lining the blood vessels are important players in many biological phenomena but are crucial in hypoxia-dependent diseases where their deregulation contributes to pathology. On the other hand, processes mediated by ECs, such as angiogenesis, vessel permeability, interactions with cells and factors circulating in the blood, maintain homeostasis of the organism. Understanding the diversity and heterogeneity of ECs in different tissues and during various biological processes is crucial in biomedical research to properly develop our knowledge on many diseases, including cancer. Here, we review the most important aspects related to ECs’ heterogeneity and list the available in vitro tools to study different angiogenesis-related pathologies. We focus on the relationship between functions of ECs and their organo-specificity but also point to how the microenvironment, mainly hypoxia, shapes their activity. We believe that taking into account the specific features of ECs that are relevant to the object of the study (organ or disease state), especially in a simplified in vitro setting, is important to truly depict the biology of endothelium and its consequences. This is possible in many instances with the use of proper in vitro tools as alternative methods to animal testing.

A microfluidic platform for modeling metastatic cancer cell matrix invasion

Invasion of the extracellular matrix is a critical step in the colonization of metastatic tumors. The invasion process is thought to be driven by both chemokine signaling and interactions between invading cancer cells and physical components of the metastatic niche, including endothelial cells that line capillary walls and serve as a barrier to both diffusion and invasion of the underlying tissue. Transwell chambers, a tool for generating artificial chemokine gradients to induce cell migration, have facilitated recent work to investigate the chemokine contributions to matrix invasion. These chambers, however, are poorly designed for imaging, which limits their use in investigating the physical cell-cell and cell-matrix interactions driving matrix invasion. Microfluidic devices offer a promising model in which the invasion process can be imaged. Many current designs, however, have limited surface areas and possess intricate geometries that preclude the use of standard staining protocols to visualize cells and matrix proteins. In this work, we present a novel microfluidic platform for imaging cell-cell and cell-matrix interactions driving metastatic cancer cell matrix invasion. Our model is applied to investigate how endothelial cell-secreted matrix proteins and the physical endothelial monolayer itself interact with invading metastatic breast cancer cells to facilitate invasion of an underlying type I collagen gel. The results show that matrix invasion of metastatic breast cancer cells is significantly enhanced in the presence of live endothelial cells. Probing this interaction further, our platform revealed that, while the fibronectin-rich matrix deposited by endothelial cells was not sufficient to drive invasion alone, metastatic breast cancer cells were able to exploit components of energetically inactivated endothelial cells to gain entry into the underlying matrix. These findings reveal novel cell-cell interactions driving a key step in the colonization of metastatic tumors and have important implications for designing drugs targeted at preventing cancer metastasis.

Cell Systems to Investigate the Impact of Polyphenols on Cardiovascular Health

Polyphenols are a diverse group of micronutrients from plant origin that may serve as antioxidants and that contribute to human health in general. More specifically, many research groups have investigated their protective effect against cardiovascular diseases in several animal studies and human trials. Yet, because of the excessive processing of the polyphenol structure by human cells and the residing intestinal microbial community, which results in a large variability between the test subjects, the exact mechanisms of their protective effects are still under investigation. To this end, simplified cell culture systems have been used to decrease the inter-individual variability in mechanistic studies. In this review, we will discuss the different cell culture models that have been used so far for polyphenol research in the context of cardiovascular diseases. We will also review the current trends in cell culture research, including co-culture methodologies. Finally, we will discuss the potential of these advanced models to screen for cardiovascular effects of the large pool of bioactive polyphenols present in foods and their metabolites.

Glycosylation characteristics of colorectal cancer

Glycans on proteins and lipids are known to alter with malignant transformation. The study of these may contribute to the discovery of biomarkers and treatment targets as well as understanding of cancer biology. We here describe the change of glycosylation specifically defining colorectal cancer with view on N-glycans, O-glycans, and glycosphingolipid glycans in colorectal cancer cells and tissues as well as patient sera. Glycan alterations observed in colon cancer include increased β1,6-branching and correlating higher abundance of (poly-)N-acetyllactosamine extensions of N-glycans as well as an increase in (truncated) high-mannose type glycans, while bisected structures decrease. Colorectal cancer-associated O-glycan changes are predominated by reduced expression of core 3 and 4 glycans, whereas higher levels of core 1 glycans, (sialyl) T-antigen, (sialyl) Tn-antigen, and a generally higher density of O-glycans are observed. Specific changes for glycosphingolipid glycans are lower abundances of disialylated structures as well as globo-type glycosphingolipid glycans with exception of Gb3. In general, alterations affecting all discussed glycan types are increased sialylation, fucosylation as well as (sialyl) Lewis-type antigens and type-2 chain glycans. As a consequence, interactions with glycan-binding proteins can be affected and the biological function and cellular consequences of the altered glycosylation with regard to tumorigenesis, metastasis, modulation of immunity, and resistance to antitumor therapy will be discussed. Finally, analytical approaches aiding in the field of glycomics will be reviewed with focus on binding assays and mass spectrometry.

Development of quinic acid-conjugated nanoparticles as a drug carrier to solid tumors

Nanometer-sized drug carriers including polymeric nanoparticles (NPs) have been used to increase biodistribution of a drug in tumors, thereby reducing the effective dose of chemotherapy. NPs increase drug delivery to tumors to a certain extent, but the amount reaching tumors is only a small fraction of the total administered NPs because they depend on passive accumulation via the leaky vasculature surrounding tumors. In an attempt to further increase the drug delivery to tumors, we develop a polymeric NP system that interacts with an endothelial tumor marker. The NPs are decorated with quinic acid, a synthetic mimic of sialyl Lewis-x, which binds to E-selectin, overexpressed on the surface of endothelial cells surrounding solid tumors. The NPs selectively bind to endothelial cells activated with tumor necrosis factor-α, with weak affinity at a relatively high shear stress. These properties may help NPs reach tumors by increasing the encounter of NPs with the peritumoral endothelium without hindering subsequent transport of the NPs.

Microfluidic devices for modeling cell-cell and particle-cell interactions in the microvasculature

Cell-fluid and cell-cell interactions are critical components of many physiological and pathological conditions in the microvasculature. Similarly, particle-cell interactions play an important role in targeted delivery of therapeutics to tissue. Development of in vitro fluidic devices to mimic these microcirculatory processes has been a critical step forward in our understanding of the inflammatory process, developing of nano-particulate drug carriers, and developing realistic in vitro models of the microvasculature and its surrounding tissue. However, widely used parallel plate flow based devices and assays have a number of important limitations for studying the physiological conditions in vivo. In addition, these devices are resource hungry and time consuming for performing various assays. Recently developed, more realistic, microfluidic based devices have been able to overcome many of these limitations. In this review, an overview of the fluidic devices and their use in studying the effects of shear forces on cell-cell and cell-particle interactions is presented. In addition, use of mathematical models and computational fluid dynamics (CFD) based models for interpreting the complex flow patterns in the microvasculature is highlighted. Finally, the potential of 3D microfluidic devices and imaging for better representing in vivo conditions under which cell-cell and cell-particle interactions take place is discussed.

Systemic and peritoneal inflammatory response after laparoscopic-assisted gastrectomy and the effect of inflammatory cytokines on adhesion of gastric cancer cells to peritoneal mesothelial cells

INTRODUCTION

There still remain concerns over the potential for peritoneal metastasis after laparoscopic surgery. We designed this trial to investigate the effects of the inflammatory cytokines interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) on the interaction between gastric cancer cells and mesothelial cells, and to evaluate differences in both the peritoneal and systemic cytokine (IL-1β and TNF-α) concentrations after laparoscopic and conventional surgical approaches, thus offering another possible advantage of laparoscopic procedures for treatment of gastric cancer.

EXPERIMENTAL DESIGN

A reproducible human in vitro assay was developed to study adhesion of SGC-7901 and MKN-45 human gastric cancer cells to monolayers of primary cultured human peritoneal mesothelial cells (HPMCs). Tumor cell adhesion to a mesothelial monolayer was assessed after preincubation of the monolayer with IL-1β and TNF-α using flow cytometry. Expression of adhesion molecules (ICAM-1, VCAM-1, and CD44) and their counterparts (LFA-1 and VLA-4) was investigated by real-time polymerase chain reaction (PCR) immunocytochemical staining. Furthermore, the proinflammatory cytokines IL-1β and TNF-α were measured perioperatively in peritoneal drain fluid and in serum by enzyme immunoassay.

RESULTS

Preincubation of the mesothelial monolayer with IL-1β and TNF-α resulted in enhanced tumor cell adhesion of SGC-7901 and MKN-45 cells. Mesothelial cells showed significant enhancement of expression of ICAM-1, VCAM-1, and CD44 after stimulation with IL-1β and TNF-α. Meanwhile their counterparts (LFA-1, VLA-4, and CD44) were identified in gastric cancer cells. The level of IL-1β in peritoneal drain fluid and in serum perioperatively in the laparoscopy-assisted gastrectomy group was lower than in the conventional open gastrectomy group, whereas there were no significant differences between the laparoscopic-assisted distal gastrectomy (LADG) and conventional open distal gastrectomy(CODG) groups with respect to TNF-α.

CONCLUSIONS

The presented results prove that IL-1β and TNF-α are significant stimulating factors in gastric cancer cell adhesion in vitro and may therefore partly account for local tumor recurrence and peritoneal metastasis in vivo. Owing to less impact on the postoperative abdominal regional and systemic immune responses, laparoscopic surgery not only shows clinically relevant advantages but also causes less effect of inflammatory factors on local recurrence and peritoneal metastasis of gastric cancer than conventional operations. Thus, we offer another possible advantage of laparoscopic procedures for treatment of gastric cancer.