ABSTRACT
The natural environment of a living cell is not only organized on a micrometer, but also on a nanometer scale. Mimicking such a nanoscale topography in implantable biomaterials is critical to guide cellular behavior. Also, a correct positioning of cells on biomaterials is supposed to be very important for promoting wound healing and tissue regeneration. The exact mechanism by which nanotextures can control cellular behavior are thus far not well understood and it is thus far unknown how cells recognize and respond to certain surface patterns, whereas a directed response appears to be absent on other pattern types. Focal adhesions (FAs) are known to be involved in the process of specific pattern recognition and subsequent response by cells. In this study, we used a high throughput screening "Biochip" containing 40 different nanopatterns to evaluate the influence of several nanotopographical cues like depth, width, (an)isotropy and spacing (ridge-groove ratio) on osteoblast behavior. Microscopical analysis and time lapse imaging revealed that an isotropic topography did not alter cell morphology, but it highly induced cell motility. Cells cultured on anisotropic topographies on the other hand, were highly elongated and aligned. Time-lapse imaging revealed that cell motility is highly dependent on the ridge-groove ratio of anisotropic patterns. The highest motility was observed on grooves with a ratio of 1:3, whereas the lowest motility was observed on ratios of 1:1 and 3:1. FA measurements demonstrated that FA-length decreased with increasing motility. From the study it can be concluded that osteoblast behavior is tightly controlled by nanometer surface features.
Subject(s)
Cell Movement , Nanostructures/chemistry , Osteoblasts/cytology , Animals , Anisotropy , Cells, Cultured , Focal Adhesions/metabolism , Osteoblasts/physiology , Osteoblasts/ultrastructure , Rats , Surface Properties , Time-Lapse Imaging , Tissue Engineering/methodsABSTRACT
In 1990 Clauss et al. first reported on a 44-kDa polypeptide, later called Endothelial Monocyte Activating Polypeptide II (EMAP II). This protein was discovered in the supernatant of Meth-A fibrosarcoma cells and was shown to enhance the induction of the procoagulant Tissue Factor (TF) on endothelial cells. Besides up-regulation of TF mRNA, EMAP II increases cellular receptors for TNF on endothelial cells, which is likely to enhance the predisposition of tumors to undergo thrombosis and hemorrhagic necrosis, once challenged with TNF. This feature enables EMAP II to up-regulate the TNF sensitivity of TNF-resistant tumors, an observation of importance in developing new approaches aimed at improving the efficacy of TNF as an anticancer treatment. We describe the potential additional effects of EMAP II, when used in combination with TNF, with regards to antitumor activity in the Isolated Limb Perfusion (ILP) setting. In addition, we describe our experimental data in human sarcoma, which also supports this hypothesis.
Subject(s)
Antineoplastic Agents/pharmacology , Cytokines/physiology , Neoplasm Proteins/physiology , Neoplasms/drug therapy , RNA-Binding Proteins/physiology , Tumor Necrosis Factor-alpha/pharmacology , Animals , Cytokines/biosynthesis , Cytokines/genetics , Cytokines/pharmacology , Drug Synergism , Humans , Neoplasm Proteins/biosynthesis , Neoplasm Proteins/genetics , Neoplasm Proteins/pharmacology , Neoplasms/genetics , Neoplasms/metabolism , RNA-Binding Proteins/biosynthesis , RNA-Binding Proteins/genetics , RNA-Binding Proteins/pharmacologyABSTRACT
BACKGROUND: Experiments with tumor necrosis factor alpha (TNF) in rodents have shown that a high dose can lead to hemorrhagic necrosis in tumors. Endothelial monocyte-activating polypeptide II (EMAP-II) is a novel tumor-derived cytokine, and its expression increases the TNF-1 receptor on tumor endothelium, enhances the induction of tissue factor on tumor endothelial cells, and has an antiangiogenic effect. It has recently been shown that in vivo sensitivity of tumor vasculature to TNF is determined by tumor production of EMAP-II. METHODS: We measured the level of EMAP-II in a TNF-resistant soft tissue sarcoma. We subsequently stabile-transfected this cell line with a retroviral construct containing the EMAP gene. In an extremity perfusion model in tumor-bearing rats, we measured response rates to TNF therapy. RESULTS: Functional EMAP-II production was increased after this transfection. Immunostaining of paraffin-embedded tumor tissue sections in rats showed an overexpression of human EMAP-II. Results of the TNF perfusions in rats suggest that this tumor is more sensitive to TNF therapy. CONCLUSIONS: EMAP-II is produced in various levels. One can increase the sensitivity of tumor for TNF therapy in vivo by upregulating the EMAP-II production. This result leaves an opportunity for enhanced TNF response of tumors in future settings.
