Cell migration on 2D surfaces is governed by a balance between counteracting tractile and adhesion forces. Although biochemical factors such as adhesion receptor and ligand concentration and binding, signaling through cell adhesion complexes, and cytoskeletal structure assembly/disassembly have been studied in detail in a 2D context, the critical biochemical and biophysical parameters that affect cell migration in 3D matrices have not been quantitatively investigated. We demonstrate that, in addition to adhesion and tractile forces, matrix stiffness is a key factor that influences cell movement in 3D. Cell migration assays in which Matrigel density, fibronectin concentration, and β1 integrin binding are systematically varied show that at a specific Matrigel density the migration speed of DU-145 human prostate carcinoma cells is a balance between tractile and adhesion forces. However, when biochemical parameters such as matrix ligand and cell integrin receptor levels are held constant, maximal cell movement shifts to matrices exhibiting lesser stiffness. This behavior contradicts current 2D models but is predicted by a recent force-based computational model of cell movement in a 3D matrix. As expected, this 3D motility through an extracellular environment of pore size much smaller than cellular dimensions does depend on proteolytic activity as broad-spectrum matrix metalloproteinase (MMP) inhibitors limit the migration of DU-145 cells and also HT-1080 fibrosarcoma cells. Our experimental findings here represent, to our knowledge, discovery of a previously undescribed set of balances of cell and matrix properties that govern the ability of tumor cells to migration in 3D environments.

We developed a deep-ultraviolet (UV) microscope capable of imaging cell mitosis and motility at 280 nm for 45 min with minimal UV-induced toxicity, and for 6 h before the onset of visible cell death in cultured human and mouse cells. Combined with computational methods that convert the intensity of each pixel into an estimate of mass, deep-UV microscopy images generate maps of nucleic acid mass, protein mass and fluorescence yield in unlabeled cells.

Analyzing coagulability often hinges on patient surveillance using prothrombin time (PT) or international normalized ratio (INR) and activated partial thromboplastin time (aPTT) to monitor the extrinsic and intrinsic coagulation pathways, respectively A more complete assessment, however, can often be obtained using thromboelastography (TEG), a coagulation assay that evaluates the efficiency of clot formation, as well as the viscoelastic properties of the clot. Developed by Dr. Helmut Hartert in 1948 at the UniversityofHeidelberg, it provides information regarding hemostasis as a dynamic process [1,2]. Here, the TEG technique will be described, as well as its current applications and future directions for its use.

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