Real space observation of three-dimensional network structure of hydrated fibrin gel

Rheometrical detection of incipient blood clot formation by Fourier transform mechanical spectroscopy

“…These ideas, which have been expressed in other areas of gel formation as 'decorating' or 'dressing' the network, accord with theoretical studies of gels formed by heterogeneous (fractal) networks of branching colloidal fibres and the analysis of network structure, which is represented in part by a fractal dimension, may be useful for understanding the physical properties of clots formed under various physiological conditions [22]. In this context it is useful to recall that the value of the viscoelastic stress relaxation exponent α in the Gel Equation is a sensitive measure of the degree of branching in a gel and has been related to the fractal dimension of the sample-spanning network formed at the GP [23].…”

Protein–polymer conjugates for forming photopolymerizable biomimetic hydrogels for tissue engineering

“…In contrast to reconstituted collagen gels, cell migration in reconstituted fibrin clots (430 mg/ml) is more dependent upon cell-associated proteolytic activity, which results from the smaller mesh size of the fibrin's fibrillar matrix. This mesh size is owing to the nature of the fibrin network formation and covalent stabilization of the fibrin fibrils after cross-linking [8,38]. One of the distinct advantages of the PEGylated fibrinogen and PEGylated collagen hydrogels is that the porosity and proteolytic susceptibility of the network can be controlled by the PEG constituent so that there is no longer a porous fibril network controlling the migration and spreading of the cells.…”

Mechanobiology in the Third Dimension

“…169 Saltzman also notes that average fiber spacing in collagen only depends weakly on the concentration of the gel; it decreases as 1/ √ c. 169 Fibrin gel spacing may also be larger than previously thought; recent confocal measurements that also put average fiber spacing in a fibrin gel at between 5 and 10 µm. 189 Electron microscopy measurements on fibrin clots yielded average fiber spacing of between 0.1 and 0.5 µm (calculated from Ryan et al 167 ). Clearly, more work is needed to definitively determine the fiber spacing in 3D meshes without preparation artifacts, but recent evidence suggests that the pore size of most reconstituted collagen and fibrin matrices are on the order of several microns.…”

“…52,181 It has the advantage that mechanical properties and network architecture are tunable to a greater extent than those of collagen by varying its composition (i.e., relative amounts of fibrinogen, thrombin, and Ca 2+ ). 167,189 Furthermore, it forms a useful matrix into which fusion proteins (such as growth factors) can be attached to the matrix via the clotting transglutaminase factor XIIIa. 168 Cells must proteolytically degrade the dense fibrin mesh by releasing plasmin activators or MMPs (matrix metalloproteinases) in order to successfully migrate; 97,117,162 thus, fibrin is a useful matrix to study protease-dependent cell migration.…”