Artificial matrix barriers: A diffusion study utilizing dextrans and microspheres

Abstract

Eight artificial matrices (AMs) were evaluated for the ability to restrict the passage of diffusion probes. Three AMs were composed exclusively of interstitial type I collagen (Col I) and differed from each other in thickness only. Four AMs consisted of reconstituted basement membrane (RBM) -coated polycarbonate filters (containing 10 microns diameter pores) and also only differed in thickness. One AM consisted of an uncoated 10 microns pore polycarbonate filter. The diffusion probes were uncharged fluorescein isothiocyanate-labeled dextrans, having molecular weights of 17,900, 42,000, 71,200, and 148,900 and negatively charged latex microspheres, having diameters of 0.08, 0.30, and 0.95 microns. Probes were applied to the AMs, incubated for 72 hr at 37 degrees C, and then analyzed spectrophotometrically. Dextran passage was increasingly restricted for Col I matrices as either molecular weight or collagen thickness increased (range 7% to 0.7%). Thin RBM-coated filters were more permeable to dextrans (range 100% to 30%) than Col I matrices. The diffusion rate of microspheres for Col I matrices (range 3.5% to 0) was similar to both thick and thin RBM-coated filters (range 4% to 0). The uncoated filter permitted the most diffusion for both dextrans and microspheres (range 100% to 7%). These data demonstrate that the AMs presented in this study will allow direct observation of the degradative and migratory potential of cells in vitro as they interact with various extracellular matrices.

Cell-Penetrating HIV1 TAT Peptides Can Generate Pores in Model Membranes

“…1, A-C, lower panel). This dextran has a Stokes radius of 4.3 nm (39,40) and remained completely excluded from the GUVs at AF-TAT concentrations of 2 mM. After 20 to 30 min several vesicles with 40% PS began to deform, collapse, and release their inner content (see Fig.…”

Free-radical crosslinking of specific proteins alters the function of the egg extracellular matrix at fertilization

“…Unlike proteins, neutral dextrans do not adhere to the surface of the matrix and larger dextran polymers achieve a range of secondary structures whose Stoke's radius increases proportionately with molecular mass (Persky and Hendrix, 1990). Furthermore, although barriers examined in mammals show increased permeability to some serum proteins compared with exogenous proteins or dextrans of similar molecular mass (Ambati et al, 2000;Parr and Parr, 1986), the osmolarity of the sea urchin media caused similar globular proteins to adhere to the fertilization envelope (data not shown), possibly altering its filtration dynamics.…”

Colorectal cancer desmoplastic reaction up-regulates collagen synthesis and restricts cancer cell invasion

“…Moreover, the diameter of the collagen fibers is a determinant as to whether cells are able to attach (Nuernberger et al 2011); thick collagen fibers are not an efficient substrate for migrating cells. Moreover, increased collagen thickness and density have been shown to restrict the passage of diffusion probes (Persky and Hendrix 1990); therefore, colorectal cancer cell migration and invasion could have been further restricted by lack of chemoattractants and growth factors throughout the 3D stroma. The desmoplasia surrounding colorectal tumors, composed of thick collagen fibers arranged into parallel bundles, could form a barrier preventing tumor invasion of the surrounding tissue.…”