Collagen matrices

Activation of matrix metalloproteinases (MMP) is also involved in vascular and cardiac remodelling. For example, the fibrillar collagen matrix of the heart... 

The effects of progesterone and several other steroids delivered from a collagen matrix as a means for preventing allograift skin rejection in mice and rats was reported (55). Results showed that the half-life of both progesterone and estradiol preparations was about 7 days, and about 90% of all steroid present was absorbed in 15—30 days. 

Recently, water-soluble protein fractions, isolated from extracts of bone matrix, were incorporated into a collagen matrix and shown to induce bone (67,68) and cartilage formation both in vitro and in vivo (69,70). In the latter studies, in the absence of the collajgen delivery system, the proteins were incapable of inducing cartilage formation in vivo when implanted intramuscularly into mice. The success of this approach appears to depend on delivering the active agents at an effective dose over an extended time period. 

Lipid-laden macrophages, smooth muscle cells, and necrotic debris from the death of foam cells accumulate in the subendothelial space, leading to enlargement of the fatty streak. A collagen matrix forms a fibrous cap that covers the lipid core of the lesion to establish a fibrous plaque called an atherosclerotic plaque. Initially, the diameter of the coronary artery lumen is... 

When there is no cell-supporting collagen matrix to consider, PF can be calculated a priori and put into quantitative perspective with other permeability coefficients. Otherwise, PF needs to be experimentally determined. 

Figure 17 Appearance kinetics of sucrose across untreated Transwell filters (0.4 Um pore size) and those coated with a cross-linked rat tail collagen matrix. In both cases the systems were stirred at 100 rpm.

In Figure 17, the collagen matrix on the filter is shown to decrease the flux of sucrose. The Pe for this situation is 1.12 X 1(T4 cm/sec. Accordingly,... 

As before, by dividing Pe by PABL, the transport kinetics is seen to be 32% ABL-controlled, or, upon dividing Pe by Pm the overall transport of sucrose is seen to be 51% collagen matrix-controlled by molecular size restricted diffusion. 

Schwann cells incorporated in a collagen matrix and injected into PLLA conduits were found to demonstrate comparable SFI values compared to isograft controls, but showed a statistically lower number of axons for both the high and low density Schwann cells groups and the collagen samples compared to the isograft controls (Evans et al., 2002). These results can be explained by a simple reaction diffusion model (Rutkowski and Heath, 2002b) described earlier. 

Composites made with carbon nanostructures have demonstrated their high performance as biomaterials, basically applied in the field of tissue regeneration with excellent results. For example, P.R. Supronowicz et al. demonstrated that nanocomposites fabricated with polylactic acid and CNTs can be used to expose cells to electrical stimulation, thus promoting osteoblast functions that are responsible for the chemical composition of the organic and inorganic phases of bone [277]. MacDonald et al. prepared composites containing a collagen matrix CNTs and found that CNTs do not affect the cell viability or cell proliferation [278]. 

R. U. Agu, M. Jorissen, T. Willems, P. Augustijns, R. Kinget, and N. Verbeke. In-vitro nasal drug delivery studies Comparison of derivatised, fibrillar and polymerised collagen matrix-based human nasal primary culture systems for nasal drug delivery studies. J Pharm Pharmacol 53 1447-1456 (2001). 

Minami Y, Sugihara H, Oono S. Reconstruction of cornea in three-dimensional collagen matrix culture. Invest Ophthalmol Vis Sci 34 2316-2324 (1993). 

Orwin EJ, Hubei A. In vitro culture characteristics of comeal epithelial, endothelial and keratocyte cells in a native collagen matrix. Tissue Eng 6 307-319 (2000). 

Klont B and Ten Cate JM (1991a) Remineralization of bovine incisor root lesions in vitro the role of the collagenous matrix. Caries Res 25, 39-45. 

Niggemarm B, Drell TL IV, Joseph J et al (2004) Tumor cell locomotion differential dynamics of spontaneous and induced migration in a 3D collagen matrix. Exp Cell Res 298 178-187... 

Young RG, Butler DL, Weber W, Caplan AI, Gordon SL, Fink DJ. Use of mesenchymal stem cells in a collagen matrix for Achilles tendon repair. J Orthop Res 1998 16 406 13. 

The data concerning the effect of fluoride-containing apatites on cell adhesion, proliferation and expression seem rather disparate, probably because of the variation of other surface characteristics and the use of different cell strains. No real negative effect of fluoride-containing substrates has been reported so far and the osteoblast cells seem to behave similarly [184,185] or better [183,186,187] on fluoridated apatites than on HA surfaces. Some reports mention weaker attachment and proliferation, compensated for by improved collagen matrix production [188]. The shape of cells appeared different on fluoridated apatites than on HA. Other authors have found an improvement in cell attachment [183] which has been attributed to the change in surface charge of FA compared to HA. 

Finally, collagen can form a variety of collagen composites with other water-soluble materials. Ions, peptides, proteins, and polysaccharides can all be uniformly incorporated into a collagen matrix. The methods of composite formation include ionic and covalent bonding, entrapment, entanglement, and co-precipitation. A two-phase composite can be formed between collagen, ceramics, and synthetic polymers for specific biomedical applications. 

The tannins are special phenolic compounds characterized by their ability to combine with proteins and other polymers such as polysaccharides. This characteristic explains their tanning properties as arising from a tannin-collagen matrix and then astringency caused by precipitation of the proteins and glycoproteins from saliva. Also tannins are used in fining wines because they combine with proteins. Finally, they inhibit enzymes by combining with their protein fraction. 

Engel, J., and Prockop, D. J. (1998). Does bound water contribute to the stability of collagen Matrix Biol. 17, 679-680. 

Hedlund, H., Mengarelli-Widholm, S., Heinegard, D., Reinholt, F. P., and Svensson, O. (1994). Fibromodulin distribution and associadon with collagen. Matrix Biol. 14, 227-232. 

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