Material on the basis of collagen fibers for covering wounds

Details Material on the basis of collagen fibers for covering wounds Material on the basis of collagen fibers for covering wounds

1994-10-24

1996-05-28

Phelan, D. Gabrielle

Drug, bio-affecting and body treating compositions

Preparations characterized by special physical form

Web, sheet or filament bases; compositions of bandages; or...

424445, A61K 970

Patent

active

055209254

DESCRIPTION:

BRIEF SUMMARY
This application is a 371 of PCT/EP93/02239, filed Aug. 20, 1993.


FIELD OF THE INVENTION

The invention relates to material in foil form on the basis of collagen fibers for covering wounds.


BACKGROUND OF THE INVENTION

Skin transplants are often required in connection with many injuries and also in connection with surgical operations, but suitable skin from the injured themselves or others is not always available. It has therefore been attempted for a long time to cover particularly large wound areas, such as burn injuries, with other materials in order to prevent the loss of fluids and external infections. Experiments in this field have been performed for some years with "artificial skin" on the basis of collagen fibers. The results obtained with such a type of "artificial skin" have been mixed so far.
The long-fiber, linear-colloid, scleroproteins of the extracellular matrix which, together with proteoglycan, appear in connective tissue, in the protein-containing basic substance of bones and in dentine, are called collagen. Depending on their origin, the composition of the proteins can vary, various types of collagens are known which, however, not all have a fiber structure. The small proportion of tryptophan, tyrosin and cystine in collagens is remarkable, but collagens are distinguished by a large proportion of glycine, prolin and in particular 4-hydroxy-prolin. Collagens are first synthesized in fibroblasts, i.e. cells of the connective tissue, in the form of procollagen chains of a molecular weight of approximately 140,000. Hydroxylation of prolin and lysine under the influence of ascorbic acid and glycolization only take place in the chain, after which three chains then combine in the form of levo-rotated helices which in turn are dextroverted around each other. This substance then is excreted in the extracellular space, in which peptides are split off the ends of the chains, so that so-called tropocollagen is created, which combines into fibrils. While the tropocollagen is still salt- or acid-soluble, collagen fibrils are insoluble. The tropocollagen of a molecular weight of approximately 300,000 consists of three polypeptide chains which may have a slightly different amino acid sequence. As a rule, two chains are identical, the third has a different structure.
In contrast to most proteins of the human or animal body, collagens are not continuously renewed, instead they have a long biological half-life which may be up to 300 days. The collagens are quite resistant to enzymatic decomposition, essentially, the enzymatic decomposition of native collagens can only be achieved by means of collagenase. The soluble fission products being created following the proteolysis of the collagen fibrils are hydrolized by other proteases into peptides and amino acids.
Soluble as well as insoluble collagens have already been experimentally used as "artificial skin". Corresponding products have been described, for example, in Japanese Patent Application 59 160464 or in U.S. Pat. No. 4,600,533. The material has also been suggested for endoprotheses, for example the European Patent Application 85 200045. An "artificial skin" of this type reduces fluid loss and protects against external infection, in addition, this type of artificial skin is intended to have an inflammation-reducing and hemostatic effect and to increase the growth of epithelic cells. The collagens used as the raw material up to now are soluble collagens as a rule because of easier processing. This has the disadvantage that the membranes or films have relatively only little stability because they consist of non-fibrous collagens which to not natively occur in this form. In addition, the collagen used continues to be enzymatically dissolved. Up to now, these membranes or films were made of collagen gels, which were produced in accordance with various techniques, known per se, and were then converted into solid form. Corresponding products are described, for example, in U.S. Pat. Nos. 4,600,533, 4,689,399 or 4,725,641 and 4,294,241. In accordance with

REFERENCES:
patent: 4925924 (1990-05-01), Silver
patent: 5028695 (1991-07-01), Eckmayer

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