Collagen application, medical

Since the theory and medical applications of collagen sponge were described by Chvapil et al. (52-54), they have been used to deliver steroid hormones (55), the anticancer drugs trans-retinoic acid (TRA) (56,57), and 5-fluorouracil (5-FU) (58), and antibiotics (59). 

A small number of biotechnology products are classified as medical devices and, hence, are regulated by the Center for Devices and Radiological Health (CDRH). The first approved biotech product to come under the auspices of the CDRH was OP-1 implant. Marketed by Stryker Biotech, OP-1 implant is a sterile powder composed of recombinant human oestrogenic protein-1 (OP-1) along with bovine collagen. It is used to treat fractured bones that fail to heal. The product is mixed with sterile saline immediately before application, and entails surgical insertion of the paste into the fracture. 

The purified collagen obtained from either of these techniques is subjected to additional processing to fabricate the materials into useful devices for specific medical applications. Some of these matrices and their medical applications are shown in Table 7.19 and will be briefly described. 

Table 7.19 Some Examples of Collagen Matrices and Their Medical Applications...

Fish collagen fibrillar gels have not been studied, with the exception of shark collagen (Nomura et al., 2000a,b), probably due to their low denaturation temperature (Tt]), which renders these materials difficult to handle. The Tt] of shark collagen solution is approximately 30°C (Nomura et al., 1995), which results in the dissolution of the fibrillar gel of this collagen at 37°C (Nomura et al., 2000a). This indicates that the gel could not be practically used at the actual physical temperature of human medical application. The Tt] of chum salmon is approximately 19 °C (Kimura et al., 1988 Matsui et al., 1991), which is the main reason to be unstable at the actual physical temperature of human body. As the... 

Rao, K.P. Recent developments of collagen-based materials for medical applications and drug delivery systems. J. Biomater. Sci., Polym. Ed. 1995, 7 (7), 623-645. 

Various forms of chitin-based products are available for medical applications, such as finely divided powder, nonwoven fabrics, porous beads, lyophilized soft fleeces or gels, gauges, laminated sheets, and transparent films. Water-soluble derivatives of chitin in isotonic saline can be administered intramuscularly or intravenously. Certainly, there is considerable biochemical evidence linking NAG with the metabolism of the hexamines, which are assumed to originate and cross-link wound collagen. 

For many years, collagen has been used in medical applications, like resorbable surgical sutures [110], hemostatic agents [111], and wound... 

In vascular surgery the insertion of artificial blood vessels is a common method, but limited to specific medical applications. Long-term studies have revealed that unspecific adhesion of fibrin and collagen to the implant surface leads to thrombus formation and occlusion, even though PTFE is extremely inert and hydrophobic. 

To date, coUagen-based implants have been attempted for many tissue and organ repair and regeneration applications. A complete historical survey of all potential medical applications of collagen is a formidable task but a selected survey of coUagen-based medical products and the research and development activities are summarized in Table 43.6 as a reference. 

Proteins such as collagen (see Chart 9.11), keratin, and fibroin have also been successfully employed as target polymers in the generation of films [70]. The primary structure of the target protein is retained in the deposited film, as was inferred from IR spectroscopic analysis. Interestingly, relevant research led to the application of lasers for medical purposes. Nowadays, excimer laser beams are frequently employed by ophthalmologists for the purpose of keratectomy, i.e. 

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