Decellularization, Stabilization and Functionalization of Collagenous Tissues Used as Cardiovascular Biomaterials

Abstract

Cardiovascular diseases are a worldwide problem being a significant cause of morbity and mortality every year. Patients requiring heart valve replacements include those exhibiting degenerative valvular diseases and rheumatic fever. The pathological processes include stenosis, fibrosis, myxoid change and calcification. The fibrosis causes a reaction to normal haemodynamic while the myxoid change reduces tensile strength of the valve due to replacement of dense collagenous tissue by loose tissue rich in glycosaminoglycans. Moreover, these pathologies can be observed in normal valves or fibrotic valves (Lindop, 2007). Fortunately, the development of cardiovascular prostheses, either synthetic or biological, has allowed to increase life expectancy and has improved the quality of life of patient requiring either heart valves (Flanagan & Pandit, 2003; Schoen & Levi, 1999; Vesely, 2005) or vascular grafts (Matsagas et al., 2006; Monn & West, 2008; Schmidt & Baier, 2000). The implant technology for cardiovascular systems made use of raw materials of different origins. For example, metallic materials and synthetic polymers have been widely used in mechanical valves for the replacement of diseased heart valves. However, some complications such as alterations in the hemodynamical function and thrombus formation have been found (Zilla et al., 2008). Biological prostheses provide some answers to these complications, although the bioprostheses do not fulfil their objectives satisfactorily, since they display others complications once implanted. The complications of tissue valves include calcification, remnant tissue immunogenicity, inflammatory degradation, mechanical damage and lack of repair (Zilla et al., 2008). Therefore, the need for safe, economic, physiologically acceptable and viable biomaterial has motivated the modification of collagen-rich tissues. Collagenous tissues are alternative raw materials for the manufacture of medical devices due to their physical and biomechanical properties. These tissues promote cell interactions, exhibit good ion and macromolecular binding capacity in addition to their electrostatic, hemostatical and immunological properties (Li, 2007). Since 1960s, perichardial tissues and the porcine heart valves are two of the most widely used biological tissues in the construction of cardiovascular devices. The introduction of these biological biomaterials was