Stabilized Collagen Scaffolds for Heart Valve Tissue Engineering

Abstract

Scaffolds for heart valve tissue engineering must function immediately after implantation but also need to tolerate cell infiltration and gradual remodeling. We hypothesized that moderately cross-linked collagen scaffolds would fulfill these requirements. To test our hypothesis, scaffolds prepared from decellularized porcine pericardium were treated with penta-galloyl glucose (PGG), a collagen-binding polyphenol, and tested for biodegradation, biaxial mechanical properties, and in vivo biocompatibility. For controls, we used un-cross-linked scaffolds and glutaraldehyde-treated scaffolds. Results confirmed complete pericardium decellularization and the ability of scaffolds to encourage fibroblast chemotaxis and to aid in creation of anatomically correct valve-shaped constructs. Glutaraldehyde cross-linking fully stabilized collagen but did not allow for tissue remodeling and calcified when implanted subdermally in rats. PGG-treated collagen was initially resistant to collagenase and then degraded gradually, indicating partial stabilization. Moreover, PGG-treated pericardium exhibited excellent biaxial mechanical properties, did not calcify in vivo, and supported infiltration by host fibroblasts and subsequent matrix remodeling. In conclusion, PGG-treated acellular pericardium is a promising scaffold for heart valve tissue engineering.

Functional Heart Valve Scaffolds Obtained by Complete Decellularization of Porcine Aortic Roots in a Novel Differential Pressure Gradient Perfusion System

“…This study and others 26,38 showed that immersion is effective for tissues that are thin or relatively more porous than the aorta, which contains numerous layers of elastic fibers that restrict penetration of fluids. In some applications, immersion decellularization techniques are replaced with perfusion techniques for tissues that are difficult to decellularize.…”

“…21 Other experimental approaches to building tissueengineered valves include use of cell-seeded biodegradable polymers (synthetic or fibrin-based, molded in the shape of an aortic valve root) to generate a homogeneous, isotropic collagenous structure lacking elastic fibers, before implantation, 22,23 implantation of stent-mounted acellular valves seeded with vascular fibroblasts or stem cells, 24 as well as use of polymers 22,25 and layered composites. 13,14,26 Creating structures as heterogeneous as that of the aortic roots using a bottom-up approach (such as three-dimensional printing 27 ) is quite difficult and requires major technological advances. Taken together, none of the above referenced approaches satisfied the design criteria.…”

Antibacterial activity and composition of decellularized goat lung extracellular matrix for its tissue engineering applications

“…The in vitro biodegradation of decellularized lung scaffold by 0.2% concentration of collagenase was used as an 'accelerated model' of degradation and the collagenase activities in vivo are not expected to be as harsh as in vitro [72]. Moreover, the degradation rates of the scaffold can be controlled by varying the enzyme concentrations [73] or by using various crosslinking agents (carbodiimide, glutaraldehyde), which might affect the collagen structure of the scaffold and modify the cleavage sites for collagenase enzyme [60,74,75].…”

Pulmonary heart valve replacement using stabilized acellular xenogeneic scaffolds; effects of seeding with autologous stem cells

“…To stabilize the valve extracellular matrix, the acellular roots were treated with sterile 0.1% penta galloyl glucose (PGG) in 20% isopropanol, an elastin-binding polyphenol (10) followed by a rapid glutaraldehyde treatment and complete neutralization with glycine to stabilize collagen (17). Acellular bovine pericardium, also stabilized with PGG, and used for mounting the valves within the conduit, was prepared as described before (18).…”

“…Treatment with PGG, a non-cytotoxic collagen and elastin binding polyphenol reduces susceptibility to collagenase, thus increasing the durability of matrix scaffolds upon implantation (7,15,18,22). In an attempt to re-cellularize the aortic roots, we isolated sheep ADSCs and seeded them into each of the three cusps by a single injection.…”