Platform Technologies for Decellularization, Tunic-Specific Cell Seeding, andIn VitroConditioning of Extended Length, Small Diameter Vascular Grafts

Abstract

The aim of this study was to generate extended length, small diameter vascular scaffolds that could serve as potential grafts for treatment of acute ischemia. Biological tissues are considered excellent scaffolds, which exhibit adequate biological, mechanical, and handling properties; however, they tend to degenerate, dilate, and calcify after implantation. We hypothesized that chemically stabilized acellular arteries would be ideal scaffolds for development of vascular grafts for peripheral surgery applications. Based on promising historical data from our laboratory and others, we chose to decellularize bovine mammary and femoral arteries and test them as scaffolds for vascular grafting. Decellularization of such long structures required development of a novel "bioprocessing" system and a sequence of detergents and enzymes that generated completely acellular, galactose-(α1,3)-galactose (α-Gal) xenoantigen-free scaffolds with preserved collagen, elastin, and basement membrane components. Acellular arteries exhibited excellent mechanical properties, including burst pressure, suture holding strength, and elastic recoil. To reduce elastin degeneration, we treated the scaffolds with penta-galloyl glucose and then revitalized them in vitro using a tunic-specific cell approach. A novel atraumatic endothelialization protocol using an external stent was also developed for the long grafts and cell-seeded constructs were conditioned in a flow bioreactor. Both decellularization and revitalization are feasible but cell retention in vitro continues to pose challenges. These studies support further efforts toward clinical use of small diameter acellular arteries as vascular grafts.

Pentagalloyl Glucose and Its Functional Role in Vascular Health: Biomechanics and Drug-Delivery Characteristics

“…70,88 The aforementioned advantages of PGG have paved the path for its use in tissue engineering studies of valves, development of vascular grafts, and numerous other potential therapeutic applications. 32,33,35,39,47,88,119,120,129,154,156,167,168,170,171 In this review, we critically evaluate recent work relevant to drug-delivery and translation-related applications of PGG.…”

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

“…18,21,36 While some tissues are readily decellularized by simple immersion, we and others have shown that immersion is not an effective means of cell removal from the aortic wall components of the root 21 and also from extended lengths of small and medium diameter arteries. 37 Therefore, we developed a unique perfusion decellularization setup (PDCell system; Aptus, LLC), which has been used extensively (*50 roots have been decellularized using this system in two research laboratories) and was found to be reproducible and repeatable. The system was purposefully designed so that the aortic root is pressurized, expanded, and allowed to recoil cyclically to ensure flow of fluids through the thickness of the aortic wall.…”

Perivascular extracellular matrix hydrogels mimic native matrix microarchitecture and promote angiogenesis via basic fibroblast growth factor

“…Importantly, these decellularized tissues show promise for therapeutic tissue regeneration in a variety of applications. [1-7] Development of decellularized native tissues led to the production of tissue-engineered scaffolds which retained basement membrane proteins such as collagen type IV, laminin, and fibronectin that enhance cellular adhesion [8, 9] and invoke signaling to influence cellular differentiation and regenerative potential [10-12]. Growth factors including transforming growth factor-beta, basic fibroblast growth factor (FGF), hepatocyte growth factor and vascular endothelial growth factor (VEGF) persist in their bioactive form within ECM bioscaffolds after sterilization.…”