Is Transcatheter Aortic Valve Implantation of Living Tissue‐Engineered Valves Feasible? An In Vitro Evaluation Utilizing a Decellularized and Reseeded Biohybrid Valve

Abstract

Transcatheter aortic valve implantation (TAVI) is a fast-growing, exciting field of invasive therapy. During the last years many innovations significantly improved this technique. However, the prostheses are still associated with drawbacks. The aim of this study was to create cell-seeded biohybrid aortic valves (BAVs) as an ideal implant by combination of assets of biological and artificial materials. Furthermore, the influence of TAVI procedure on tissue-engineered BAV was investigated. BAV (n=6) were designed with decellularized homograft cusps and polyurethane walls. They were seeded with fibroblasts and endothelial cells isolated from saphenous veins. Consecutively, BAV were conditioned under low pulsatile flow (500 mL/min) for 5 days in a specialized bioreactor. After conditioning, TAVI-simulation was performed. The procedure was concluded with re-perfusion of the BAV for 2 days at an increased pulsatile flow (1100 mL/min). Functionality was assessed by video-documentation. Samples were taken after each processing step and evaluated by scanning electron microscopy (SEM), immunohistochemical staining (IHC), and Live/Dead-assays. The designed BAV were fully functioning and displayed physiologic behavior. After cell seeding, static cultivation and first conditioning, confluent cell layers were observed in SEM. Additionally, IHC indicated the presence of endothelial cells and fibroblasts. A significant construction of extracellular matrix was detected after the conditioning phase. However, a large number of lethal cells were observed after crimping by Live/Dead staining. Analysis revealed that the cells while still being present directly after crimping were removed in subsequent perfusion. Extensive regions of damaged cell-layers were detected by SEM-analysis substantiating these findings. Furthermore, increased ICAM expression was detected after re-perfusion as manifestation of inflammatory reaction. The approach to generate biohybrid valves is promising. However, damages inflicted during the crimping process seem not to be immediately detectable. Due to severe impacts on seeded cells, the strategy of living TE valves for TAVI should be reconsidered.

Tissue-Engineered Grafts from Human Decellularized Extracellular Matrices: A Systematic Review and Future Perspectives

“…Thus, the fabrication of human decellularized heart valve scaffolds seeded with autologous cells prior to implantation or recolonized in vivo after surgery represents a concept for improving current valvular heart disease therapy. In the last two decades, human heart valve allografts have been prepared by decellularization of the aortic heart valve [59,162,163,164,165], the pulmonary heart valve [57,69,166,167], or both [168,169,170,171,172]. In particular, heart valves were taken from cadavers [168], procured from a tissue banking facility [164,167,169,172], removed from the heart of the recipient during transplantation surgery [166,69], or obtained from nonheartbeating [165] and heartbeating [162] organ donors.…”

“…In the perspective of engineered valve fabrication, the decellularization process plays a crucial role for its impact on ECM composition and architecture, which need to remain unchanged. According to the literature, detergents [58,61,63,65,66,67,69,163,171], enzymes [57,59,60,62,64,68,162,168,169], or both [164,165,166,167,170,172] have been used in various combinations and concentrations to achieve cell-free valve scaffolds with preserved ECM (Table 5). The marked reduction of class I and class II major histocompatibility complex expression following decellularization suggests the lowered antigenicity of valve leaflets in the perspective of in vivo implantation [57,172].…”

“…Taking advantage of the acellular aortic valve matrix, Koening and Colleagues [163] designed and manufactured a new decellularized and reseeded biohybrid prosthesis composed of a biological and a synthetic component. In this innovative construct, aortic valve homografts provided the cusps, while a polyurethane patch formed the walls.…”

“…In this innovative construct, aortic valve homografts provided the cusps, while a polyurethane patch formed the walls. The biohybrid aortic valve was repopulated by the dynamic seeding of fibroblasts and endothelial cells from human saphenous vein, obtaining confluent and uniform cell layers across the complete scaffold surface [163].…”

“…As it was demonstrated by many clinical cases and animal studies [293], the efficacy of amniotic membrane in promoting soft tissues healing and regeneration is due to its anti-inflammatory and immunological properties as well as to cytoprotective ability [120,121,122,123,124,125,126,127,128,129,130,131,132,133,134,135,136,137,138,139,140,141,142,143,144,145,146,147,148,149,150,151,152,153,154,155,156,157,158,159,160,161,162,163,164,165,166,167,168,169,170,171,172,173,174,175,176,177,178,179,180,181,182,183,184,185,186,…”