Bioengineering of a Semiautologous Arterial Vessels with Reconstructed Media and Intima, Longtime Tested In Vivo

Abstract

Goal was to engineer biological, arterial grafts with antithrombotic, autologous endothelial luminal surface combined with extraluminal smooth vascular muscle layer (VSMC) and to test in vivo. (1) Different decellularisation methods described in literature were compared to identify the most suitable one with focus on the preservation of extracellular fibre matrix. (2) Endothelial precursor cells (EPC), isolated from bone marrow and VSMC from small venous segments of donor animals were cultivated. Cells were seeded sandwich‐like on homologous decellularized venous scaffolds and conditioned under pulsatile circulation in a bioreactor. (3) The semiautologous grafts were implanted in carotidal position on both sides in five Beagle dogs (n = 10; group 2) as interposition. A group of five animals, receiving only acellular grafts in both carotid positions (n = 10; group 1) served as controls. Comparison of four in literature described decellularisation methods showed different preservation of elastic and collagen fibres compared with native veins, whereas decellularity was similar in all methods. This forced us to choose a decellularization protocol with the best preservation of the extracellular matrix. The in vivo experiments showed in group 1 (control) already after one week a complete thrombotic occlusion of the decellularized implants, whereas in group 2 9/10 semiautologous grafts were patent after 98 ± 4 days in ultrasound, angiography and histology (p = 0.0001). A complete incorporation of semiautologous grafts in the surrounding tissue could be shown. The seeding with two different cell types preserved an aneurysmatic degeneration under arterial conditions with patency without anticoagulation.

In vivo assessment of two endothelialization approaches on bioprosthetic valves for the treatment of chronic deep venous insufficiency

“…Thus, we hypothesized that early endothelialization of SIS leaflets, either by capturing circulating cells or by pre‐seeding SIS with EOCs, would limit the development of intimal hyperplasia on bioprosthetic venous valves while also providing antithrombogenic activity. Previous studies have demonstrated that EOCs can regulate platelet accumulation and coagulation factor activation similar to mature endothelial cells, and EOCs have been seeded onto vascular grafts to improve hemocompatibility . However, the utility of covering SIS with EOCs to reduce hyperplasia on SIS bioprosthetic venous valves had not been investigated.…”

“…Previous studies have demonstrated that EOCs can regulate platelet accumulation and coagulation factor activation similar to mature endothelial cells, 36 and EOCs have been seeded onto vascular grafts to improve hemocompatibility. 13,20,21,[37][38][39][40][41] However, the utility of covering SIS with EOCs to reduce hyperplasia on SIS bioprosthetic venous valves had not been investigated.…”

Endothelial Outgrowth Cells: Function and Performance in Vascular Grafts

“…To ensure complete coverage of the tubular graft lumen, seeding is generally performed using multiple inoculations with manual or automated rotation, or by perfusing a cell suspension through the graft wall. 35,36,42,66,[79][80][81] …”

“…In another study, tissue-engineered grafts were constructed by selectively seeding bone marrow-derived EOCs onto the lumen and vascular smooth muscle cells onto the exterior of decellularized vessels. 81 These constructs were cultured in a bioreactor with pulsatile flow for 7 days, then implanted as interpositional carotid grafts in canines. At 14 weeks, 9 out of the 10 seeded grafts were patent.…”

Development of Implantable Autologous Small-Calibre Vascular Grafts from Peripheral Blood Samples

“…Therefore, seeding procedure with incorporation of the cells inside the matrix using an injection moulding technique with a subsequent maturation process under physiological stimuli represents an effective method to establish coculture settings on a scaffold with desired size and shape. Other authors described the sequential seeding of a scaffold material with EC on the luminal surface surrounded by smooth muscle cells and fibroblasts on the outside (for example [14,15]). In this way cocultures of vascular cells are already initially seeded according to their arrangement in a native vascular wall.…”