Blood Outgrowth Endothelial Cells Alter Remodeling of Completely Biological Engineered Grafts Implanted into the Sheep Femoral Artery

Abstract

Hemocompatibility of tissue-engineered vascular grafts remains a major hurdle to clinical utility for small-diameter grafts. Here we assessed the feasibility of using autologous blood outgrowth endothelial cells to create an endothelium via lumenal seeding on completely biological, decellularized engineered allografts prior to implantation in the sheep femoral artery. The 4-mm-diameter, 2- to 3-cm-long grafts were fabricated from fibrin gel remodeled into an aligned tissue tube in vitro by ovine dermal fibroblasts prior to decellularization. Decellularized grafts pre-seeded with blood outgrowth endothelial cells (n=3) retained unprecedented (>95 %) monolayer coverage 1 h post-implantation and had greater endothelial coverage, smaller wall thickness, and more basement membrane after 9-week implantation, including a final week without anti-coagulation therapy, compared with contralateral non-seeded controls. These results support the use of autologous blood outgrowth endothelial cells as a viable source of endothelial cells for creating an endothelium with biological function on decellularized engineered allografts made from fibroblast-remodeled fibrin.

Arterial Decellularized Scaffolds Produced Using an Innovative Automatic System

“…Their findings were that the cell-seeded grafts had a better resolution than the cell-free ones, even if they concluded that the administration of antiplatelet drugs could have altered the outcomes. In comparison, our findings involve implants without antiplatelet therapy, strengthening the results of the study by Meier et al [2014]. Our study does have limitations, however, concerning the number of animals involved and the peculiarity of the chimeric model in which the immune-suppressive drug could have influenced the outcome.…”

“…Indeed, there is a contradiction, on the one hand, the seeded endothelial cells are lost within a few days, and on the other, it seems that cell-free implants have a worse resolution in the long term than seeded ones. Very recently, Meier et al [2014] investigated the in vivo implantation in ovine femoral arteries of fibrin-gel decellularized engineered vessels with no cells or with blood-outgrowth endothelial cell seeding. Their findings were that the cell-seeded grafts had a better resolution than the cell-free ones, even if they concluded that the administration of antiplatelet drugs could have altered the outcomes.…”

“…Synthetic grafts still perform badly with poor patency, mainly due to the cellsurface interactions and to the mechanical mismatch that leads to intimal hyperplasia of the anastomosis-adjacent vessels. In this context, decellularized blood vessels show promising results in animal models of small-diameter arterial replacements [Dahl et al, 2011;Quint et al, 2011Quint et al, , 2012Meier et al, 2014;Syedain et al, 2014].…”

“…Conflicting evidence is reported in the literature. On the one hand, it has been shown that seeded cells are lost within a few days after the implant [Roh et al, 2010;Hibino et al, 2011], and on the other hand, better resolution has been observed, in terms of patency, intimal hyperplasia and tissue regeneration for cell-seeded implants [Quint et al, 2011;Meier et al, 2014].…”

Implantation of Completely Biological Engineered Grafts Following Decellularization into the Sheep Femoral Artery

“…We report elsewhere studies of these grafts preseeded with endothelial cells. 33 It is well known that predominate circumferential alignment of the media in the native artery confers its unique biomechanical properties. 34 The method used to create the fibrin-based TEVG-cell-induced gel compaction on a nonadhesive mandrel, which allows for axial shortening, but with mechanically constrained circumferential and radial compaction-yields strong circumferential alignment.…”