Tissue-engineered blood vessel graft produced by self-derived cells and allogenic acellular matrix: a functional performance and histologic study.

INTRODUCTION: Current prosthetic alternatives to autologous vascular grafts remain poor in terms of patency. Growing biologic blood vessels has been proposed as an alternative. In this work, the authors demonstrate a method for producing a tissue-engineered vascular graft (TEVG) with self-derived endothelial cells, smooth muscle cells, and allogenic acellular matrix in vitro. The aim of this study was to find out if the graft is suitable as the carotid artery substitute.
METHODS: A canine model was developed for this study. Endothelial and smooth muscle cells were used as seeding cells, and allogenic acellular matrix was used as scaffold to produce the TEVG. Endothelial and smooth muscle cells from the saphenous vein were harvested by trypsin and collagenase digestion respectively. These isolated cells were cultured and expanded by routine cell culture technique. The common carotid artery was harvested from other fresh dog cadavers and processed by a multistep decellularizing technique to remove original cells and preserve elastic and collagen fibers. Then, the inner surface of the acellular matrix as a scaffold was sequentially seeded with cells. Smooth muscle cells were seeded onto the scaffold. It was placed in bioreactors filled Dulbecco modified Eagle medium supplemented with growth factors. After 4 weeks, the vessels were harvested from the bioreactors and seeded with endothelial cells at the lumen for 7 days. Finally, the cell-seeded graft was transplanted to the cell-donated dog to substitute part of the native common carotid artery (2 cm in length). All animals were followed up for 6 months. Twenty-four dogs were divided into 3 groups randomly: group A (native artery graft), group B (allogenic acellular matrix graft only), and group C (acellular allogenic matrix coated with endothelial and smooth muscle cells). These grafts were subjected to regular echocardiography at 1, 3, and 6 months postoperatively. Then, the TEVG were harvested for histologic evaluation at 6 months after transplantation. The vascular luminal surfaces were observed by electronic scanning microscopy.
RESULTS: The TEVG showed good functional performance demonstrated by regular Doppler ultrasonography at 1, 3, and 6 months postoperatively, compared with that of native arteries. All vascular grafts in group A and C provided patent rates of 100%; however, the patency rate of group B was 50% at 3 and 6 months postoperatively. The TEVG had a similar macroscopic appearance to that of native vessels. Histologic and immunohistochemical analyses indicated the presence of high cell density and development of a highly organized structure of ECM.
CONCLUSION: Cultured self-derived endothelial and smooth muscle cells could be used as seeding cells and allogenic acellularized matrix could be used as scaffold in producing the TEVG. The TEVG had histologic and functional properties consistent with native arteries.