First Report of Histological Evaluation of Human Tissue-Engineered Vasculature

From September 2001 to December 2004, 25 patients underwent a Fontan procedure using tissue-engineered vasculature (TEV) under informed consent and institutional review board approval. Six of these 25 patients died, although no graft-related mortality occurred. The case presented herein is the first case in which the family agreed to the performance of an autopsy to elucidate the late-term histological characteristics of human TEV.

A 16-year-old girl had a history of heart murmur and cyanosis at birth, followed by diagnoses of heterotaxy syndrome (polysplenia), a single right ventricle, pulmonary stenosis, bilateral superior vena cava, a hemiazygos connection, and a common atrium with mild to moderate regurgitation from a common atrioventricular valve. She underwent a Fontan procedure with common atrioventricular valve plasty following staged operations at the age of 4 years. A 12-mm-diameter biodegradable scaffold seeded with mononuclear bone marrow cells was interposed between the hepatic vein and pulmonary artery to accomplish the Fontan procedure. At the age of 16 years, she died of multiple organ failure, low cardiac output syndrome, disseminated intravascular coagulation, pancytopenia, and brain abscessation. An autopsy of the patient was performed, and the tissue samples were evaluated either macroscopically or microscopically for histological analyses. Macroscopic examination showed well-formed tissueengineered vessels connected to the pulmonary artery.

The tissue samples were then fixed in 10% formaldehyde, embedded in paraffin, and sectioned at 4 to 5 μm. Some sections were subjected to hematoxylin and eosin, Masson’s trichrome, Victoria blue–van Gieson, or modified von Kossa staining, which showed components of the four basic vascular layers (endothelial cells, vascular smooth muscle cells, elastic fibers, and collagen fibers) 12 years after implantation of the TEV. Calcified lesions (black-spots lesions) were not observed in any samples. Immunostaining of the remaining sections was performed as previously described using antibodies to factor VIII, alpha smooth muscle actin, myosin heavy chain, smooth muscle myosin heavy chain 1, smooth muscle myosin heavy chain 2, and calponin. Endothelialization and mature vascular smooth muscle cell proliferation  were observed in the human TEV.