AbstractBackground. We have previously reported that it is possible to use human pericytes obtained from remnants of palliative surgery in neonatal patients with congenital heart disease to engineer animal-derived prosthetic grafts. The working hypothesis is that pericytes isolated from cardiac tissue at the occasion of palliation can be expanded and incorporated in prosthetic grafts forming a living tissue implantable for definitive correction of the heart defect. In order to obtain proof of concept in an in vivo large animal model, we sought to use autologous swine cardiac pericytes as a surrogate of the human cell product, thereby surmounting the problem of immune rejection of xenogeneic cells. This thesis illustrates the progressive steps of the manufacture process of a swine cardiac pericyte engineered vascular conduit and the first demonstration of implantation in a piglet pulmonary artery.
Methods and Results. The first step consisted of an adaptation of the isolation/expansion procedure previously set up for human cardiac pericytes using swine customized reagents. Neonatal human and swine CPs were similar in terms of cardiac anatomical localization and antigenic profile following isolation using immunomagnetic beads and culture expansion. Like human pericytes, swine surrogates form clones after single cell sorting, secrete angiogenic factors and extracellular matrix proteins, and support endothelial cell migration and network formation in vitro. Seeded and unseeded (control) vascular CorMatrix® patches were kept under static culture conditions for five days, and then, were shaped into a conduit to reproduce a vessel and incubated in a bioreactor system under a perfused flow for one or two weeks. Immunohistochemistry studies showed the viability and integration of swine pericytes into the outer layer of the conduit. Acellular or pericyte-engineered conduits were implanted in two 9
week old piglets to replace the left branch of the main pulmonary artery. After four months, the anatomical and functional integration of the grafts was assessed by Doppler echocardiography and cardiac magnetic resonance imaging. The extracellular matrix remodeling, vascularization and microcalcifications were evaluated by immunohistochemistry.
Conclusions. This work demonstrates the feasibility of using neonatal swine cardiac pericytes for the reconstruction of a pulmonary artery branch in a piglet model. These results pave the way to novel tissue engineering solutions for correction of congenital heart disease using autologous cardiac pericytes.
|Date of Award||24 Mar 2020|
|Supervisor||Massimo Caputo (Supervisor) & Paolo R Madeddu (Supervisor)|