title: Decellularized allogeneic heart valves demonstrate self-regeneration potential after a long-term preclinical evaluation.
abstract: Tissue-engineered heart valves are proposed as novel viable replacements granting longer durability and growth potential. However, they require extensive in vitro cell-conditioning in bioreactor before implantation. Here, the propensity of non-preconditioned decellularized heart valves to spontaneous in body self-regeneration was investigated in a large animal model. Decellularized porcine aortic valves were evaluated for right ventricular outflow tract (RVOT) reconstruction in Vietnamese Pigs (n = 11) with 6 (n = 5) and 15 (n = 6) follow-up months. Repositioned native valves (n = 2 for each time) were considered as control. Tissue and cell components from explanted valves were investigated by histology, immunohistochemistry, electron microscopy, and gene expression. Most substitutes constantly demonstrated in vivo adequate hemodynamic performances and ex vivo progressive repopulation during the 15 implantation months without signs of calcifications, fibrosis and/or thrombosis, as revealed by histological, immunohistochemical, ultrastructural, metabolic and transcriptomic profiles. Colonizing cells displayed native-like phenotypes and actively synthesized novel extracellular matrix elements, as collagen and elastin fibers. New mature blood vessels, i.e. capillaries and vasa vasorum, were identified in repopulated valves especially in the medial and adventitial tunicae of regenerated arterial walls. Such findings correlated to the up-regulated vascular gene transcription. Neoinnervation hallmarks were appreciated at histological and ultrastructural levels. Macrophage populations with reparative M2 phenotype were highly represented in repopulated valves. Indeed, no aspects of adverse/immune reaction were revealed in immunohistochemical and transcriptomic patterns. Among differentiated elements, several cells were identified expressing typical stem cell markers of embryonic, hematopoietic, neural and mesenchymal lineages in significantly higher number and specific topographic distribution in respect to control valves. Following the longest follow-up ever realized in preclinical models, non-preconditioned decellularized allogeneic valves offer suitable microenvironment for in vivo cell homing and tissue remodeling. Manufactured with simple, timesaving and cost-effective procedures, these promising valve replacements hold promise to become an effective alternative, especially for pediatric patients.
authors.affiliation: Department of Cardiac, Thoracic and Vascular Sciences, University of Padua, Padua, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Iop
authors.affiliation: Department of Experimental and Clinical Medicine, University of Udine, Udine, Italy.
authors.forename: Antonella
authors.initials: A
authors.lastname: Bonetti
authors.affiliation: Department of Cardiac, Thoracic and Vascular Sciences, University of Padua, Padua, Italy.
authors.forename: Filippo
authors.initials: F
authors.lastname: Naso
authors.affiliation: Department of Cardiac, Thoracic and Vascular Sciences, University of Padua, Padua, Italy.
authors.forename: Stefania
authors.initials: S
authors.lastname: Rizzo
authors.affiliation: Department of Biology and C.R.I.B.I. Biotechnology Centre, University of Padua, Padua, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Cagnin
authors.affiliation: Department of Cardiac, Thoracic and Vascular Sciences, University of Padua, Padua, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Bianco
authors.affiliation: Department of Cardiac, Thoracic and Vascular Sciences, University of Padua, Padua, Italy.
authors.forename: Carlo
authors.initials: C
authors.lastname: Dal Lin
authors.affiliation: Department of Biology and C.R.I.B.I. Biotechnology Centre, University of Padua, Padua, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Martini
authors.affiliation: Department of Animal Medicine, Productions and Health, University of Padua, Legnaro, Italy.
authors.forename: Helen
authors.initials: H
authors.lastname: Poser
authors.affiliation: Department of Animal Medicine, Productions and Health, University of Padua, Legnaro, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Franci
authors.affiliation: Department of Biology and C.R.I.B.I. Biotechnology Centre, University of Padua, Padua, Italy.
authors.forename: Gerolamo
authors.initials: G
authors.lastname: Lanfranchi
authors.affiliation: Department of Animal Medicine, Productions and Health, University of Padua, Legnaro, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Busetto
authors.affiliation: Department of Biomedical Sciences, University of Padua, Padua, Italy.
authors.forename: Michel
authors.initials: M
authors.lastname: Spina
authors.affiliation: Department of Cardiac, Thoracic and Vascular Sciences, University of Padua, Padua, Italy.
authors.forename: Cristina
authors.initials: C
authors.lastname: Basso
authors.affiliation: Department of Experimental and Clinical Medicine, University of Udine, Udine, Italy.
authors.forename: Maurizio
authors.initials: M
authors.lastname: Marchini
authors.affiliation: Department of Cardiac, Thoracic and Vascular Sciences, University of Padua, Padua, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Gandaglia
authors.affiliation: Department of Experimental and Clinical Medicine, University of Udine, Udine, Italy.
authors.forename: Fulvia
authors.initials: F
authors.lastname: Ortolani
authors.affiliation: Department of Cardiac, Thoracic and Vascular Sciences, University of Padua, Padua, Italy.
authors.forename: Gino
authors.initials: G
authors.lastname: Gerosa
mesh_terms: D064591:Allografts / Q000648:ultrastructure; D000818:Animals; D048430:Cell Shape; D002470:Cell Survival; D002478:Cells, Cultured; D020869:Gene Expression Profiling; D006350:Heart Valve Prosthesis; D019918:Heart Valve Prosthesis Implantation; D007150:Immunohistochemistry; D016130:Immunophenotyping; D012038:Regeneration / Q000502:physiology*; D034421:Sus scrofa; D014184:Transplantation, Homologous