Decellularized aortic conduits: could their cryopreservation affect post-implantation outcomes? A morpho-functional study on porcine homografts

Abstract

Explanted D grafts exhibited near-normal features, whereas the presence of calcification, inflammatory infiltrates, and disarray of elastic lamellae occurred in some DC grafts. In the unaltered regions of AVCs from both groups, almost complete re-endothelialization was observed for both valve cusps and aorta walls. In addition, side-by-side repopulation by recipient's fibroblasts, myofibroblasts, and smooth muscle cells was paralleled by ongoing tissue remodeling, as revealed by the ultrastructural identification of typical canals of collagen fibrillogenesis and elastogenesis-related features. Incipient neo-vascularization and re-innervation of medial and adventitial tunicae of grafted aortic walls were also detected for both D and DC groups. Cryopreservation did not affect post-implantation AVC hemodynamic behavior and was topically propensive to cell repopulation and tissue renewal, although graft deterioration including calcification was present in several areas. Thus, these preliminary data provide essential information on feasibility of decellularization and cryopreservation coupling in the perspective of treatment optimization and subsequent clinical Abstract Decellularized porcine aortic valve conduits (AVCs) implanted in a Vietnamese Pig (VP) experimental animal model were matched against decellularized and then cryopreserved AVCs to assess the effect of cryopreservation on graft hemodynamic performance and propensity to in vivo repopulation by host's cells. VPs (n = 12) underwent right ventricular outflow tract substitution using AVC allografts and were studied for 15-month follow-up. VPs were randomized into two groups, receiving AVCs treated with decellularization alone (D; n = 6) or decellularization/ cryopreservation (DC; n = 6), respectively. Serial echocardiography was carried out to follow up hemodynamic function. All explanted AVCs were processed for light and electron microscopy. No signs of dilatation, progressive stenosis, regurgitation, and macroscopic calcification were echocardiographically observed in both D and DC groups. Heart Vessels 1 3 trials using similarly treated human allografts as innovative heart valve substitutes.

Multi-stage bioengineering of a layered oesophagus with in vitro expanded muscle and epithelial adult progenitors

“…Having a cryopreserved organ increased the possibility of commercialization and benefit to a larger number of patients. Slow-cooling cryopreservation has already been used for successful preservation of decellularised scaffolds including the oesophagus 29 , 62 , 63 , but has never been applied to cell-seeded scaffolds. The same protocol was used here to cryopreserve constructs, after the first stage of the bio-engineering process, for 2 weeks in liquid nitrogen.…”

Long-term cryopreservation of decellularised oesophagi for tissue engineering clinical application

“…The absence of cells in a cryopreserved ECM-derived scaffold could change the effect of the storage method on the structure, composition and biomechanical properties of the tissue of interest. Gallo et al decellularised porcine aortic valve conduits and randomised 12 Vietnamese Pigs to receive either decellularised or decellularised and cryopreserved conduits in a transplantation model [35]. No signs of dilatation, stenosis or regurgitation were seen in either group by echocardiography and cryopreserved conduits allowed cell repopulation and tissue renewal, although demonstrating signs of deterioration in some areas, suggesting a need to fine-tune the cryopreservation protocol.…”

Six-Year-Old Sheep as a Clinically Relevant Large Animal Model for Aortic Valve Replacement Using Tissue-Engineered Grafts Based on Decellularized Allogenic Matrix

“…Gallo et al reported finding spindle-shaped cells throughout the cusp interstitium when cellular AV allografts were im-planted in 12-month-old Vietnamese pigs for a period of 15 months. 24 In our study, we found that interstitial cells were repopulating the cusp, but that even after 12 months in vivo only the distal and middle sections of the cusps had been partially repopulated with host's cells. While cells infiltrating the wall were identified as mostly fibroblasts, the ratio of cells positive for SMA was higher in the cusps.…”