Dynamic Autologous Reendothelialization of Small-Caliber Arterial Extracellular Matrix: A Preclinical Large Animal Study

Abstract

Effective cellularization is a key approach to prevent small-caliber (<4 mm) tissue-engineered vascular graft (TEVG) failure and maintain patency and contractility following implantation. To achieve this goal, however, improved biomimicking designs and/or relatively long production times (typically several months) are required. We previously reported on porcine carotid artery decellularization yielding biomechanically stable and cell supportive small-caliber (3–4 mm diameter, 5 cm long) arterial extracellular matrix (scaECM) vascular grafts. In this study, we aimed to study the scaECM graft patency in vivo and possibly improve that patency by graft pre-endothelialization with the recipient porcine autologous cells using our previously reported custom-designed dynamic perfusion bioreactor system. Decellularized scaECM vascular grafts were histologically characterized, their immunoreactivity studied in vitro, and their biocompatibility profile evaluated as a xenograft subcutaneous implantation in a mouse model. To study the scaECM cell support and remodeling ability, pig autologous endothelial and smooth muscle cells (SMCs) were seeded and dynamically cultivated within the scaECM lumen and externa/media, respectively. Finally, endothelialized-only scaECMs—hypothesized as a prerequisite for maintaining graft patency and controlling intimal hyperplasia—were transplanted as an interposition carotid artery graft in a porcine model. Graft patency was evaluated through angiography online and endpoint pathological assessment for up to 6 weeks. Our results demonstrate the scaECM-TEVG biocompatibility preserving a structurally and mechanically stable vascular wall not just following decellularization and recellularization but also after implantation. Using our dynamic perfusion bioreactor, we successfully demonstrated the ability of this TEVG to support in vitro recellularization and remodeling by primary autologous endothelial and SMCs, which were seeded on the lumen and the externa/media layers, respectively. Following transplantation, dynamically endothelialized scaECM-TEVGs remained patent for 6 weeks in a pig carotid interposition bypass model. When compared with nonrevitalized control grafts, reendothelialized grafts provided excellent antithrombogenic activity, inhibited intimal hyperplasia formation, and encouraged media wall infiltration and reorganization with recruited host SMCs. We thus demonstrate that readily available decellularized scaECM can be promptly revitalized with autologous cells in a 3-week period before implantation, indicating applicability as a future platform for vascular reconstructive procedures.

Implantation of VEGF‐functionalized cell‐free vascular grafts: regenerative and immunological response

“…Over the past decade, several groups have demonstrated the feasibility of completely acellular, off-the-shelf grafts in various animal models as well as human clinical trials. Decellularized and devitalized tissue-engineered constructs have been utilized with increasing frequency and have demonstrated improved patency and regeneration potential (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13). Devitalized constructs are based on bioengineered tissue constructs that are stripped of the cellular components while leaving extracellular matrix (ECM) components intact and then implanted into the animal model of choice (14).…”

Enhanced Vascular Biocompatibility and Remodeling of Decellularized and Secured Xenogeneic/Allogeneic Matrices in a Porcine Model

“…These results are encouraging, and a longer follow-up will indicate new vessels’ long-term permeability essentially dependent on intimal hyperplasia evolution. This is obviously crucial, and some authors recommend decellularized matrices in vitro endothelial cell seeding before implantation to improve patency rate [19, 30, 31]. In a previous work, seeded DHFL with stem cells for parietal reconstructions were quickly obtained, confirming the absence of treatment cytotoxicity [32].…”

Processed Tissue–Derived Extracellular Matrices: Tailored Platforms Empowering Diverse Therapeutic Applications

“…A growing number of patients worldwide are in need of vascular grafts for the replacement of obstructed blood vessels as a result of vascular and arterial diseases such as atherosclerosis. While native perfusion‐decellularized vascular ECM is highly advantageous as it retains the inherent tubular structure of blood vessels, the produced graft is limited in terms of its length, diameter, and wall thickness, determined by the parameters of the available tissue. The restructuring of the native dECM through processing techniques could overcome this limitation, allowing the manufacturing of vascular grafts with desired geometries suiting the addressed application.…”