Synthetic vascular grafts seeded with genetically modified endothelium in the dog: Evaluation of the effect of seeding technique and retroviral vector on cell persistence in vivo

Unique characteristics of endothelium make it an attractive target cell for gene transfer. Genetically modified endothelial cells (ECs) seeded on synthetic vascular grafts offer the potential to control neointimal hyperplasia, decrease graft thrombogenicity and improve small diameter graft patency. This study addresses the issue of synthetic vascular graft colonization with endothelial cells transduced with noninducible retroviral marker genes in the dog. Autologous endothelial cells were enzymatically harvested and transduced with either the bacterial NeoR gene or human growth hormone gene using retroviral vectors. All transduced cells were positive by polymerase chain reaction (PCR) amplification for the transduced gene sequence prior to graft seeding. Transduced ECs were seeded on Dacron grafts (n = 3) pre-clotted with autologous blood. These grafts exhibited complete endothelialization at times from 250 to 360 days. Recovered DNA, however, was negative for the transduced gene sequence when analyzed by PCR and Southern blotting. Expanded polytetrafluoroethylene (ePTFE) was evaluated (n = 8) using several different cell seeding protocols. Grafts were seeded at 3 densities (ranging from 6 × 103 to 1.5 × 105 cells/cm2) and 2 different adherence times. Seeding substrate was also evaluated. Grafts were either preclotted with whole blood or incubated with 20 or 120 μg/ml fibronectin for 60 min. Graft biopsies were evaluated from 2 to 52 wk. Limited endothelialization was present in 4 dogs as early as 2 wk, but never progressed to full luminal coverage. The remaining dogs failed to ever exhibit any luminal EC adherence. Two dogs with limited EC coverage had positive DNA by PCR for the NeoR gene sequence at 2 and 3 wk. In contrast to transduced EC's, nontransduced EC colonization of ePTFE was complete at 2 wk when seeded under conditions that transduced cells had failed to persist. Neither seeding density, adherence time, seeding substrate or retroviral vector used influenced the uniformly poor graft coverage seen with transduced cells. Results of this study indicate that despite successful gene transfer using 4 different retroviral vectors, transduced endothelial cells seeded under varying conditions appear altered in their ability to stably adhere and colonize synthetic vascular grafts in vivo.

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Antithrombogenic surface modifications in xenogenic pericardial vascular grafts: Initial in-vivo evaluation

The Thoracic and Cardiovascular Surgeon ◽

10.1055/s-0030-1269233 ◽

2011 ◽

Vol 59 (S 01) ◽

Author(s):

J Linneweber ◽

F Voss ◽

P Dohmen ◽

W Erdbrügger ◽

W Konertz

Keyword(s):

Vascular Grafts ◽

Surface Modifications ◽

In Vivo Evaluation

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Faculty Opinions recommendation of Lymphocytes genetically modified to express tumor antigens target DCs in vivo and induce antitumor immunity.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1092410.546844 ◽

2007 ◽

Author(s):

Pedro Romero

Keyword(s):

Antitumor Immunity ◽

Tumor Antigens ◽

Genetically Modified

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Faculty Opinions recommendation of In vivo tracking of T cells in humans unveils decade-long survival and activity of genetically modified T memory stem cells.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.725338082.793510500 ◽

2015 ◽

Author(s):

Nina Drize

Keyword(s):

Stem Cells ◽

T Cells ◽

Genetically Modified ◽

Long Survival

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Surface Modification by Nanobiomaterials for Vascular Tissue Engineering Applications

Current Medicinal Chemistry ◽

10.2174/0929867325666180914104633 ◽

2020 ◽

Vol 27 (10) ◽

pp. 1634-1646 ◽

Cited By ~ 1

Author(s):

Huey-Shan Hung ◽

Shan-hui Hsu

Keyword(s):

Tissue Engineering ◽

Vascular Tissue ◽

Thrombus Formation ◽

Vascular Grafts ◽

Vascular Tissue Engineering ◽

Great Success ◽

Natural Polymers ◽

Vascular Biomaterials

Treatment of cardiovascular disease has achieved great success using artificial implants, particularly synthetic-polymer made grafts. However, thrombus formation and restenosis are the current clinical problems need to be conquered. New biomaterials, modifying the surface of synthetic vascular grafts, have been created to improve long-term patency for the better hemocompatibility. The vascular biomaterials can be fabricated from synthetic or natural polymers for vascular tissue engineering. Stem cells can be seeded by different techniques into tissue-engineered vascular grafts in vitro and implanted in vivo to repair the vascular tissues. To overcome the thrombogenesis and promote the endothelialization effect, vascular biomaterials employing nanotopography are more bio-mimic to the native tissue made and have been engineered by various approaches such as prepared as a simple surface coating on the vascular biomaterials. It has now become an important and interesting field to find novel approaches to better endothelization of vascular biomaterials. In this article, we focus to review the techniques with better potential improving endothelization and summarize for vascular biomaterial application. This review article will enable the development of biomaterials with a high degree of originality, innovative research on novel techniques for surface fabrication for vascular biomaterials application.

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Assessment of Electrospun Pellethane-Based Scaffolds for Vascular Tissue Engineering

Materials ◽

10.3390/ma14133678 ◽

2021 ◽

Vol 14 (13) ◽

pp. 3678

Author(s):

Vera Chernonosova ◽

Alexandr Gostev ◽

Ivan Murashov ◽

Boris Chelobanov ◽

Andrey Karpenko ◽

...

Keyword(s):

Vascular Tissue ◽

Ex Vivo ◽

Vascular Grafts ◽

Wistar Rat ◽

Graft Occlusion ◽

Suitable Candidate ◽

Large Animals ◽

Cell Adhesion And Proliferation

We examined the physicochemical properties and the biocompatibility and hemocompatibility of electrospun 3D matrices produced using polyurethane Pellethane 2363-80A (Pel-80A) blends Pel-80A with gelatin or/and bivalirudin. Two layers of vascular grafts of 1.8 mm in diameter were manufactured and studied for hemocompatibility ex vivo and functioning in the infrarenal position of Wistar rat abdominal aorta in vivo (n = 18). Expanded polytetrafluoroethylene (ePTFE) vascular grafts of similar diameter were implanted as a control (n = 18). Scaffolds produced from Pel-80A with Gel showed high stiffness with a long proportional limit and limited influence of wetting on mechanical characteristics. The electrospun matrices with gelatin have moderate capacity to support cell adhesion and proliferation (~30–47%), whereas vascular grafts with bivalirudin in the inner layer have good hemocompatibility ex vivo. The introduction of bivalirudin into grafts inhibited platelet adhesion and does not lead to a change hemolysis and D-dimers concentration. Study in vivo indicates the advantages of Pel-80A grafts over ePTFE in terms of graft occlusion, calcification level, and blood velocity after 6 months of implantation. The thickness of neointima in Pel-80A–based grafts stabilizes after three months (41.84 ± 20.21 µm) and does not increase until six months, demonstrating potential for long-term functioning without stenosis and as a suitable candidate for subsequent preclinical studies in large animals.

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Review: Tissue Engineering of Small-Diameter Vascular Grafts and Their In Vivo Evaluation in Large Animals and Humans

Cells ◽

10.3390/cells10030713 ◽

2021 ◽

Vol 10 (3) ◽

pp. 713

Author(s):

Shu Fang ◽

Ditte Gry Ellman ◽

Ditte Caroline Andersen

Keyword(s):

Animal Models ◽

Vascular Grafts ◽

Small Diameter ◽

Large Animal ◽

Large Animal Models ◽

Graft Outcome ◽

Limited Success ◽

Large Animals

To date, a wide range of materials, from synthetic to natural or a mixture of these, has been explored, modified, and examined as small-diameter tissue-engineered vascular grafts (SD-TEVGs) for tissue regeneration either in vitro or in vivo. However, very limited success has been achieved due to mechanical failure, thrombogenicity or intimal hyperplasia, and improvements of the SD-TEVG design are thus required. Here, in vivo studies investigating novel and relative long (10 times of the inner diameter) SD-TEVGs in large animal models and humans are identified and discussed, with emphasis on graft outcome based on model- and graft-related conditions. Only a few types of synthetic polymer-based SD-TEVGs have been evaluated in large-animal models and reflect limited success. However, some polymers, such as polycaprolactone (PCL), show favorable biocompatibility and potential to be further modified and improved in the form of hybrid grafts. Natural polymer- and cell-secreted extracellular matrix (ECM)-based SD-TEVGs tested in large animals still fail due to a weak strength or thrombogenicity. Similarly, native ECM-based SD-TEVGs and in-vitro-developed hybrid SD-TEVGs that contain xenogeneic molecules or matrix seem related to a harmful graft outcome. In contrast, allogeneic native ECM-based SD-TEVGs, in-vitro-developed hybrid SD-TEVGs with allogeneic banked human cells or isolated autologous stem cells, and in-body tissue architecture (IBTA)-based SD-TEVGs seem to be promising for the future, since they are suitable in dimension, mechanical strength, biocompatibility, and availability.

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