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Watkins MT. Early research in the Department of Surgery, Uniformed Services University of the Health Sciences. World J Surg 2005; 29 Suppl 1:S108-10. [PMID: 15815817 DOI: 10.1007/s00268-004-2076-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- Michael T Watkins
- Department of Surgery, Division of Vascular and Endovascular Surgery, Harvard Medical School, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.
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Dixit P, Hern-Anderson D, Ranieri J, Schmidt CE. Vascular graft endothelialization: comparative analysis of canine and human endothelial cell migration on natural biomaterials. JOURNAL OF BIOMEDICAL MATERIALS RESEARCH 2001; 56:545-55. [PMID: 11400132 DOI: 10.1002/1097-4636(20010915)56:4<545::aid-jbm1126>3.0.co;2-v] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Canines are typically used as the standard preclinical model to gauge the success of vascular graft materials. However, canines spontaneously re-endothelialize vascular grafts, whereas humans do not, even after years. This raises questions of why there are differences in vascular healing between humans and other species and whether the canine is the appropriate preclinical model. In the present study we evaluated human and canine endothelial cell (EC) migration on the novel cross-linked collagen biomaterial PhotoFix(TM) pericardium. We compared in vitro migration of these cells on PhotoFix alone and on PhotoFix adsorbed with various growth factors (aFGF and bFGF) and adhesion proteins (fibronectin, collagen IV, vitronectin, and laminin). We also compared human and canine ECs in terms of their morphologies and prostacyclin production. We found that human umbilical vein ECs (HUVECs) and canine ECs (CECs) migrated well on PhotoFix, suggesting that this biomaterial may be a good vascular graft candidate. Both cell types responded similarly to different growth factors and adhesive proteins, but HUVEC migration was consistently higher than that for CECs. This suggested that human in vivo graft re-endothelialization is likely not hindered by poor endothelial migration but is hindered by other cellular or graft properties.
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Affiliation(s)
- P Dixit
- Department of Chemical Engineering, University of Texas at Austin, 26th and Speedway, MC C0400, Austin, Texas 78712-1062, USA
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Bhat VD, Klitzman B, Koger K, Truskey GA, Reichert WM. Improving endothelial cell adhesion to vascular graft surfaces: clinical need and strategies. JOURNAL OF BIOMATERIALS SCIENCE. POLYMER EDITION 1998; 9:1117-35. [PMID: 9860176 DOI: 10.1163/156856298x00686] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Synthetic vascular grafts do not spontaneously endothelialize in humans and require some form of anticoagulation to maintain patency. Preseeding synthetic graft materials such as expanded polytetrafluoroethylene (ePTFE) and polyethylene terephthalate (PET) with endothelial cells (EC) has been examined in various in vitro and in vivo models. Although various studies provide encouraging results, clinical trials for EC seeding on synthetic grafts have not been equally successful. This paper provides a brief review of the various reports on EC seeding in animal and clinical studies. We discuss the inefficiencies associated with the EC seeding process and examine plasma protein treatment of the graft surfaces as a viable option for improving EC attachment, retention and spreading. As an alternative to existing therapies we present data on a heterogeneous ligand treatment of fibronectin (Fn) and avidin-biotin for enhanced human umbilical vein endothelial cell (HUVEC) adhesion to ePTFE graft surfaces. Control consisted of HUVECs seeded on Fn treated ePTFE graft surfaces. Functionality of HUVECs was assessed by measuring prostacyclin production of cells on both homogeneous and heterogeneous ligand treated surfaces. Laminar flow studies with a variable width flow chamber and scanning electron microscopy were used to measure initial cell retention and observe initial cell spreading on ePTFE surfaces, respectively. HUVEC retention on heterogeneous ligand treated graft surface was significantly (p < 0.001) higher compared to homogeneous ligand treated surfaces for shear stress in the range of 10-30 dyn cm(-2). HUVEC showed more cellular spreading on the heterogeneous ligand treated surface after seeding for 1-2 h. In vivo experimentation was performed in immune deficient (nude) rats by replacing a section of both the femoral arteries with 8 mnm long, 1 mm internal diameter denucleated ePTFE grafts treated with homogeneous and heterogeneous ligands respectively. Both grafts were seeded with similar cell density for 15 min prior to implantation. EC attachment and retention was measured by staining EC with hematoxylin and counting the cells before and after flow using light microscopy. The results indicate that a heterogeneous ligand treatment of graft surfaces using avidin-biotin and Fn-integrin attachment mechanisms increase cell seeding efficiency, initial cell retention and cellular spreading.
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Affiliation(s)
- V D Bhat
- Department of Biomedical Engineering & Centre for Cellular and Biosurface Engineering, Duke University, Durham, NC 27708-0281, USA
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Welch M, Durrans D, Carr HM, Vohra R, Rooney OB, Walker MG. Endothelial cell seeding: a review. Ann Vasc Surg 1992; 6:473-84. [PMID: 1467191 DOI: 10.1007/bf02007007] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The concept of endothelial cell seeding, designed to provide vascular grafts with a nonthrombogenic lining, has progressed from crude animal experiments during the past two decades to detailed in vitro functional studies using human cells. Although favorable results have been obtained in animal studies this has yet to be translated to humans, where current application of these techniques has been limited to a very few clinical trials. The history, current status and future directions are reviewed herein.
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Affiliation(s)
- M Welch
- Department of Vascular Surgery, Manchester Royal Infirmary, United Kingdom
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Prendiville EJ, Coleman JE, Callow AD, Gould KE, Laliberte-Verdon S, Ramberg K, Connolly RJ. Increased in-vitro incubation time of endothelial cells on fibronectin-treated ePTFE increases cell retention in blood flow. EUROPEAN JOURNAL OF VASCULAR SURGERY 1991; 5:311-9. [PMID: 1864396 DOI: 10.1016/s0950-821x(05)80515-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Endothelial cell (EC) seeding is postulated as a mechanism of improving patency of small calibre vascular grafts. However, the majority of seeded cells are lost within hours following restoration of blood flow. We postulated that incubating EC in-vitro on a graft will improve adherence and resistance to the sheer stresses of pulsatile blood flow. Fibronectin-treated ePTFE (5 cm x 4 mm ID) seeded with Indium-111-labelled autologous canine EC (1.5 x 10(5) cells/cm2) were incubated for four different time periods; 90 min, 24 h, 72 h and 6 days. Incubated grafts were subjected to blood flow of 75 ml/min for 6 h, in a canine ex-vivo arteriovenous shunt circuit. EC retention during perfusion was studied by measuring gamma activity emitted by the grafts. Cell morphology of non-perfused control groups and perfused groups was compared using scanning electron microscopy (SEM). SEM of control grafts showed progressive EC spreading on the ePTFE surface for up to 72 h incubation. Gamma activity was significantly higher at 6 h perfusion in grafts incubated for 72 h (82 +/- 4%) and 24 h (63 +/- 6%) vs. 90 min (34 +/- 13%, p less than 0.05), and between grafts incubated for 72 h vs. 6 days (55 +/- 7%, p less than 0.05). Perfused grafts incubated for 72 h showed unaltered EC morphology on SEM, few cells remained on 90 min incubated grafts. We conclude that incubating EC on fibronectin-treated ePTFE for 72 h in-vitro after seeding improves cell retention during blood flow.
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Affiliation(s)
- E J Prendiville
- Department of Surgery, Tufts University School of Medicine, New England Medical Center Hospitals, Boston, Massachusetts
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Sterpetti AV, Schultz RD, Hunter WJ, Cisternino S, Fontaine M. Comparison of two techniques to isolate microvascular endothelial cells from the omentum. J Surg Res 1990; 48:101-6. [PMID: 2304336 DOI: 10.1016/0022-4804(90)90199-c] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The purpose of the study was to compare two different techniques for isolation of omental microvascular endothelial cells (ECs). Segments of unreinforced polytetrafluorethylene (PTFE) grafts, 9 cm long and 6 mm in diameter, were implanted in 22 dogs as an aortic interposition. Fourteen grafts were seeded with a mean of 7 x 10(5) viable ECs, derived from the microvessels of the omentum: eight grafts (group A) were seeded with ECs obtained by collagenase digestion and by filtration through a pore mesh; six grafts (group B) were seeded with ECs obtained by collagenase digestion and by Percoll gradient separation. In eight grafts (group C), the ECs were not added to the preclot mixture and served as a control. Animals were sacrificed 5 weeks after surgery. The percentage of thrombus-free area was 65 +/- 22% for group A grafts and 74 +/- 15% for group B grafts (NS). The subendothelial layer was 280 +/- 60 microns thick in group A and 220 +/- 30 microns thick in group B (P less than 0.05). Seeded grafts showed a higher production of 6-keto-PGF1 alpha after addition of sodium arachidonate than control grafts. Percoll gradient separation allows isolation of a more purified suspension of ECs. Refinements in omental EC procurement are still required to minimize contamination with other types of cells.
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Affiliation(s)
- A V Sterpetti
- Department of Surgery and Pathology, Creighton University School of Medicine, Omaha, Nebraska 68131
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Zilla P, Fasol R, Deutsch M, Fischlein T, Minar E, Hammerle A, Krapicka O, Kadletz M. Endothelial cell seeding of polytetrafluoroethylene vascular grafts in humans: A preliminary report. J Vasc Surg 1987. [DOI: 10.1016/0741-5214(87)90266-7] [Citation(s) in RCA: 84] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Shindo S, Takagi A, Whittemore AD. Improved patency of collagen-impregnated grafts after in vitro autogenous endothelial cell seeding. J Vasc Surg 1987. [DOI: 10.1016/0741-5214(87)90002-4] [Citation(s) in RCA: 80] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Hollier L, Fowl R, Pennell R, Heck C, Winter K, Fass D, Kaye M. Are seeded endothelial cells the origin of neointima on prosthetic vascular grafts? J Vasc Surg 1986. [DOI: 10.1016/0741-5214(86)90069-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Hess F. History of (micro) vascular surgery and the development of small-caliber blood vessel prostheses (with some notes on patency rates and re-endothelialization). Microsurgery 1985; 6:59-69. [PMID: 3894875 DOI: 10.1002/micr.1920060202] [Citation(s) in RCA: 34] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The historical development of vascular surgery is reviewed from ancient times (Ruphus of Ephesus, Aëtius of Amida) to recent developments (sutured anastomosis by Carrel). Attempts to anastomose blood vessels by means of nonsuturing technique, using a ring or short tube of diverse materials called prostheses, were undertaken at the start of this century and continued until shortly after World War II. With the advent of modern polymeric materials, prostheses of different types, sizes, structures, and fabrics have been used to substitute for blood vessels, both experimentally and clinically. Recently, blood vessel prostheses with small (1-1.5 mm) internal diameters became available and have been implanted experimentally. Patency rates, biophysical and structural properties, the re-endothelialization and the neointima formation of several types of microvascular prostheses are briefly reviewed.
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Abstract
Endothelial cells can be harvested from segments of adult human saphenous vein in a varicose condition removed from patients having single or bilateral vein ligation and stripping. The cells are harvested by scraping with a scalpel, seeded on to gelatin coated or Primaria flasks and are passaged by removal with a rubber policeman. The cells cultured in this manner are maintained in a growth medium that is not supplemented with growth factors. The cells grow with a cobblestone monolayer morphology, possess angiotensin converting enzyme activity and react with antibodies to Factor VIII antigen. The cells fluoresce brightly after reaction with monoclonal antibodies specific for human endothelial cells. Thus, stripped varicose vein segments provide a readily available source of endothelial cells.
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Schmidt SP, Hunter TJ, Sharp WV, Malindzak GS, Evancho M. Endothelial cell—seeded four-millimeter Dacron vascular grafts: Effects of blood flow manipulation through the grafts. J Vasc Surg 1984. [DOI: 10.1016/0741-5214(84)90082-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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