HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Dominique Shum-Tim John E. Mayer, Jr Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Shum-Tim, D. Articles by Mayer, J. E. Search for Related Content PubMed PubMed Citation Articles by Shum-Tim, D. Articles by Mayer, J. E., Jr Related Collections Related Article

Ann Thorac Surg 1999;68:2298-2304
© 1999 The Society of Thoracic Surgeons

---

Original Articles

Tissue engineering of autologous aorta using a new biodegradable polymer

^a Department of Cardiovascular Surgery, Children’s Hospital, Harvard Medical School, Boston, Massachusetts, USA
^b Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
^c Department of Surgery, Children’s Hospital, Harvard Medical School, Boston, Massachusetts, USA
^d Department of Radiology, Children’s Hospital, Harvard Medical School, Boston, Massachusetts, USA
^e Department of Cardiology, Children’s Hospital, Harvard Medical School, Boston, Massachusetts, USA
^f Department of Orthopedic Surgery, Children’s Hospital, Harvard Medical School, Boston, Massachusetts, USA

Address reprint requests to Dr Mayer, Department of Cardiovascular Surgery, Children’s Hospital, 300 Longwood Ave, Boston, MA 02115

Presented at the Poster Session of the Thirty-fifth Annual Meeting of The Society of Thoracic Surgeons, San Antonio, TX, Jan 25–29, 1999.

	Abstract

Top Abstract Introduction Material and methods Results Comment References

 
Background. Ovine pulmonary valve leaflets and pulmonary arteries have been tissue-engineered (TE) from autologous cells and biodegradable polyglycolic acid (PGA)-polyglactin copolymers. Use of this cell-polymer construct in the systemic circulation resulted in aneurysm formation. This study evaluates a TE vascular graft in the systemic circulation which is based on a new copolymer of PGA and polyhydroxyalkanoate (PHA).

Methods. Ovine carotid arteries were harvested, expanded in vitro, and seeded onto 7-mm diameter PHA-PGA tubular scaffolds. The autologous cell-polymer vascular constructs were used to replace 3–4 cm abdominal aortic segments in lambs (group TE, n = 7). In a control group (n = 4), aortic segments were replaced with acellular polymer tubes. Vascular patency was evaluated with echography. All control animals were sacrificed when the grafts became occluded. Animals in TE group were sacrificed at 10 days (n = 1), 3 (n = 3), and 5 months (n = 3). Explanted TE conduits were evaluated for collagen content, deoxyribonucleic acid (DNA) content, structural and ultrastructural examination, mechanical strength, and matrix metalloproteinase (MMP) activity.

Results. The 4 control conduits became occluded at 1, 2, 55, and 101 days. All TE grafts remained patent, and no aneurysms developed by the time of sacrifice. There was one mild stenosis at the anastomotic site after 5 months postoperatively. The percent collagen and DNA contents approached the native aorta over time (% collagen = 25.7% ± 3.4 [3 months] vs 99.6% ± 11.7 [5 months], p < 0.05; and % DNA = 30.8% ± 6.0 [3 months] vs 150.5% ± 16.9 [5 months], p < 0.05). Histology demonstrated elastic fibers in the medial layer and endothelial specific von Willebrand factor on the luminal surface. The mechanical strain-stress curve of the TE aorta approached that of the native vessel. A 66 kDa MMP-2 was found in the TE and native aorta but not in control group.

Conclusions. Autologous aortic grafts with biological characteristics resembling the native aorta can be created using TE approach. This may allow the development of "live" vascular grafts.

	Introduction

Top Abstract Introduction Material and methods Results Comment References

 
Current clinically available cardiovascular prosthetic substitutes have many disadvantages. These prosthetic foreign materials predispose the patients to lifelong risks of infection. They lack the ability to repair, remodel, and grow which are vital characteristics for pediatric populations. Creation of "living" autologous cardiovascular structures may overcome many of these limitations associated with the currently used prosthetic substitutes. Our laboratory has previously reported the use of a biodegradable polyglactin-polyglycolic acid (PGA) copolymer scaffold to deliver autologous cells which had been expanded in vitro. Once cells are attached to the three-dimensional polymer, the resulting cell-polymer construct can be reimplanted into the experimental subject. As cellular structures and matrix develop, the polymer degrades, ultimately leaving only "engineered" tissue without foreign material. Through this approach, we have successfully created autologous pulmonary valve leaflets and pulmonary artery [1–3]. The polymer was designed to be biodegraded over a 6 to 8 week period in these early studies [4]. Preliminary studies using this polyglactin-PGA copolymer to create vascular substitutes in the systemic circulation resulted in aneurysm formation. The present study evaluates whether a new PGA-polyhydroxyalkanoate (PHA) copolymer, which has a much longer degradation time, can withstand systemic pressure and can be used to create a vascular autograft for use in the aortic position.

	Material and methods

Top Abstract Introduction Material and methods Results Comment References

 
Cell isolation
The techniques of cell isolation, culture, and seeding have been previously described in detail and slight modification has been adopted for this experiment [5]. Briefly, 2–3 cm sections of carotid artery were harvested from 20-day-old Dover lambs, which would be survived for the subsequent aortic replacement operation. Under sterile condition, the carotid arteries were minced into 1–2 mm pieces and cultured in Dulbecco’s Modified Eagle Medium (Gibco BRL–Life Technologies, Grand Island, NY) supplemented with 10% fetal bovine serum (Sigma Chemical Co, St. Louis, MO) and 1% antibiotic solution (10,000 units/mL penicillin G sodium, 10 g/mL streptomycin, and 25 µg/mL amphotericin (Sigma Chemical Co). The culture media were changed every 7 days and placed in a humidified incubator maintained at 37°C with 5% carbon dioxide for 6 to 8 weeks. During this period of time, cells typically migrated off the explants to form mixed cell populations of endothelial cells, smooth muscle cells and fibroblasts. Once the cultured cells became confluent in vitro, 8 to 10 million mixed cells were seeded onto the luminal surface of the polymer tube at 7 days prior to implantation. This number was usually sufficient for the seeded cells to become attached and confluent on the polymer surface. In contrast to our previous method, this mixed cell population of endothelial cells, smooth muscle cells, and fibroblasts were seeded directly onto the polymer without cell sorting and staged seeding. This approach minimized the risk of potential cell culture infection.

Scaffold design
The polymeric scaffold consisted of two components which were fashioned into a tubular conduit (4 cm long x 7 mm internal diameter [ID]). The inner layer was made of randomly arrayed fibers of nonwoven PGA mesh (Albany International Research Co, Mansfield, MA). This mesh matrix was adopted from the first generation polymer which had a density of 70.0 mg/cm³ and was greater than 95% porous before seeding. This inner layer created a three-dimensional matrix for cell attachment and growth which served as a cell delivery system and a template to provide structural cues which could direct tissue development. The PGA layer was designed to degrade by hydrolysis over a 6 to 8 week period. The outer part of the conduit was made of three layers of nonporous polyhydroxyoctanoate (PHO) which is a member of the biodegradable polyhydroxyalkanoates (PHA) polymer family (Metabolix Inc, Cambridge, MA) [6, 7]. Polyhydroxyoctanoate is a natural, linear polyester produced by controlled fermentation process. The polymer contains (R)-3-hydroxyoctanoic acid copolymerized with 10% of (R)-3-hydroxyhexanoic acid and has a melting and glass transition temperatures of 50° to 60°C and -35°C, respectively. The polymer has a high tensile set of 35% after 100% elongation. The acellular PGA-PHA composite was less than 1.5 mm in wall thickness and completely impermeable to fluid. The PHA layer provides the temporary biomechanical characteristics of the tubular scaffold as the cells lay down their own extracellular matrix on the PGA surface, which ultimately takes over the structural integrity and biomechanical profile of the engineered tissue.

Infrarenal aortic replacement
Seven days after cell seeding onto the conduit was performed, the lambs from which the cells were originally harvested underwent reoperation for infrarenal aortic replacement (mean weight, 15.7 ± 2.7 kg, mean age, 81.3 ± 8.3 days). Four lambs were randomized into a control group (group C) and 7 into tissue-engineered group (group TE). Acellular tubular conduits treated similarly to those of the group TE were used to replace the aorta in the control animals.

All lambs were premedicated with 30 mg/kg of intramuscular ketamine, intubated, and mechanically ventilated. General anesthesia was maintained with continuous infusion of diprivan at 0.2 mg/kg/min (Stuart Pharmaceuticals, Wilmington, DE) throughout the operative procedure. The vital signs were monitored with an arterial line through a superficial femoral arterial side branch. The animal was positioned in right decubitus fashion, shaved, prepared with proviodine, and sterilely draped. A longitudinal left flank incision was made lateral to the paraspinal muscle. A plane was developed anterior to the spinal process without entering the peritoneum. Once the abdominal aorta was identified, it was dissected free from the surrounding tissue proximally up to the renal arteries and distally to the iliac bifurcation. Care was taken to preserve all the spinal branches above and below the segment of aortic replacement. An intravenous bolus of heparin (100 IU/kg) was given. Once the core temperature reached 35°C, aortic cross-clamp was applied immediately below the renal arteries and above the iliac bifurcation. The abdominal aorta was then resected and replaced with a 3-cm to 4-cm tissue-engineered (TE) PGA-PHA conduit. The anastomoses were carried out with continuous 7-0 prolene sutures. No anticoagulation was given postoperatively. After the surgical procedure was completed, the animal was extubated and resumed normal activities. Postoperatively, palpation of femoral pulses and/or Doppler evaluation of femoral artery flow were carried out daily for 2 weeks, weekly for 1 month, and then monthly until the predetermined date of euthanasia. All animals were sacrificed either at the time of conduit occlusion or at about 10 days (n = 1 in group TE), 3 months (n = 3 in group TE), or 5 months (n = 3 in group TE).

All animals received humane care in compliance with the "Guide for the Care and Use of Laboratory Animals" published by the National Institutes of Health (NIH publication no. 85-23, revised 1985).

Evaluation of tissue-engineered autografts
Imaging studies
The graft patency was confirmed by periodic Doppler ultrasound (Model 128 xp10, Acuson Corp, Mountain View, CA), which was performed at 7 days postoperatively, then every 3 to 4 weeks until sacrifice. Angiographic assessment was also performed in an experimental group of TE animal 5 months postoperatively and one control lamb prior to sacrifice.

Structural and ultrastructural studies
After the animal was sacrificed, the graft was explanted, opened longitudinally, examined macroscopically, and photographed. A portion of the aortic explant was fixed with 10% formalin for histologic evaluation with hematoxylin-eosin and Miller’s elastic stain. Another portion was immersed in 0.9% saline solution to determine cell density in the TE conduit using a deoxyribonucleic acid (DNA) assay and to measure collagen content using 4-hydroxyproline assay. An additional section of the conduit was also stained for endothelial specific von Willebrand factor (VWF) using immunohistochemical technique (Bio-Genes, San Ramon, CA). A representative segment of the TE aortic graft was fixed with 2.5% purified glutaraldehyde in 0.1 mol/L cacodylate-hydrochloride-buffered glutaraldehyde and postfixed in 1% osmium tetroxide buffered with 0.1% cacodylate and stained en bloc in tannic acid. The specimens were then dehydrated in graded alcohols and embedded in epoxy resin and examined by transmission electron microscopy (Philips 300; Philips Medical Systems North America, Shelton, CT).

Matrix metalloproteinase (MMP) assay
Samples from control, TE and, native aortic explants were immersed in cold phosphate-buffer-solution and stored frozen (-20°C) until assay. The presence of MMP was determined by a substrate gel electrophoresis (zymography) using a sodium dodecyl sulfate (SDS)-polyacrylamide gel copolymerized with gelatin according to the method of Moses and colleagues [8].

Biomechanical testing
The mechanical strain-stress characteristics of the polymer, native aorta as well as the TE conduit at 3 and 5 months postimplantation were profiled by a Vitrodyne V-1000 mechanical tester (Lifeco Inc, Burlington, VT).

Statistical analysis
All quantitative results of the structural analysis (collagen content, DNA assay) were expressed as percent of the native aorta and analyzed by unpaired 2-tailed Student’s t-test. A p value less than 0.05 was considered statistically significant.

	Results

Top Abstract Introduction Material and methods Results Comment References

 
Imaging studies
The four control conduits became occluded at 1, 2, 55, and 101 days, respectively. The two early occlusions were manifested by sudden lower limb paralysis, whereas the later two occluded grafts were demonstrated by Doppler ultrasound and angiography. These 2 animals did not manifest any neurological deficit, because of the development of large collaterals. All TE grafts were patent and no aneurysms were identified at the time of predetermined sacrifice (n = 1 at 10 days, n = 3 at 84 days ± 4, n = 3 at 150 days ± 13) (Fig 1). One animal developed mild stenosis at the proximal anastomotic site.

View larger version (64K): [in this window] [in a new window]   Fig 1. Echographic appearance of a tissue-engineered aorta.

View larger version (65K): [in this window] [in a new window]   Fig 2. (A) Two control explants thrombosed acutely (1 and 2 days) and marked by a fresh clot within the lumen (top). Two other control aorta occluded at 55 and 101 days. Note the lack of tissue formation within the polymer (bottom). (B) Tissue formation was visible 10 days after implantation (top). All tissue-engineered conduits were patent at 3 and 5 months postoperatively with one developing mild stenosis in the proximal anastomosis (bottom).

View larger version (103K): [in this window] [in a new window]   Fig 3. (A) Structural appearance of tissue-engineered and native aorta (hematoxylin-eosin, original magnification x 100). (B) Miller’s elastic staining confirmed the presence of elastic and collagen fibers in the constructed and native aorta (original magnification x 200).

Biochemical evaluation
The 4-hydroxyproline assay suggested that the collagen content significantly increased from 3 to 5 months period in the TE group. The percent collagen approached that of native aorta at 5 months after implantation (Fig 4).

View larger version (15K): [in this window] [in a new window]   Fig 4. The percent 4-hydroxyproline assay increased significantly from 3 to 5 months in the tissue-engineered explants (*p < 0.05).

View larger version (14K): [in this window] [in a new window]   Fig 5. The percent DNA content in the tissue-engineered conduits increased significantly over time from 3 to 5 months (*p < 0.05).

View larger version (103K): [in this window] [in a new window]   Fig 6. Electron microscopy identified cellular structures in the tissue-engineered arterial wall and their orientation paralleled the blood flow (original magnification x 750).

View larger version (40K): [in this window] [in a new window]   Fig 7. The substrate gel electrophoresis confirmed the presence of 66 kDa MMP-2 in the tissue-engineered and native aorta but not in the control group.

View larger version (18K): [in this window] [in a new window]   Fig 8. The strain-stress curve of the tissue-engineered grafts changed and resembled the native aorta over time.

	Comment

Top Abstract Introduction Material and methods Results Comment References

Over the past few years, we have successfully created autologous pulmonary valve leaflet and pulmonary artery using the methods and principles of TE. With this approach, we believe that it is important to use biomaterials that are not simply biocompatible and act as a static replacement, but rather have the ability to elicit a desirable cellular response and encourage the formation of tissue which can grow and repair. We have previously documented that the use of a biodegradable polyglactin-PGA copolymer (which is the basic material for absorbable suture materials used clinically) could be used to create a three-dimensional scaffold upon which cells could organize themselves into "tissues" which could then serve as replacements for valve leaflets and conduits. However, the limitations of the polyglactin-PGA composite polymer included high porosity, stiffness, and a relatively short degradation time. Thus far, all successful experiments with this scaffold design have been carried out in the low pressure pulmonary circulation [1–3]. When we attempted to use this polymer scaffold to create a TE graft for the systemic circulation, development of aneurysms was found after a few weeks. The current study evaluates a new composite polymer using a similar PGA inner layer, which has been shown to promote cell attachment and tissue formation, with an outer PHA layer. The PHA is a biocompatible thermoplastic material made by various microorganisms, and it is degraded by simple hydrolysis over longer periods of time (> 52 weeks) than the polyglactin. The PHA-PGA composite graft had superior tensile strength, flexibility, ease of handling and suturing. We hypothesized that the in vivo tolerance and degradation time would make it suitable for aortic substitution.

Morphological examination demonstrated no early thrombosis in any of the TE grafts and tissue formation was noted as early as 10 days after implantation. With the exception of one stricture, all specimens remained patent and functional without aneurysm or infection during the period of observation. Histological analysis revealed insignificant evidence of inflammatory reaction to these polymeric materials. Instead, increased cell density and collagen formation associated with changes in mechanical properties suggested that favorable biological events are ongoing within the graft maintained by the polymeric scaffold. The presence of MMP-2 family of gelatinases further supports this hypothesis and suggests that at least one of the key enzymes involved in the balance of matrix formation and degradation existed in the native and TE arteries. The cells in the TE structure have the capacity to generate collagen, elastic fibers, and von-Willebrand factor, and the TE grafts developed a mechanical profile which approached that of native aorta. The presence of endothelium (VWF positive cells) likely contributed to the lack of thrombosis. In addition, the metabolic activities tended to increase significantly over time. Although the maturation period has not been determined, there has been suggestion in a long-term animal model of small diameter vascular implants that progressive thickening of the inner capsules with myofibroblasts and collagen stabilized after 3 to 4 months [15, 16].

The importance of cell seeding of the polymer prior to implantation has also been confirmed by the current study. The acellular nonwoven PGA mesh is generally very thrombogenic as was demonstrated by the previous pulmonary artery experiment in which a progressive organized thrombus formation was identified in the control conduit at 2 weeks postimplantation [3]. The two acutely paralyzed control animals in this study had received acellular conduits and examination of the conduits also showed fresh thrombus within the lumen of these conduits. The other control animals developed graft occlusion at a later date, and these conduits had a complete occlusion at the proximal anastomotic sites with minimal tissue formation within the conduit. The tissue that did form was very thin and loose and seemed unlikely to be able to maintain its integrity under systemic pressure. This finding was contrary to that reported by Greisler and associates who replaced rabbit aorta with absorbable (3.5 mm ID x 24 mm in length) cell-free prostheses [16, 17]. The authors were able to demonstrate the generation of endothelialized vessels containing smooth muscle-like myofibroblasts and dense fibrous tissue, without thrombosis or infection. However, 11% of the grafts in this report developed some degree of dilatation [17]. The tissue genesis was hypothesized to be attributed to transanastomotic cell migration, transinterstitial ingrowth, capillary infiltration, and endothelialization from circulating cells. Our previous studies with valvular leaflet and pulmonary artery together with the current aortic replacement failed to reproduce such results using acellular polymers in an ovine model. There are clear differences in animal species, polymeric design, wall stress (pressure x diameter) and length of vessel replaced which could account for the difference in results. The use of cell tracing techniques will provide the information regarding the cell sources in these TE aortic grafts.

While it remains very possible that recipient cell migration from native aorta onto the polymer and circulating endothelial cells may contribute to the formation of tissue [16, 17], our previous and current studies strongly suggest that most of the cells in the TE structures remained from in vitro seeding. Without cell seeding, none of the plain acellular scaffolds remained patent. In addition, the combined single-staged seeding of mixed endothelial cells, smooth muscle cells, and fibroblasts resulted in the formation of a TE conduit that resembled native aorta with a properly oriented von Willebrand stained thromboresistant endothelial cell layer in the luminal surface. Similar to the native aorta, the elastic and collagen fibers seemed to organize uniformly according to the direction of blood flow despite random cell seeding in vitro. Previous studies have suggested that a variety of adaptation processes in terms of structure and function could be affected by the environmental conditions to which the cells were exposed [18, 19]. In the presence of steady-state laminar flow, for example, vascular endothelial cells elongate in shape and align their major axis with the direction of flow. Pulsatile flow equally introduced similar but quantitatively different alternations in cell culture.

Autologous aortic conduits with biological characteristics resembling native aorta can be created using TE approach. These early results with TE aorta and the newly improved biodegradable polymer appear promising and may have the potential to improve the current management of patients who require vascular substitutes. Further manipulations of the PHA surface characteristics, and components are underway in our laboratory to simplify the current copolymer design, to optimize the cell attachment, degradation time, and to evaluate longer-term patency. We remain hopeful that these efforts may lead to the ultimate goal of creating a "live" vascular graft suitable for clinical application.

	Acknowledgments

 
The authors acknowledge the assistance of Karen Hodgens, BSc in the preparation of electron microscopic materials, and Lucy D’Onofrio and Susan Boissonneault for the assistance in preparing the manuscript.

	References

Top Abstract Introduction Material and methods Results Comment References

 

1. Shinoka T., Ma P.X., Shum-Tim D., et al. Tissue-engineered heart valves. Circulation 1996;94(Suppl II):II164-II168.
2. Shinoka T., Shum-Tim D., Ma P.X., et al. Tissue-engineered heart valve leaflets. Circulation 1997;96(Suppl II):II102-II107.
3. Shinoka T., Shum-Tim D., Ma P.X., et al. Creation of viable pulmonary artery autografts through tissue engineering. J Thorac Cardiovasc Surg 1998;115:536-546.[Abstract/Free Full Text]
4. Ma P.X., Langer R. Degradation structure and properties of fibrous non-woven poly (glycolic acid) scaffolds for tissue engineering. In: Mikos A.G., Leong K.W., Radomsky M.L., Tamada J.A., Yaszemski M.J., eds. . Polymers in medicine and pharmacy. Pittsburgh: Materials Research Society, 1995:99-104.
5. Breuer C.K., Shinoka T., Tanel R.E., et al. Tissue engineering lamb heart valve leaflets. Biotech Bioeng 1996;50:562-567.
6. Williams S.F., Peoples O.P. Biodegradable plastics from plants. Chemtech 1996;9:38-44.
7. Williams S.F., Peoples O.P. Making plastics green. Chemistry in Britain 1997;33:29-32.
8. Moses M.A., Wiederschain D., Loughlin K.R., Zurakowski D., Lamb C.C., Freeman M.R. Increased incidence of matrix metalloproteinases in urine of cancer patients. Cancer Research 1998;58:1395-1399.[Abstract/Free Full Text]
9. Ritter E.F., Fata M.M., Rudner A.M., Klitzman B. Heparin bonding increases patency of long microvascular prostheses. Plastic & Reconstructive Surgery 1998;101:142-146.[Medline]
10. Stanley J.C., Burkel W.E., Ford J.W., et al. Enhanced patency of small-diameter, externally supported Dacron iliofemoral grafts seeded with endothelial cells. Surg 1982;92:994-1005.
11. Greisler H.P., Gosselin C., Ren D., Kang S.S., Kim D.U. Biointeractive polymers and tissue engineered blood vessels. Biomaterials 1996;17:329-336.[Medline]
12. Dardik H., Dardik I.I. Successful arterial substitution with modified human umbilical vein. Ann Surg 1976;183:252-258.[Medline]
13. Dardik H., Miller N., Dardik A., et al. A decade of experience with the glutaraldehyde-tanned human umbilical cord vein graft for revascularization of the lower limb. J Vasc Surg 1988;7:336-346.[Medline]
14. Jones L., Braithwaite B.D., Davies B., Heather B.P., Earnshaw J.J. Mechanism of late prosthetic vascular graft infection. Cardiovasc Surg 1997;5:486-489.[Medline]
15. Greisler H.P., Tattersall C.W., Henderson S.C., Cabusao E.A. Polypropylene small-diameter vascular grafts. J Biomed Mater Res 1992;26:1383-1394.[Medline]
16. Greisler H.P., Ellinger J., Schwarcz T.H., Golan J., Raymond R.M., Kim D.U. Arterial regeneration over polydioxanone prostheses in the rabbit. Arch Surg 1987;122:715-721.[Abstract/Free Full Text]
17. Greisler H.P. Arterial regeneration over absorbable prostheses. Arch Surg 1982;117:1425-1431.[Abstract/Free Full Text]
18. Levesque M.J., Sprague E.A., Schwartz C.J., Nerem R.M. The influence of shear stress on cultured vascular endothelial cells. Biotech Prog 1989;5:1-8.
19. Nerem R.M., Girard P.R. Hemodynamic influences on vascular endothelial biology. Toxicol Pathol 1990;18:572-582.[Medline]

This article has been cited by other articles:

				H. Takahashi, T. Yokota, E. Uchimura, S. Miyagawa, T. Ota, K. Torikai, A. Saito, K. Hirakawa, K. Kitabayashi, K. Okada, et al. Newly developed tissue-engineered material for reconstruction of vascular wall without cell seeding. Ann. Thorac. Surg., October 1, 2009; 88(4): 1269 - 1276. [Abstract] [Full Text] [PDF]

				G. N. Nelson, T. Mirensky, M. P. Brennan, J. D. Roh, T. Yi, Y. Wang, and C. K. Breuer Functional Small-Diameter Human Tissue-Engineered Arterial Grafts in an Immunodeficient Mouse Model: Preliminary Findings Arch Surg, May 1, 2008; 143(5): 488 - 494. [Abstract] [Full Text] [PDF]

				Y. Ikada Challenges in tissue engineering J R Soc Interface, October 22, 2006; 3(10): 589 - 601. [Abstract] [Full Text] [PDF]

				S. P. Hoerstrup, I. Cummings MRCS, M. Lachat, F. J. Schoen, R. Jenni, S. Leschka, S. Neuenschwander, D. Schmidt, A. Mol, C. Gunter, et al. Functional Growth in Tissue-Engineered Living, Vascular Grafts: Follow-Up at 100 Weeks in a Large Animal Model Circulation, July 4, 2006; 114(1_suppl): I-159 - I-166. [Abstract] [Full Text] [PDF]

				A. Patel, B. Fine, M. Sandig, and K. Mequanint Elastin biosynthesis: The missing link in tissue-engineered blood vessels Cardiovasc Res, July 1, 2006; 71(1): 40 - 49. [Abstract] [Full Text] [PDF]

				B. C. Isenberg, C. Williams, and R. T. Tranquillo Small-Diameter Artificial Arteries Engineered In Vitro Circ. Res., January 6, 2006; 98(1): 25 - 35. [Abstract] [Full Text] [PDF]

				J. P. Stegemann, H. Hong, and R. M. Nerem Mechanical, biochemical, and extracellular matrix effects on vascular smooth muscle cell phenotype J Appl Physiol, June 1, 2005; 98(6): 2321 - 2327. [Abstract] [Full Text] [PDF]

				M. R. Hoenig, G. R. Campbell, B. E. Rolfe, and J. H. Campbell Tissue-Engineered Blood Vessels: Alternative to Autologous Grafts? Arterioscler Thromb Vasc Biol, June 1, 2005; 25(6): 1128 - 1134. [Abstract] [Full Text] [PDF]

				F. Opitz, K. Schenke-Layland, T. U Cohnert, B. Starcher, K. J. Halbhuber, D. P Martin, and U. A Stock Tissue engineering of aortic tissue: dire consequence of suboptimal elastic fiber synthesis in vivo Cardiovasc Res, September 1, 2004; 63(4): 719 - 730. [Abstract] [Full Text] [PDF]

				A. Kadner, G. Zund, C. Maurus, C. Breymann, S. Yakarisik, G. Kadner, M. Turina, and S. P. Hoerstrup Human umbilical cord cells for cardiovascular tissue engineering: a comparative study Eur. J. Cardiothorac. Surg., April 1, 2004; 25(4): 635 - 641. [Abstract] [Full Text] [PDF]

				C. A. Thompson, B. A. Nasseri, J. Makower, S. Houser, M. McGarry, T. Lamson, I. Pomerantseva, J. Y. Chang, H. K. Gold, J. P. Vacanti, et al. Percutaneous transvenous cellular cardiomyoplasty: A novel nonsurgical approach for myocardial cell transplantation J. Am. Coll. Cardiol., June 4, 2003; 41(11): 1964 - 1971. [Abstract] [Full Text] [PDF]

				A. Kadner, S. P. Hoerstrup, J. Tracy, C. Breymann, C. F. Maurus, S. Melnitchouk, G. Kadner, G. Zund, and M. Turina Human umbilical cord cells: a new cell source for cardiovascular tissue engineering Ann. Thorac. Surg., October 1, 2002; 74(4): S1422 - 1428. [Abstract] [Full Text] [PDF]

				S. P. Hoerstrup, A. Kadner, C. Breymann, C. F. Maurus, C. I. Guenter, R. Sodian, J. F. Visjager, G. Zund, and M. I. Turina Living, autologous pulmonary artery conduits tissue engineered from human umbilical cord cells Ann. Thorac. Surg., July 1, 2002; 74(1): 46 - 52. [Abstract] [Full Text] [PDF]

				C. Jux, H. Bertram, P. Wohlsein, M. Brugmann, P. Wuboldt, C. Fink, T. Paul, and G. Hausdorf Experimental ASD closure using autologous cell-seeded interventional closure devices Cardiovasc Res, January 1, 2002; 53(1): 181 - 191. [Abstract] [Full Text] [PDF]

				J. R. Fuchs, B. A. Nasseri, and J. P. Vacanti Tissue engineering: a 21st century solution to surgical reconstruction Ann. Thorac. Surg., August 1, 2001; 72(2): 577 - 591. [Abstract] [Full Text] [PDF]

				U. A. Stock, M. Nagashima, P. N. Khalil, G. D. Nollert, T. Herden, J. S. Sperling, A. Moran, J. Lien, D. P. Martin, F. J. Schoen, et al. TISSUE-ENGINEERED VALVED CONDUITS IN THE PULMONARY CIRCULATION J. Thorac. Cardiovasc. Surg., April 1, 2000; 119(4): 732 - 740. [Abstract] [Full Text] [PDF]

This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Dominique Shum-Tim John E. Mayer, Jr Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Shum-Tim, D. Articles by Mayer, J. E. Search for Related Content PubMed PubMed Citation Articles by Shum-Tim, D. Articles by Mayer, J. E., Jr Related Collections Related Article