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Abstract
The vascular endothelium resides in a unique biomechanical stress environment resulting from the hemodynamics of the system. In vivo studies indicate that there are regional differences in endothelial biology and that this may be due to the influence of the local hemodynamic environment. To investigate this further, cell culture studies have been conducted using well-defined mechanical stress environments. To study flow effects, we have employed a parallel plate chamber in which endothelial cell monolayers are exposed to laminar flow. In such experiments and concomitant with changes in morphology, there are a variety of other alterations in cell function, including a decrease in the rate of cell proliferation for subconfluent monolayers. Changes in cell behavior due to the direct effect of pressure and in cultured cells which are in a cyclical stress field also have been observed. In the recognition/transduction of such a mechanical signal, the pathway may possibly include a membrane event linked to the control of intracellular calcium. It may be that the same signaling mechanisms are involved both in cytoskeletal/shape changes and in the control of the cell's growth program and, in exercising such an influence, hemodynamics may have an important role in the response of the arterial wall to injury and the resulting repair and/or disease processes.
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Affiliation(s)
- Robert M. Nerem
- School of Mechanical Engineering and Biomechanics Laboratory, Georgia Institute of Technology, Atlanta, Georgia 30332-0405
| | - Peggy R. Girard
- School of Mechanical Engineering and Biomechanics Laboratory, Georgia Institute of Technology, Atlanta, Georgia 30332-0405
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Esmerats JF, Villa-Roel N, Kumar S, Gu L, Salim MT, Ohh M, Taylor WR, Nerem RM, Yoganathan AP, Jo H. Disturbed Flow Increases UBE2C (Ubiquitin E2 Ligase C) via Loss of miR-483-3p, Inducing Aortic Valve Calcification by the pVHL (von Hippel-Lindau Protein) and HIF-1α (Hypoxia-Inducible Factor-1α) Pathway in Endothelial Cells. Arterioscler Thromb Vasc Biol 2019; 39:467-481. [PMID: 30602302 PMCID: PMC6393167 DOI: 10.1161/atvbaha.118.312233] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Objective- Calcific aortic valve (AV) disease, characterized by AV sclerosis and calcification, is a major cause of death in the aging population; however, there are no effective medical therapies other than valve replacement. AV calcification preferentially occurs on the fibrosa side, exposed to disturbed flow (d-flow), whereas the ventricularis side exposed to predominantly stable flow remains protected by unclear mechanisms. Here, we tested the role of novel flow-sensitive UBE2C (ubiquitin E2 ligase C) and microRNA-483-3p (miR-483) in flow-dependent AV endothelial function and AV calcification. Approach and Results- Human AV endothelial cells and fresh porcine AV leaflets were exposed to stable flow or d-flow. We found that UBE2C was upregulated by d-flow in human AV endothelial cells in the miR-483-dependent manner. UBE2C mediated OS-induced endothelial inflammation and endothelial-mesenchymal transition by increasing the HIF-1α (hypoxia-inducible factor-1α) level. UBE2C increased HIF-1α by ubiquitinating and degrading its upstream regulator pVHL (von Hippel-Lindau protein). These in vitro findings were corroborated by immunostaining studies using diseased human AV leaflets. In addition, we found that reduction of miR-483 by d-flow led to increased UBE2C expression in human AV endothelial cells. The miR-483 mimic protected against endothelial inflammation and endothelial-mesenchymal transition in human AV endothelial cells and calcification of porcine AV leaflets by downregulating UBE2C. Moreover, treatment with the HIF-1α inhibitor (PX478) significantly reduced porcine AV calcification in static and d-flow conditions. Conclusions- These results suggest that miR-483 and UBE2C and pVHL are novel flow-sensitive anti- and pro-calcific AV disease molecules, respectively, that regulate the HIF-1α pathway in AV. The miR-483 mimic and HIF-1α pathway inhibitors may serve as potential therapeutics of calcific AV disease.
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Affiliation(s)
- Joan Fernandez Esmerats
- Wallace H. Coulter Department of Biomedical Engineering at Georgia Institute of Technology and Emory University
| | - Nicolas Villa-Roel
- Wallace H. Coulter Department of Biomedical Engineering at Georgia Institute of Technology and Emory University
| | - Sandeep Kumar
- Wallace H. Coulter Department of Biomedical Engineering at Georgia Institute of Technology and Emory University
| | - Lina Gu
- Wallace H. Coulter Department of Biomedical Engineering at Georgia Institute of Technology and Emory University
| | - Md Tausif Salim
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology
| | - Michael Ohh
- Department of Biochemistry, Faculty of Medicine, University of Toronto, Toronto, CA
| | - W. Robert Taylor
- Wallace H. Coulter Department of Biomedical Engineering at Georgia Institute of Technology and Emory University
- Division of Cardiology, Department of Medicine, Emory University
| | - Robert M. Nerem
- Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology. Atlanta, GA, USA
| | - Ajit P. Yoganathan
- Wallace H. Coulter Department of Biomedical Engineering at Georgia Institute of Technology and Emory University
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology
| | - Hanjoong Jo
- Wallace H. Coulter Department of Biomedical Engineering at Georgia Institute of Technology and Emory University
- Division of Cardiology, Department of Medicine, Emory University
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Kamm RD, Bashir R, Arora N, Dar RD, Gillette MU, Griffith LG, Kemp ML, Kinlaw K, Levin M, Martin AC, McDevitt TC, Nerem RM, Powers MJ, Saif TA, Sharpe J, Takayama S, Takeuchi S, Weiss R, Ye K, Yevick HG, Zaman MH. Perspective: The promise of multi-cellular engineered living systems. APL Bioeng 2018; 2:040901. [PMID: 31069321 PMCID: PMC6481725 DOI: 10.1063/1.5038337] [Citation(s) in RCA: 84] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Accepted: 09/18/2018] [Indexed: 12/31/2022] Open
Abstract
Recent technological breakthroughs in our ability to derive and differentiate induced pluripotent stem cells, organoid biology, organ-on-chip assays, and 3-D bioprinting have all contributed to a heightened interest in the design, assembly, and manufacture of living systems with a broad range of potential uses. This white paper summarizes the state of the emerging field of "multi-cellular engineered living systems," which are composed of interacting cell populations. Recent accomplishments are described, focusing on current and potential applications, as well as barriers to future advances, and the outlook for longer term benefits and potential ethical issues that need to be considered.
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Affiliation(s)
- Roger D. Kamm
- Massachusetts Institute of Technology, Boston, Massachusetts 02139, USA
| | - Rashid Bashir
- University of Illinois at Urbana-Champaign, Urbana, Illinois 61820, USA
| | - Natasha Arora
- Massachusetts Institute of Technology, Boston, Massachusetts 02139, USA
| | - Roy D. Dar
- University of Illinois at Urbana-Champaign, Urbana, Illinois 61820, USA
| | | | - Linda G. Griffith
- Massachusetts Institute of Technology, Boston, Massachusetts 02139, USA
| | - Melissa L. Kemp
- Georgia Institute of Technology, Atlanta, Georgia 30332, USA
| | | | | | - Adam C. Martin
- Massachusetts Institute of Technology, Boston, Massachusetts 02139, USA
| | | | - Robert M. Nerem
- Georgia Institute of Technology, Atlanta, Georgia 30332, USA
| | - Mark J. Powers
- Thermo Fisher Scientific, Frederick, Maryland 21704, USA
| | - Taher A. Saif
- University of Illinois at Urbana-Champaign, Urbana, Illinois 61820, USA
| | - James Sharpe
- EMBL Barcelona, European Molecular Biology Laboratory, Barcelona 08003, Spain
| | | | | | - Ron Weiss
- Massachusetts Institute of Technology, Boston, Massachusetts 02139, USA
| | - Kaiming Ye
- Binghamton University, Binghamton, New York 13902, USA
| | - Hannah G. Yevick
- Massachusetts Institute of Technology, Boston, Massachusetts 02139, USA
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Avent CM, Boyce AS, Servance LD, DeStefano LA, Nerem RM, Platt MO. Implementation of a Biomedical Engineering Research Experience for African-American High School Students at a Tier One Research University. J Biomech Eng 2018; 140:2682438. [PMID: 30003257 DOI: 10.1115/1.4040310] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Enriching science experiences and competencies for underrepresented students during high school years is crucial to increasing their entry into the science pipeline and to improving their preparedness for success in college and STEM careers. The purpose of this paper is to describe the implementation of project ENGAGES, a high school STEM year-long research program for African–American students, mentored by graduate students and postdoctoral researchers at Georgia Tech. It aims to provide an authentic research experience and expose student to the possibility and benefits of attaining an advanced degree and careers in STEM fields. Initial program outcomes include student reported satisfaction with research experience, improved technical skill development, and increased curiosity and interest in STEM careers. Additionally, students indicated increases in college readiness, research skill development, and exposure to STEM careers as a result of interactions with faculty advisors and graduate student mentors, along with laboratory assignments. Lessons learned and potential pitfalls and barriers to acceptance are also discussed.
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Affiliation(s)
- Cherie M. Avent
- Department of Educational Research Methodology, University of North Carolina Greensboro, 1300 Spring Garden Street, Greensboro, NC 27412 e-mail:
| | - Ayesha S. Boyce
- Department of Educational Research Methodology, University of North Carolina Greensboro, 1300 Spring Garden Street, Greensboro, NC 27412 e-mail:
| | - Lakeita D. Servance
- Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, 315 Ferst Drive, Atlanta, GA 30332 e-mail:
| | - Lizanne A. DeStefano
- Center for Education Integrating Science, Mathematics and Computing, Georgia Institute of Technology, 817 W. Peachtree Street, NW, Suite 300, Atlanta, GA 30308 e-mail:
| | - Robert M. Nerem
- Fellow ASME Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, 315 Ferst Drive, NW, Atlanta, GA 30332 e-mail:
| | - Manu O. Platt
- Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, 950 Atlantic Dr. Suite 3015, Atlanta, GA 30332 e-mail:
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Abstract
Stem cells and other functionally defined therapeutic cells (e.g., T cells) are promising to bring hope of a permanent cure for diseases and disorders that currently cannot be cured by conventional drugs or biological molecules. This paradigm shift in modern medicine of using cells as novel therapeutics can be realized only if suitable manufacturing technologies for large-scale, cost-effective, reproducible production of high-quality cells can be developed. Here we review the state of the art in therapeutic cell manufacturing, including cell purification and isolation, activation and differentiation, genetic modification, expansion, packaging, and preservation. We identify current challenges and discuss opportunities to overcome them such that cell therapies become highly effective, safe, and predictively reproducible while at the same time becoming affordable and widely available.
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Affiliation(s)
- Kyung-Ho Roh
- The Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory, Atlanta, Georgia 30332-0313; .,The Parker H. Petit Institute for Bioengineering and Biosciences, Georgia Institute of Technology, Atlanta, Georgia 30332
| | - Robert M Nerem
- The Parker H. Petit Institute for Bioengineering and Biosciences, Georgia Institute of Technology, Atlanta, Georgia 30332.,The George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332
| | - Krishnendu Roy
- The Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory, Atlanta, Georgia 30332-0313; .,The Parker H. Petit Institute for Bioengineering and Biosciences, Georgia Institute of Technology, Atlanta, Georgia 30332
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Affiliation(s)
- Marcia McNutt
- Marcia McNutt is president of the U.S. National Academy of Sciences, Washington, DC, and is the former Editor-in-Chief of Science
| | - Robert M. Nerem
- Robert M. Nerem is Institute Professor Emeritus at the Georgia Institute of Technology, Atlanta, GA, and chair of the NASEM Committee on the report Fostering Integrity in Research
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Rathan S, Ankeny CJ, Arjunon S, Ferdous Z, Kumar S, Fernandez Esmerats J, Heath JM, Nerem RM, Yoganathan AP, Jo H. Identification of side- and shear-dependent microRNAs regulating porcine aortic valve pathogenesis. Sci Rep 2016; 6:25397. [PMID: 27151744 PMCID: PMC4858741 DOI: 10.1038/srep25397] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Accepted: 04/05/2016] [Indexed: 02/06/2023] Open
Abstract
Aortic valve (AV) calcification is an inflammation driven process that occurs preferentially in the fibrosa. To explore the underlying mechanisms, we investigated if key microRNAs (miRNA) in the AV are differentially expressed due to disturbed blood flow (oscillatory shear (OS)) experienced by the fibrosa compared to the ventricularis. To identify the miRNAs involved, endothelial-enriched RNA was isolated from either side of healthy porcine AVs for microarray analysis. Validation using qPCR confirmed significantly higher expression of 7 miRNAs (miR-100, -130a, -181a/b, -199a-3p, -199a-5p, and -214) in the fibrosa versus the ventricularis. Upon bioinformatics analysis, miR-214 was selected for further investigation using porcine AV leaflets in an ex vivo shear system. Fibrosa and ventricularis sides were exposed to either oscillatory or unidirectional pulsatile shear for 2 days and 3 & 7 days in regular and osteogenic media, respectively. Higher expression of miR-214, increased thickness of the fibrosa, and calcification was observed when the fibrosa was exposed to OS compared to the ventricularis. Silencing of miR-214 by anti-miR-214 in whole AV leaflets with the fibrosa exposed to OS significantly increased the protein expression of TGFβ1 and moderately increased collagen content but did not affect AV calcification. Thus, miR-214 is identified as a side- and shear-dependent miRNA that regulates key mechanosensitive gene in AV such as TGFβ1.
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Affiliation(s)
- Swetha Rathan
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA, USA
| | - Casey J Ankeny
- School of Biological and Health Systems Engineering, Arizona State University, Tempe, AZ, USA
| | - Sivakkumar Arjunon
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
| | - Zannatul Ferdous
- Mechanical, Aerospace and Biomedical Engineering, University of Tennessee Knoxville, TN, USA
| | - Sandeep Kumar
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
| | - Joan Fernandez Esmerats
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
| | - Jack M Heath
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
| | - Robert M Nerem
- Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA, USA
| | - Ajit P Yoganathan
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA, USA.,The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
| | - Hanjoong Jo
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
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9
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Abstract
The inclusion of engineering ideas and approaches makes medicine a quantitative and systems-based discipline that facilitates precision diagnostics and therapeutics to improve health care delivery for all.
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Affiliation(s)
- Shu Chien
- Department of Bioengineering, University of California, San Diego, CA 92037, USA.
| | - Rashid Bashir
- Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Robert M Nerem
- Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Roderic Pettigrew
- National Institute of Biomedical Imaging and Bioengineering (NIBIB), National Institutes of Health, Bethesda, MD 20892, USA
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Jo H, Hong M, Shim JB, Ankeny RF, Kim H, Nerem RM, Khang G. The role of demineralized bone particle in a PLGA scaffold designed to create a media equivalent for a tissue engineered blood vessel. Macromol Res 2015. [DOI: 10.1007/s13233-015-3138-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Alberts B, Cicerone RJ, Fienberg SE, Kamb A, McNutt M, Nerem RM, Schekman R, Shiffrin R, Stodden V, Suresh S, Zuber MT, Pope BK, Jamieson KH. SCIENTIFIC INTEGRITY. Self-correction in science at work. Science 2015; 348:1420-2. [PMID: 26113701 DOI: 10.1126/science.aab3847] [Citation(s) in RCA: 88] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
| | | | | | | | - Marcia McNutt
- Science, American Association for the Advancement of Science, Washington, DC, USA.
| | | | - Randy Schekman
- Howard Hughes Medical Institute and University of California, Berkeley, CA, USA
| | | | | | | | - Maria T Zuber
- Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Barbara Kline Pope
- National Academies Press, National Academy of Sciences, National Academy of Engineering, Institute of Medicine, National Research Council, Washington, DC, USA
| | - Kathleen Hall Jamieson
- Annenberg Retreat at Sunnylands, Rancho Mirage, CA, USA. Annenberg Public Policy Center, University of Pennsylvania, Philadelphia, PA, USA
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Shim JB, Ankeny RF, Kim H, Nerem RM, Khang G. A study of a three-dimensional PLGA sponge containing natural polymers co-cultured with endothelial and mesenchymal stem cells as a tissue engineering scaffold. Biomed Mater 2014; 9:045015. [PMID: 25065725 DOI: 10.1088/1748-6041/9/4/045015] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The interaction between vascular endothelial cells (ECs) and vascular smooth muscle cells (VSMCs) in a complex hemodynamic and mechanical environment plays an important role in the control of blood vessel growth and function. Despite the importance of VSMCs, substitutes are needed for vascular therapies. A potential VSMC substitute is human adult bone marrow derived mesenchymal stem cells (hMSCs). In this study, the effect of poly(lactic-co-glycolic acid) (PLGA) scaffolds containing three natural polymers (demineralized bone particles, silk, and small intestine submucosa) on the phenotype of MSCs and SMCs cultured with or without ECs was investigated. The study objective was to create a media equivalent for a tissue engineered blood vessel using PLGA, natural polymers, and MSCs co-cultured with ECs. The PLGA containing the natural polymers silk and SIS showed increased proliferation and cell adhesion. The presence of silk and DBP promoted a MSC phenotype change into a SMC-like phenotype at the mRNA level; however these differences at the protein level were not seen. Additionally, PLGA containing SIS did not induce SMC gene or protein upregulation. Finally, the effect of ECs in combination with the natural polymers was tested. When co-cultured with ECs, the mRNA of SMC specific markers in MSCs and SMCs were increased when compared to SMCs or MSCs alone. However, MSCs, when co-cultured with ECs on PLGA containing silk, exhibited significantly increased α-SMA and calponin expression when compared to PLGA only scaffolds. These results indicate that the natural polymer silk in combination with the co-culture of endothelial cells was most effective at increasing cell viability and inducing a SMC-like phenotype at the mRNA and protein level in MSCs.
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Affiliation(s)
- Jung Bo Shim
- Department of BIN Fusion Technology & Polymer Fusion Research Center, Chonbuk National University, Jeonju, Republic of Korea
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Affiliation(s)
- Kevin E Healy
- Kevin E. Healy is the Jan Fandrianto Distinguished Chair, Department of Bioengineering, University of California at Berkeley, Berkeley, CA 94720, USA
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Mow VC, Butler DL, Nerem RM. A brief history of USNCB: motivation and formation. J Biomech Eng 2014; 136:060301. [PMID: 24687029 DOI: 10.1115/1.4027332] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2014] [Accepted: 03/28/2014] [Indexed: 11/08/2022]
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Affiliation(s)
- Robert M Nerem
- Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology , Atlanta, Georgia
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Abstract
Over the last 2 years a global assessment of stem cell engineering (SCE) was conducted with the sponsorship of the National Science Foundation, the National Cancer Institute at the National Institutes of Health, and the National Institute of Standards and Technology. The purpose was to gather information on the worldwide status and trends in SCE, that is, the involvement of engineers and engineering approaches in the stem cell field, both in basic research and in the translation of research into clinical applications and commercial products. The study was facilitated and managed by the World Technology Evaluation Center. The process involved site visits in both Asia and Europe, and it also included several different workshops. From this assessment, the panel concluded that there needs to be an increased role for engineers and the engineering approach. This will provide a foundation for the generation of new markets and future economic growth. To do this will require an increased investment in engineering, applied research, and commercialization as it relates to stem cell research and technology. It also will require programs that support interdisciplinary teams, new innovative mechanisms for academic-industry partnerships, and unique translational models. In addition, the global community would benefit from forming strategic partnerships between countries that can leverage existing and emerging strengths in different institutions. To implement such partnerships will require multinational grant programs with appropriate review mechanisms.
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Affiliation(s)
- Jeanne F Loring
- 1 Director, Center for Regenerative Medicine, the Scripps Research Institute , LaJolla, California
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Bao G, Nerem RM. Frontiers in bioengineering research. Ann Biomed Eng 2014; 42:241-2. [PMID: 24510229 DOI: 10.1007/s10439-014-0982-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Gang Bao
- Robert A. Milton Chair in Biomedical Engineering, Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA,
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Nsiah BA, Ahsan T, Griffiths S, Cooke M, Nerem RM, McDevitt TC. Fluid shear stress pre-conditioning promotes endothelial morphogenesis of embryonic stem cells within embryoid bodies. Tissue Eng Part A 2014; 20:954-65. [PMID: 24138406 DOI: 10.1089/ten.tea.2013.0243] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Pluripotent embryonic stem cells (ESCs) are capable of differentiating into all mesoderm-derived cell lineages, including endothelial, hematopoietic, and cardiac cell types. Common strategies to direct mesoderm differentiation of ESCs rely on exposing the cells to a series of biochemical and biophysical cues at different stages of differentiation to promote maturation toward specific cell phenotypes. Shear forces that mimic cardiovascular physiological forces can evoke a myriad of responses in somatic and stem cell populations, and have, thus, been studied as a means to direct stem cell differentiation. However, elucidating the effects of shear pre-conditioning on the subsequent vascular differentiation and morphogenesis of ESCs has yet to be examined. In this study, ESC monolayers were subjected to physiological shear (5 dyn/cm(2)) or static conditions for 2 days on collagen IV-coated substrates before initiating embryoid body (EB) differentiation. Immediately after the pre-conditioning period, shear pre-conditioned and statically cultured ESCs exhibited similar morphologies and largely retained a pluripotent phenotype; however, ESCs exposed to fluid shear expressed increased levels of endothelial marker genes Flk-1 (∼3-fold), VE-cadherin (∼3-fold), and PECAM (∼2-fold), compared with statically cultured ESCs. After 7 days of EB culture, ∼70% of EBs formed from shear pre-conditioned ESCs expressed significantly higher levels of endothelial marker genes compared with EBs formed from statically cultured ESCs. Interestingly, unlike EBs formed from statically cultured ESCs, EBs formed from fluid shear stress pre-conditioned ESCs exhibited a centrally localized region of VE-cadherin(+) cells that persisted for at least 10 days of differentiation. These results demonstrate that fluid shear stress pre-conditioning not only promotes ESC endothelial gene expression but also subsequently impacts the organization of endothelial cells within EBs. Together, these studies highlight a novel approach to promote in vitro morphogenesis of developmental vasculogenic models and potentially promote pre-vascularization of tissue-engineered constructs derived from pluripotent stem cells.
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Affiliation(s)
- Barbara A Nsiah
- 1 George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology , Atlanta, Georgia
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Nerem RM. Stem Cell Engineering. Tissue Eng Part A 2014. [DOI: 10.1089/ten.fp2014.2013.0764] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Hong M, Jo H, Ankeny RF, Holliday-Ankeny CJ, Kim H, Khang G, Nerem RM. Influence of mesenchymal stem cells on the response of endothelial cells to laminar flow and shear stress. Cells Tissues Organs 2013; 198:289-99. [PMID: 24335258 DOI: 10.1159/000356319] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/08/2013] [Indexed: 11/19/2022] Open
Abstract
The interactions between endothelial cells (ECs) and smooth muscle cells (SMCs) in a complex hemodynamic environment play an important role in the control of blood vessel function. Since autologous SMCs are not readily available for the tissue engineering of a blood vessel substitute, a substitute for SMCs, such as human adult bone marrow-derived mesenchymal stem cells (MSCs), is needed. The objective of this study was to use a three-dimensional coculture model of the blood vessel wall, comprised of ECs and MSCs, to determine how the presence of MSCs affects EC function. Two vascular coculture models with an EC monolayer were created using type I collagen. All models were exposed to steady laminar flow with a shear stress of 15 dyn/cm(2) for up to 48 h. ECs in both the MSC and SMC coculture models expressed up-regulated EC-specific markers compared to the EC-only control model. The most dramatic difference observed between the two coculture models was in the experiments assessing monocyte adhesion. Here, fewer monocytes bound after laminar shear compared to static conditions; however, the number of bound monocytes was much lower for the EC-MSC coculture model than the EC-SMC coculture model for both static and shear conditions. These results suggest the feasibility of developing a tissue-engineered blood vessel substitute using MSCs as a substitute for SMCs.
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Affiliation(s)
- Minsung Hong
- Department of BIN Fusion Technology and Polymer Fusion Research Center, Chonbuk National University, Jeonju, Korea
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Abstract
The development of the modern era of bioengineering and the advances in our understanding of the cardiovascular system have been intertwined over the past one-half century. This is true of bioengineering as an area for research in universities. Bioengineering is ultimately the beginning of a new engineering discipline, as well as a new discipline in the medical device industry.
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Affiliation(s)
- Robert M Nerem
- Institute Professor Emeritus, Parker H. Petit Institute for Bioengineering and Bioscience Georgia Institute of Technology, Atlanta, GA 30332-0363, USA
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Ankeny RF, Nerem RM. Regulation of thrombotic and inflammatory responses in baboon endothelial outgrowth cells under various hemodynamic conditions. Cardiovasc Pathol 2013. [DOI: 10.1016/j.carpath.2013.01.038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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Holliday-Ankeny CJ, Ankeny RF, Ferdous Z, Nerem RM, Jo H. The function of shear-responsive and side-dependent microRNA-486-5p in aortic valve endothelium. Cardiovasc Pathol 2013. [DOI: 10.1016/j.carpath.2013.01.073] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Ankeny RF, Hinds MT, Nerem RM. Dynamic shear stress regulation of inflammatory and thrombotic pathways in baboon endothelial outgrowth cells. Tissue Eng Part A 2013; 19:1573-82. [PMID: 23406430 DOI: 10.1089/ten.tea.2012.0300] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Endothelial outgrowth cells (EOCs) have garnered much attention as a potential autologous endothelial source for vascular implants or in tissue engineering applications due to their ease of isolation and proliferative ability; however, how these cells respond to different hemodynamic cues is ill-defined. This study investigates the inflammatory and thrombotic response of baboon EOCs (BaEOCs) to four hemodynamic conditions using the cone and plate shear apparatus: steady, laminar shear stress (SS); pulsatile, nonreversing laminar shear stress (PS); oscillatory, laminar shear stress (OS); and net positive, pulsatile, reversing laminar shear stress (RS). In summary, endothelial nitric oxide synthase (eNOS) mRNA was significantly upregulated by SS compared to OS. No differences were found in the mRNA levels of the inflammatory markers intercellular adhesion molecule-1 (ICAM-1), E-selectin, and vascular cell adhesion molecule-1 (VCAM-1) between the shear conditions; however, OS significantly increased the number of monocytes bound when compared to SS. Next, SS increased the anti-thrombogenic mRNA levels of CD39, thrombomodulin, and endothelial protein-C receptor (EPCR) compared to OS. SS also significantly increased CD39 and EPCR mRNA levels compared to RS. Finally, no significant differences were detected when comparing pro-thrombotic tissue factor mRNA or its activity levels. These results indicate that shear stress can have beneficial (SS) or adverse (OS, RS) effects on the inflammatory or thrombotic potential of EOCs. Further, these results suggest SS hemodynamic preconditioning may be optimal in increasing the efficacy of a vascular implant or in tissue-engineered applications that have incorporated EOCs.
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Affiliation(s)
- Randall F Ankeny
- Parker H. Petit Institute for Bioengineering and Bioscience and Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA.
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Abstract
Mechanobiology to date has focused on differentiated cells or progenitors, yet the effects of mechanical forces on early differentiation of pluripotent stem cells are still largely unknown. To study the effects of cellular deformation, we utilize a fluid flow bioreactor to apply steady laminar shear stress to mouse embryonic stem cells (ESCs) cultured on a two dimensional surface. Shear stress was found to affect pluripotency, as well as germ specification to the mesodermal, endodermal, and ectodermal lineages, as indicated by gene expression of OCT4, T-BRACHY, AFP, and NES, respectively. The ectodermal and mesodermal response to shear stress was dependent on stress magnitude (ranging from 1.5 to 15 dynes cm(-2)). Furthermore, increasing the duration from one to four days resulted in a sustained increase in T-BRACHY and a marked suppression of AFP. These changes in differentiation occurred concurrently with the activation of Wnt and estrogen pathways, as determined by PCR arrays for signalling molecules. Together these studies show that the mechanical microenvironment may be an important regulator during early differentiation events, including gastrulation. This insight furthers understanding of normal and pathological events during development, as well as facilitates strategies for scale up production of stem cells for clinical therapies.
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Affiliation(s)
- Russell P Wolfe
- Tulane University Department of Biomedical Engineering, 500 Lindy Boggs, New Orleans, LA 70118, USA
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26
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Pineda ET, Nerem RM, Ahsan T. Differentiation patterns of embryonic stem cells in two- versus three-dimensional culture. Cells Tissues Organs 2013; 197:399-410. [PMID: 23406658 DOI: 10.1159/000346166] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/26/2012] [Indexed: 11/19/2022] Open
Abstract
Pluripotent stem cells are attractive candidates as a cell source for regenerative medicine and tissue engineering therapies. Current methods of differentiation result in low yields and impure populations of target phenotypes, with attempts for improved efficiency often comparing protocols that vary multiple parameters. This basic science study focused on a single variable to understand the effects of two-dimensional (2D) versus three-dimensional (3D) culture on directed differentiation. We compared mouse embryonic stem cells (ESCs) differentiated on collagen type I-coated surfaces (SLIDEs), embedded in collagen type I gels (GELs), and in suspension as embryoid bodies (EBs). For a systematic analysis in these studies, key parameters were kept identical to allow for direct comparison across culture configurations. We determined that all three configurations supported differentiation of ESCs and that the kinetics of differentiation differed greatly for cells cultured in 2D versus 3D. SLIDE cultures induced overall differentiation more quickly than 3D configurations, with earlier expression of cytoskeletal and extracellular matrix proteins. For 3D culture as GELs or EBs, cells clustered similarly, formed complex structures and promoted differentiation towards cardiovascular phenotypes. GEL culture, however, also allowed for contraction of the collagen matrix. For differentiation towards fibroblasts and smooth muscle cells which actively remodel their environment, GEL culture may be particularly beneficial. Overall, this study determined the effects of dimensionality on differentiation and helps in the rational design of protocols to generate phenotypes needed for tissue engineering and regenerative medicine.
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Affiliation(s)
- Emma T Pineda
- Department of Biomedical Engineering, Tulane University, New Orleans, LA 70118, USA
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27
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Ferdous Z, Jo H, Nerem RM. Strain Magnitude-Dependent Calcific Marker Expression in Valvular and Vascular Cells. Cells Tissues Organs 2013; 197:372-83. [DOI: 10.1159/000347007] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/08/2013] [Indexed: 11/19/2022] Open
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Abramson S, Ackermann DM, Akins R, Anders R, Andersen PJ, Anderson JM, Ankrum JA, Anseth KS, Antonucci J, Atzet S, Badylak SF, Baura GD, Bellamkonda RV, Best SM, Bhumiratana S, Bianco RW, Bokros JC, Borovetz HS, Boskey AL, Brown JL, Brown BN, Brown SA, Brunski JB, Cahn F, Ritchie AC, Caplan AI, Carpenedo RL, Chilkoti A, Chung S, Cimetta E, Cleary G, Clements IP, Colas A, Coleman KP, Conway DE, Cooper SL, Costerton B, Coury AJ, Cunanan C, Curtis J, D’Amore A, DeMeo P, Desai TA, Dickens S, Domingo G, Duncan E, Eskin SG, Feigal DW, Ferreira L, Fuller J, Gallegos RP, Gawalt E, Ghosh K, Ghosn B, Gilbert TW, Glaser DE, Godier-Furnemont A, Gombotz WR, Grainger DW, Grunkemeier GL, Hacking SA, Hallab NJ, Hall-Stoodley L, Hanson SR, Haubold AD, Hauch KD, Hawkins KR, Heath DE, Helm DL, Hench LL, Hensten A, Hill RT, Hobson C, Hoerstrup SP, Hoffman AS, Horbett TA, Hubbell JA, Humayun MS, Ideker R, Ingber DE, Jain R, Jacob J, Jacobs JJ, Jacobsen N, Jin R, Johnson RJ, Karp JM, Kasper FK, Kathju S, Khademhosseini A, Kim S, King MW, Kleiner LW, Kohn J, Koschwanez HE, Kumbar SG, Kuo CK, LaFleur L, Lahti MT, Lambert B, Langer R, Laurencin CT, Lee-Parritz D, Lemons JE, Levin M, Levy RJ, Lewerenz GM, Li WJ, Lin CC, Liu F, Lowrie WG, Lu Y, Lysaght MJ, Maidhof R, Mansbridge J, Cristina M, Martins L, Martin J, Mayesh JP, McDevitt TC, McIntire LV, Merrit K, Migliaresi C, Mikos AG, Misch CE, Mitchell RN, More RB, Moss CW, Munson JM, Navarro M, Nerem RM, Ogawa R, Orgill BD, Orgill DP, Padera RF, Pandit A, Park K, Patel AS, Peck RB, Peckham PH, Peppas NA, Pereira MN, Planell J, Popat KC, Prestwich GD, Pun SH, Rabolt J, Rainbow RS, Rajab T, Ratner BD, Reichert WM, Rivard AL, Rowley AP, Ruan G, Sacks M, Sarkar D, Schaefer S, Schmidt CE, Schoen FJ, Schutte SC, Sefton MV, Shalaby SW, Shirtliff M, Simon MA, Singh M, Slack SM, Spelman FA, Starr A, Stayton PS, Steinert R, Stoodley P, Suri S, Swi Chang TM, Tandon N, Tanguay AR, Taylor MS, Teo GS, Thodeti CK, Tolkoff J, Treiser M, Tuan RS, Tucker EI, Venugopalan R, Vicari AR, Viney C, Voight JM, Vunjak-Novakovic G, Wagner WR, Wang L, Wasiluk KR, Watts DC, Weigl BH, Weiland JD, Whalen JJ, Williams DF, Williams RL, Wilson JT, Wilson CG, Winter J, Wolf MF, Wright JC, Yager P, Zhao W. Contributors. Biomater Sci 2013. [DOI: 10.1016/b978-0-08-087780-8.00150-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Ankeny RF, Ankeny CJ, Nerem RM, Jo H. Maturing EPCs into endothelial cells: may the force be with the EPCs: focus on "Fluid shear stress induces differentiation of circulating phenotype endothelial progenitor cells". Am J Physiol Cell Physiol 2012; 303:C589-91. [PMID: 22763124 DOI: 10.1152/ajpcell.00224.2012] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Ensley AE, Nerem RM, Anderson DEJ, Hanson SR, Hinds MT. Fluid shear stress alters the hemostatic properties of endothelial outgrowth cells. Tissue Eng Part A 2011; 18:127-36. [PMID: 21787250 DOI: 10.1089/ten.tea.2010.0290] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Surface endothelialization is an attractive means to improve the performance of small diameter vascular grafts. While endothelial outgrowth cells (EOCs) are considered a promising source of autologous endothelium, the ability of EOCs to modulate coagulation-related blood activities is not well understood. The goal of this study was to assess the role of arterial flow conditions on the thrombogenic phenotype of EOCs. EOCs derived from baboon peripheral blood, as well as mature arterial endothelial cells from baboons, were seeded onto adsorbed collagen, then exposed to physiologic levels of fluid shear stress. For important hemostatic pathways, cellular responses to shear stress were characterized at the gene and protein level and confirmed with a functional assay for activated protein C (APC) activity. For EOCs, fluid shear stress upregulated gene and protein expression of anticoagulant and platelet inhibitory factors, including thrombomodulin, tissue factor pathway inhibitor, and nitric oxide synthase 3 (eNOS). Fluid shear stress significantly altered the functional activity of EOCs by increasing APC levels. This study demonstrates that fluid shear stress is an important determinant of EOC hemostatic properties. Accordingly, manipulation of EOC phenotype by mechanical forces may be important for the development of thrombo-resistant surfaces on engineered vascular implants.
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Affiliation(s)
- Ann E Ensley
- Parker H. Petit Institute for Bioengineering and Bioscience and Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia, USA
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31
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Abstract
Tissue engineering is an emerging multidisciplinary and interdisciplinary field involving the development of bioartificial implants and/or the fostering of tissue remodeling with the purpose of repairing or enhancing tissue or organ function. Bioartificial constructs generally consist of cells and biomaterials, so tissue engineering draws from both cell and biomaterials science and technology. Successful applications require a thorough understanding of the environment experienced by cells in normal tissues and by cells in bioartificial devices before and after implantation. This paper reviews these topics, as well as the current status and future possibilities in the development of different bioartificial constructs, including bioartificial skin, cardiovascular implants, bioartificial pancreas, and encapsulated secretory cells. Issues that need to be addressed in the future are also discussed. These include, but are not limited to, the development of new cell lines and biomaterials, the evaluation of the optimal construct architecture, and the reproducible manufacture and preservation of bioartificial devices until ready for use.
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Affiliation(s)
- R M Nerem
- Schools of Chemical and Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332
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32
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Holliday CJ, Ankeny RF, Jo H, Nerem RM. Discovery of shear- and side-specific mRNAs and miRNAs in human aortic valvular endothelial cells. Am J Physiol Heart Circ Physiol 2011; 301:H856-67. [PMID: 21705672 DOI: 10.1152/ajpheart.00117.2011] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The role of endothelial cells (ECs) in aortic valve (AV) disease remains relatively unknown; however, disease preferentially occurs in the fibrosa. We hypothesized oscillatory shear (OS) present on the fibrosa stimulates ECs to modify mRNAs and microRNAs (miRNAs) inducing disease. Our goal was to identify mRNAs and miRNAs differentially regulated by OS and laminar shear (LS) in human AVECs (HAVECs) from the fibrosa (fHAVECs) and ventricularis (vHAVECs). HAVECs expressed EC markers as well as some smooth muscle cell markers and functionally aligned with the flow. HAVECs were exposed to OS and LS for 24 h, and total RNA was analyzed by mRNA and miRNA microarrays. We found over 700 and 300 mRNAs down- and upregulated, respectively, by OS; however, there was no side dependency. mRNA microarray results were validated for 26 of 28 tested genes. Ingenuity Pathway Analysis revealed thrombospondin 1 (Thbs1) and NF-κB inhibitor-α (Nfkbia) as highly connected, shear-sensitive genes. miRNA array analysis yielded 30 shear-sensitive miRNAs and 3 side-specific miRNAs. miRNA validation confirmed 4 of 17 shear-sensitive miRNAs and 1 of 3 side-dependent miRNAs. Using miRWalk and several filtering steps, we identified shear-sensitive mRNAs potentially targeted by shear-sensitive miRNAs. These genes and signaling pathways could act as therapeutic targets of AV disease.
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Affiliation(s)
- Casey J Holliday
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia, USA
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33
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Schutte SC, Chen Z, Brockbank KGM, Nerem RM. Tissue engineering of a collagen-based vascular media: Demonstration of functionality. Organogenesis 2011; 6:204-11. [PMID: 21220958 DOI: 10.4161/org.6.4.12651] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The property of vasoactivity is important for both resistance vessels and larger arteries. Evaluation of smooth muscle cell phenotype is often done in place of functional testing in engineered tissues, assuming a direct correlation between cell phenotype and tissue contractile force. In this study we look at a large panel of vasoactive agents to determine the functionality of our collagen-based tissue. The engineered vascular media elicited a measurable change in force in response to seven of the nine agents used. As part of this characterization, TGF-β1 and TNF-α were used to promote a more contractile and synthetic cell phenotype respectively. Both smooth muscle α-actin and vasoconstriction were evaluated in ring sections. Due to large differences in cell-compaction and cell distribution in the tissues, no correlation was found between α-actin expression and contractile strength. This highlights the need for functional testing of engineered tissue and the importance of cell-matrix interactions in vasoactivity.
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Affiliation(s)
- Stacey C Schutte
- Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA, USA
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34
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Schenke-Layland K, Nerem RM. In vitro human tissue models--moving towards personalized regenerative medicine. Adv Drug Deliv Rev 2011; 63:195-6. [PMID: 21600252 DOI: 10.1016/j.addr.2011.05.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2011] [Accepted: 04/11/2011] [Indexed: 12/26/2022]
Abstract
The field of tissue engineering is a rapidly growing interdisciplinary field within regenerative medicine involving biology, chemistry, physics, engineering and medical sciences, which focuses on the fabrication of replacement tissues and organs. Another major focus of tissue engineering is the creation of ex vivo-manufactured multi-organ test systems, in order to explore fundamental questions of cell, matrix and developmental biology. These ex-vivo manufactured systems can also be used to study drug delivery dynamics.
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Affiliation(s)
- Katja Schenke-Layland
- Department of Cell and Tissue Engineering, Fraunhofer-Institute for Interfacial Engineering and Biotechnology (IGB), Nobelstrasse 12, 70569 Stuttgart, Germany.
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35
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Ferdous Z, Jo H, Nerem RM. Differences in valvular and vascular cell responses to strain in osteogenic media. Biomaterials 2011; 32:2885-93. [PMID: 21284997 DOI: 10.1016/j.biomaterials.2011.01.030] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2010] [Accepted: 01/12/2011] [Indexed: 10/18/2022]
Abstract
Calcification is the primary cause of failure of bioprosthetic and tissue-engineered vascular and valvular grafts. We used tissue-engineered collagen gels containing human aortic smooth muscle cells (HASMC) and human aortic valvular interstitial cells (HAVIC) as a model to investigate cell-mediated differences in early markers of calcification. The HASMCs and HAVICs were isolated from non-sclerotic human tissues. After 21 days of culture in either regular or osteogenic media with or without 10% cyclic strain at 1 Hz, the collagen gels were assessed for DNA content, collagen I, matrix metalloproteinase (MMP)-2 and glycosaminoglycan (GAG) content. The collagen gels containing HASMCs contained significantly greater amounts of collagen I and GAG compared to HAVICs. Although strain increased MMP-2 activity for both cell types, this trend was significant (p ≤ 0.05) only for HAVICs. Cultured gels were also assessed for osteogenic markers calcium content, alkaline phosphatase (ALP), and Runx2 and were present at greater amounts in gels containing HASMCs than HAVICs. Calcium content, Runx2 expression, and ALP activity were also modulated by mechanical strain. The results indicate that cell-mediated differences exist between the vascular and valvular calcification processes. Further investigation is necessary for improved understanding and to detect biomarkers for early detection or prevention of these diseases.
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Affiliation(s)
- Zannatul Ferdous
- Institute of Bioengineering and Biosciences, Georgia Institute of Technology, 315 Ferst Drive, Mail code 0363, Atlanta, GA 30332, USA.
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36
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Schutte SC, Chen Z, Brockbank KGM, Nerem RM. Cyclic strain improves strength and function of a collagen-based tissue-engineered vascular media. Tissue Eng Part A 2011; 16:3149-57. [PMID: 20504073 DOI: 10.1089/ten.tea.2010.0009] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Tissue-engineered blood vessels may provide a solution to the lack of suitable blood vessels for coronary and peripheral vessel bypass grafting. Cyclic strain can be used to provide a more physiological environment that may result in tissue that more closely resembles native artery. In this study, cyclic strain is applied to a collagen-based, tissue-engineered vascular medium. An increased culture time was used to allow the tissue to adhere to the silastic sleeve and to eliminate longitudinal compaction. Cyclic strain improved tissue strength through increased collagen content as well as some radial tissue compaction. Mechanical stimulation promoted a more contractile phenotype and led to a greater contractile response to the vasoconstrictor endothelin-1.
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Affiliation(s)
- Stacey C Schutte
- Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
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37
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Duffy GP, D'Arcy S, Ahsan T, Nerem RM, O'Brien T, Barry F. Mesenchymal stem cells overexpressing ephrin-b2 rapidly adopt an early endothelial phenotype with simultaneous reduction of osteogenic potential. Tissue Eng Part A 2010; 16:2755-68. [PMID: 20491587 DOI: 10.1089/ten.tea.2009.0623] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Restoration of the vascular supply to ischemic tissues is of high clinical relevance, and proangiogenic therapies aim to reduce morbidity and mortality rates associated with the onset of cardiovascular disease. Stem cell therapy has been proposed as a potentially useful proangiogenic therapy. Mesenchymal stem cells (MSCs) have been shown to be proangiogenic and produce a number of cytokines involved in vessel development and maturation. Preclinical studies have reported increased angiogenesis after MSC delivery to the heart, and similar outcomes have been reported in recent clinical trials. Stem-cell-mediated neovascularization has been augmented by genetic modification with overexpression of angiogenic cytokines, including vascular endothelial growth factor (VEGF) and platelet-derived growth factor, showing promising results. In this study we aimed to enhance the proangiogenic capability of MSCs. MSCs were genetically modified to overexpress a versatile molecule, Ephrin-B2, involved in tissue morphogenesis and vascular development to enhance inherent neovascularization potential. Using nucleofection, Ephrin-B2 was transiently overexpressed on the cell surface of MSCs to recapitulate embryonic signaling and promote neovascularization. Ephrin-B2-expressing MSCs adopted an early endothelial phenotype under endothelial cell culture conditions increasing expression of von Willebrand factor and VEGF-Receptor 2. The cells had an increased ability to form vessel-like structures, produce VEGF, and incorporate into newly formed endothelial cell structures. These data indicate that MSCs expressing Ephrin-B2 represent a novel proangiogenic cell source to promote neovascularization in ischemic tissues.
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Affiliation(s)
- Garry P Duffy
- Regenerative Medicine Institute (REMEDI), National University of Ireland Galway, Ireland
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38
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Abstract
Over the last quarter of a century there has been an emergence of a tissue engineering industry, one that has now evolved into the broader area of regenerative medicine. There have been 'ups and downs' in this industry; however, it now appears to be on a track that may be described as 'back to the future'. The latest data indicate that for 2007 the private sector activity in the world for this industry is approaching $2.5 billion, with 167 companies/business units and more than 6000 employee full time equivalents. Although small compared with the medical device and also the pharmaceutical industries, these numbers are not insignificant. Thus, there is the indication that this industry, and the related technology, may still achieve its potential and address the needs of millions of patients worldwide, in particular those with needs that currently are unmet.
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Affiliation(s)
- Robert M Nerem
- Parker H Petit Institute for Bioengineering and Bioscience, Georgia Tech/Emory Center for Regenerative Medicine, Georgia Institute of Technology, 315 Ferst Drive, NW, Atlanta, GA 30332-0363, USA.
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39
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Ahsan T, Nerem RM. Fluid shear stress promotes an endothelial-like phenotype during the early differentiation of embryonic stem cells. Tissue Eng Part A 2010; 16:3547-53. [PMID: 20666609 DOI: 10.1089/ten.tea.2010.0014] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Stem and progenitor cells are emerging as a potential source for cell-based therapies, in which large homogenous populations of differentiated cells are frequently deemed necessary for efficacy. Methods focused on biochemical cues have not yet yielded the numbers of endothelial cells thought necessary for cardiovascular applications. Interest in alternate methods has prompted the study of physical cues on stem and progenitor cell differentiation. In this study, fluid-based shear stress, at levels comparable to those experienced by endothelial cells in large vessels, was applied during the first few days of mouse embryonic stem cell differentiation. After 2 days of applied shear stress, there were increases in cell proliferation and in protein expression of endothelial markers (FLK1, VECAD, and PECAM). Further, treatment increased the number of FLK1+ cells from 1% to 40%, which were then capable of forming vessel-like structures in vitro. Thus, shear stress may be used to direct differentiation of embryonic stem cells toward an endothelial-like phenotype, helping to address the cell sourcing issue in cardiovascular regenerative medicine and tissue engineering.
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Affiliation(s)
- Tabassum Ahsan
- Department of Biomedical Engineering, Tulane University, New Orleans, Louisiana 70118, USA.
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40
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Butler DL, Goldstein SA, Guldberg RE, Guo XE, Kamm R, Laurencin CT, McIntire LV, Mow VC, Nerem RM, Sah RL, Soslowsky LJ, Spilker RL, Tranquillo RT. The impact of biomechanics in tissue engineering and regenerative medicine. Tissue Eng Part B Rev 2010; 15:477-84. [PMID: 19583462 DOI: 10.1089/ten.teb.2009.0340] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Biomechanical factors profoundly influence the processes of tissue growth, development, maintenance, degeneration, and repair. Regenerative strategies to restore damaged or diseased tissues in vivo and create living tissue replacements in vitro have recently begun to harness advances in understanding of how cells and tissues sense and adapt to their mechanical environment. It is clear that biomechanical considerations will be fundamental to the successful development of clinical therapies based on principles of tissue engineering and regenerative medicine for a broad range of musculoskeletal, cardiovascular, craniofacial, skin, urinary, and neural tissues. Biomechanical stimuli may in fact hold the key to producing regenerated tissues with high strength and endurance. However, many challenges remain, particularly for tissues that function within complex and demanding mechanical environments in vivo. This paper reviews the present role and potential impact of experimental and computational biomechanics in engineering functional tissues using several illustrative examples of past successes and future grand challenges.
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Affiliation(s)
- David L Butler
- Biomedical Engineering, University of Cincinnati , Cincinnati, Ohio, USA
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41
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Gauvin R, Ahsan T, Larouche D, Lévesque P, Dubé J, Auger FA, Nerem RM, Germain L. A Novel Single-Step Self-Assembly Approach for the Fabrication of Tissue-Engineered Vascular Constructs. Tissue Eng Part A 2010; 16:1737-47. [DOI: 10.1089/ten.tea.2009.0313] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Robert Gauvin
- Laboratoire d'Organogénèse Expérimentale/LOEX, Centre de Recherche FRSQ du CHA Universitaire de Québec and Département de Chirurgie, Université Laval, Québec, QC, Canada
| | - Taby Ahsan
- Department of Biomedical Engineering, Tulane University, New Orleans, Louisiana
| | - Danielle Larouche
- Laboratoire d'Organogénèse Expérimentale/LOEX, Centre de Recherche FRSQ du CHA Universitaire de Québec and Département de Chirurgie, Université Laval, Québec, QC, Canada
| | - Philippe Lévesque
- Laboratoire d'Organogénèse Expérimentale/LOEX, Centre de Recherche FRSQ du CHA Universitaire de Québec and Département de Chirurgie, Université Laval, Québec, QC, Canada
| | - Jean Dubé
- Laboratoire d'Organogénèse Expérimentale/LOEX, Centre de Recherche FRSQ du CHA Universitaire de Québec and Département de Chirurgie, Université Laval, Québec, QC, Canada
| | - François A. Auger
- Laboratoire d'Organogénèse Expérimentale/LOEX, Centre de Recherche FRSQ du CHA Universitaire de Québec and Département de Chirurgie, Université Laval, Québec, QC, Canada
| | - Robert M. Nerem
- Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology and Georgia Tech-Emory Center for the Engineering of Living Tissues, Atlanta, Georgia
| | - Lucie Germain
- Laboratoire d'Organogénèse Expérimentale/LOEX, Centre de Recherche FRSQ du CHA Universitaire de Québec and Département de Chirurgie, Université Laval, Québec, QC, Canada
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Affiliation(s)
| | - Jeffrey R. Morgan
- Bio Med Molecular Pharmacology, Physiology, and Biotechnology, Brown University, Providence, Rhode Island
| | - Robert M. Nerem
- Georgia Tech/Emory Center (GTEC) for Regenerative Medicine, Emory University, Atlanta, Georgia
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Duffy GP, Ahsan T, O'Brien T, Barry F, Nerem RM. Bone marrow-derived mesenchymal stem cells promote angiogenic processes in a time- and dose-dependent manner in vitro. Tissue Eng Part A 2009; 15:2459-70. [PMID: 19327020 DOI: 10.1089/ten.tea.2008.0341] [Citation(s) in RCA: 116] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Bone marrow-derived mesenchymal stem cells (MSCs) have received much attention as a potential treatment for myocardial infarction because of their potential to integrate into the host myocardium and repair the injured heart. The mode of action of stem cell-mediated cardiac repair is still somewhat unclear, including the potential role of MSCs in neovascularization. The objective of this study was to determine the in vitro effect of MSCs on angiogenesis-related endothelial cell (EC) behavior, including migration, monolayer permeability, and vessel formation and stabilization. In a noncontact coculture system, we found that MSCs increase EC proliferation and migration, promoting early events of angiogenesis, while also decreasing EC monolayer permeability. Further, in a time- and dose-dependent manner, MSCs in direct coculture with ECs on Matrigel can increase the persistence of preexisting vessels by greater than threefold, with complex vessels remaining stable for more than 10 days. The results demonstrate that MSCs play an active role in the cellular processes involved in the formation, stabilization, and maturation of newly formed vessels. Further, these outcomes are not governed solely by either paracrine or direct contact effects and are both time and dose dependent.
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Affiliation(s)
- Garry P Duffy
- Regenerative Medicine Institute, National University of Ireland, Galway, Ireland
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44
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Abstract
The formation of an endothelial cell (EC) monolayer is one critical factor in the development of a tissue engineered vascular graft. One potential method of endothelialization is the migration of native ECs from the surrounding blood vessel onto the newly implanted graft. In the present study, in vitro experiments were performed to investigate the potential of ECs to migrate on a tissue-engineered blood vessel wall model (TEWM) and form a new monolayer. The TEWM was composed of a three-dimensional, type I collagen matrix seeded with smooth muscle cells. The potential of ECs to form new monolayer was evaluated in the absence and presence of fluid shear stress (10 dynes/cm(2)). The monolayer formation on the TEWM was compared to a control, two-dimensional substrate of glass coated with type I collagen. Results from these studies showed that EC monolayer formation was inhibited on the TEWM in comparison to glass coated with collagen. This correlated with an inhibition of proliferation on the TEWM. The application of shear stress to the EC on the glass coated with collagen also caused an inhibition of monolayer formation, with a corresponding inhibition of proliferation. Furthermore, blocking proliferation by incubation with mitomycin C caused a dose-response inhibition of monolayer formation. In contrast, stimulating proliferation with basic fibro- blast growth factor (bFGF) did not further increase monolayer formation on glass coated with collagen. These results suggest that proliferation is one necessary factor for monolayer formation, although not the only factor, where EC proliferation is regulated by its environment, including both substrate and the local shear stress. Continued investigation into the mechanism and stimulation of EC proliferation on the TEWM may lead to developing new strategies for the endothelialization of a tissue engineered vascular graft.
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Affiliation(s)
- S M Kladakis
- Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia 30332-0363, USA
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45
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Doyle AM, Nerem RM, Ahsan T. Human Mesenchymal Stem Cells Form Multicellular Structures in Response to Applied Cyclic Strain. Ann Biomed Eng 2009; 37:783-93. [DOI: 10.1007/s10439-009-9644-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2008] [Accepted: 01/13/2009] [Indexed: 12/01/2022]
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46
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Hinds MT, Ma M, Tran N, Ensley AE, Kladakis SM, Vartanian KB, Markway BD, Nerem RM, Hanson SR. Potential of baboon endothelial progenitor cells for tissue engineered vascular grafts. J Biomed Mater Res A 2008; 86:804-12. [DOI: 10.1002/jbm.a.31672] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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47
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Gao J, Ensley AE, Nerem RM, Wang Y. Poly(glycerol sebacate) supports the proliferation and phenotypic protein expression of primary baboon vascular cells. J Biomed Mater Res A 2008; 83:1070-1075. [PMID: 17584900 DOI: 10.1002/jbm.a.31434] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Poly(glycerol sebacate) (PGS) is a biodegradable and biocompatible elastomer specifically developed for soft tissue engineering. Vascular cells adhered to an elastomer may exhibit more physiological behavior because the substrate's mechanical properties more closely match those of the tissue. To investigate the feasibility of using PGS as a scaffold material for vascular tissue engineering, the authors examined the adhesion, proliferation, and phenotypic and morphologic properties of primary baboon endothelial progenitor cells (BaEPCs) and baboon smooth muscle cells (BaSMCs) cultured on PGS films and scaffolds. Tissue culture-treated polystyrene plates were used as controls. Phase contrast microscopy indicated that both types of cells showed normal morphology on PGS films. Immuofluorescent staining revealed that von Willebrand factor and alpha-smooth muscle actin were expressed by BaEPCs and BaSMCs, respectively. Both types of cells proliferated well on PGS surfaces. When cultured in PGS scaffolds, BaSMCs were distributed throughout the scaffolds and synthesized extracellular matrix, as indicated by histological evaluations. The distribution of the BaSMCs in the constructs was confirmed by scanning electron microscopy. Immunofluorescent staining of cocultured constructs indicated that the BaSMC-seeded constructs provided suitable surfaces for BaEPC adhesion, and both types of cells maintained their specific phenotypes. These results suggest that PGS is an appropriate scaffold material for blood vessel tissue engineering.
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Affiliation(s)
- Jin Gao
- Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332
- Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia 30332
| | - Ann E Ensley
- Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332
- Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia 30332
| | - Robert M Nerem
- Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332
- Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia 30332
| | - Yadong Wang
- Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332
- Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia 30332
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48
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Han JW, Shimada K, Ma-Krupa W, Johnson TL, Nerem RM, Goronzy JJ, Weyand CM. Vessel Wall–Embedded Dendritic Cells Induce T-Cell Autoreactivity and Initiate Vascular Inflammation. Circ Res 2008; 102:546-53. [DOI: 10.1161/circresaha.107.161653] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Human medium-sized and large arteries are targeted by inflammation with innate and adaptive immune responses occurring within the unique microspace of the vessel wall. How 3D spatial arrangements influence immune recognition and cellular response thresholds and which cell populations sense immunoactivating ligands and function as antigen-presenting cells are incompletely understood. To mimic the 3D context of human arteries, bioartificial arteries were engineered from collagen type I matrix, human vascular smooth muscle cells (VSMCs), and human endothelial cells and populated with cells implicated in antigen presentation and T-cell stimulation, including monocytes, macrophages, and myeloid dendritic cells (DCs). Responsiveness of wall-embedded antigen-presenting cells was probed with the Toll-like receptor ligand lipopolysaccharide, and inflammation was initiated by adding autologous CD4
+
T cells. DCs colonized the outermost VSMC layer, recapitulating their positioning at the media–adventitia border of normal arteries. Wall-embedded DCs responded to the microbial product lipopolysaccharide by entering the maturation program and upregulating the costimulatory ligand CD86. Activated DCs effectively stimulated autologous CD4 T cells, which produced the proinflammatory cytokine interferon-γ and infiltrated deeply into the VSMC layer, causing matrix damage. Lipopolysaccharide-triggered macrophages were significantly less efficacious in recruiting T cells and promoting T-cell stimulation. CD14
+
monocytes, even when preactivated, failed to support initial steps of vascular wall inflammation. Innate immune cells, including monocytes, macrophages, and DCs, display differential functions in the vessel wall. DCs are superior in sensing pathogen-derived motifs and are highly efficient in breaking T-cell tolerance, guiding T cells toward proinflammatory and tissue-invasive behavior.
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Affiliation(s)
- Ji W. Han
- From the Kathleen B. and Mason I. Lowance Center for Human Immunology (J.W.H., K.S., W.M.-K., J.J.G., C.M.W.), Department of Medicine, Emory University School of Medicine, Atlanta, Ga; and Parker H. Petit Institute for Bioengineering and Bioscience (T.L.J., R.M.N.), Georgia Institute of Technology, Atlanta
| | - Kazunori Shimada
- From the Kathleen B. and Mason I. Lowance Center for Human Immunology (J.W.H., K.S., W.M.-K., J.J.G., C.M.W.), Department of Medicine, Emory University School of Medicine, Atlanta, Ga; and Parker H. Petit Institute for Bioengineering and Bioscience (T.L.J., R.M.N.), Georgia Institute of Technology, Atlanta
| | - Wei Ma-Krupa
- From the Kathleen B. and Mason I. Lowance Center for Human Immunology (J.W.H., K.S., W.M.-K., J.J.G., C.M.W.), Department of Medicine, Emory University School of Medicine, Atlanta, Ga; and Parker H. Petit Institute for Bioengineering and Bioscience (T.L.J., R.M.N.), Georgia Institute of Technology, Atlanta
| | - Tiffany L. Johnson
- From the Kathleen B. and Mason I. Lowance Center for Human Immunology (J.W.H., K.S., W.M.-K., J.J.G., C.M.W.), Department of Medicine, Emory University School of Medicine, Atlanta, Ga; and Parker H. Petit Institute for Bioengineering and Bioscience (T.L.J., R.M.N.), Georgia Institute of Technology, Atlanta
| | - Robert M. Nerem
- From the Kathleen B. and Mason I. Lowance Center for Human Immunology (J.W.H., K.S., W.M.-K., J.J.G., C.M.W.), Department of Medicine, Emory University School of Medicine, Atlanta, Ga; and Parker H. Petit Institute for Bioengineering and Bioscience (T.L.J., R.M.N.), Georgia Institute of Technology, Atlanta
| | - Jörg J. Goronzy
- From the Kathleen B. and Mason I. Lowance Center for Human Immunology (J.W.H., K.S., W.M.-K., J.J.G., C.M.W.), Department of Medicine, Emory University School of Medicine, Atlanta, Ga; and Parker H. Petit Institute for Bioengineering and Bioscience (T.L.J., R.M.N.), Georgia Institute of Technology, Atlanta
| | - Cornelia M. Weyand
- From the Kathleen B. and Mason I. Lowance Center for Human Immunology (J.W.H., K.S., W.M.-K., J.J.G., C.M.W.), Department of Medicine, Emory University School of Medicine, Atlanta, Ga; and Parker H. Petit Institute for Bioengineering and Bioscience (T.L.J., R.M.N.), Georgia Institute of Technology, Atlanta
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49
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Affiliation(s)
- Kiki B. Hellman
- The Hellman Group, LLC, Clarksburg, Maryland
- Formerly Senior Scientist, Food and Drug Administration; Co-Chair, Multi-Agency Tissue Engineering Science Interagency Working Group, 2000–2003
| | - Robert M. Nerem
- Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia
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50
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Abstract
Endothelial cells are critical mediators of haemodynamic forces and as such are important foci for initiation of vascular pathology. Valvular leaflets are also lined with endothelial cells, though a similar role in mechanosensing has not been demonstrated. Recent evidence has shown that valvular endothelial cells respond morphologically to shear stress, and several studies have implicated valvular endothelial dysfunction in the pathogenesis of disease. This review seeks to combine what is known about vascular and valvular haemodynamics, endothelial response to mechanical stimuli and the pathogenesis of valvular diseases to form a hypothesis as to how mechanical stimuli can initiate valvular endothelial dysfunction and disease progression. From this analysis, it appears that inflow surface-related bacterial/thrombotic vegetative endocarditis is a high shear-driven endothelial denudation phenomenon, while the outflow surface with its related calcific/atherosclerotic degeneration is a low/oscillatory shear-driven endothelial activation phenomenon. Further understanding of these mechanisms may help lead to earlier diagnostic tools and therapeutic strategies.
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Affiliation(s)
- Jonathan T Butcher
- Department of Biomedical Engineering, 270 Olin Hall, Cornell University, Ithaca, NY 14850, USA.
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