1
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Namgung B, Dai H, Prathyushaa Vikraman P, Saha T, Sengupta S, Lin Jang H. An inexpensive "do-it-yourself" device for rapid generation of uniform tumor spheroids. Device 2024; 2:100255. [PMID: 38617078 PMCID: PMC11008532 DOI: 10.1016/j.device.2024.100255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/16/2024]
Abstract
Three-dimensional (3D) cancer cell culture models such as tumor spheroids better recapitulate in vivo tumors than conventional two-dimensional (2D) models. However, two major challenges limit the routine use of 3D tumor spheroids. Firstly, most existing methods of generating tumor spheroids are not high-throughput. Secondly, tumor spheroids generated using current methods are highly variable in dimension. Here, we describe a simple 'Do-It-Yourself (DIY)' device that can be assembled for less than $7 of parts and generate uniform tumor spheroids in a high-throughput manner. We used a simple phone coin vibrating motor to superimpose the vibration for breaking a laminar jet of cell-loaded alginate solution into equally sized spherical beads. We generated 3,970 tumor spheroids/min, which exhibited a hypoxic core recapitulating in vivo tumors and could be used to test the diffusion efficacy of anticancer drugs. Such low-cost, easy-to-fabricate, simple-to-operate systems with high-throughput outcomes are essential to democratize and standardize cancer research.
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Affiliation(s)
- Bumseok Namgung
- Center for Engineered Therapeutics, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA
- Harvard-MIT Division of Health Sciences and Technology, Cambridge, MA, USA
- Division of Rheumatology, Inflammation, and Immunity, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA
- Department of Orthopaedic Surgery, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA
| | - Hongqing Dai
- Center for Engineered Therapeutics, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA
- Harvard-MIT Division of Health Sciences and Technology, Cambridge, MA, USA
- Contributed equally
| | - Pooja Prathyushaa Vikraman
- Center for Engineered Therapeutics, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA
- Harvard-MIT Division of Health Sciences and Technology, Cambridge, MA, USA
- Contributed equally
| | - Tanmoy Saha
- Center for Engineered Therapeutics, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA
- Harvard-MIT Division of Health Sciences and Technology, Cambridge, MA, USA
| | - Shiladitya Sengupta
- Center for Engineered Therapeutics, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA
- Harvard-MIT Division of Health Sciences and Technology, Cambridge, MA, USA
- Dana Farber Cancer Institute, Boston, MA, USA
| | - Hae Lin Jang
- Center for Engineered Therapeutics, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA
- Division of Rheumatology, Inflammation, and Immunity, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA
- Department of Orthopaedic Surgery, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA
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2
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Lee VK, Lee T, Ghosh A, Saha T, Bais MV, Bharani KK, Chag M, Parikh K, Bhatt P, Namgung B, Venkataramanan G, Agrawal A, Sonaje K, Mavely L, Sengupta S, Mashelkar RA, Jang HL. An architecturally rational hemostat for rapid stopping of massive bleeding on anticoagulation therapy. Proc Natl Acad Sci U S A 2024; 121:e2316170121. [PMID: 38252814 PMCID: PMC10835033 DOI: 10.1073/pnas.2316170121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [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] [Received: 09/17/2023] [Accepted: 12/08/2023] [Indexed: 01/24/2024] Open
Abstract
Hemostatic devices are critical for managing emergent severe bleeding. With the increased use of anticoagulant therapy, there is a need for next-generation hemostats. We rationalized that a hemostat with an architecture designed to increase contact with blood, and engineered from a material that activates a distinct and undrugged coagulation pathway can address the emerging need. Inspired by lung alveolar architecture, here, we describe the engineering of a next-generation single-phase chitosan hemostat with a tortuous spherical microporous design that enables rapid blood absorption and concentrated platelets and fibrin microthrombi in localized regions, a phenomenon less observed with other classical hemostats without structural optimization. The interaction between blood components and the porous hemostat was further amplified based on the charged surface of chitosan. Contrary to the dogma that chitosan does not directly affect physiological clotting mechanism, the hemostat induced coagulation via a direct activation of platelet Toll-like receptor 2. Our engineered porous hemostat effectively stopped the bleeding from murine liver wounds, swine liver and carotid artery injuries, and the human radial artery puncture site within a few minutes with significantly reduced blood loss, even under the anticoagulant treatment. The integration of engineering design principles with an understanding of the molecular mechanisms can lead to hemostats with improved functions to address emerging medical needs.
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Affiliation(s)
- Vivian K. Lee
- Center for Engineered Therapeutics, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115
- Division of Rheumatology, Inflammation and Immunity, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115
- Department of Orthopaedic Surgery, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115
- Division of Health Sciences and Technology, Harvard–Massachusetts Institute of Technology, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Taewoo Lee
- Center for Engineered Therapeutics, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115
- Division of Rheumatology, Inflammation and Immunity, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115
- Department of Orthopaedic Surgery, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115
- Division of Health Sciences and Technology, Harvard–Massachusetts Institute of Technology, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Amrit Ghosh
- Center for Engineered Therapeutics, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115
- Division of Health Sciences and Technology, Harvard–Massachusetts Institute of Technology, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Tanmoy Saha
- Center for Engineered Therapeutics, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115
- Division of Health Sciences and Technology, Harvard–Massachusetts Institute of Technology, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Manish V. Bais
- Division of Rheumatology, Inflammation and Immunity, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115
- Department of Translational Dental Medicine, Boston University Henry M. Goldman School of Dental Medicine, Boston, MA02118
| | - Kala Kumar Bharani
- Department of Veterinary Pharmacology and Toxicology, College of Veterinary Science, P. V. Narasimha Rao Telangana Veterinary University, Hyderabad 500030, India
| | - Milan Chag
- Care Institute of Medical Sciences, Ahmedabad 380060, India
| | - Keyur Parikh
- Care Institute of Medical Sciences, Ahmedabad 380060, India
| | - Parloop Bhatt
- Care Institute of Medical Sciences, Ahmedabad 380060, India
| | - Bumseok Namgung
- Center for Engineered Therapeutics, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115
- Division of Rheumatology, Inflammation and Immunity, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115
- Department of Orthopaedic Surgery, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115
- Division of Health Sciences and Technology, Harvard–Massachusetts Institute of Technology, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Geethapriya Venkataramanan
- Center for Engineered Therapeutics, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115
- Division of Health Sciences and Technology, Harvard–Massachusetts Institute of Technology, Massachusetts Institute of Technology, Cambridge, MA 02139
| | | | - Kiran Sonaje
- Axio Biosolutions Private Limited, Ahmedabad 382220, India
| | - Leo Mavely
- Axio Biosolutions Private Limited, Ahmedabad 382220, India
- Advamedica Inc., Boston, MA 02138
| | - Shiladitya Sengupta
- Center for Engineered Therapeutics, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115
- Division of Health Sciences and Technology, Harvard–Massachusetts Institute of Technology, Massachusetts Institute of Technology, Cambridge, MA 02139
| | | | - Hae Lin Jang
- Center for Engineered Therapeutics, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115
- Division of Rheumatology, Inflammation and Immunity, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115
- Department of Orthopaedic Surgery, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115
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3
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Namgung B, Ravi K, Vikraman PP, Sengupta S, Jang HL. Engineered cell-laden alginate microparticles for 3D culture. Biochem Soc Trans 2021; 49:761-773. [PMID: 33860783 DOI: 10.1042/bst20200673] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [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] [Received: 11/11/2020] [Revised: 02/18/2021] [Accepted: 03/22/2021] [Indexed: 12/24/2022]
Abstract
Advanced microfabrication technologies and biocompatible hydrogel materials facilitate the modeling of 3D tissue microenvironment. Encapsulation of cells in hydrogel microparticles offers an excellent high-throughput platform for investigating multicellular interaction with their surrounding microenvironment. Compartmentalized microparticles support formation of various unique cellular structures. Alginate has emerged as one of the most dominant hydrogel materials for cell encapsulation owing to its cytocompatibility, ease of gelation, and biocompatibility. Alginate hydrogel provides a permeable physical boundary to the encapsulated cells and develops an easily manageable 3D cellular structure. The interior structure of alginate hydrogel can further regulate the spatiotemporal distribution of the embedded cells. This review provides a specific overview of the representative engineering approaches to generate various structures of cell-laden alginate microparticles in a uniform and reproducible manner. Capillary nozzle systems, microfluidic droplet systems, and non-chip based high-throughput microfluidic systems are highlighted for developing well-regulated cellular structure in alginate microparticles to realize potential drug screening platform and cell-based therapy. We conclude with the discussion of current limitations and future directions for realizing the translation of this technology to the clinic.
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Affiliation(s)
- Bumseok Namgung
- Center for Engineered Therapeutics, Division of Engineering in Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, U.S.A
- Division of Health Sciences & Technology, Harvard-Massachusetts Institute of Technology, Massachusetts Institute of Technology, Boston, MA, U.S.A
| | - Kalpana Ravi
- Center for Engineered Therapeutics, Division of Engineering in Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, U.S.A
- Division of Health Sciences & Technology, Harvard-Massachusetts Institute of Technology, Massachusetts Institute of Technology, Boston, MA, U.S.A
| | - Pooja Prathyushaa Vikraman
- Center for Engineered Therapeutics, Division of Engineering in Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, U.S.A
- Division of Health Sciences & Technology, Harvard-Massachusetts Institute of Technology, Massachusetts Institute of Technology, Boston, MA, U.S.A
| | - Shiladitya Sengupta
- Center for Engineered Therapeutics, Division of Engineering in Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, U.S.A
- Division of Health Sciences & Technology, Harvard-Massachusetts Institute of Technology, Massachusetts Institute of Technology, Boston, MA, U.S.A
- Dana Farber Cancer Institute, Boston, MA, U.S.A
| | - Hae Lin Jang
- Center for Engineered Therapeutics, Division of Engineering in Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, U.S.A
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4
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Chng KZ, Ng YC, Namgung B, Tan JKS, Park S, Tien SL, Leo HL, Kim S. Assessment of transient changes in oxygen diffusion of single red blood cells using a microfluidic analytical platform. Commun Biol 2021; 4:271. [PMID: 33654170 PMCID: PMC7925684 DOI: 10.1038/s42003-021-01793-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [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: 06/02/2020] [Accepted: 01/26/2021] [Indexed: 02/07/2023] Open
Abstract
Red blood cells (RBCs) capability to deliver oxygen (O2) has been routinely measured by P50. Although this defines the ability of RBCs to carry O2 under equilibrium states, it cannot determine the efficacy of O2 delivery in dynamic blood flow. Here, we developed a microfluidic analytical platform (MAP) that isolates single RBCs for assessing transient changes in their O2 release rate. We found that in vivo (biological) and in vitro (blood storage) aging of RBC could lead to an increase in the O2 release rate, despite a decrease in P50. Rejuvenation of stored RBCs (Day 42), though increased the P50, failed to restore the O2 release rate to basal level (Day 0). The temporal dimension provided at the single-cell level by MAP could shed new insights into the dynamics of O2 delivery in both physiological and pathological conditions.
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Affiliation(s)
- Kevin Ziyang Chng
- Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore
| | - Yan Cheng Ng
- Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore.,NUS Graduate School for Integrative Sciences and Efngineering, National University of Singapore, Singapore, Singapore
| | - Bumseok Namgung
- Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore
| | - Justin Kok Soon Tan
- Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore
| | - Soyeon Park
- Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore.,Institute for Health Innovation & Technology, National University of Singapore, Singapore, Singapore
| | - Sim Leng Tien
- Department of Hematology, Singapore General Hospital, Singapore, Singapore
| | - Hwa Liang Leo
- Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore.,NUS Graduate School for Integrative Sciences and Efngineering, National University of Singapore, Singapore, Singapore
| | - Sangho Kim
- Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore. .,NUS Graduate School for Integrative Sciences and Efngineering, National University of Singapore, Singapore, Singapore. .,Institute for Health Innovation & Technology, National University of Singapore, Singapore, Singapore.
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5
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Freag MS, Namgung B, Reyna Fernandez ME, Gherardi E, Sengupta S, Jang HL. Human Nonalcoholic Steatohepatitis on a Chip. Hepatol Commun 2021; 5:217-233. [PMID: 33553970 PMCID: PMC7850303 DOI: 10.1002/hep4.1647] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 10/29/2020] [Accepted: 11/02/2020] [Indexed: 02/04/2023] Open
Abstract
Nonalcoholic steatohepatitis (NASH), an advanced stage of nonalcoholic fatty liver disease (NAFLD), is a rapidly growing and global health problem compounded by the current absence of specific treatments. A major limiting factor in the development of new NASH therapies is the absence of models that capture the unique cellular structure of the liver microenvironment and recapitulate the complexities of NAFLD progression to NASH. Organ-on-a-chip platforms have emerged as a powerful approach to dynamically model diseases and test drugs. Herein, we describe a NASH-on-a-chip platform. Four main types of human primary liver cells (hepatocytes [HCs], Kupffer cells, liver sinusoidal endothelial cells, and hepatic stellate cells [HSCs]) were cocultured under microfluidic dynamics. Our chip-based model successfully recapitulated a functional liver cellular microenvironment with stable albumin and urea secretion for at least 2 weeks. Exposing liver chips to a lipotoxic environment led to gradual development of NASH phenotypic characteristics, including intracellular lipid accumulation, hepatocellular ballooning, HSC activation, and elevation of inflammatory and profibrotic markers. Further, exposure of the chip to elafibranor, a drug under study for the therapy of NASH, inhibited the development of NASH-specific hallmarks, causing an ~8-fold decrease in intracellular lipids, a 3-fold reduction in number of ballooned HCs, a significant reduction in HSC activation, and a significant decrease in the levels of inflammatory and profibrotic markers compared with controls. Conclusion: We have successfully developed a microfluidic NASH-on-a-chip platform that recapitulates the main NASH histologic endpoints in a single chip and that can emerge as a powerful noninvasive, human-relevant, in vitro platform to study disease pathogenesis and develop novel anti-NASH drugs.
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Affiliation(s)
- May S Freag
- Center for Engineered TherapeuticsDivision of Engineering in MedicineDepartment of MedicineBrigham and Women's HospitalHarvard Medical SchoolBostonMAUSA.,Division of Health Sciences and TechnologyHarvard-Massachusetts Institute of TechnologyMassachusetts Institute of TechnologyBostonMAUSA
| | - Bumseok Namgung
- Center for Engineered TherapeuticsDivision of Engineering in MedicineDepartment of MedicineBrigham and Women's HospitalHarvard Medical SchoolBostonMAUSA.,Division of Health Sciences and TechnologyHarvard-Massachusetts Institute of TechnologyMassachusetts Institute of TechnologyBostonMAUSA
| | - Maria E Reyna Fernandez
- Center for Engineered TherapeuticsDivision of Engineering in MedicineDepartment of MedicineBrigham and Women's HospitalHarvard Medical SchoolBostonMAUSA.,Division of Health Sciences and TechnologyHarvard-Massachusetts Institute of TechnologyMassachusetts Institute of TechnologyBostonMAUSA
| | - Ermanno Gherardi
- Unit of Immunology and General PathologyDepartment of Molecular MedicineUniversity of PaviaPaviaItaly
| | - Shiladitya Sengupta
- Center for Engineered TherapeuticsDivision of Engineering in MedicineDepartment of MedicineBrigham and Women's HospitalHarvard Medical SchoolBostonMAUSA.,Division of Health Sciences and TechnologyHarvard-Massachusetts Institute of TechnologyMassachusetts Institute of TechnologyBostonMAUSA.,Dana Farber Cancer InstituteBostonMAUSA
| | - Hae Lin Jang
- Center for Engineered TherapeuticsDivision of Engineering in MedicineDepartment of MedicineBrigham and Women's HospitalHarvard Medical SchoolBostonMAUSA
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6
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Craig M, Jenner AL, Namgung B, Lee LP, Goldman A. Engineering in Medicine To Address the Challenge of Cancer Drug Resistance: From Micro- and Nanotechnologies to Computational and Mathematical Modeling. Chem Rev 2020; 121:3352-3389. [PMID: 33152247 DOI: 10.1021/acs.chemrev.0c00356] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Drug resistance has profoundly limited the success of cancer treatment, driving relapse, metastasis, and mortality. Nearly all anticancer drugs and even novel immunotherapies, which recalibrate the immune system for tumor recognition and destruction, have succumbed to resistance development. Engineers have emerged across mechanical, physical, chemical, mathematical, and biological disciplines to address the challenge of drug resistance using a combination of interdisciplinary tools and skill sets. This review explores the developing, complex, and under-recognized role of engineering in medicine to address the multitude of challenges in cancer drug resistance. Looking through the "lens" of intrinsic, extrinsic, and drug-induced resistance (also referred to as "tolerance"), we will discuss three specific areas where active innovation is driving novel treatment paradigms: (1) nanotechnology, which has revolutionized drug delivery in desmoplastic tissues, harnessing physiochemical characteristics to destroy tumors through photothermal therapy and rationally designed nanostructures to circumvent cancer immunotherapy failures, (2) bioengineered tumor models, which have benefitted from microfluidics and mechanical engineering, creating a paradigm shift in physiologically relevant environments to predict clinical refractoriness and enabling platforms for screening drug combinations to thwart resistance at the individual patient level, and (3) computational and mathematical modeling, which blends in silico simulations with molecular and evolutionary principles to map mutational patterns and model interactions between cells that promote resistance. On the basis that engineering in medicine has resulted in discoveries in resistance biology and successfully translated to clinical strategies that improve outcomes, we suggest the proliferation of multidisciplinary science that embraces engineering.
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Affiliation(s)
- Morgan Craig
- Department of Mathematics and Statistics, University of Montreal, Montreal, Quebec H3C 3J7, Canada.,Sainte-Justine University Hospital Research Centre, Montreal, Quebec H3S 2G4, Canada
| | - Adrianne L Jenner
- Department of Mathematics and Statistics, University of Montreal, Montreal, Quebec H3C 3J7, Canada.,Sainte-Justine University Hospital Research Centre, Montreal, Quebec H3S 2G4, Canada
| | - Bumseok Namgung
- Division of Engineering in Medicine, Brigham and Women's Hospital, Boston, Massachusetts 02115, United States.,Department of Medicine, Harvard Medical School, Boston, Massachusetts 02139, United States
| | - Luke P Lee
- Division of Engineering in Medicine, Brigham and Women's Hospital, Boston, Massachusetts 02115, United States.,Department of Medicine, Harvard Medical School, Boston, Massachusetts 02139, United States
| | - Aaron Goldman
- Division of Engineering in Medicine, Brigham and Women's Hospital, Boston, Massachusetts 02115, United States.,Department of Medicine, Harvard Medical School, Boston, Massachusetts 02139, United States
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7
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Namgung B, Lee T, Tan JKS, Poh DKH, Park S, Chng KZ, Agrawal R, Park SY, Leo HL, Kim S. Vibration motor-integrated low-cost, miniaturized system for rapid quantification of red blood cell aggregation. Lab Chip 2020; 20:3930-3937. [PMID: 32966494 DOI: 10.1039/d0lc00619j] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Human red blood cells (RBCs) aggregate under low shear conditions, which significantly modulates flow resistance and tissue perfusion. A higher aggregation tendency in blood thus serves as an important clinical indicator for the screening of cardiovascular disorders. Conventional ways of measuring RBC aggregation still require large sample volumes, cumbersome manual procedures, and expensive benchtop systems. These inconvenient and high-cost measurement methods hamper their clinical applicability. Here, we propose a low-cost, miniaturized system to overcome the limitations of these methods. Our system utilizes a coin vibration motor (CVM) to generate a localized vortex for disaggregating RBCs in a disposable fluidic chip. The design of the chip was optimized with fluid dynamics simulations to ensure sufficient shear flow in the localized vortex for RBC disaggregation. The time-dependent increase in light transmittance from an LED light source through the plasma gap while the RBCs re-aggregate is captured with a CMOS camera under stasis conditions to quantify the level of RBC aggregation. Our CVM-based aggregometer was validated against a commercial benchtop system for human blood samples under physiological and pathological conditions, and showed an excellent performance with a high intraclass correlation coefficient of 0.995. In addition, we were able to achieve a rapid measurement (<4 min) with the CVM-based aggregometer, requiring only a 6 μl blood sample. These illustrate the potential of our CVM-based aggregometer for low-cost point-of-care diagnostics without compromising the measurement sensitivity.
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Affiliation(s)
- Bumseok Namgung
- Department of Biomedical Engineering, National University of Singapore, 9 Engineering Drive 1, 117575, Singapore.
| | - Taewoo Lee
- Department of Biomedical Engineering, National University of Singapore, 9 Engineering Drive 1, 117575, Singapore.
| | - Justin Kok Soon Tan
- Department of Biomedical Engineering, National University of Singapore, 9 Engineering Drive 1, 117575, Singapore. and Institute for Health Innovation and Technology, National University of Singapore, 117599, Singapore
| | - Daren Kiat How Poh
- Department of Biomedical Engineering, National University of Singapore, 9 Engineering Drive 1, 117575, Singapore.
| | - Soyeon Park
- Department of Biomedical Engineering, National University of Singapore, 9 Engineering Drive 1, 117575, Singapore. and Institute for Health Innovation and Technology, National University of Singapore, 117599, Singapore
| | - Kevin Ziyang Chng
- Department of Biomedical Engineering, National University of Singapore, 9 Engineering Drive 1, 117575, Singapore. and Institute for Health Innovation and Technology, National University of Singapore, 117599, Singapore
| | - Rupesh Agrawal
- Department of Ophthalmology, National Healthcare Group Eye Institute, Tan Tock Seng Hospital, 308433, Singapore
| | - Sung-Yong Park
- Department of Mechanical Engineering, San Diego State University, San Diego, CA 92182, USA
| | - Hwa Liang Leo
- Department of Biomedical Engineering, National University of Singapore, 9 Engineering Drive 1, 117575, Singapore.
| | - Sangho Kim
- Department of Biomedical Engineering, National University of Singapore, 9 Engineering Drive 1, 117575, Singapore. and Institute for Health Innovation and Technology, National University of Singapore, 117599, Singapore and The N.1 Institute for Health, National University of Singapore, 117456, Singapore
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8
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Namgung B, Ng YC, Leo HL, Rifkind JM, Kim S. Near-Wall Migration Dynamics of Erythrocytes in Vivo: Effects of Cell Deformability and Arteriolar Bifurcation. Front Physiol 2017; 8:963. [PMID: 29238303 PMCID: PMC5712576 DOI: 10.3389/fphys.2017.00963] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Accepted: 11/13/2017] [Indexed: 01/12/2023] Open
Abstract
Red blood cell (RBC) deformability has a significant impact on microcirculation by affecting cell dynamics. Despite previous studies that have demonstrated the margination of rigid cells and particles in vitro, little information is available on the in vivo margination of deformability-impaired RBCs under physiological flow and hematocrit conditions. Thus, in this study, we examined how the deformability-dependent, RBC migration alters the cell distribution under physiological conditions, particularly in arteriolar network flows. The hardened RBCs (hRBCs) were found to preferentially flow near the vessel walls of small arterioles (diameter = 47.1-93.3 μm). The majority of the hRBCs (63%) were marginated within the range of 0.7R-0.9R (R: radial position normalized by vessel radius), indicating that the hRBCs preferentially accumulated near the vessel walls. The laterally marginated hRBCs maintained their lateral positions near the walls while traversing downstream with attenuated radial dispersion. In addition, the immediate displacement of RBCs while traversing a bifurcation also contributes to the near-wall accumulation of hRBCs. The notable difference in the inward migration between the marginated nRBCs and hRBCs after bifurcations further supports the potential role of bifurcations in the accumulation of hRBCs near the walls.
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Affiliation(s)
- Bumseok Namgung
- Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore
- Biomedical Institute for Global Health Research and Technology, National University of Singapore, Singapore, Singapore
| | - Yan Cheng Ng
- Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore
- NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore, Singapore
| | - Hwa Liang Leo
- Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore
| | - Joseph M. Rifkind
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins Medicine, Baltimore, MD, United States
| | - Sangho Kim
- Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore
- Biomedical Institute for Global Health Research and Technology, National University of Singapore, Singapore, Singapore
- NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore, Singapore
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9
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Namgung B, Sakai H, Kim S. Influence of erythrocyte aggregation at pathological levels on cell-free marginal layer in a narrow circular tube. Clin Hemorheol Microcirc 2016; 61:445-57. [PMID: 25335815 DOI: 10.3233/ch-141909] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Human red blood cells (RBCs) were perfused in a circular micro-tube (inner diameter of 25 μm) to examine the dynamic changes of cell-free marginal region at both physiological (normal) and pathophysiological (hyper) levels of RBC aggregation. The cell-free area (CFA) was measured to provide additional information on the cell-free layer (CFL) width changes in space and time domains. A prominent enhancement in the mean CFL width was found in hyper-aggregating conditions as compared to that in non-aggregating conditions (P < 0.001). The frequent contacts between RBC and the tube wall were observed and the contact frequency was greatly decreased when the aggregation level was increased from none to normal (P < 0.05) and to hyper (P < 0.001) levels. In addition, the enhanced aggregation from none to hyper levels significantly enlarged the CFA (P < 0.01). We concluded that the RBC aggregation at pathophysiological levels could promote not only the CFL width (one-dimensional parameter) but also the spatiotemporal variation of CFA (two-dimensional parameter).
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Affiliation(s)
- Bumseok Namgung
- Department of Biomedical Engineering and Department of Surgery, National University of Singapore, Singapore
| | - Hiromi Sakai
- Department of Chemistry, School of Medicine, Nara Medical University, Nara, Japan
| | - Sangho Kim
- Department of Biomedical Engineering and Department of Surgery, National University of Singapore, Singapore
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10
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Ng YC, Fisher LK, Salim V, Kim S, Namgung B. Visualization and Quantification of the Cell-free Layer in Arterioles of the Rat Cremaster Muscle. J Vis Exp 2016. [PMID: 27805612 DOI: 10.3791/54550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
The cell-free layer is defined as the parietal plasma layer in the microvessel flow, which is devoid of red blood cells. The measurement of the in vivo cell-free layer width and its spatiotemporal variations can provide a comprehensive understanding of hemodynamics in microcirculation. In this study, we used an intravital microscopic system coupled with a high-speed video camera to quantify the cell-free layer widths in arterioles in vivo. The cremaster muscle of Sprague-Dawley rats was surgically exteriorized to visualize the blood flow. A custom-built imaging script was also developed to automate the image processing and analysis of the cell-free layer width. This approach enables the quantification of spatiotemporal variations more consistently than previous manual measurements. The accuracy of the measurement, however, partly depends on the use of a blue filter and the selection of an appropriate thresholding algorithm. Specifically, we evaluated the contrast and quality of images acquired with and without the use of a blue filter. In addition, we compared five different image histogram-based thresholding algorithms (Otsu, minimum, intermode, iterative selection, and fuzzy entropic thresholding) and illustrated the differences in their determination of the cell-free layer width.
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Affiliation(s)
- Yan Cheng Ng
- NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore; Department of Biomedical Engineering, National University of Singapore
| | - Liam K Fisher
- Department of Biomedical Engineering, National University of Singapore
| | - Veena Salim
- Department of Biomedical Engineering, National University of Singapore
| | - Sangho Kim
- NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore; Department of Biomedical Engineering, National University of Singapore; Department of Surgery, National University of Singapore
| | - Bumseok Namgung
- Department of Biomedical Engineering, National University of Singapore;
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11
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Namgung B, Tan JKS, Wong PA, Park SY, Leo HL, Kim S. Biomimetic Precapillary Flow Patterns for Enhancing Blood Plasma Separation: A Preliminary Study. Sensors (Basel) 2016; 16:E1543. [PMID: 27657090 PMCID: PMC5038815 DOI: 10.3390/s16091543] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Revised: 09/06/2016] [Accepted: 09/13/2016] [Indexed: 12/03/2022]
Abstract
In this study, a biomimetic microfluidic plasma separation device is discussed. The design of the device drew inspiration from in vivo observations of enhanced cell-free layer (CFL) formation downstream of vascular bifurcations. The working principle for the plasma separation was based on the plasma skimming effect in an arteriolar bifurcation, which is modulated by CFL formation. The enhancement of the CFL width was achieved by a local hematocrit reduction near the collection channel by creating an uneven hematocrit distribution at the bifurcation of the channel. The device demonstrated a high purity of separation (~99.9%) at physiological levels of hematocrit (~40%).
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Affiliation(s)
- Bumseok Namgung
- Department of Biomedical Engineering, National University of Singapore, Singapore 117583, Singapore.
| | - Justin Kok Soon Tan
- Department of Biomedical Engineering, National University of Singapore, Singapore 117583, Singapore.
| | - Peter Agustinus Wong
- Department of Biomedical Engineering, National University of Singapore, Singapore 117583, Singapore.
| | - Sung-Yong Park
- Department of Mechanical Engineering, National University of Singapore, Singapore 117575, Singapore.
| | - Hwa Liang Leo
- Department of Biomedical Engineering, National University of Singapore, Singapore 117583, Singapore.
| | - Sangho Kim
- Department of Biomedical Engineering, National University of Singapore, Singapore 117583, Singapore.
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12
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Ng YC, Namgung B, Tien SL, Leo HL, Kim S. Symmetry recovery of cell-free layer after bifurcations of small arterioles in reduced flow conditions: effect of RBC aggregation. Am J Physiol Heart Circ Physiol 2016; 311:H487-97. [PMID: 27233764 DOI: 10.1152/ajpheart.00223.2016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Accepted: 05/26/2016] [Indexed: 11/22/2022]
Abstract
Heterogeneous distribution of red blood cells (RBCs) in downstream vessels of arteriolar bifurcations can be promoted by an asymmetric formation of cell-free layer (CFL) in upstream vessels. Consequently, the CFL widths in subsequent downstream vessels become an important determinant for tissue oxygenation (O2) and vascular tone change by varying nitric oxide (NO) availability. To extend our previous understanding on the formation of CFL in arteriolar bifurcations, this study investigated the formation of CFL widths from 2 to 6 vessel-diameter (2D-6D) downstream of arteriolar bifurcations in the rat cremaster muscle (D = 51.5 ± 1.3 μm). As the CFL widths are highly influenced by RBC aggregation, the degree of aggregation was adjusted to simulate levels seen during physiological and pathological states. Our in vivo experimental results showed that the asymmetry of CFL widths persists along downstream vessels up to 6D from the bifurcating point. Moreover, elevated levels of RBC aggregation appeared to retard the recovery of CFL width symmetry. The required length of complete symmetry recovery was estimated to be greater than 11D under reduced flow conditions, which is relatively longer than interbifurcation distances of arterioles for vessel diameter of ∼50 μm. In addition, our numerical prediction showed that the persistent asymmetry of CFL widths could potentially result in a heterogeneous vasoactivity over the entire arteriolar network in such abnormal flow conditions.
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Affiliation(s)
- Yan Cheng Ng
- NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore; Department of Biomedical Engineering, National University of Singapore, Singapore
| | - Bumseok Namgung
- Department of Biomedical Engineering, National University of Singapore, Singapore
| | - Sim Leng Tien
- Department of Hematology, Singapore General Hospital, Singapore; and
| | - Hwa Liang Leo
- NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore; Department of Biomedical Engineering, National University of Singapore, Singapore
| | - Sangho Kim
- NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore; Department of Biomedical Engineering, National University of Singapore, Singapore; Department of Surgery, National University of Singapore, Singapore
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13
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Ng YC, Namgung B, Leo HL, Kim S. Erythrocyte aggregation may promote uneven spatial distribution of NO/O2 in the downstream vessel of arteriolar bifurcations. J Biomech 2015; 49:2241-2248. [PMID: 26684432 DOI: 10.1016/j.jbiomech.2015.11.051] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Accepted: 11/07/2015] [Indexed: 11/16/2022]
Abstract
This study examined the effect of red blood cell (RBC) aggregation on nitric oxide (NO) and oxygen (O2) distributions in the downstream vessels of arteriolar bifurcations. Particular attention was paid to the inherent formation of asymmetric cell-free layer (CFL) widths in the downstream vessels and its consequential impact on the NO/O2 bioavailability after the bifurcations. A microscopic image-based two-dimensional transient model was used to predict the NO/O2 distribution by utilizing the in vivo CFL width data obtained under non-, normal- and hyper-aggregating conditions at the pseudoshear rate of 15.6±2.0s(-1). In vivo experimental result showed that the asymmetry of CFL widths was enhanced by the elevation in RBC aggregation level. The model demonstrated that NO bioavailability was regulated by the dynamic fluctuation of the local CFL widths, which is corollary to its modulation of wall shear stress. Accordingly, the uneven distribution of NO/O2 was prominent at opposite sides of the arterioles up to six vessel-diameter (6D) away from the bifurcating point, and this was further enhanced by increasing the levels of RBC aggregation. Our findings suggested that RBC aggregation potentially augments both the formation of asymmetric CFL widths and its influence on the uneven distribution of NO/O2 in the downstream flow of an arteriolar bifurcation. The extended heterogeneity of NO/O2 downstream (2D-6D) also implied its potential propagation throughout the entire arteriolar microvasculature.
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Affiliation(s)
- Yan Cheng Ng
- NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore; Department of Biomedical Engineering, National University of Singapore, Singapore
| | - Bumseok Namgung
- Department of Biomedical Engineering, National University of Singapore, Singapore
| | - Hwa Liang Leo
- NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore; Department of Biomedical Engineering, National University of Singapore, Singapore
| | - Sangho Kim
- NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore; Department of Biomedical Engineering, National University of Singapore, Singapore; Department of Surgery, National University of Singapore, Singapore.
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14
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Cho S, Namgung B, Kim HS, Leo HL, Kim S. Effect of erythrocyte aggregation at pathological levels on NO/O2 transport in small arterioles. Clin Hemorheol Microcirc 2015; 59:163-75. [PMID: 24732346 DOI: 10.3233/ch-141837] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
This study examined the effects of red blood cell (RBC) aggregation at pathological levels on NO/O2 transport in small arterioles. Transient gas diffusion simulations were performed with in vivo cell-free layer (CFL) widths data obtained from arteriolar flows in the rat cremaster muscle. The CFL data were measured at physiological and pathological levels of aggregation under reduced flow conditions (pseudoshear rate = 31.4 ± 10.5 s-1). Our results showed that the mean peak NO concentration significantly decreased with increasing the aggregation level from non-aggregating to normal-aggregating (P < 0.05) and to hyper-aggregating (P < 0.01) conditions. In contrast, the partial O2 pressure (PO2) in pathological aggregating conditions significantly increased from those under non-aggregating (P < 0.001) and normal-aggregating (P < 0.05) conditions. Although the NO scavenging by RBCs could be impaired with a thicker CFL at higher levels of aggregation, the overall decrease in NO production due to reduction of wall shear stress with the thicker CFL dominantly limited the NO availability in tissue. On the other hand, the O2 availability in tissue increased due to the relatively high core hematocrit in the blood lumen with the thicker CFL.
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Affiliation(s)
- Seungkwan Cho
- Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore Department of Biomedical Engineering, Yonsei University, Wonju, Gangwon, Korea
| | - Bumseok Namgung
- Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore
| | - Han Sung Kim
- Department of Biomedical Engineering, Yonsei University, Wonju, Gangwon, Korea
| | - Hwa Liang Leo
- Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore
| | - Sangho Kim
- Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore Department of Surgery, National University of Singapore, Singapore, Singapore
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15
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Nam J, Tan JKS, Khoo BL, Namgung B, Leo HL, Lim CT, Kim S. Hybrid capillary-inserted microfluidic device for sheathless particle focusing and separation in viscoelastic flow. Biomicrofluidics 2015; 9:064117. [PMID: 26734115 PMCID: PMC4691257 DOI: 10.1063/1.4938389] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Accepted: 12/07/2015] [Indexed: 05/22/2023]
Abstract
A novel microfluidic device which consists of two stages for particle focusing and separation using a viscoelastic fluid has been developed. A circular capillary tube was used for three-dimensional particle pre-alignment before the separation process, which was inserted in a polydimethylsiloxane microchannel. Particles with diameters of 5 and 10 μm were focused at the centerline in the capillary tube, and the location of particles was initialized at the first bifurcation. Then, 5 and 10 μm particles were successfully separated in the expansion region based on size-dependent lateral migration, with ∼99% separation efficiency. The proposed device was further applied to separation of MCF-7 cells from leukocytes. Based on the cell size distribution, an approximate size cutoff for separation was determined to be 16 μm. At 200 μl/min, 94% of MCF-7 cells were separated with the purity of ∼97%. According to the trypan blue exclusion assay, high viability (∼90%) could be achieved for the separated MCF-7 cells. The use of a commercially available capillary tube enables the device to be highly versatile in dealing with particles in a wide size range by using capillary tubes with different inner diameters.
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Affiliation(s)
- Jeonghun Nam
- Department of Biomedical Engineering, National University of Singapore , 9 Engineering Drive 1, Singapore 117575
| | - Justin Kok Soon Tan
- Department of Biomedical Engineering, National University of Singapore , 9 Engineering Drive 1, Singapore 117575
| | - Bee Luan Khoo
- Department of Biomedical Engineering, National University of Singapore , 9 Engineering Drive 1, Singapore 117575
| | - Bumseok Namgung
- Department of Biomedical Engineering, National University of Singapore , 9 Engineering Drive 1, Singapore 117575
| | - Hwa Liang Leo
- Department of Biomedical Engineering, National University of Singapore , 9 Engineering Drive 1, Singapore 117575
| | - Chwee Teck Lim
- Department of Biomedical Engineering, National University of Singapore , 9 Engineering Drive 1, Singapore 117575
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16
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Namgung B, Ng YC, Nam J, Leo HL, Kim S. Alteration of Blood Flow in a Venular Network by Infusion of Dextran 500: Evaluation with a Laser Speckle Contrast Imaging System. PLoS One 2015; 10:e0140038. [PMID: 26466371 PMCID: PMC4605724 DOI: 10.1371/journal.pone.0140038] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Accepted: 09/21/2015] [Indexed: 11/18/2022] Open
Abstract
This study examined the effect of dextran-induced RBC aggregation on the venular flow in microvasculature. We utilized the laser speckle contrast imaging (LSCI) as a wide-field imaging technique to visualize the flow distribution in venules influenced by abnormally elevated levels of RBC aggregation at a network-scale level, which was unprecedented in previous studies. RBC aggregation in rats was induced by infusing Dextran 500. To elucidate the impact of RBC aggregation on microvascular perfusion, blood flow in the venular network of a rat cremaster muscle was analyzed with a stepwise reduction of the arterial pressure (100 → 30 mmHg). The LSCI analysis revealed a substantial decrease in the functional vascular density after the infusion of dextran. The relative decrease in flow velocity after dextran infusion was notably pronounced at low arterial pressures. Whole blood viscosity measurements implied that the reduction in venular flow with dextran infusion could be due to the elevation of medium viscosity in high shear conditions (> 45 s-1). In contrast, further augmentation to the flow reduction at low arterial pressures could be attributed to the formation of RBC aggregates (< 45 s-1). This study confirmed that RBC aggregation could play a dominant role in modulating microvascular perfusion, particularly in the venular networks.
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Affiliation(s)
- Bumseok Namgung
- Department of Biomedical Engineering, National University of Singapore, Singapore
| | - Yan Cheng Ng
- Department of Biomedical Engineering, National University of Singapore, Singapore
- NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore
| | - Jeonghun Nam
- Department of Biomedical Engineering, National University of Singapore, Singapore
| | - Hwa Liang Leo
- Department of Biomedical Engineering, National University of Singapore, Singapore
- NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore
| | - Sangho Kim
- Department of Biomedical Engineering, National University of Singapore, Singapore
- NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore
- Department of Surgery, National University of Singapore, Singapore
- * E-mail:
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17
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Nam J, Namgung B, Lim CT, Bae JE, Leo HL, Cho KS, Kim S. Microfluidic device for sheathless particle focusing and separation using a viscoelastic fluid. J Chromatogr A 2015; 1406:244-50. [DOI: 10.1016/j.chroma.2015.06.029] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Revised: 06/10/2015] [Accepted: 06/12/2015] [Indexed: 11/30/2022]
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18
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Ng YC, Namgung B, Kim S. Two-dimensional transient model for prediction of arteriolar NO/O2 modulation by spatiotemporal variations in cell-free layer width. Microvasc Res 2014; 97:88-97. [PMID: 25312045 DOI: 10.1016/j.mvr.2014.08.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2014] [Revised: 08/13/2014] [Accepted: 08/14/2014] [Indexed: 10/24/2022]
Abstract
Despite the significant roles of the cell-free layer (CFL) in balancing nitric oxide (NO) and oxygen (O2) bioavailability in arteriolar tissue, many previous numerical approaches have relied on a one-dimensional (1-D) steady-state model for simplicity. However, these models are unable to demonstrate the influence of spatiotemporal variations in the CFL on the NO/O2 transport under dynamic flow conditions. Therefore, the present study proposes a new two-dimensional (2-D) transient model capable of predicting NO/O2 transport modulated by the spatiotemporal variations in the CFL width. Our model predicted that NO bioavailability was inversely related to the CFL width as expected. The enhancement of NO production by greater wall shear stress with a thinner CFL could dominate the diffusion barrier role of the CFL. In addition, NO/O2 availability along the vascular wall was inhomogeneous and highly regulated by dynamic changes of local CFL width variation. The spatial variations of CFL widths on opposite sides of the arteriole exhibited a significant inverse relation. This asymmetric formation of CFL resulted in a significantly imbalanced NO/O2 bioavailability on opposite sides of the arteriole. The novel integrative methodology presented here substantially highlighted the significance of spatiotemporal variations of the CFL in regulating the bioavailability of NO/O2, and provided further insight about the opposing effects of the CFL on arteriolar NO production.
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Affiliation(s)
- Yan Cheng Ng
- Department of Biomedical Engineering, National University of Singapore, Singapore
| | - Bumseok Namgung
- Department of Biomedical Engineering, National University of Singapore, Singapore
| | - Sangho Kim
- Department of Biomedical Engineering, National University of Singapore, Singapore; Department of Surgery, National University of Singapore, Singapore.
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19
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Kim S, Ng YC, Namgung B. Two‐dimensional model for prediction of arteriolar NO/O
2
modulation by spatiotemporal variations in cell‐free layer (678.13). FASEB J 2014. [DOI: 10.1096/fasebj.28.1_supplement.678.13] [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: 11/11/2022]
Affiliation(s)
- Sangho Kim
- Biomedical Engineering National University of SingaporeSingaporeSingapore
| | - Yan Cheng Ng
- Biomedical Engineering National University of SingaporeSingaporeSingapore
| | - Bumseok Namgung
- Biomedical Engineering National University of SingaporeSingaporeSingapore
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20
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Namgung B, Kim S. Effect of uneven red cell influx on formation of cell-free layer in small venules. Microvasc Res 2014; 92:19-24. [PMID: 24472285 DOI: 10.1016/j.mvr.2014.01.007] [Citation(s) in RCA: 8] [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] [Received: 10/03/2013] [Revised: 12/16/2013] [Accepted: 01/17/2014] [Indexed: 10/25/2022]
Abstract
This study examined how the uneven influx of red blood cells (RBCs) from feeding vessels influences formation of cell-free layer (CFL) in the downstream vessel of a venular bifurcation. Spatio-temporal variations of the CFL width along the downstream vessel (19-41-μm inner diameter, D) were determined at 0.5D intervals from 0.5D to 3.0D away from the bifurcation. Upstream flow conditions were quantified by the ratio of volume flow rates (Q*=Q(High)/Q(Low)) between high flow (Q(High)) and low flow feeding (Q(Low)) vessels. The RBC aggregation level in the rats was adjusted to be at healthy human levels by infusing Dextran 500. Our results suggested that the CFL formation process could be seen only from 2.0D away from the bifurcating point. The mean CFL width at the wall adjacent to the feeding vessel with a higher flow rate was consistently greater than that at the opposite wall, leading to an asymmetric CFL formation in the vessel. A positive relation (P<0.05) between the asymmetry of the CFL width and the volume flow rate ratio (Q*) was found. Our numerical prediction showed that flow resistance in the venular network could be significantly increased by the asymmetric formation of CFL downstream and this effect might become more pronounced under pathological flow conditions such as hyper-aggregating and/or low shear conditions.
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Affiliation(s)
- Bumseok Namgung
- Department of Biomedical Engineering, National University of Singapore, Singapore
| | - Sangho Kim
- Department of Biomedical Engineering, National University of Singapore, Singapore; Department of Surgery, National University of Singapore, Singapore.
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21
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Namgung B, Liang LH, Kim S. Physiological Significance of Cell-Free Layer and Experimental Determination of its Width in Microcirculatory Vessels. Visualization and Simulation of Complex Flows in Biomedical Engineering 2014. [DOI: 10.1007/978-94-007-7769-9_4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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22
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23
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Abstract
In this review, we provide an overview of the simulation techniques employed for modelling the flow of red blood cells (RBCs) in blood plasma. The scope of this review omits the fluid modelling aspect while focusing on other key components in the RBC-plasma model such as (1) describing the RBC deformation with shell-based and spring-based RBC models, (2) constitutive models for RBC aggregation based on bridging theory and depletion theory and (3) additional strategies required for completing the RBC-plasma flow model. These include topics such as modelling fluid-structure interaction with the immersed boundary method and boundary integral method, and updating the variations in multiphase fluid property through the employment of index field methods. Lastly, we summarily discuss the current state and aims of RBC modelling and suggest some research directions for the further development of this field of modelling.
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Affiliation(s)
- Meongkeun Ju
- a Department of Bioengineering , National University of Singapore , Singapore
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24
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Abstract
This article reviews numerical simulations of red blood cells (RBCs) mainly using the lattice Boltzmann method (LBM), focusing on the 2-dimensional deformation and aggregation of the cells in simple shear flow. We outline the incorporation of the immersed boundary method into the LBM, in which the membrane forces are obtained from the membrane model. The RBCs are simulated as a single biconcave capsule and as a doublet of biconcave capsules. The transition from swinging to tumbling motions of the RBCs, as induced by reducing the shear rate or increasing the membrane bending stiffness, is discussed. Also discussed is the aggregation tendency of the doublet of RBCs, for which homogenous deformability maintained RBC aggregation, whereas an increased deformability difference resulted in RBC dissociation.
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Affiliation(s)
- Hong-Tong Low
- Division of Bioengineering, Department of Mechanical Engineering, National University of Singapore, Singapore 117576
| | - M Ju
- Department of Biomedical Engineering, National University of Singapore, Singapore
| | - Y Sui
- School of Engineering and Materials Science, Queen Mary University of London, London, United Kingdom
| | - T Nazir
- Department of Mechanical Engineering, National University of Singapore, Singapore
| | - B Namgung
- Department of Biomedical Engineering, National University of Singapore, Singapore
| | - Sangho Kim
- Department of Bioengineering, National University of Singapore, Singapore 117575
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25
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Namgung B, Ju M, Cabrales P, Kim S. Two-phase model for prediction of cell-free layer width in blood flow. Microvasc Res 2012; 85:68-76. [PMID: 23116701 DOI: 10.1016/j.mvr.2012.10.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Revised: 10/09/2012] [Accepted: 10/19/2012] [Indexed: 11/26/2022]
Abstract
This study aimed to develop a numerical model capable of predicting changes in the cell-free layer (CFL) width in narrow tubes with consideration of red blood cell aggregation effects. The model development integrates to empirical relations for relative viscosity (ratio of apparent viscosity to medium viscosity) and core viscosity measured on independent blood samples to create a continuum model that includes these two regions. The constitutive relations were derived from in vitro experiments performed with three different glass-capillary tubes (inner diameter=30, 50 and 100 μm) over a wide range of pseudoshear rates (5-300 s(-1)). The aggregation tendency of the blood samples was also varied by adding Dextran 500 kDa. Our model predicted that the CFL width was strongly modulated by the relative viscosity function. Aggregation increased the width of CFL, and this effect became more pronounced at low shear rates. The CFL widths predicted in the present study at high shear conditions were in agreement with those reported in previous studies. However, unlike previous multi-particle models, our model did not require a high computing cost, and it was capable of reproducing results for a thicker CFL width at low shear conditions, depending on aggregating tendency of the blood.
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Affiliation(s)
- Bumseok Namgung
- Department of Bioengineering, National University of Singapore, Singapore
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26
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Cho S, Ong PK, Namgung B, Kim S. Numerical simulation of time‐dependent NO/O2 transport in arterioles. FASEB J 2012. [DOI: 10.1096/fasebj.26.1_supplement.860.7] [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: 11/11/2022]
Affiliation(s)
- Seungkwan Cho
- Bioengineering&SurgeryNational University of SingaporeSingporeSingapore
| | - Peng Kai Ong
- Bioengineering&SurgeryNational University of SingaporeSingporeSingapore
| | - Bumseok Namgung
- Bioengineering&SurgeryNational University of SingaporeSingporeSingapore
| | - Sangho Kim
- Bioengineering&SurgeryNational University of SingaporeSingporeSingapore
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27
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Kim S, Cho S, Namgung B. Effects of wall shear stress on NO simulation in arterioles. FASEB J 2012. [DOI: 10.1096/fasebj.26.1_supplement.860.6] [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: 11/11/2022]
Affiliation(s)
- Sangho Kim
- National University of SingaporeSingaporeSingapore
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28
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Ong PK, Cho S, Namgung B, Kim S. Effects of cell-free layer formation on NO/O2 bioavailability in small arterioles. Microvasc Res 2011; 83:168-77. [PMID: 22155421 DOI: 10.1016/j.mvr.2011.11.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2011] [Revised: 11/04/2011] [Accepted: 11/27/2011] [Indexed: 11/25/2022]
Abstract
We developed a new time-dependent computational model for coupled NO/O(2) transport in small arterioles that incorporates potential physiological responses (temporal changes in NO scavenging rate and O(2) partial pressure in blood lumen and NO production rate in endothelium) to the temporal cell-free layer width variations. Two relations between wall shear stress (WSS) and NO production rate based on the linear and sigmoidal functions were considered in this simulation study. The cell-free layer data used for the simulation were acquired from arteriolar flows (D=48.3 ± 1.9 μm) in the rat cremaster muscles under normal flow conditions (WSS=3.4-5.6 Pa). For both cases of linear and sigmoidal relations, temporal layer width variations were found to be capable of significantly enhancing NO bioavailability and this effect was more pronounced in the latter (P<0.0005) than the former (P<0.005). In contrast, O(2) bioavailability in the arteriolar wall was not considerably altered by the temporal layer width variations, irrespective of the relation. Prominent enhancement (P<0.005) of soluble guanylyl cyclase (sGC) activation in the smooth muscle by the temporal layer width variations were predicted for both relations. The extent of sGC activation was generally lower (P<0.01) in the case of the sigmoidal relation than that of the linear relation, suggesting a lesser tendency for arterioles to dilate with the former.
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Affiliation(s)
- Peng Kai Ong
- Department of Bioengineering, National University of Singapore, Singapore
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Ong PK, Jain S, Namgung B, Woo YI, Sakai H, Lim D, Chun KJ, Kim S. An automated method for cell-free layer width determination in small arterioles. Physiol Meas 2011; 32:N1-12. [PMID: 21252418 DOI: 10.1088/0967-3334/32/3/n01] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Histogram-based thresholding techniques utilized for cell-free layer width measurement in arteriolar flow may produce an overestimation of the layer width since they do not consider faint shaded regions near the vessel wall as part of the erythrocyte column. To address this problem, we developed a new method for detecting the boundary of the erythrocyte column based on an edge detection algorithm. This automated method (grayscale method) provides local detections of the inner vessel wall as well as the boundary between the cell-free layer and the erythrocyte column without binarization of grayscale images. The cell-free layer width measurements using the grayscale method and existing techniques (minimum method and Otsu's method) were compared with those determined manually in arteriolar flows of the rat cremaster muscle. In the absence of the shaded regions, values obtained by the grayscale method and minimum method were statistically in good agreement with the manual method but not in the case of Otsu's method. When the faint shaded regions were present, the grayscale method appeared to produce more accurate results than the minimum method and Otsu's method.
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Affiliation(s)
- P K Ong
- Division of Bioengineering and Department of Surgery, National University of Singapore, Singapore
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Namgung B, Ong PK, Wong YH, Lim D, Chun KJ, Kim S. A comparative study of histogram-based thresholding methods for the determination of cell-free layer width in small blood vessels. Physiol Meas 2010; 31:N61-70. [PMID: 20664158 DOI: 10.1088/0967-3334/31/9/n01] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
We have recently proposed a computer-based method utilizing a thresholding algorithm (the Otsu method) to provide a convenient way of measuring the cell-free layer width in vivo and in vitro. However, this method does not seem to be a universal method that can be applied to all microvascular studies. Thus, we examined four different histogram-based thresholding algorithms (Otsu, intermode, minimum and second peak) to provide a technical suggestion on the selection of a suitable thresholding algorithm for the cell-free layer measurement. All the measurements were taken in microvascular flows in the rat cremaster muscle recorded with a high-speed camera. The width of the cell-free layer manually measured was compared with that determined by the automated method utilizing the four thresholding algorithms. With our experimental system, results showed that the cell-free layer width determined by the minimum algorithm was in best accordance with the manual measurement. We concluded that the accuracy of the automated methods for determination of the cell-free layer width would depend on the image quality, in particular on the contrast between the red blood cell core and background, which might differ due to the different microscopic setup. Therefore, one may need to examine several appropriate thresholding methods when selecting the best suitable algorithm for the experimental conditions.
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Affiliation(s)
- Bumseok Namgung
- Department of Surgery, National University of Singapore, Singapore.
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Lim D, Namgung B, Woo DG, Choi JS, Kim HS, Tack GR. Effect of Input Waveform Pattern and Large Blood Vessel Existence on Destruction of Liver Tumor Using Radiofrequency Ablation: Finite Element Analysis. J Biomech Eng 2010; 132:061003. [DOI: 10.1115/1.4001029] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [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
Much research has been directed at improving the effectiveness of the radiofrequency (RF) ablation of hepatocellular carcinomas. In that point of view, this study was performed to provide comprehensive information of the relation between RF waveforms and thermodynamic response of the tissue with the consideration of four different types of RF waveforms (half-sine, half-square, half-exponential, and damped-sine) to maximize the amount of tumor tissue removed while maintaining the advantages of RF ablation. For the aim of this study, finite element models incorporating results from previous numerical models were used and validated with ex vivo experiments. From analyses of the entire results, we concluded that this study may prove valuable as a first step in providing comprehensive information of the relation between various RF waveforms and thermodynamic responses within the tissue during the RF ablation process. This study may also contribute toward studies to determine an optimum RF waveform capable of maximizing the amount of tumor tissue removed while maintaining the advantages of RF ablation.
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Affiliation(s)
- Dohyung Lim
- Gerontechnology Center, Korea Institute of Industrial Technology, Cheonan, Chungnam 330-825, Korea
| | - Bumseok Namgung
- Division of Bioengineering, and Department of Surgery, National University of Singapore, Singapore 117574, Singapore; Department of Biomedical Engineering, and Research Institute for Medical Instruments and Rehabilitation Engineering, Yonsei University, Wonju, Gangwon 220-710, Korea
| | - Dae Gon Woo
- Department of Biomedical Engineering, and Research Institute for Medical Instruments and Rehabilitation Engineering, Yonsei University, Wonju, Gangwon 220-710, Korea
| | - Jin Seung Choi
- Department of Biomedical Engineering, Konkuk University, Chungju, Chungbuk 380-701, Korea
| | - Han Sung Kim
- Department of Biomedical Engineering, and Research Institute for Medical Instruments and Rehabilitation Engineering, Yonsei University, Wonju, Gangwon 220-710, Korea
| | - Gye Rae Tack
- Department of Biomedical Engineering, Konkuk University, Chungju, Chungbuk 380-701, Korea
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Namgung B, Ong PK, Jain S, Lim D, Chun KJ, Kim S. Study of time‐dependent characteristics of a syllectrogram in the presence of aggregation inhibition. FASEB J 2010. [DOI: 10.1096/fasebj.24.1_supplement.1065.2] [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: 11/11/2022]
Affiliation(s)
- Bumseok Namgung
- BioengineeringNational University of SingaporeSingapore
- Gernotechnology CenterKorea Institute of Industrial TechnologyCheonanRepublic of Korea
| | - Peng Kai Ong
- BioengineeringNational University of SingaporeSingapore
| | - Swati Jain
- BioengineeringNational University of SingaporeSingapore
| | - Dohyung Lim
- Gernotechnology CenterKorea Institute of Industrial TechnologyCheonanRepublic of Korea
| | - Keyoung Jin Chun
- Gernotechnology CenterKorea Institute of Industrial TechnologyCheonanRepublic of Korea
| | - Sangho Kim
- BioengineeringNational University of SingaporeSingapore
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Abstract
Formation of a cell-free layer is an important dynamic feature of microcirculatory blood flow, which can be influenced by rheological parameters, such as red blood cell aggregation and flow rate. In this study, we investigate the effect of these two rheological parameters on cell-free layer characteristics in the arterioles (20-60 mum inner diameter). For the first time, we provide here the detailed temporal information of the arteriolar cell-free layer in various rheological conditions to better describe the characteristics of the layer variation. The rat cremaster muscle was used to visualize arteriolar flows, and the extent of aggregation was raised by dextran 500 infusion to levels seen in normal human blood. Our results show that cell-free layer formation in the arterioles is enhanced by a combination of flow reduction and red blood cell aggregation. A positive relation (P < 0.005) was found between mean cell-free layer widths and their corresponding SDs for all conditions. An analysis of the frequency and magnitudes of cell-free layer variation from their mean value revealed that the layer deviated with significantly larger magnitudes into the red blood cell core after flow reduction and dextran infusion (P < 0.05). In accordance, the disparity of cell-free layer width distribution found in opposite radial directions from its mean became greater with aggregation in reduced flow conditions. This study shows that the cell-free layer width in arterioles is dependent on both flow rate and red blood cell aggregability, and that the temporal variations in width are asymmetric with a greater excursion into the red blood cell core than toward the vessel wall.
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Affiliation(s)
- Peng Kai Ong
- Division of Bioengineering and Department of Surgery, National University of Singapore, Singapore
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