1
|
Ohara M, Ishikawa J, Yoshimoto S, Hakamata Y, Kobayashi E. A rat model of dual-flow liver machine perfusion system. Acta Cir Bras 2023; 38:e387723. [PMID: 37909599 PMCID: PMC10664844 DOI: 10.1590/acb387723] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Accepted: 10/01/2023] [Indexed: 11/03/2023] Open
Abstract
PURPOSE As clinical liver perfusion systems use portal vein and artery flow, dual perfusion techniques are required even in small animal models in order to reproduce clinical setting. The aim of this study was to construct a new dual-flow perfusion system in rat model and optimized the oxygen supply to ensure the aerobic metabolization. METHODS The dual-flow circuit was fabricated using rat liver and whole blood samples as perfusates. The oxygen supply was controlled according to the amount of dissolved oxygen in the perfusate. Perfusate parameters and adenosine triphosphate (ATP) levels were analyzed to evaluate organ function and metabolic energy state. Stored whole blood also tested the suitability as perfusate. RESULTS Stored blood showed decrease oxygen delivery and liver function compared to fresh blood. Using fresh blood as perfusate with air only, the dissolved oxygen levels remained low and anaerobic metabolism increased. In contrast, with oxygen control at living body level, anaerobic metabolism was well suppressed, and tissue ATP content was increased. CONCLUSIONS We developed a new dual-flow system that enable to reproduce the clinical settings. The perfusion system showed the possibility to improve the energy metabolic state of the perfused organ under appropriate partial pressure of oxygen.
Collapse
Affiliation(s)
- Masayuki Ohara
- Nippon Veterinary and Life Science University – School of Veterinary Nursing and Technology – Tokyo, Japan
- Screen Holdings Co., Ltd. – Innovation Development Department – Tokyo, Japan
| | - Jun Ishikawa
- Nippon Veterinary and Life Science University – School of Veterinary Nursing and Technology – Tokyo, Japan
- Screen Holdings Co., Ltd. – Innovation Development Department – Tokyo, Japan
| | - Syuhei Yoshimoto
- Screen Holdings Co., Ltd. – Innovation Development Department – Tokyo, Japan
| | - Yoji Hakamata
- Nippon Veterinary and Life Science University – School of Veterinary Nursing and Technology – Tokyo, Japan
| | - Eiji Kobayashi
- Nippon Veterinary and Life Science University – School of Veterinary Nursing and Technology – Tokyo, Japan
- Jikei University School of Medicine – Department of Kidney Regenerative Medicine – Kyoto, Japan
| |
Collapse
|
2
|
A fully automated bioreactor system for precise control of stem cell proliferation and differentiation. Biochem Eng J 2019. [DOI: 10.1016/j.bej.2019.107258] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
|
3
|
Sundby ØH, Høiseth LØ, Mathiesen I, Jørgensen JJ, Weedon-Fekjær H, Hisdal J. Application of intermittent negative pressure on the lower extremity and its effect on macro- and microcirculation in the foot of healthy volunteers. Physiol Rep 2017; 4:4/17/e12911. [PMID: 27630148 PMCID: PMC5027346 DOI: 10.14814/phy2.12911] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Accepted: 07/22/2016] [Indexed: 12/16/2022] Open
Abstract
Intermittent negative pressure (INP) applied to the lower leg and foot may increase peripheral circulation. However, it is not clear how different patterns of INP affect macro‐ and microcirculation in the foot. The aim of this study was therefore to determine the effect of different patterns of negative pressure on foot perfusion in healthy volunteers. We hypothesized that short periods with INP would elicit an increase in foot perfusion compared to no negative pressure. In 23 healthy volunteers, we continuously recorded blood flow velocity in a distal foot artery, skin blood flow, heart rate, and blood pressure during application of different patterns of negative pressure (−40 mmHg) to the lower leg. Each participant had their right leg inside an airtight chamber connected to an INP generator. After a baseline period at atmospheric pressure, we applied four different 120 sec sequences with either constant negative pressure or different INP patterns, in a randomized order. The results showed corresponding fluctuations in blood flow velocity and skin blood flow throughout the INP sequences. Blood flow velocity reached a maximum at 4 sec after the onset of negative pressure (average 44% increase above baseline, P < 0.001). Skin blood flow and skin temperature increased during all INP sequences (P < 0.001). During constant negative pressure, average blood flow velocity, skin blood flow, and skin temperature decreased (P < 0.001). In conclusion, we observed increased foot perfusion in healthy volunteers after the application of INP on the lower limb.
Collapse
Affiliation(s)
- Øyvind H Sundby
- Section of Vascular Investigations, Division of Cardiovascular and Pulmonary Diseases, Department of Vascular Surgery, Oslo University Hospital, Oslo, Norway Faculty of Medicine, Institute of Clinical Medicine, University of Oslo, Oslo, Norway Otivio AS, Gaustadalléen 21, Oslo, 0349, Norway
| | - Lars Øivind Høiseth
- Section of Vascular Investigations, Division of Cardiovascular and Pulmonary Diseases, Department of Vascular Surgery, Oslo University Hospital, Oslo, Norway Department of Anesthesiology, Oslo University Hospital, Oslo, Norway
| | | | - Jørgen J Jørgensen
- Faculty of Medicine, Institute of Clinical Medicine, University of Oslo, Oslo, Norway Department of Vascular Surgery, Oslo University Hospital, Oslo, Norway
| | - Harald Weedon-Fekjær
- Oslo Center for Biostatistics and Epidemiology, Research Support Services Oslo University Hospital, Oslo, Norway
| | - Jonny Hisdal
- Section of Vascular Investigations, Division of Cardiovascular and Pulmonary Diseases, Department of Vascular Surgery, Oslo University Hospital, Oslo, Norway
| |
Collapse
|
4
|
Lever MJ. The Role of Haemodynamic Forces in the Localization of Atherosclerotic Lesions. ACTA ACUST UNITED AC 2016. [DOI: 10.1177/1358863x9400500407] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Affiliation(s)
- M John Lever
- Physiological Flow Studies Group, Centre for Biological and Medical Systems, Imperial College of Science, Technology and Medicine, London, UK
| |
Collapse
|
5
|
Kirby PL, Buerk DG, Parikh J, Barbee KA, Jaron D. Mathematical model for shear stress dependent NO and adenine nucleotide production from endothelial cells. Nitric Oxide 2016; 52:1-15. [PMID: 26529478 PMCID: PMC4703509 DOI: 10.1016/j.niox.2015.10.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Revised: 10/21/2015] [Accepted: 10/27/2015] [Indexed: 11/19/2022]
Abstract
We developed a mass transport model for a parallel-plate flow chamber apparatus to predict the concentrations of nitric oxide (NO) and adenine nucleotides (ATP, ADP) produced by cultured endothelial cells (ECs) and investigated how the net rates of production, degradation, and mass transport for these three chemical species vary with changes in wall shear stress (τw). These simulations provide an improved understanding of experimental results obtained with parallel-plate flow chambers and allows quantitative analysis of the relationship between τw, adenine nucleotide concentrations, and NO produced by ECs. Experimental data obtained after altering ATP and ADP concentrations with apyrase were analyzed to quantify changes in the rate of NO production (RNO). The effects of different isoforms of apyrase on ATP and ADP concentrations and nucleotide-dependent changes in RNO could be predicted with the model. A decrease in ATP was predicted with apyrase, but an increase in ADP was simulated due to degradation of ATP. We found that a simple proportional relationship relating a component of RNO to the sum of ATP and ADP provided a close match to the fitted curve for experimentally measured changes in RNO with apyrase. Estimates for the proportionality constant ranged from 0.0067 to 0.0321 μM/s increase in RNO per nM nucleotide concentration, depending on which isoform of apyrase was modeled, with the largest effect of nucleotides on RNO at low τw (<6 dyn/cm(2)).
Collapse
Affiliation(s)
- Patrick L Kirby
- School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, PA 19104, USA
| | - Donald G Buerk
- School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, PA 19104, USA
| | - Jaimit Parikh
- School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, PA 19104, USA
| | - Kenneth A Barbee
- School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, PA 19104, USA
| | - Dov Jaron
- School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, PA 19104, USA.
| |
Collapse
|
6
|
Rodriguez JN, Hwang W, Horn J, Landsman TL, Boyle A, Wierzbicki MA, Hasan SM, Follmer D, Bryant J, Small W, Maitland DJ. Design and biocompatibility of endovascular aneurysm filling devices. J Biomed Mater Res A 2014; 103:1577-94. [PMID: 25044644 DOI: 10.1002/jbm.a.35271] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Revised: 06/01/2014] [Accepted: 06/12/2014] [Indexed: 12/13/2022]
Abstract
The rupture of an intracranial aneurysm, which can result in severe mental disabilities or death, affects approximately 30,000 people in the United States annually. The traditional surgical method of treating these arterial malformations involves a full craniotomy procedure, wherein a clip is placed around the aneurysm neck. In recent decades, research and device development have focused on new endovascular treatment methods to occlude the aneurysm void space. These methods, some of which are currently in clinical use, utilize metal, polymeric, or hybrid devices delivered via catheter to the aneurysm site. In this review, we present several such devices, including those that have been approved for clinical use, and some that are currently in development. We present several design requirements for a successful aneurysm filling device and discuss the success or failure of current and past technologies. We also present novel polymeric-based aneurysm filling methods that are currently being tested in animal models that could result in superior healing.
Collapse
Affiliation(s)
- Jennifer N Rodriguez
- Department of Biomedical Engineering, Texas A&M University, 3120 TAMU, College Station, Texas, 77843
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
7
|
Vascular Endothelium. TISSUE FUNCTIONING AND REMODELING IN THE CIRCULATORY AND VENTILATORY SYSTEMS 2013. [DOI: 10.1007/978-1-4614-5966-8_9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
|
8
|
Abstract
Extracellular adenine nucleotides ATP and ADP on vascular endothelial cells may play a role in the localization of atherogenesis by regulating the release of nitric oxide from endothelial cells and modulating intracellular calcium levels. To quantitatively investigate the concentration distribution of nucleotides on the luminal surface of the human thoracic aorta, we numerically simulated the transport of nucleotides using an aorta model constructed based on MRI images and analyzed the effects of different factors on nucleotide transport, such as ATP release rate (S(ATP)), pulsatile flow and the absence of ATP in the main blood stream. The numerical results revealed that the combined concentration of ATP and ADP (c(w-ATP+ADP)) on the aortic surface varied from place to place, being relatively low in disturbed flow regions. In addition, c(w-ATP+ADP) was significantly affected by S(ATP). For relatively slow S(ATP), such as the moderate sigmoidal release model, c(w-ATP+ADP) was very low in certain flow regions with low wall shear stress. However, for very rapid S(ATP), such as the rapid linear release model, c(w-ATP+ADP) was relatively high in these same regions. The results also demonstrated that for relatively slow S(ATP), pulsatile blood flow enhanced c(w-ATP+ADP). However, for very rapid S(ATP), pulsatile blood flow would reduce c(w-ATP+ADP). Moreover, the absence of ATP within the main blood stream would not influence the distribution of c(w-ATP+ADP). In conclusion, the concentration distribution of nucleotides along the aortic wall was quite uneven and determined by both the ATP release rate and the blood flow pattern in the aorta.
Collapse
Affiliation(s)
- Xiao Liu
- Key Laboratory for Biomechanics and Mechanobiology of the Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing, China
| | | | | | | |
Collapse
|
9
|
Martens DE, Nollen EA, Hardeveld M, Velden-de Groot CA, Gooijer CD, Beuvery EC, Tramper J. Death rate in a small air-lift loop reactor of vero cells grown on solid microcarriers and in macroporous microcarriers. Cytotechnology 2012; 23:61-75. [PMID: 22358522 DOI: 10.1023/b:cyto.0000010399.23373.65] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The death rate of Vero cells grown on Cytodex-3 microcarrierswas studied as a function of the gas flow rate in a smallair-lift loop reactor. The death rate may be described byfirst-order death-rate kinetics. The first-order death-rateconstant as calculated from the decrease in viable cells, theincrease in dead cells and the increase in LDH activity islinear proportional to the gas flow rate, with a specifichypothetical killing volume in which all cells are killed ofabout 2.10(-3)m(3) liquid per m(3) of air bubbles.In addition, an experiment was conducted in the sameair-lift reactor with Vero cells grown inside porous Asahimicrocarriers. The specific hypothetical killing volumecalculated from this experiment has a value of 3.10(-4)m(3) liquid per m(3) of air bubbles, which shows thatthe porous microcarriers were at least in part able to protectthe cells against the detrimental hydrodynamic forcesgenerated by the bubbles.
Collapse
Affiliation(s)
- D E Martens
- Department of Food Science, Food and Bioengeneering Group, Agricultural University, Bomenweg 2, 6703 HD, Wageningen, The Netherlands
| | | | | | | | | | | | | |
Collapse
|
10
|
Freyberg MA, Friedl P. The use of a conventional tissue culture plate as an optically accessible perfusion chamber for in situ assays and for long-term cultivation of mammalian cells. Cytotechnology 2012; 26:49-58. [PMID: 22359006 DOI: 10.1023/a:1007989802251] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
An alternative culture system has been developed based on a conventional tissue culture plate (3.5 cm diameter) which is changed into a closed perfusion chamber. The system can easily be scaled up from one to several chambers. The shape and the size of the area of cell growth may be designed to individual experimental demands. The whole culture chamber is optically accessible, so cell growth and morphology can be evaluated by light microscopy. Furthermore the cellular physiology can be characterised by any fluorimetric assay using a bottom type fluorescence reader. A peristaltic pump sustains a constant medium flow through the chamber thus creating true homeostasis. The use of HPLC-valves and connectors allows the switching between different media or assay solutions. Thus it is possible to perform in situ assays also measuring transient effects. A protocol for vitality tests using calcein-AM is worked out for an adherent cell line and for a suspension cell line. The lower detection limits are 7 × 10(2) cells cm(-2) for the adherent cells and 5 × 10(4) cells mL(-1) for the suspension cells. The upper limits are 1-2 × 10(5) cells cm(-2) respectively 8 × 10(6) cells mL(-1).
Collapse
Affiliation(s)
- M A Freyberg
- Technische Hochschule Darmstadt, Inst. f. Biochemie, Petersenstr. 22, D-64287, Darmstadt, Germany
| | | |
Collapse
|
11
|
Bahi A, Dreyer JL. Hippocampus-specific deletion of tissue plasminogen activator "tPA" in adult mice impairs depression- and anxiety-like behaviors. Eur Neuropsychopharmacol 2012; 22:672-82. [PMID: 22377193 DOI: 10.1016/j.euroneuro.2012.01.008] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Revised: 12/12/2011] [Accepted: 01/12/2012] [Indexed: 10/28/2022]
Abstract
Anxiety and depression are multifactorial disorders that have become prominent health problems all over the world. Neurotrophic factors have emerged underlying pathogenesis of these diseases. Although a number of studies indicate that the hippocampus-brain-derived neurotrophic factor (BDNF) may be involved in these psychiatric illnesses, little is known about the molecular mediators of these disorders. In this study we further investigate the role of tissue plasminogen activator (tPA), a serine protease involved in pro-BDNF cleavage to BDNF, in depression and anxiety-like behaviors in adult mice. To address this issue, we investigated the effect of hippocampus tPA manipulation, using viral vectors, on anxiety- and depression-like behaviors, including the marble burying test (MBT), elevated plus maze (EPM), tail suspension test (TST), novelty suppressed feeding (NSF) and forced swim test (FST). Our results showed that tPA knock-down - using lentiviral vectors expressing specific short hairpin RNAs (LV-shRNA) - increased the number of buried marbles together with the digging time in the MBT and decreased the time spent in open the arms of an EPM. In addition, tPA-knock down in the hippocampus increased immobility in the FST and TST, and increased time to feed in the NSF test. These effects were reversed when tPA-over-expressing vectors (LV-tPA) were injected in the hippocampus. We also found that BDNF protein levels were elevated in the hippocampus of mice receiving tPA-expressing vectors. Together, our results imply that tPA manipulation may provide an effective therapeutic intervention for depression and anxiety disorders.
Collapse
Affiliation(s)
- Amine Bahi
- Department of Anatomy, Tawam Medical Campus, United Arab Emirates University, Al Ain, United Arab Emirates.
| | | |
Collapse
|
12
|
Flow-dependent mass transfer may trigger endothelial signaling cascades. PLoS One 2012; 7:e35260. [PMID: 22558132 PMCID: PMC3338739 DOI: 10.1371/journal.pone.0035260] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Accepted: 03/14/2012] [Indexed: 01/08/2023] Open
Abstract
It is well known that fluid mechanical forces directly impact endothelial signaling pathways. But while this general observation is clear, less apparent are the underlying mechanisms that initiate these critical signaling processes. This is because fluid mechanical forces can offer a direct mechanical input to possible mechanotransducers as well as alter critical mass transport characteristics (i.e., concentration gradients) of a host of chemical stimuli present in the blood stream. However, it has recently been accepted that mechanotransduction (direct mechanical force input), and not mass transfer, is the fundamental mechanism for many hemodynamic force-modulated endothelial signaling pathways and their downstream gene products. This conclusion has been largely based, indirectly, on accepted criteria that correlate signaling behavior and shear rate and shear stress, relative to changes in viscosity. However, in this work, we investigate the negative control for these criteria. Here we computationally and experimentally subject mass-transfer limited systems, independent of mechanotransduction, to the purported criteria. The results showed that the negative control (mass-transfer limited system) produced the same trends that have been used to identify mechanotransduction-dominant systems. Thus, the widely used viscosity-related shear stress and shear rate criteria are insufficient in determining mechanotransduction-dominant systems. Thus, research should continue to consider the importance of mass transfer in triggering signaling cascades.
Collapse
|
13
|
Youssef K, Mack JJ, Iruela-Arispe ML, Bouchard LS. Macro-scale topology optimization for controlling internal shear stress in a porous scaffold bioreactor. Biotechnol Bioeng 2012; 109:1844-54. [PMID: 22252902 DOI: 10.1002/bit.24440] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2011] [Revised: 12/29/2011] [Accepted: 01/06/2012] [Indexed: 11/07/2022]
Abstract
Shear stress is an important physical factor that regulates proliferation, migration, and morphogenesis. In particular, the homeostasis of blood vessels is dependent on shear stress. To mimic this process ex vivo, efforts have been made to seed scaffolds with vascular and other cell types in the presence of growth factors and under pulsatile flow conditions. However, the resulting bioreactors lack information on shear stress and flow distributions within the scaffold. Consequently, it is difficult to interpret the effects of shear stress on cell function. Such knowledge would enable researchers to improve upon cell culture protocols. Recent work has focused on optimizing the microstructural parameters of the scaffold to fine tune the shear stress. In this study, we have adopted a different approach whereby flows are redirected throughout the bioreactor along channels patterned in the porous scaffold to yield shear stress distributions that are optimized for uniformity centered on a target value. A topology optimization algorithm coupled to computational fluid dynamics simulations was devised to this end. The channel topology in the porous scaffold was varied using a combination of genetic algorithm and fuzzy logic. The method is validated by experiments using magnetic resonance imaging readouts of the flow field.
Collapse
Affiliation(s)
- K Youssef
- Department of Biomedical Engineering, University of California, Los Angeles, California 90095, USA
| | | | | | | |
Collapse
|
14
|
Patrick CW, McIntire LV. Fluid Shear Stress Effects on Endothelial Cell Cytosolic pH. ACTA ACUST UNITED AC 2011; 1:53-70. [PMID: 19877915 DOI: 10.1089/ten.1995.1.53] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Fluid flow can modulate endothelial cell intracellular pH (pH(i)). Venous and arterial shear stresses of 1.4 and 14 dyn/cm2, respectively, induced intracellular acidification. The kinetics of the process and magnitude of acidification were dependent on the level of shear stress. Endothelial cells exposed to a venous shear stress were able to recover from the acidification, whereas cells exposed to an arterial shear stress remained acidic. Addition of SITS (1 mM), a HCO(3) (-)/CI(-) exchange inhibitor, greatly reduced the shear stress induced acidification, suggesting that the HCO(3) (-)/C1(-) exchanger is activated by shear stress. Shear stress may activate the exchanger by lowering the [HCO(3) (-)] at the cell surface via convective mass transfer. Altering the HCO(3) (-) gradient across the cell membrane activates the exchanger and, as a consequence, results in intracellular acidification. Perfusion with media containing ATP (10 microM) altered the kinetics of flow-induced acidification observed at both shear stress levels. ATP modulation of pH(i) may be coupled to the rise in [Ca(2+)](j) known to occur with ATP stimulation. To summarize, media perfusion induces intracellular acidification in endothelial cells, and there is evidence to suggest that pH(i) may serve as a second messenger to modulate flow associated changes in endothelial cell metabolism.
Collapse
Affiliation(s)
- C W Patrick
- Cox Laboratory for Biomedical Engineering, Institute of Biosciences and Bioengineering, Rice University, Houston, Texas 77005-1892
| | | |
Collapse
|
15
|
Comerota AJ. Intermittent pneumatic compression: physiologic and clinical basis to improve management of venous leg ulcers. J Vasc Surg 2010; 53:1121-9. [PMID: 21050701 DOI: 10.1016/j.jvs.2010.08.059] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2010] [Revised: 08/19/2010] [Accepted: 08/19/2010] [Indexed: 11/16/2022]
Abstract
Venous leg ulcers (VLUs) are a significant health problem that afflicts 1% of the population at some point during their lifetime. Intermittent pneumatic compression (IPC) is widely used to prevent deep venous thrombosis. However, IPC seems to have application to a broader base of circulatory diseases. The intermittent nature of pulsatile external compression produces beneficial physiologic changes, which include hematologic, hemodynamic, and endothelial effects, which should promote healing of VLUs. Clinical studies of the management of VLUs show that IPC increases overall healing and accelerates the rate of healing, leading to current guideline recommendations for care of patients with VLUs. Proper prescription of IPC to improve the management of patients with VLUs requires further definition. It seems that application of IPC in combination with sustained graduated compression improves outcome in patients with the most advanced venous disease.
Collapse
|
16
|
Study of cell seeding on porous poly(d,l-lactic-co-glycolic acid) sponge and growth in a Couette–Taylor bioreactor. Chem Eng Sci 2010. [DOI: 10.1016/j.ces.2009.12.006] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
|
17
|
Van Doormaal MA, Ethier CR. Design optimization of a helical endothelial cell culture device. Biomech Model Mechanobiol 2010; 9:523-31. [PMID: 20148347 DOI: 10.1007/s10237-010-0192-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2009] [Accepted: 01/18/2010] [Indexed: 11/28/2022]
Abstract
The specific roles of mass transfer and fluid dynamic stresses on endothelial function, important in atherogenesis, are not known. Further, the effects of mass transfer and fluid dynamic stresses are difficult to separate because areas of "abnormal" mass transfer and "abnormal" wall shear stress tend to co-localize (where abnormal is defined as any deviation from the mass transfer rate or wall shear stress present in a long straight artery with the same flow rate and diameter). Our goal was to design a cell culture device which gives maximum separation between areas of abnormal shear stress and areas of abnormal mass transfer. We used design optimization principles to design a helical cell culture device. Using shear stress and mass transfer fields predicted by solving the governing equations, the area of the device which was exposed to low rates of mass transfer and normal levels of wall shear stress was determined. The design optimization method then maximized this area by varying the design variables, resulting in the optimum design. The optimum design had Reynolds number = 50, helical radius = 3.23 and helical pitch = 3.82. The area of the device which was exposed to low rates of mass transfer and regular levels of wall shear stress was about 4.5 times the inlet cross-sectional area of the device or about 5% of the device total internal surface area. An optimum design was successfully determined and the methodology used was shown to be robust. The area of the device which was exposed to low rates of mass transfer and regular levels of wall shear stress occurred in a defined region which should aid further experimental work.
Collapse
|
18
|
Choi HW, Barakat AI. Modulation of ATP/ADP concentration at the endothelial cell surface by flow: effect of cell topography. Ann Biomed Eng 2009; 37:2459-68. [PMID: 19763828 PMCID: PMC2778776 DOI: 10.1007/s10439-009-9793-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2009] [Accepted: 08/31/2009] [Indexed: 11/30/2022]
Abstract
Determining how flow affects the concentration of the adenine nucleotides ATP and ADP at the vascular endothelial cell (EC) surface is essential for understanding flow-induced mobilization of intracellular calcium. Previously, mathematical models were formulated to describe the ATP/ADP concentration at the EC surface; however, all previous models assumed the endothelium to be flat. In the present study we investigate the effect of surface undulations on ATP/ADP concentration at the EC surface. The results demonstrate that under certain geometric and flow conditions, the ATP + ADP concentration at the EC surface is considerably lower for a wavy cell surface than for a flat surface. Because ECs in regions of disturbed arterial flow are expected to have larger undulations than cells in non-disturbed flow zones, our findings suggest that ECs in regions of flow disturbance would exhibit lower ATP + ADP concentrations at their surfaces, which may lead to impaired calcium signaling. If validated experimentally, the present results may contribute to our understanding of endothelial cell dysfunction observed in regions of disturbed flow.
Collapse
Affiliation(s)
- Hyo Won Choi
- Department of Mechanical and Aeronautical Engineering, University of California, Davis, One Shields Avenue, Davis, CA 95616 USA
| | - Abdul I. Barakat
- Department of Mechanical and Aeronautical Engineering, University of California, Davis, One Shields Avenue, Davis, CA 95616 USA
| |
Collapse
|
19
|
Ranjan A, Webster TJ. Increased endothelial cell adhesion and elongation on micron-patterned nano-rough poly(dimethylsiloxane) films. NANOTECHNOLOGY 2009; 20:305102. [PMID: 19581692 DOI: 10.1088/0957-4484/20/30/305102] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The success of synthetic vascular grafts is largely determined by their ability to promote vital endothelial cell functions such as adhesion, alignment, proliferation, and extracellular matrix (ECM) deposition. Developing such biomaterials requires the design and fabrication of materials that mimic select properties of native extracellular matrices. Furthermore, cells of the native endothelium have elongated and aligned morphology in the direction of blood flow, yet few materials promote this type of morphology initially, but rather rely on blood flow to orient endothelial cells. Therefore, the objective of this in vitro study was to design a biomaterial that mimics the conditions of the micro- and nano-environment of vascular intima tissue suitable for endothelial cell adhesion and elongation to improve the efficacy of small synthetic vascular grafts. Towards this end, patterned poly(dimethylsiloxane) (PDMS) films consisting of periodic arrays of nano-grooves (500 nm), with spacings ranging from 22 to 80 microm, and alternating nano- and micron roughness were fabricated using a novel electron beam physical vapor deposition method followed by polymer casting. By varying pattern spacing, the area of micron- and nano-rough surface was controlled. In vitro rat aortic endothelial cell adhesion and elongation studies indicated that endothelial cell function was enhanced on patterned PDMS surfaces with the widest spacing and greatest surface area of nano-roughness, as compared to more narrow pattern spacings and non-patterned PDMS surfaces. Specifically, endothelial cells adherent on PDMS patterned films of the widest spacing (greatest nano-rough area) displayed almost twice as much elongation as cells on non-patterned surfaces. For these reasons, the present study highlighted design criteria (the use of micron patterns of nano-features on PDMS) that may contribute to the intelligent design of new-generation vascular grafts.
Collapse
Affiliation(s)
- Ashwini Ranjan
- Division of Engineering, Brown University, Providence, RI 02912, USA
| | | |
Collapse
|
20
|
Yin H, Zhang X, Pattrick N, Klauke N, Cordingley HC, Haswell SJ, Cooper JM. Influence of Hydrodynamic Conditions on Quantitative Cellular Assays in Microfluidic Systems. Anal Chem 2007; 79:7139-44. [PMID: 17658886 DOI: 10.1021/ac071146k] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
This study demonstrates the importance of the hydrodynamic environment in microfluidic systems in quantitative cellular assays using live cells. Commonly applied flow conditions used in microfluidics were evaluated using the quantitative intracellular Ca2+ analysis of Chinese hamster ovary (CHO) cells as a model system. Above certain thresholds of shear stress, hydrodynamically induced intracellular Ca2+ fluxes were observed which mimic the responses induced by chemical stimuli, such as the agonist uridine 5'-triphosphate tris salt (UTP). This effect is of significance given the increasing application of microfluidic devices in high-throughput cellular analysis for biophysical applications and pharmacological screening.
Collapse
Affiliation(s)
- Huabing Yin
- Department of Electronics and Electrical Engineering, University of Glasgow, Glasgow, G12 8LT, U.K
| | | | | | | | | | | | | |
Collapse
|
21
|
Qin KR, Xiang C, Xu Z, Cao LL, Ge SS, Jiang ZL. Dynamic modeling for shear stress induced ATP release from vascular endothelial cells. Biomech Model Mechanobiol 2007; 7:345-53. [PMID: 17497190 DOI: 10.1007/s10237-007-0088-8] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2006] [Accepted: 04/04/2007] [Indexed: 11/25/2022]
Abstract
A dynamic model is proposed for shear stress induced adenosine triphosphate (ATP) release from endothelial cells (ECs). The dynamic behavior of the ATP/ADP concentration at the endothelial surface by viscous shear flow is investigated through simulation studies based on the dynamic ATP release model. The numerical results demonstrate that the ATP/ADP concentration against time at endothelium-fluid interface predicted by the dynamic ATP release model is more consistent with the experimental observations than that predicted by previous static ATP release model.
Collapse
Affiliation(s)
- Kai Rong Qin
- Institute of Mechanobiology and Medical Engineering, Shanghai Jiao Tong University, Mailbox 888, 800 Dongchuan Road, Minhang, Shanghai 200240, China.
| | | | | | | | | | | |
Collapse
|
22
|
Choi HW, Barakat AI. Modulation of ATP/ADP concentration at the endothelial surface by shear stress: effect of flow disturbance. CONFERENCE PROCEEDINGS : ... ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL CONFERENCE 2007; 2004:5065-8. [PMID: 17271456 DOI: 10.1109/iembs.2004.1404400] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
The adenine nucleotides ATP and ADP modulate the release of endothelial-derived relaxing factors and hence play an important role in flow-mediated arterial vasoregulation. Adenine nucleotide concentration at the endothelial cell (EC) surface within an artery is determined by a balance of convective-diffusive delivery of blood-borne nucleotides to the EC surface, hydrolysis of these nucleotides at the cell surface, and flow-induced ATP release from ECs. Previous numerical simulations in a parallel plate flow chamber had demonstrated that flow-induced ATP release has a profound effect on nucleotide concentration under both steady and pulsatile flow conditions. In the present study, we have extended this analysis to probe the impact of disturbed flow downstream of a backward facing step on adenine nucleotide concentration at the EC surface. The results have demonstrated that over a wide range of applied wall shear stress, the ATP concentration at the EC surface drops abruptly within the disturbed flow zone due to increased nucleotide residence time within this region. The concentration is intricately sensitive to the kinetics of flow-induced ATP release, and this sensitivity is more pronounced at lower levels of wall shear stress.
Collapse
Affiliation(s)
- H W Choi
- Department of Mechanical & Aeronautical Engineering, California University, Davis, CA, USA
| | | |
Collapse
|
23
|
Choi HW, Ferrara KW, Barakat AI. Modulation of ATP/ADP concentration at the endothelial surface by shear stress: effect of flow recirculation. Ann Biomed Eng 2007; 35:505-16. [PMID: 17253149 DOI: 10.1007/s10439-006-9247-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2006] [Accepted: 12/05/2006] [Indexed: 10/23/2022]
Abstract
The extracellular presence of the adenine nucleotides ATP and ADP induces calcium mobilization in vascular endothelial cells (ECs). ATP/ADP concentration at the EC surface is determined by a balance of convective-diffusive transport to and from the EC surface, hydrolysis by ectonucleotidases at the cell surface, and flow-induced ATP release from ECs. Our previous numerical simulations in a parallel plate geometry had demonstrated that flow-induced ATP release has a profound effect on nucleotide concentration at the EC surface. In the present study, we have extended the modeling to probe the impact of flow separation and recirculation downstream of a backward facing step (BFS) on ATP/ADP concentration at the EC surface. The results show that for both steady and pulsatile flow over a wide range of wall shear stresses, the ATP+ADP concentration at the EC surface is considerably lower within the flow recirculation region than in areas of undisturbed flow outside the recirculation zone. Pulsatile flow also leads to sharp temporal gradients in nucleotide concentration. If confirmed experimentally, the present findings suggest that disturbed and undisturbed flow may affect EC calcium mobilization differently. Such differences might, in turn, contribute to the observed endothelial dysfunction in regions of disturbed flow.
Collapse
Affiliation(s)
- Hyo Won Choi
- Department of Mechanical and Aeronautical Engineering, University of California, Davis, CA 95616, USA
| | | | | |
Collapse
|
24
|
Zeng Y, Lee TS, Yu P, Low HT. Numerical Simulation on Mass Transport in a Microchannel Bioreactor for Co-culture Applications. J Biomech Eng 2006; 129:365-73. [PMID: 17536903 DOI: 10.1115/1.2720913] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Microchannel bioreactors have applications for manipulating and investigating the fluid microenvironment on cell growth and functions in either single culture or co-culture. This study considers two different types of cells distributed randomly as a co-culture at the base of a microchannel bioreactor: absorption cells, which only consume species based on the Michaelis-Menten process, and release cells, which secrete species, assuming zeroth order reaction, to support the absorption cells. The species concentrations at the co-culture cell base are computed from a three-dimensional numerical flow-model incorporating mass transport. Combined dimensionless parameters are proposed for the co-culture system, developed from a simplified analysis under the condition of decreasing axial-concentration. The numerical results of species concentration at the co-culture cell-base are approximately correlated by the combined parameters under the condition of positive flux-parameter. Based on the correlated results, the critical value of the inlet concentration is determined, which depends on the effective microchannel length. For the flow to develop to the critical inlet concentration, an upstream length consisting only of release cells is needed; this upstream length is determined from an analytical solution. The generalized results may find applications in analyzing the mass transport requirements in a co-culture microchannel bioreactor.
Collapse
Affiliation(s)
- Yan Zeng
- Department of Mechanical Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117576
| | | | | | | |
Collapse
|
25
|
Zeng Y, Lee TS, Yu P, Roy P, Low HT. Mass transport and shear stress in a microchannel bioreactor: numerical simulation and dynamic similarity. J Biomech Eng 2006; 128:185-93. [PMID: 16524329 DOI: 10.1115/1.2170118] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Microchannel bioreactors have been used in many studies to manipulate and investigate the fluid microenvironment around cells. In this study, substrate concentrations and shear stresses at the base were computed from a three-dimensional numerical flow-model incorporating mass transport. Combined dimensionless parameters were developed from a simplified analysis. The numerical results of substrate concentration were well correlated by the combined parameters. The generalized results may find applications in design analysis of microchannel bioreactors. The mass transport and shear stress were related in a generalized result. Based on the generalized results and the condition of dynamic similarity, various means to isolate their respective effects on cells were considered.
Collapse
Affiliation(s)
- Yan Zeng
- Department of Mechanical Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117576
| | | | | | | | | |
Collapse
|
26
|
Ye T, Bull JL. Direct numerical simulations of micro-bubble expansion in gas embolotherapy. J Biomech Eng 2005; 126:745-59. [PMID: 15796333 DOI: 10.1115/1.1824131] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
We are currently developing a novel gas embolotherapy technique that involves the selective, acoustic vaporization of liquid perfluorocarbon droplets in or near a tumor as a possible treatment for cancer The resulting bubbles can then stick within the tumor vasculature to occlude blood flow and "starve" the tumor The potential development of high stresses during droplet vaporization is a major concern for safe implementation of this technique. No prior study, either experimentally or theoretically, addresses this important issue. In this work, the acoustic vaporization procedure of the therapy is investigated by direct numerical simulations. The nonlinear, multiphase, computational model is comprised of an ideal gas bubble surrounded by liquid inside a long tube. Convective and unsteady inertia, viscosity, and surface tension affect the bubble dynamics and are included in this model, which is solved by a novel fixed-grid, sharp-interface, moving boundary method. We assess the potential for flow-induced wall stresses to rupture the vessel or damage the endothelium during vaporization under a range of operating conditions by varying dimensionless parameters--Reynolds, Weber, and Strouhal numbers, inertial energy and initial droplet size. It is found that the wall pressure is typically highest at the start of the bubble expansion, but the maximum wall shear stress occurs at a later time. Smaller initial bubble diameters, relative to the vessel diameter, result in lower wall stresses.
Collapse
Affiliation(s)
- Tao Ye
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109, USA
| | | |
Collapse
|
27
|
Yu X, Botchwey EA, Levine EM, Pollack SR, Laurencin CT. Bioreactor-based bone tissue engineering: the influence of dynamic flow on osteoblast phenotypic expression and matrix mineralization. Proc Natl Acad Sci U S A 2004; 101:11203-8. [PMID: 15277663 PMCID: PMC509184 DOI: 10.1073/pnas.0402532101] [Citation(s) in RCA: 190] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2004] [Indexed: 01/13/2023] Open
Abstract
An important issue in tissue engineering concerns the possibility of limited tissue ingrowth in tissue-engineered constructs because of insufficient nutrient transport. We report a dynamic flow culture system using high-aspect-ratio vessel rotating bioreactors and 3D scaffolds for culturing rat calvarial osteoblast cells. 3D scaffolds were designed by mixing lighter-than-water (density, <1g/ml) and heavier-than-water (density, >1g/ml) microspheres of 85:15 poly(lactide-co-glycolide). We quantified the rate of 3D flow through the scaffolds by using a particle-tracking system, and the results suggest that motion trajectories and, therefore, the flow velocity around and through scaffolds in rotating bioreactors can be manipulated by varying the ratio of heavier-than-water to lighter-than-water microspheres. When rat primary calvarial cells were cultured on the scaffolds in bioreactors for 7 days, the 3D dynamic flow environment affected bone cell distribution and enhanced cell phenotypic expression and mineralized matrix synthesis within tissue-engineered constructs compared with static conditions. These studies provide a foundation for exploring the effects of dynamic flow on osteoblast function and provide important insight into the design and optimization of 3D scaffolds suitable in bioreactors for in vitro tissue engineering of bone.
Collapse
Affiliation(s)
- Xiaojun Yu
- Department of Orthopaedic Surgery, University of Virginia, Charlottesville, VA 22903, USA
| | | | | | | | | |
Collapse
|
28
|
Botchwey EA, Dupree MA, Pollack SR, Levine EM, Laurencin CT. Tissue engineered bone: Measurement of nutrient transport in three-dimensional matrices. ACTA ACUST UNITED AC 2003; 67:357-67. [PMID: 14517896 DOI: 10.1002/jbm.a.10111] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The classic paradigm for in vitro tissue engineering of bone involves the isolation and culture of donor osteoblasts or osteoprogenitor cells within three-dimensional (3D) scaffold biomaterials under conditions that support tissue growth and mineralized osteoid formation. Our studies focus on the development and utilization of new dynamic culture technologies to provide adequate nutrient flux within 3D scaffolds to support ongoing tissue formation. In this study, we have developed a basic one-dimensional (1D) model to characterize the efficiency of passive nutrient diffusion and transport flux to bone cells within 3D scaffolds under static and dynamic culture conditions. Internal fluid perfusion within modeled scaffolds increased rapidly with increasing pore volume and pore diameter to a maximum of approximately 1% of external fluid flow. In contrast, internal perfusion decreased significantly with increasing pore channel tortuosity. Calculations of associated nutrient flux indicate that static 3D culture and some inappropriately designed dynamic culture environments lead to regions of insufficient nutrient concentration to maintain cell viability, and can result in steep nutrient concentration gradients within the modeled constructs. These quantitative studies provide a basis for development of new dynamic culture methodologies to overcome the limitations of passive nutrient diffusion in 3D cell-scaffold composite systems proposed for in vitro tissue engineering of bone.
Collapse
Affiliation(s)
- Edward A Botchwey
- Department of Biomedical Engineering, The University of Virginia, 400 Ray C. Hunt Drive, Suite 330, Charlottesville, Virginia 22903, USA
| | | | | | | | | |
Collapse
|
29
|
Wang GX, Cai SX, Rao XC, Deng XY, Guidoin R. The phenomenon of cell membrane tensile stress accumulation and its effect on endothelin-1 secretion by vascular endothelial cells. Colloids Surf B Biointerfaces 2003. [DOI: 10.1016/s0927-7765(02)00157-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
|
30
|
Wang GX, Cai SX, Rao XC, Deng XY, Wang YL, Guidoin R. Endothelin-1 and angiotensin II secretion at different lengths of endothelial cell monolayer in the view of tensile stress accumulation in the upper endothelial cell membrane. Colloids Surf B Biointerfaces 2003. [DOI: 10.1016/s0927-7765(02)00098-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
31
|
Keane JT, Ryan D, Gray PP. Effect of shear stress on expression of a recombinant protein by Chinese hamster ovary cells. Biotechnol Bioeng 2003; 81:211-20. [PMID: 12451557 DOI: 10.1002/bit.10472] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
A flow chamber was used to impart a steady laminar shear stress on a recombinant Chinese hamster ovary (CHO) cell line expressing human growth hormone (hGH). The cells were subjected to shear stress ranging from 0.005 to 0.80 N m(-2). The effect of shear stress on the cell specific glucose uptake, cell specific hGH, and lactate productivity rates were calculated. No morphological changes to the cells were observed over the range of shear stresses examined. When the cells were subjected to 0.10 N m(-2) shear in protein-free media without Pluronic F-68, recombinant protein production ceased with no change in cell morphology, whereas control cultures were expressing hGH at 0.35 microg/10(6 )cells/h. Upon addition of the shear protectants, Pluronic F-68 (0.2% [w/v]) or fetal bovine serum (1.0% [v/v] FBS), the productivity of the cells was restored. The effect of increasing shear stress on the cells in protein-free medium containing Pluronic F-68 was also investigated. Cell specific metabolic rates were calculated for cells under shear stress and for no-shear control cultures performed in parallel, with shear stress rates expressed as a percentage of those obtained for control cultures. Upon increasing shear from 0.005 to 0.80 N m(-2), the cell specific hGH productivity decreased from 100% at 0.005 N m(-2) to 49% at 0.80 N m(-2) relative to the no-shear control. A concurrent increase in the glucose uptake rate from 115% at 0.01 N m(-2) to 142% at 0.80 N m(-2), and decreased lactate productivity from 92% to 50%, revealed a change in the yield of products from glucose compared with the static control. It was shown that shear stress, at sublytic levels in medium containing Pluronic F-68, could decrease hGH specific productivity.
Collapse
Affiliation(s)
- Julian T Keane
- Department of Biotechnology, University of New South Wales, Sydney 2052, Australia.
| | | | | |
Collapse
|
32
|
Passerini AG, Milsted A, Rittgers SE. Shear stress magnitude and directionality modulate growth factor gene expression in preconditioned vascular endothelial cells. J Vasc Surg 2003; 37:182-90. [PMID: 12514598 DOI: 10.1067/mva.2003.66] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
OBJECTIVE The purpose of this study was to simultaneously monitor the transcriptional levels of 12 endothelial growth factor genes in response to alterations in wall shear stress (WSS) under conditions relevant to the development of intimal hyperplasia, a major cause of arterial bypass graft failure. METHODS Human umbilical vein endothelial cells were preconditioned in vitro under steady flow (WSS, 15 dynes/cm(2)) for 24 hours before being subjected to WSS at 25 (Delta = +10), 15 (Delta = 0), 5 (Delta = -10), 2.5 (Delta = -12.5), and 0 (Delta = -15) dynes/cm(2) or low magnitude WSS reversal (-2.5 dynes/cm(2)) for 6 hours. A focused complementary DNA array was used to simultaneously measure messenger RNA expression levels for END1, endothelial nitric oxide synthase (NOS3), platelet-derived growth factor A, platelet-derived growth factor B (PDGFB), acidic fibroblast growth factor, basic fibroblast growth factor, transforming growth factor-alpha, transforming growth factor-beta, vascular endothelial growth factor, insulin-like growth factor-1, epidermal growth factor, and angiotensin converting enzyme. RESULTS Preconditioning significantly (P <.05) increased the fold expression of NOS3 (4.1 +/- 1.4), basic fibroblast growth factor (3.90 +/- 1.16), vascular endothelial growth factor (3.39 +/- 1.04), and insulin-like growth factor-1 (2.8 +/- 0.7) but decreased END1 (0.47 +/- 0.05) and PDGFB (0.70 +/- 0.04) messenger RNA expression levels relative to no-flow controls, an effect that was sustained on removal from flow for 6 hours. Notably, the ratio of END1/NOS3 expression was diminished (0.11 +/- 0.03) relative to that of cells maintained in static culture. Although few differences in gene expression from baseline (15 dynes/cm(2)) were measured in cells exposed to either constant (Delta = 0) or step decreases (Delta = -10, -12.5, or -15 dynes/cm(2)) in WSS, marked changes were seen in the group exposed to a step increase in WSS (Delta = +10) or to WSS reversal. Low magnitude retrograde WSS evoked significant (P <.05) transcriptional changes in multiple genes, including elevated END1 (4.1 +/- 0.5), platelet-derived growth factor A (1.5 +/- 0.2), PDGFB (2.3 +/- 0.3), and transforming growth factor-beta (1.5 +/- 0.2) levels, but depressed NOS3 (0.60 +/- 0.17) levels, and a marked increase in END1/NOS3 (6.7 +/- 1.6) when compared with equal magnitude antegrade WSS (2.5 dynes/cm(2)). CONCLUSION These results support the implementation of a preconditioning phase for in vitro WSS studies to establish a physiologic baseline. Our findings complement previous macroscale findings and are consistent with a cellular mechanism involving increased END1 and PDGFB levels, but decreased NOS3 levels, leading to intimal hyperplasia at regions of low magnitude reversing WSS.
Collapse
|
33
|
Ma N, Koelling KW, Chalmers JJ. Fabrication and use of a transient contractional flow device to quantify the sensitivity of mammalian and insect cells to hydrodynamic forces. Biotechnol Bioeng 2002; 80:428-37. [PMID: 12325151 DOI: 10.1002/bit.10387] [Citation(s) in RCA: 105] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
A microfluidic device was fabricated via photolithographic techniques which can create transient elongational and shear forces ranging over three orders of magnitude while still maintaining laminar flow conditions. The contractional fluid flow inside the microfluidic device was simulated with FLUENT (a computational fluid dynamics computer program) and the local deformation forces were characterized with the scalar quantity, local energy dissipation rate. The sensitivities of four cell lines (CHO, HB-24, Sf-9, and MCF7) were tested in the device. The results indicate that all four cell lines are able to withstand relatively intense energy dissipation rates (up to 10(4)-10(5) kW/m(3)), which is orders of magnitude higher than the maximum local energy dissipation rates generated by impellers in bioreactors, but comparable to that associated with small bursting bubbles. While the concept that suspended animal cells are relatively robust with respect to purely hydrodynamic forces in bioprocess equipment is well known, these results quantitatively demonstrate these observations.
Collapse
Affiliation(s)
- Ningning Ma
- Department of Chemical Engineering, The Ohio State University, 140W 19th Ave., Columbus, Ohio 43210, USA
| | | | | |
Collapse
|
34
|
Dai G, Tsukurov O, Chen M, Gertler JP, Kamm RD. Endothelial nitric oxide production during in vitro simulation of external limb compression. Am J Physiol Heart Circ Physiol 2002; 282:H2066-75. [PMID: 12003813 DOI: 10.1152/ajpheart.00288.2001] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
External pneumatic compression (EPC) is effective in preventing deep vein thrombosis (DVT) and is thought to alter endothelial thromboresistant properties. We investigated the effect of EPC on changes in nitric oxide (NO), a critical mediator in the regulation of vasomotor and platelet function. An in vitro cell culture system was developed to simulate flow and vessel collapse conditions under EPC. Human umbilical vein endothelial cells were cultured and subjected to tube compression (C), pulsatile flow (F), or a combination of the two (FC). NO production and endothelial nitric oxide synthase (eNOS) mRNA expression were measured. The data demonstrate that in the F and FC groups, there is a rapid release of NO followed by a sustained increase. NO production levels in the F and FC groups were almost identical, whereas the C group produced the same low amount of NO as the control group. Conditions F and FC also upregulate eNOS mRNA expression by a factor of 2.08 +/- 0.25 and 2.11 +/- 0.21, respectively, at 6 h. Experiments with different modes of EPC show that NO production and eNOS mRNA expression respond to different time cycles of compression. These results implicate enhanced NO release as a potentially important factor in the prevention of DVT.
Collapse
Affiliation(s)
- Guohao Dai
- Division of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | | | | | | | | |
Collapse
|
35
|
Wang GX, Cai SX, Wang PQ, Ouyang KQ, Wang YL, Xu SR. Shear-induced changes in endothelin-1 secretion of microvascular endothelial cells. Microvasc Res 2002; 63:209-17. [PMID: 11866544 DOI: 10.1006/mvre.2001.2387] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Human glomerular microvascular endothelial cell (HGMEC) culture monolayers were maintained in static culture as controls or subjected to steady laminar shear stress of 0.5, 1.0, or 1.5 N/m2. Over 25 h of shear, the cumulative secretion of ET-1 was 705.4 pg/cm2 in the control, 820.7 pg/cm2 at 0.5 N/m2, 1063.2 pg/cm2 at 1.0 N/m2, and 644.7 pg/cm2 at 1.5 N/m2. The average ET-1 secretion rate for the HGMEC monolayers exposed to 0.5, 1.0, or 1.5 N/m2 of shear stress was 32.83 +/- 2.01 pg/cm2 x h, 42.53 +/- 3.74 pg/cm2 x h, and 25.79 +/- 1.29 pg/cm2 x h, respectively. The average ET-1 secretion rate of the static controls was 28.22 +/- 3.11 pg/cm2 x h. The results showed that low shear stress (0.5 N/m2) elevated and high shear stress (1.5 N/m2) suppressed secretion of ET-1, while an intermediate level of shear stress (1.0 N/m2) led to the maximum secretion of ET-1, and furthermore, ET-1 secretion varied with the duration of shear in a nonlinear fashion, and the logistic equations may be used to describe relationship between the duration of shear and the ET-1 secretion. The major secretion period of ET-1 occurred between 5.3 and 22.3 h, with the peak secretion rate occurring at approximately 10.7-15.2 h. Our findings showed also that the major secretion period and peak secretion rate of HGMECs varied with the level of shear stress. Thus, the response of cultured human microvascular endothelial cells to shear stress differed from that of large-vessel endothelial cell cultures in terms of ET-1 secretion. In addition to the level of shear stress, the duration of shear is an important determinant in ET-1 secretion. Consequently, the heterogeneity of vascular endothelial cells and the duration of shear should both be considered in future research on the secretion of vascular endothelial cell cultures.
Collapse
Affiliation(s)
- G-X Wang
- College of Bioengineering, Key Laboratory for Biomechanics and Tissue Engineering, Chongqing University, Chongqing, 400044, PR China
| | | | | | | | | | | |
Collapse
|
36
|
Abstract
"Somatic" angiotensin I-converting enzyme (ACE) appears to be one of the evolutionary advances that made a closed circulation possible, and may have contributed to the Cambrian "explosion" of species approximately 540 million years ago. It also appears to be at the origin of a large number of common human diseases. A model is proposed in which the duplicated form of ACE ("somatic" ACE) functions as a mechanotransducer, defending downstream vessels and tissues from an increase in pressure. In the model, ACE senses shear stress (blood velocity) in regions of turbulent blood flow. An increase in shear stress strips an autoinhibitor tripeptide, FQP, from the N-terminal active site, thereby activating it. The C-terminal domain is constitutively activated by chloride. This model explains the clinical superiority of hydrophobic ACE inhibitors relative to hydrophilic ones.
Collapse
|
37
|
Levenson J, Pessana F, Gariepy J, Armentano R, Simon A. Gender differences in wall shear-mediated brachial artery vasoconstriction and vasodilation. J Am Coll Cardiol 2001; 38:1668-74. [PMID: 11704379 DOI: 10.1016/s0735-1097(01)01604-7] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
OBJECTIVES We sought to investigate wall shear rate (WSR) and brachial artery diameter (BAD) changes simultaneously and to determine whether any gender differences exist in arterial reactivity. BACKGROUND Wall shear rate/stress and arterial reactivity are rarely assessed at the same time. Furthermore, flow-mediated vasoconstriction has received less attention than flow-mediated vasodilation in humans. METHODS A new noninvasive evaluation of WSR in the brachial artery, using multigated, pulsed Doppler velocimeter and a double-transducer probe moved and fixed by a robotic system, was developed. RESULTS The validity of the system was tested in vitro with calibrated tubes and showed a high correlation (r = 0.98, p < 0.001). In 10 men and 10 women of similar age, induction of low and high shear rates by forearm occlusion produced significant vasoconstriction and vasodilation, respectively. The time lag for maximal BAD changes was 3 min for vasoconstriction and 1 min for vasodilation. A greater half-time for vasodilation (96 +/- 6 for men and 86 +/- 12 s for women) than for shear rate (31 +/- 5 s for men and 34 +/- 4 s for women) was observed after discontinuation of occlusion. Relative BAD was correlated with WSR changes, showing a significantly higher slope in women than in men (p < 0.01). Moreover, a larger normalized arterial diameter per shear rate was observed for vasoconstriction (p < 0.01) and vasodilation (p < 0.01) in women than in men. CONCLUSIONS Shear-mediated arterial vasodilation and vasoconstriction were more pronounced in women than in men, suggesting different gender-related sensitivity in the regulation of large-artery vascular tone.
Collapse
Affiliation(s)
- J Levenson
- Centre de Médecine Préventive Cardiovasculaire, Institut National de la Santé et de la Recherche Médicale (INSERM), Hôpital Broussais, Paris, France.
| | | | | | | | | |
Collapse
|
38
|
Stamatas GN, Patrick CW, McIntire LV. Intracellular pH changes in human aortic smooth muscle cells in response to fluid shear stress. TISSUE ENGINEERING 2001; 3:391-403. [PMID: 11543590 DOI: 10.1089/ten.1997.3.391] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The smooth muscle cell (SMC) layers of human arteries may be exposed to blood flow after endothelium denudation, for example, following balloon angioplasty treatment. These SMCs are also constantly subjected to pressure driven transmural fluid flow. Flow-induced shear stress can alter SMC growth and metabolism. Signal transduction mechanisms involved in these flow effects on SMCs are still poorly understood. In this work, the hypothesis that shear stress alters the intracellular pH (pHi) of SMC is examined. When exposed to venous and arterial levels of shear stress, human aortic smooth muscle cells (hASMC) undergo alkalinization. The alkalinization plateau persisted even after 20 min of cell exposure to flow. Addition of amiloride (10 micromoles) or its 5-(N-ethyl-N-isopropyl) analog (EIPA, 10 micromoles), both Na+/H+ exchanger inhibitors, attenuated intracellular alkalinization, suggesting the involvement of the Na+/H+ exchanger in this response. The same concentrations of these inhibitors did not show an effect on pHi of hASMCs in static culture. 4-Acetamido-4'-isothio-cyanatostilbene-2,2'-disulfonic acid (SITS, 1 mM), a Cl-/HCO3- exchange inhibitor, affected the pHi of hASMCs both in static and flow conditions. Our results suggest that flow may perturb the Na+/H+ exchanger leading to an alkalinization of hASMCs, a different response from the flow-induced acidification seen with endothelial cells at the same levels of shear stress. Understanding the flow-induced signal transduction pathways in the vascular cells is of great importance in the tissue engineering of vascular grafts. In the case of SMCs, the involvement of pHi changes in nitric oxide production and proliferation regulation highlights further the significance of such studies.
Collapse
Affiliation(s)
- G N Stamatas
- Cox Laboratory for Biomedical Engineering, Institute of Biosciences and Bioengineering, Rice University, Houston, Texas 77251-1892, USA
| | | | | |
Collapse
|
39
|
Abstract
AIMS In a biofilm reactor, detachment force resulting from hydraulic shear is a major factor that determines the formation and structure of steady state biofilm. The metabolic response of biofilm to change in shear stress was therefore investigated. METHODS AND RESULTS A conventional annular reactor made of PVC was used, in which shearing over the rotating disc surface was strictly defined. Results from the steady state aerobic biofilm reactor showed that the biofilm structure (density and thickness) and metabolic behaviour (growth yield and dehydrogenase activity) were closely related to the shear stress exerted on the biofilm. Smooth, dense and stable biofilm formed at relatively high shear stress. Higher dehydrogenase activity and lower growth yield were obtained when the shear stress was raised. Growth yield was inversely correlated with the catabolic activity of biofilm. The reduced growth yield, together with the enhanced catabolic activity, suggests that a dissociation of catabolism from anabolism would occur at high shear stress. CONCLUSION Biofilms may respond to shear stress by regulating metabolic pathways associated with the substrate flux flowing between catabolism and anabolism. A biological phenomenon, besides a simple physical effect, is underlying the observed relation between the shear stress and resulting biofilm structure. SIGNIFICANCE AND IMPACT OF THE STUDY A hypothesis is proposed that the shear-induced energy spilling would be associated with a stimulated proton translocation across the cell membrane, which favours formation of a stronger biofilm. This research may provide a basis for experimental data on biofilm obtained at different shear stresses to be interpreted in relation to energy.
Collapse
Affiliation(s)
- Y Liu
- Environmental Engineering Research Center, School of Civil and Structural Engineering, Nanyang Technological University, Singapore.
| | | |
Collapse
|
40
|
Kretzmer G. Influence of stress on adherent cells. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2000; 67:123-37. [PMID: 10857223 DOI: 10.1007/3-540-47865-5_4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
Stress is a broad term often used with animal cells. Frequently mechanical forces are meant using this term but chemical stress is also important cultivating animal cells. The chemical environment of the cell in a reactor have to be considered very carefully. The complexity of the medium requirements and the metabolic pathway cause very often growth limitations. Studying these limitations in order to find the reasons showed to be difficulty because of the complexity of the system. Nevertheless, glucose, glutamine, lactate and ammonia are found to be critical parameter as well as the osmotic pressure. The influence of mechanical forces on cell viability is of great importance when growing the cells in agitated systems. By far the greatest amount of work reported in the literature has been done on suspension cells but adherent cells also experience shear forces not only in bioreactors also in vivo. Therefore, most research has be done on endothelial cells but studies exists done on non-endothelial cells. The influence of shear forces on cell growth, morphology and productivity will be discussed as well as possibilities of making the cells more resistant.
Collapse
Affiliation(s)
- G Kretzmer
- Institut für Technische Chemie, Universität Hannover, Germany.
| |
Collapse
|
41
|
Ranjan V, Waterbury R, Xiao Z, Diamond SL. Fluid shear stress induction of the transcriptional activator c-fos in human and bovine endothelial cells, HeLa, and Chinese hamster ovary cells. Biotechnol Bioeng 2000; 49:383-90. [DOI: 10.1002/(sici)1097-0290(19960220)49:4<383::aid-bit4>3.0.co;2-l] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
|
42
|
Peng CA, Palsson BØ. Cell growth and differentiation on feeder layers is predicted to be influenced by bioreactor geometry. Biotechnol Bioeng 2000; 50:479-92. [DOI: 10.1002/(sici)1097-0290(19960605)50:5<479::aid-bit2>3.0.co;2-c] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
|
43
|
Papadaki M, Eskin SG, Ruef J, Runge MS, McIntire LV. Fluid shear stress as a regulator of gene expression in vascular cells: possible correlations with diabetic abnormalities. Diabetes Res Clin Pract 1999; 45:89-99. [PMID: 10588360 DOI: 10.1016/s0168-8227(99)00036-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Diabetes mellitus is associated with increased frequency, severity and more rapid progression of cardiovascular diseases. Metabolic perturbations from hyperglycemia result in disturbed endothelium-dependent relaxation, activation of coagulation pathways, depressed fibrinolysis, and other abnormalities in vascular homeostasis. Atherosclerosis is localized mainly at areas of geometric irregularity at which blood vessels branch, curve and change diameter, and where blood is subjected to sudden changes in velocity and/or direction of flow. Shear stress resulting from blood flow is a well known modulator of vascular cell function. This paper presents what is currently known regarding the molecular mechanisms responsible for signal transduction and gene regulation in vascular cells exposed to shear stress. Considering the importance of the hemodynamic environment of vascular cells might be vital to increasing our understanding of diabetes.
Collapse
Affiliation(s)
- M Papadaki
- Department of Chemical Engineering and Harvard-MIT Health Science and Technology, Massachusetts Institute of Technology, Cambridge 02139, USA
| | | | | | | | | |
Collapse
|
44
|
Malone MD, Cisek PL, Comerota AJ, Holland B, Eid IG, Comerota AJ. High-pressure, rapid-inflation pneumatic compression improves venous hemodynamics in healthy volunteers and patients who are post-thrombotic. J Vasc Surg 1999; 29:593-9. [PMID: 10194485 DOI: 10.1016/s0741-5214(99)70303-4] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
PURPOSE Deep vein thrombosis (DVT) is a preventable cause of morbidity and mortality in patients who are hospitalized. An important part of the mechanism of DVT prophylaxis with intermittent pneumatic compression (IPC) is reduced venous stasis with increased velocity of venous return. The conventional methods of IPC use low pressure and slow inflation of the air bladder on the leg to augment venous return. Recently, compression devices have been designed that produce high pressure and rapid inflation of air cuffs on the plantar plexus of the foot and the calf. The purpose of this study is to evaluate the venous velocity response to high-pressure, rapid-inflation compression devices versus standard, low-pressure, slow-inflation compression devices in healthy volunteers and patients with severe post-thrombotic venous disease. METHOD Twenty-two lower extremities from healthy volunteers and 11 lower extremities from patients with class 4 to class 6 post-thrombotic chronic venous insufficiency were studied. With duplex ultrasound scanning (ATL-Ultramark 9, Advanced Tech Laboratory, Bothell, Wash), acute DVT was excluded before subject evaluation. Venous velocities were monitored after the application of each of five IPC devices, with all the patients in the supine position. Three high-pressure, rapid-compression devices and two standard, low-pressure, slow-inflation compression devices were applied in a random sequence. Maximal venous velocities were obtained at the common femoral vein and the popliteal vein for all the devices and were recorded as the mean peak velocity of three compression cycles and compared with baseline velocities. RESULTS The baseline venous velocities were higher in the femoral veins than in the popliteal veins in both the volunteers and the post-thrombotic subjects. Standard and high-pressure, rapid-inflation compression significantly increased the popliteal and femoral vein velocities in healthy and post-thrombotic subjects. High-pressure, rapid-inflation compression produced significantly higher maximal venous velocities in the popliteal and femoral veins in both healthy volunteers and patients who were post-thrombotic as compared with standard compression. Compared with the healthy volunteers, the patients who were post-thrombotic had a significantly attenuated velocity response at both the popliteal and the femoral vein levels. CONCLUSION High-pressure, rapid-inflation pneumatic compression increases popliteal and femoral vein velocity as compared with standard, low-pressure, slow-inflation pneumatic compression. Patients with post-thrombotic venous disease have a compromised hemodynamic response to all IPC devices. However, an increased velocity response to the high-pressure, rapid-inflation compression device is preserved. High-pressure, rapid-inflation pneumatic compression may offer additional protection from thrombotic complications on the basis of an improved hemodynamic response, both in healthy volunteers and in patients who were post-thrombotic.
Collapse
Affiliation(s)
- M D Malone
- Section of Vascular Surgery, Temple University Hospital, Department of Biostatistics, Philadelphia, PA, USA
| | | | | | | | | | | |
Collapse
|
45
|
Calvo WJ, Hajduczok G, Russell JA, Diamond SL. Inhibition of nitric oxide but not prostacyclin prevents poststenotic dilatation in rabbit femoral artery. Circulation 1999; 99:1069-76. [PMID: 10051302 DOI: 10.1161/01.cir.99.8.1069] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Poststenotic dilatation (PSD) occurs in a low-pressure region where recirculation eddies oscillate in size during the cardiac cycle. NO may be an important mediator of PSD. METHODS AND RESULTS Femoral arteries of 7 adult male New Zealand White rabbits were stenosed bilaterally to achieve a diameter reduction of 70. 9+/-6.7% (n=14). At the time of stenosis, the adventitia of one of the arteries was coated with 1 mmol/L of NG-nitro-L-arginine methyl ester (L-NAME) in 22% (wt/vol) Pluronic gel, while the contralateral vessel was coated with gel without L-NAME. In stenosed femoral arteries that were treated with gel without L-NAME, a maximum PSD of 30.99+/-7.92% (n=7) was observed in polymer casts at 3 days relative to the mean proximal diameter of 1.57+/-0.25 mm at a position 12 mm upstream of each stenosis. In contrast, the vessels treated with L-NAME exhibited a maximum PSD of only 7.16+/-8.81% (n=7) relative to the mean proximal diameter of 1.55+/-0.16 mm. L-NAME caused a 76. 9% reduction (P<0.001, n=7) of PSD. Similarly, NG-monomethyl-L-arginine 1 mmol/L and NG-nitro-L-arginine 10 micromol/L attenuated PSD by 57.5% (P<0.001, n=6) and 63.9% (P<0.05, n=6), respectively. Indomethacin 10 micromol/L caused no reduction in PSD. Arterial rings obtained from the poststenotic region were more sensitive and responsive to acetylcholine than those obtained proximal to the stenosis. CONCLUSIONS NO, but not prostacyclin, is a major mediator of PSD.
Collapse
Affiliation(s)
- W J Calvo
- Bioengineering Laboratory, Department of Chemical Engineering, School of Medicine, State University of New York at Buffalo, New York, USA
| | | | | | | |
Collapse
|
46
|
Gagnet C, Devynck MA, Simon A, Levenson J. Influence of hypercholesterolemia and endothelin-3 pre-treatment on the effects of shear forces on platelet aggregation and cyclic GMP content. Atherosclerosis 1999; 143:91-7. [PMID: 10208483 DOI: 10.1016/s0021-9150(98)00282-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Shear forces induce platelet aggregation and stimulate the endothelial production of anti-aggregatory factors. Among them, endothelin-3 (ET-3) has been reported to reduce aggregation and to increase platelet cyclic GMP (cGMP) content. Since hypercholesterolemia modifies both platelet aggregability and endothelial function, we compared in 14 hypercholesterolemic and 15 normocholesterolemic subjects the influences of shear forces (240 and 650 s(-1)) on platelet aggregation and cGMP content, and their modulation by ET-3. Spontaneous maximal aggregation occurred earlier and at a greater extent in hypercholesterolemic than in normocholesterolemic subjects (63+/-2 vs 46+/-6% P < 0.01). Pre-treatment with ET-3 abolished the shear-induced facilitation of maximal aggregation in platelets of normocholesterolemic (from 70+/-2 to 52+2% at 240 s(-1) and from 73+/-1 to 59+/-2S at 650s(-1); P < 0.05) and hypercholesterolemic (from 78+/-3 to 64+/-2 at 240 s(-1) and from 78+/-2 to 66+/-3 at 650 s(-1); P < 0.05) subjects. cGMP content did not significantly differ between normocholesterolemic and hypercholesterolemic subjects (6.1+/-0.5 vs 6.9+/-0.7 pmol/10(9) platelets). It was reduced in platelets submitted to shear forces (P < 0.05). This shear-dependent reduction was suppressed by ET-3 pre-treatment. These results demonstrate that shear forces enhance platelet aggregation and diminish their cGMP content. ET-3 reduces the pro-aggregating effects of shear, suggesting a rise in cGMP content as a dynamic associated mechanism.
Collapse
Affiliation(s)
- C Gagnet
- Centre de Médecine Préventive, Cardio-Vasculaire, CRI (INSEAM), Hôpital Broussais, Paris, France
| | | | | | | |
Collapse
|
47
|
Stamatas GN, McIntire LV. Novel optical methodologies in studying mechanical signal transduction in mammalian cells. Ind Eng Chem Res 1999; 38:601-9. [PMID: 11757568 DOI: 10.1021/ie980426a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
For the last 3 decades evidence has been accumulating that some types of mammalian cells respond to their mechanically active environment by altering their morphology, growth rate, and metabolism. The study of such responses is very important in understanding, physiological and pathological conditions ranging from bone formation to atherosclerosis. Obtaining this knowledge has been the goal for an active research area in bioengineering termed cell mechanotransduction. The advancement of optical methodologies used in cell biology research has given the tools to elucidate cellular mechanisms that would otherwise be impossible to visualize. Combined with molecular biology techniques, they give engineers invaluable tools in understanding the chemical pathways involved in mechanotransduction. Herein we briefly review the current knowledge on mechanical signal transduction in mammalian cells, focusing on the application of novel optical techniques in the ongoing research.
Collapse
MESH Headings
- Animals
- Cell Physiological Phenomena
- Endothelium, Vascular/cytology
- Endothelium, Vascular/physiology
- Fluorescent Antibody Technique
- Hemorheology
- Microscopy, Atomic Force
- Microscopy, Confocal
- Microscopy, Fluorescence
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/physiology
- Signal Transduction/physiology
- Stress, Mechanical
Collapse
Affiliation(s)
- G N Stamatas
- Cox Laboratory for Biomedical Engineering, Institute of Biosciences and Bioengineering, Rice University, Houston, Texas 77251-1892, USA
| | | |
Collapse
|
48
|
Qiu HY, Henrion D, Benessiano J, Heymes C, Tournier B, Levy BI. Decreased flow-induced dilation and increased production of cGMP in spontaneously hypertensive rats. Hypertension 1998; 32:1098-103. [PMID: 9856981 DOI: 10.1161/01.hyp.32.6.1098] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
-We investigated flow (shear stress)- and agonist-induced cGMP release in mesenteric vascular beds of spontaneously hypertensive rats (SHR) and normotensive Wistar Kyoto rats (WKY). The mesenteric vascular bed was perfused in situ with Tyrode's solution. Vascular relaxation and cGMP release in the perfusate were determined on stimulation by flow or by acetylcholine (0.1 micromol/L) or sodium nitroprusside (0.1 mmol/L). Flow-induced release of cGMP was significantly greater in SHR than in WKY (P<0.01), despite a lower flow-induced dilation in SHR. In both strains, NG-nitro-L-arginine methyl ester (L-NAME) completely inhibited cGMP release in response to flow (P<0.001), although flow-induced dilation was not affected by L-NAME in SHR. Moreover, the activity of the constitutive nitric oxide synthase (NOS) was significantly greater in SHR (82+/-3.5 fmol/min) than in WKY (66+/-3.5 fmol/min; P<0.05) and was associated with increased expression of endothelial NOS mRNA in SHR. Sodium nitroprusside induced larger increases in cGMP release in SHR (3593+/-304 fmol/min) than in WKY (2467+/-302 fmol/min; P<0.05). The release of cGMP in response to acetylcholine was significantly lower in SHR (292+/-80 fmol/min) than in WKY (798+/-218 fmol/min; P<0.05) in parallel with smaller acetylcholine-induced relaxation in SHR. Despite increased cGMP production in response to flow and NOS activity, flow-induced dilation was decreased in SHR, suggesting an upregulation of the NO/cGMP pathway to compensate for the increased vascular tone in SHR.
Collapse
Affiliation(s)
- H Y Qiu
- Institut National de la Santé et de la Recherche Médicale (INSERM) Unit 141, IFR Circulation-Lariboisière, Université Paris VII, Hôpital Lariboisière, Paris, France
| | | | | | | | | | | |
Collapse
|
49
|
Vedrinne C, Tronc F, Martinot S, Robin J, Garhib C, Ninet J, Lehot JJ, Franck M, Champsaur G. Effects of various flow types on maternal hemodynamics during fetal bypass: is there nitric oxide release during pulsatile perfusion? J Thorac Cardiovasc Surg 1998; 116:432-9. [PMID: 9731785 DOI: 10.1016/s0022-5223(98)70009-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
OBJECTIVE This study investigates the role of various flow conditions on maternal hemodynamics during fetal cardiopulmonary bypass. METHODS Normothermic fetal bypass was conducted under pulsatile, or steady flow, for a 60-minute period. Fetal lamb preparations were randomly assigned to 1 of the 3 groups: steady flow (n=7), pulsatile flow (n=7), or pulsatile blocked flow bypass (n=7), where fetuses were perfused with Nomega-nitro-L-arginine after the first 30 minutes of pulsatile flow to assess the potential role of endothelial autacoids. RESULTS Maternal oximetry and pressures remained unchanged throughout the procedure. Under fetal pulsatile flow, maternal cardiac output increased after 20 minutes of bypass and remained significantly higher than under steady flow at minute 30 (8.8+/-0.7 L x min(-1) vs 5.9+/-0.5 L x min(-1), P=.02). Maternal cardiac output in the pulsatile group also remained higher than in both steady and pulsatile blocked flow groups, reaching respectively 8.7+/-0.9 L x min(-1) vs 5.8+/-0.4 L x min(-1) (P=.02) and 5.9+/-0.3 L min(-1) (P=.01) at minute 60. Maternal systemic vascular resistances were significantly lower under pulsatile than under steady flow after 30 minutes and until the end of bypass (respectively, 9.1+/-0.6 IU vs 12.7+/-1.1 IU, P=.02 and 8.9+/-0.5 IU vs 12.9+/-1.2 IU, P=.01). Infusion of Nomega-nitro-L-arginine was followed by an increase in systemic vascular resistances from 9.3+/-0.7 IU, similar to that of the pulsatile group, to 13.5+/-1 IU at 60 minutes, similar to that of the steady flow group. CONCLUSIONS Maternal hemodynamic changes observed under fetal pulsatile flow are counteracted after infusion of Nomega-nitro-L-arginine, suggesting nitric oxide release from the fetoplacental unit under pulsatile fetal flow conditions.
Collapse
Affiliation(s)
- C Vedrinne
- Department of Anesthesia and Intensive Care Medicine in Cardiovascular Surgery, Louis Pradel Cardiologic Hospital, Lyon, France
| | | | | | | | | | | | | | | | | |
Collapse
|
50
|
Takeda T, Kitagawa T, Takeuchi Y, Seki M, Furusaki S. Metabolic responses of plant cell culture to hydrodynamic stress. CAN J CHEM ENG 1998. [DOI: 10.1002/cjce.5450760215] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|