1
|
Kolmogorov V, Erofeev A, Vaneev A, Gorbacheva L, Kolesov D, Klyachko N, Korchev Y, Gorelkin P. Scanning Ion-Conductance Microscopy for Studying Mechanical Properties of Neuronal Cells during Local Delivery of Glutamate. Cells 2023; 12:2428. [PMID: 37887273 PMCID: PMC10604991 DOI: 10.3390/cells12202428] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Revised: 10/06/2023] [Accepted: 10/08/2023] [Indexed: 10/28/2023] Open
Abstract
Mechanical properties of neuronal cells have a key role for growth, generation of traction forces, adhesion, migration, etc. Mechanical properties are regulated by chemical signaling, neurotransmitters, and neuronal ion exchange. Disturbance of chemical signaling is accompanied by several diseases such as ischemia, trauma, and neurodegenerative diseases. It is known that the disturbance of chemical signaling, like that caused by glutamate excitotoxicity, leads to the structural reorganization of the cytoskeleton of neuronal cells and the deviation of native mechanical properties. Thus, to investigate the mechanical properties of living neuronal cells in the presence of glutamate, it is crucial to use noncontact and low-stress methods, which are the advantages of scanning ion-conductance microscopy (SICM). Moreover, a nanopipette may be used for the local delivery of small molecules as well as for a probe. In this work, SICM was used as an advanced technique for the simultaneous local delivery of glutamate and investigation of living neuronal cell morphology and mechanical behavior caused by an excitotoxic effect of glutamate.
Collapse
Affiliation(s)
- Vasilii Kolmogorov
- Research Laboratory of Biophysics, National University of Science and Technology “MISIS”, Moscow 119049, Russia
- Faculty of Chemistry, Lomonosov Moscow State University, Moscow 119991, Russia
| | - Alexander Erofeev
- Research Laboratory of Biophysics, National University of Science and Technology “MISIS”, Moscow 119049, Russia
| | - Alexander Vaneev
- Research Laboratory of Biophysics, National University of Science and Technology “MISIS”, Moscow 119049, Russia
- Faculty of Chemistry, Lomonosov Moscow State University, Moscow 119991, Russia
| | - Lyubov Gorbacheva
- Faculty of Biology, Lomonosov Moscow State University, Moscow 119991, Russia
- Faculty of Biomedicine, Pirogov Russian National Research Medical University, Moscow 117997, Russia
| | - Dmitry Kolesov
- Research Laboratory of SPM, Moscow Polytechnic University, Moscow 107023, Russia
| | - Natalia Klyachko
- Faculty of Chemistry, Lomonosov Moscow State University, Moscow 119991, Russia
| | - Yuri Korchev
- Department of Medicine, Imperial College London, London SW7 2BX, UK
- Nano Life Science Institute (WPI-NanoLSI), Kanazawa University, Kanazawa 920-1192, Japan
| | - Petr Gorelkin
- Research Laboratory of Biophysics, National University of Science and Technology “MISIS”, Moscow 119049, Russia
| |
Collapse
|
2
|
Atashgar F, Shafieian M, Abolfathi N. The effect of the properties of cell nucleus and underlying substrate on the response of finite element models of astrocytes undergoing mechanical stimulations. Comput Methods Biomech Biomed Engin 2023; 26:1572-1581. [PMID: 36324266 DOI: 10.1080/10255842.2022.2128673] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Revised: 08/23/2022] [Accepted: 09/21/2022] [Indexed: 11/06/2022]
Abstract
Astrocyte cells play a critical role in the mechanical behaviour of the brain tissue; hence understanding the properties of Astrocytes is a big step toward understanding brain diseases and abnormalities. Conventionally, atomic force microscopy (AFM) has been used as one of the most powerful tools to characterize the mechanical properties of cells. However, due to the complexities of experimental work and the complex behaviour of living cells, the finite element method (FEM) is commonly used to estimate the cells' response to mechanical stimulations. In this study, we developed a finite element model of the Astrocyte cells to investigate the effect of two key parameters that could affect the response of the cell to mechanical loading; the properties of the underlying substrate and the nucleus. In this regard, the cells were placed on two different substrates in terms of thickness and stiffness (gel and glass) with varying properties of the nucleus. The main achievement of this study was to develop an insight to investigate the response of the Astrocytes to mechanical loading for future studies, both experimentally and computationally.
Collapse
Affiliation(s)
- Fatemeh Atashgar
- Department of Biomedical Engineering, Amirkabir University of Technology, Tehran, Iran
| | - Mehdi Shafieian
- Department of Biomedical Engineering, Amirkabir University of Technology, Tehran, Iran
| | - Nabiollah Abolfathi
- Department of Biomedical Engineering, Amirkabir University of Technology, Tehran, Iran
| |
Collapse
|
3
|
Chin IL, Amos SE, Jeong JH, Hool L, Hwang Y, Choi YS. Volume adaptation of neonatal cardiomyocyte spheroids in 3D stiffness gradient GelMA. J Biomed Mater Res A 2023; 111:801-813. [PMID: 36239543 PMCID: PMC10952714 DOI: 10.1002/jbm.a.37456] [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: 06/11/2022] [Revised: 08/25/2022] [Accepted: 09/28/2022] [Indexed: 11/11/2022]
Abstract
Present understandings of cardiomyocyte mechanobiology have primarily been developed using 2-dimensional, monocellular cell cultures, however the emergence of 3-dimensional (3D) multicellular cardiac constructs has enabled us to develop more sophisticated recapitulations of the cardiac microenvironment. Several of these strategies have illustrated that incorporating elements of the extracellular matrix (ECM) can promote greater maturation and enhance desirable cardiac functions, such as contractility, but the responses of these cardiac constructs to biophysically aberrant conditions, such as in the post-infarct heart, has remained relatively unexplored. In our study, we employ a stiffness gradient gelatin methacryloyl (GelMA) hydrogel platform to unpack the mechanobiology of cardiac spheroids. We encapsulated neonatal rat cardiac cell spheroids in a 4.4-18.7 kPa linear stiffness gradient up to 120 h. We found the proportion of viable cells within the spheroids increased over time, but the cell number per spheroid decreased. Spheroids expand more in softer matrices while stiffer matrices promote larger nuclei without changing nuclei shape. Volume expansion came primarily from cells expressing vimentin. We did not observe any correlations between stiffness and mechanomarker expression, however we found that after 120 h post-encapsulation, the localization of YAP, the localization of MRTF-A and the expression of Lamin-A was correlated with spheroid morphology. The same trends were not observed 24 h post-encapsulation, indicating that volume adaptation can take a relatively long time. Our data demonstrates that cardiac spheroids are mechanosensitive and that their capacity to respond to ECM-based cues depends on their capacity to adapt their volume with a 3D microenvironment.
Collapse
Affiliation(s)
- Ian L. Chin
- School of Human SciencesThe University of Western AustraliaPerthWestern AustraliaAustralia
| | - Sebastian E. Amos
- School of Human SciencesThe University of Western AustraliaPerthWestern AustraliaAustralia
| | - Ji Hoon Jeong
- Soonchunhyang Institute of Medi‐bio Science (SIMS)Soonchunhyang UniversityCheonan‐siChungnam‐doRepublic of Korea
- Department of Integrated Biomedical ScienceSoonchunhyang UniversityAsan‐siChungnam‐doRepublic of Korea
| | - Livia Hool
- School of Human SciencesThe University of Western AustraliaPerthWestern AustraliaAustralia
- Victor Chang Cardiac Research InstituteSydneyNew South WalesAustralia
| | - Yongsung Hwang
- Soonchunhyang Institute of Medi‐bio Science (SIMS)Soonchunhyang UniversityCheonan‐siChungnam‐doRepublic of Korea
- Department of Integrated Biomedical ScienceSoonchunhyang UniversityAsan‐siChungnam‐doRepublic of Korea
| | - Yu Suk Choi
- School of Human SciencesThe University of Western AustraliaPerthWestern AustraliaAustralia
| |
Collapse
|
4
|
Goode D, Dhaliwal R, Mohammadi H. Valve interstitial cells under impact load, a mechanobiology study. J Med Eng Technol 2023; 47:54-66. [PMID: 35856893 DOI: 10.1080/03091902.2022.2097328] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Understanding the relationship between mechanobiology and the biosynthetic activities of the valve interstitial cells (VICs) in health and disease under severe dynamic loading conditions is of particular interest. The purpose of this study is to further understand the mechanobiology of heart valve leaflet tissue and the VICs under impact forces. Two novel computational and experimental platforms were developed to study the effect of impact load on the VICs to monitor for apoptosis. The first objective was to design and develop an apparatus to experimentally study viability (apoptosis) of the porcine heart valve leaflet tissue VICs in the aortic position under controlled impact forces. Apoptosis was assessed based on terminal transferase dUTP nick end-labelling (TUNEL) assay. The second objective was to develop a computational platform to estimate the stress and strain fields in the vicinity of VICs when the tissue experiences impact forces. A nonlinear finite element (FE) model with an anisotropic, hyperelastic and heterogeneous material model for the matrix and cells was developed. Preliminary results confirm that interstitial cells are successfully resistant to impact loads up to 30 times more than normal physiological conditions. Additionally, the structure and composition of heart valve leaflet tissue provides a mechanical shield for VICs protecting them from excessive mechanical forces such as impact loads. Although, the entire tissue may experience excessive stresses, which may lead to structural damage, the stresses around and near VICs remain consistency low. Results of this study may be used for heart valve leaflet tissue-engineering, as well as further understanding the mechanobiology of the VICs in health and disease.
Collapse
Affiliation(s)
- Dylan Goode
- Heart Valve Performance Laboratory, School of Engineering, University of British Columbia, Kelowna, Canada
| | - Ruby Dhaliwal
- Heart Valve Performance Laboratory, School of Engineering, University of British Columbia, Kelowna, Canada
| | - Hadi Mohammadi
- Heart Valve Performance Laboratory, School of Engineering, University of British Columbia, Kelowna, Canada
| |
Collapse
|
5
|
Nagayama K. A Loss of Nuclear-Cytoskeletal Interactions in Vascular Smooth Muscle Cell Differentiation Induced by a Micro-Grooved Collagen Substrate Enabling the Modeling of an In Vivo Cell Arrangement. Bioengineering (Basel) 2021; 8:124. [PMID: 34562946 DOI: 10.3390/bioengineering8090124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Accepted: 09/09/2021] [Indexed: 11/25/2022] Open
Abstract
Vascular smooth muscle cells (VSMCs) remodel vascular walls actively owing to mechanical cues and dedifferentiate to the synthetic phenotype from contractile phenotype in pathological conditions. It is crucial to clarify the mechanisms behind the VSMC phenotypic transition for elucidating their role in the vascular adaptation and repair and for designing engineered tissues. We recently developed novel micro-grooved collagen substrates with “wavy wrinkle” grooves to induce cell–substrate adhesion, morphological polarization, and a tissue-like cell arrangement with cytoskeletal rearrangements similar to those in vascular tissue in vivo. We found that cultivation with this micro-grooved collagen significantly induced VSMC contractile differentiation. Nonetheless, the detailed mechanism underlying the promotion of such VSMC differentiation by micro-grooved collagen has not been clarified yet. Here, we investigated the detailed mechanism of the cell arrangement into a tissue and contractile-differentiation improvement by our micro-grooved collagen substrates in terms of nuclear–cytoskeletal interactions that possibly affect the nuclear mechanotransduction involved in the activation of transcription factors. We found that VSMCs on micro-grooved collagen manifested significant cell arrangement into a tissue and nucleus slimming with a volume reduction in response to the remodeling of the actin cytoskeleton, with consequent inhibition of nuclear shuttling of a transcriptional coactivator, Yes-associated protein (YAP), and improved contractile differentiation. Furthermore, VSMC nuclei rarely deformed during macroscopic cell stretching and featured a loss of nesprin-1–mediated nuclear–cytoskeletal interactions. These results indicate that our micro-grooved collagen induces a cell alignment mimicking in vivo VSMC tissue and promotes contractile differentiation. In such processes of contractile differentiation, mechanical interaction between the nucleus and actin cytoskeleton may diminish to prevent a nuclear disturbance from the excess mechanical stress that might be essential for maintaining vascular functions.
Collapse
|
6
|
Beshay PE, Ibrahim AM, Jeffrey SS, Howe RT, Anis YH. Encapsulated Cell Dynamics in Droplet Microfluidic Devices with Sheath Flow. Micromachines (Basel) 2021; 12:mi12070839. [PMID: 34357249 PMCID: PMC8304737 DOI: 10.3390/mi12070839] [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] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/04/2021] [Revised: 07/15/2021] [Accepted: 07/16/2021] [Indexed: 11/16/2022]
Abstract
In this paper we study the dynamics of single cells encapsulated in water-in-oil emulsions in a microchannel. The flow field of a microfluidic channel is coupled to the internal flow field of a droplet through viscous traction at the interface, resulting in a rotational flow field inside the droplet. An encapsulated single cell being subjected to this flow field responds by undergoing multiple orbits, spins, and deformations that depend on its physical properties. Monitoring the cell dynamics, using a high-speed camera, can lead to the development of new label-free methods for the detection of rare cells, based on their biomechanical properties. A sheath flow microchannel was proposed to strengthen the rotational flow field inside droplets flowing in Poiseuille flow conditions. A numerical model was developed to investigate the effect of various parameters on the rotational flow field inside a droplet. The multi-phase flow model required the tracking of the fluid–fluid interface, which deforms over time due to the applied shear stresses. Experiments confirmed the significant effect of the sheath flow rate on the cell dynamics, where the speed of cell orbiting was doubled. Doubling the cell speed can double the amount of extracted biomechanical information from the encapsulated cell, while it remains within the field of view of the camera used.
Collapse
Affiliation(s)
- Peter E. Beshay
- Mechanical Design and Production Department, Faculty of Engineering, Cairo University, Giza 12613, Egypt; (P.E.B.); (A.M.I.)
| | - Ali M. Ibrahim
- Mechanical Design and Production Department, Faculty of Engineering, Cairo University, Giza 12613, Egypt; (P.E.B.); (A.M.I.)
| | - Stefanie S. Jeffrey
- Department of Surgery, Stanford University School of Medicine, Stanford, CA 94305, USA;
| | - Roger T. Howe
- Department of Electrical Engineering, Stanford University, Stanford, CA 94305, USA;
| | - Yasser H. Anis
- Mechanical Design and Production Department, Faculty of Engineering, Cairo University, Giza 12613, Egypt; (P.E.B.); (A.M.I.)
- Correspondence:
| |
Collapse
|
7
|
Kubiak A, Zieliński T, Pabijan J, Lekka M. Nanomechanics in Monitoring the Effectiveness of Drugs Targeting the Cancer Cell Cytoskeleton. Int J Mol Sci 2020; 21:E8786. [PMID: 33233645 PMCID: PMC7699791 DOI: 10.3390/ijms21228786] [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] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 11/19/2020] [Accepted: 11/19/2020] [Indexed: 12/13/2022] Open
Abstract
Increasing attention is devoted to the use of nanomechanics as a marker of various pathologies. Atomic force microscopy (AFM) is one of the techniques that could be applied to quantify the nanomechanical properties of living cells with a high spatial resolution. Thus, AFM offers the possibility to trace changes in the reorganization of the cytoskeleton in living cells. Impairments in the structure, organization, and functioning of two main cytoskeletal components, namely, actin filaments and microtubules, cause severe effects, leading to cell death. That is why these cytoskeletal components are targets for antitumor therapy. This review intends to describe the gathered knowledge on the capability of AFM to trace the alterations in the nanomechanical properties of living cells induced by the action of antitumor drugs that could translate into their effectiveness.
Collapse
Affiliation(s)
| | | | | | - Małgorzata Lekka
- Department of Biophysical Microstructures, Institute of Nuclear Physics, Polish Academy of Sciences, PL-31342 Kraków, Poland; (A.K.); (T.Z.); (J.P.)
| |
Collapse
|
8
|
Del Favero G, Bonifacio A, Rowland TJ, Gao S, Song K, Sergo V, Adler ED, Mestroni L, Sbaizero O, Taylor MRG. Danon Disease-Associated LAMP-2 Deficiency Drives Metabolic Signature Indicative of Mitochondrial Aging and Fibrosis in Cardiac Tissue and hiPSC-Derived Cardiomyocytes. J Clin Med 2020; 9:E2457. [PMID: 32751926 DOI: 10.3390/jcm9082457] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2020] [Revised: 07/15/2020] [Accepted: 07/21/2020] [Indexed: 12/15/2022] Open
Abstract
Danon disease is a severe X-linked disorder caused by deficiency of the lysosome-associated membrane protein-2 (LAMP-2). Clinical manifestations are phenotypically diverse and consist of hypertrophic and dilated cardiomyopathies, skeletal myopathy, retinopathy, and intellectual dysfunction. Here, we investigated the metabolic landscape of Danon disease by applying a multi-omics approach and combined structural and functional readouts provided by Raman and atomic force microscopy. Using these tools, Danon patient-derived cardiac tissue, primary fibroblasts, and human induced pluripotent stem cells differentiated into cardiomyocytes (hiPSC-CMs) were analyzed. Metabolic profiling indicated LAMP-2 deficiency promoted a switch toward glycolysis accompanied by rerouting of tryptophan metabolism. Cardiomyocytes' energetic balance and NAD+/NADH ratio appeared to be maintained despite mitochondrial aging. In turn, metabolic adaption was accompanied by a senescence-associated signature. Similarly, Danon fibroblasts appeared more stress prone and less biomechanically compliant. Overall, shaping of both morphology and metabolism contributed to the loss of cardiac biomechanical competence that characterizes the clinical progression of Danon disease.
Collapse
|
9
|
Hajjarian Z, Nadkarni SK. Tutorial on laser speckle rheology: technology, applications, and opportunities. J Biomed Opt 2020; 25:1-19. [PMID: 32358928 PMCID: PMC7195443 DOI: 10.1117/1.jbo.25.5.050801] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Accepted: 04/10/2020] [Indexed: 05/27/2023]
Abstract
SIGNIFICANCE The onset of several diseases is frequently marked with anomalous mechanical alteration of the affected tissue at the intersection of cells and their microenvironment. Therefore, mapping the micromechanical attributes of the tissues could enhance our understanding of the etiology of human disease, improve the diagnosis, and help stratify therapies that target these mechanical aberrations. AIM We review the tremendous opportunities offered through using optics for imaging the micromechanical properties, at length scales inaccessible to other modalities, in both basic research and clinical medicine. We specifically focus on laser speckle rheology (LSR), a technology that quantifies the mechanical properties of tissues in a rapid, noncontact manner. APPROACH In LSR, the shear viscoelastic modulus is measured from the time-variant speckle intensity fluctuations reflected off the tissue. The LSR technology is engineered and configured into several embodiments, including bench-top optical systems, endoscopes for minimally invasive procedures, portable point-of-care devices, and microscopes. RESULTS These technological nuances have primed the LSR for widespread applications in diagnosis and therapeutic monitoring, as demonstrated here, in cardiovascular disease, coagulation disorders, and tumor malignancies. CONCLUSION The fast-paced technological advancements, elaborated here, position the LSR as a competent candidate for many more exciting opportunities in basic research and medicine.
Collapse
Affiliation(s)
- Zeinab Hajjarian
- Massachusetts General Hospital, Harvard Medical School, Wellman Center for Photomedicine, Boston, Massachusetts, United States
| | - Seemantini K. Nadkarni
- Massachusetts General Hospital, Harvard Medical School, Wellman Center for Photomedicine, Boston, Massachusetts, United States
| |
Collapse
|
10
|
Abstract
Mechanical forces play an important role in the behavior and development of biological systems and disease at all spatial scales, from cells and their constituents to tissues and organs. Such forces have a profound influence on the health, structural integrity, and normal function of cells and organs. Accurate knowledge of cell and tissue biomechanical properties is essential to map the distribution of forces and mechanical cues in biological systems. Cell and tissue biomechanical properties are also known to be important on their own as indicators of health or diseases state. Hence, optical elastography and biomechanics methods can aid in the understanding and clinical diagnosis of a wide variety of diseases. We provide a brief overview and highlight of the Optical Elastography and Tissue Biomechanics VI conference, which took place in San Francisco, February 2 and 3, 2019, as a part of Photonics West symposium.
Collapse
Affiliation(s)
- Kirill V. Larin
- University of Houston, Department of Biomedical Engineering, Houston, Texas, United States
| | - Giuliano Scarcelli
- University of Maryland, Department of Biomedical Engineering, College Park, Maryland, United States
| | - Vladislav V. Yakovlev
- Texas A&M University, Department of Biomedical Engineering, College Station, Texas, United States
| |
Collapse
|
11
|
Oliveira VR, Uriarte JJ, Falcones B, Jorba I, Zin WA, Farré R, Navajas D, Almendros I. Biomechanical Response of Lung Epithelial Cells to Iron Oxide and Titanium Dioxide Nanoparticles. Front Physiol 2019; 10:1047. [PMID: 31474879 PMCID: PMC6707084 DOI: 10.3389/fphys.2019.01047] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [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: 12/05/2018] [Accepted: 07/30/2019] [Indexed: 11/30/2022] Open
Abstract
Increasing evidence shows that lungs can be damaged by inhalation of nanoparticles (NPs) at environmental and occupational settings. Recent findings have associated the exposure to iron oxide (Fe2O3) and titanium dioxide (TiO2) – NPs widely used in biomedical and clinical research – with pulmonary oxidative stress and inflammation. Although changes on cellular mechanics could contribute to pulmonary inflammation, there is no information regarding the effects of Fe2O3 and TiO2 on alveolar epithelial cell biomechanics. The aim was to investigate the NPs-induced biomechanical effects in terms of cell stiffness and traction forces exerted by human alveolar epithelial cells. Cell Young’s modulus (E) measured by atomic force microscopy in alveolar epithelial cells significantly decreased after exposure to Fe2O3 and TiO2 (∼28 and ∼25%, respectively) compared to control conditions. Moreover, both NPs induced a similar reduction in the traction forces exerted by the alveolar epithelial cells in comparison to the control conditions. Accordingly, immunofluorescence images revealed a reduction of actomyosin stress fibers in response to the exposure to NPs. However, no inflammatory response was detected. In conclusion, an acute exposure of epithelial pulmonary cells to Fe2O3 and TiO2 NPs, which was mild since it was non-cytotoxic and did not induce inflammation, modified cell biomechanical properties which could be translated into damage of the epithelial barrier integrity, suggesting that mild environmental inhalation of Fe2O3 and TiO2 NPs could not be innocuous.
Collapse
Affiliation(s)
- Vinícius Rosa Oliveira
- Unitat de Biofísica i Bioenginyeria, Facultat de Medicina, Universitat de Barcelona, Barcelona, Spain.,Laboratório de Fisiologia da Respiração, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Juan José Uriarte
- Unitat de Biofísica i Bioenginyeria, Facultat de Medicina, Universitat de Barcelona, Barcelona, Spain
| | - Bryan Falcones
- Unitat de Biofísica i Bioenginyeria, Facultat de Medicina, Universitat de Barcelona, Barcelona, Spain
| | - Ignasi Jorba
- Unitat de Biofísica i Bioenginyeria, Facultat de Medicina, Universitat de Barcelona, Barcelona, Spain.,Institute for Bioengineering of Catalonia, The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Walter Araujo Zin
- Laboratório de Fisiologia da Respiração, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Ramon Farré
- Unitat de Biofísica i Bioenginyeria, Facultat de Medicina, Universitat de Barcelona, Barcelona, Spain.,Centro de Investigación Biomédica en Red Enfermedades Respiratorias (CIBERES), Madrid, Spain.,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | - Daniel Navajas
- Unitat de Biofísica i Bioenginyeria, Facultat de Medicina, Universitat de Barcelona, Barcelona, Spain.,Institute for Bioengineering of Catalonia, The Barcelona Institute of Science and Technology, Barcelona, Spain.,Centro de Investigación Biomédica en Red Enfermedades Respiratorias (CIBERES), Madrid, Spain
| | - Isaac Almendros
- Unitat de Biofísica i Bioenginyeria, Facultat de Medicina, Universitat de Barcelona, Barcelona, Spain.,Centro de Investigación Biomédica en Red Enfermedades Respiratorias (CIBERES), Madrid, Spain.,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| |
Collapse
|
12
|
Wang Y, Zhang Y, Zhang M, Li J, Pan Y, Liu L, Deng L. Saponins of Dioscorea Nipponicae Inhibits IL-17A-Induced Changes in Biomechanical Behaviors of In Vitro Cultured Human Airway Smooth Muscle Cells. ACTA ACUST UNITED AC 2019; 2:0110021-110027. [PMID: 32328572 PMCID: PMC7164499 DOI: 10.1115/1.4042317] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2018] [Revised: 12/03/2018] [Indexed: 11/08/2022]
Abstract
Airway hyperresponsiveness (AHR) is one of the main pathologic features of bronchial asthma, which is largely attributable to enhanced contractile response of asthmatic airway smooth muscle. Although β2 adrenergic receptor agonists are commonly used to relax airway smooth muscle for treating AHR, there are side effects such as desensitization of long-term use. Therefore, it is desirable to develop alternative relaxant for airway smooth muscle, preferably based on natural products. One potential candidate is the inexpensive and widely available natural herb saponins of Dioscorea nipponicae (SDN), which has recently been reported to suppress the level of inflammatory factor IL-17A in ovalbumin-induced mice, thereby alleviating the inflammation symptoms of asthma. Here, we evaluated the biomechanical effect of SDN on IL-17A-mediated changes of cultured human airway smooth muscle cells (HASMCs) in vitro. The stiffness and traction force of the cells were measured by optical magnetic twisting cytometry (OMTC), and Fourier transform traction microscopy (FTTM), respectively. The cell proliferation was evaluated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) colorimetry, the cell migration was measured by cell scratch test, and the changes of cell cytoskeleton were assessed by laser confocal microscopy. We found that the stiffness and traction force of HASMCs were enhanced along with the increases of IL-17A concentration and exposure time, and SDN treatment dose-dependently reduced these IL-17A-induced changes in cell mechanical properties. Furthermore, SDN alleviated IL-17A-mediated effects on HASMCs proliferation, migration, and cytoskeleton remodeling. These results demonstrate that SDN could potentially be a novel drug candidate as bronchodilator for treating asthma-associated AHR.
Collapse
Affiliation(s)
- Yue Wang
- Changzhou Key Laboratory ofRespiratory Medical Engineering, Institute of Biomedical Engineering and Health Sciences
| | - Yifan Zhang
- Changzhou Key Laboratory ofRespiratory Medical Engineering, Institute of Biomedical Engineering and Health Sciences; School of Pharmaceutical Engineering & Life Science/School of Nursing, Changzhou University, Changzhou, Jiangsu 213164, China
| | - Ming Zhang
- Department of Thoracic and Cardiovascular Surgery, Changzhou No. 2 People's Hospital, Nanjing Medical University, Changzhou, Jiangsu 213003, China
| | - Jingjing Li
- Changzhou Key Laboratory of Respiratory Medical Engineering, Institute of Biomedical Engineering and Health Sciences, Changzhou University, Changzhou, Jiangsu 213164, China
| | - Yan Pan
- Changzhou Key Laboratory of Respiratory Medical Engineering, Institute of Biomedical Engineering and Health Sciences, Changzhou University, Changzhou, Jiangsu 213164, China
| | - Lei Liu
- Changzhou Key Laboratory of Respiratory Medical Engineering, Institute of Biomedical Engineering and Health Sciences, Changzhou University, Changzhou, Jiangsu 213164, China
| | - Linhong Deng
- Changzhou Key Laboratory of Respiratory Medical Engineering, Institute of Biomedical Engineering and Health Sciences; School of Pharmaceutical Engineering & Life Science/School of Nursing, Changzhou University, Changzhou, Jiangsu 213164, China e-mail:
| |
Collapse
|
13
|
Caluori G, Pribyl J, Pesl M, Oliver-De La Cruz J, Nardone G, Skladal P, Forte G. Advanced and Rationalized Atomic Force Microscopy Analysis Unveils Specific Properties of Controlled Cell Mechanics. Front Physiol 2018; 9:1121. [PMID: 30174612 PMCID: PMC6107778 DOI: 10.3389/fphys.2018.01121] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [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: 03/31/2018] [Accepted: 07/25/2018] [Indexed: 01/01/2023] Open
Abstract
The cell biomechanical properties play a key role in the determination of the changes during the essential cellular functions, such as contraction, growth, and migration. Recent advances in nano-technologies have enabled the development of new experimental and modeling approaches to study cell biomechanics, with a level of insights and reliability that were not possible in the past. The use of atomic force microscopy (AFM) for force spectroscopy allows nanoscale mapping of the cell topography and mechanical properties under, nearly physiological conditions. A proper evaluation process of such data is an essential factor to obtain accurate values of the cell elastic properties (primarily Young's modulus). Several numerical models were published in the literature, describing the depth sensing indentation as interaction process between the elastic surface and indenting probe. However, many studies are still relying on the nowadays outdated Hertzian model from the nineteenth century, or its modification by Sneddon. The lack of comparison between the Hertz/Sneddon model with their modern modifications blocks the development of advanced analysis software and further progress of AFM promising technology into biological sciences. In this work, we applied a rationalized use of mechanical models for advanced postprocessing and interpretation of AFM data. We investigated the effect of the mechanical model choice on the final evaluation of cellular elasticity. We then selected samples subjected to different physicochemical modulators, to show how a critical use of AFM data handling can provide more information than simple elastic modulus estimation. Our contribution is intended as a methodological discussion of the limitations and benefits of AFM-based advanced mechanical analysis, to refine the quantification of cellular elastic properties and its correlation to undergoing cellular processes in vitro.
Collapse
Affiliation(s)
- Guido Caluori
- International Clinical Research Center of the St. Anne's University Hospital Brno (FNUSA-ICRC), Interventional Cardiac Electrophysiology, Brno, Czechia.,Central European Institute of Technology of Masaryk University, Nanobiotechnology, Brno, Czechia
| | - Jan Pribyl
- Central European Institute of Technology of Masaryk University, Nanobiotechnology, Brno, Czechia
| | - Martin Pesl
- International Clinical Research Center of the St. Anne's University Hospital Brno (FNUSA-ICRC), Interventional Cardiac Electrophysiology, Brno, Czechia.,Department of Biology, Faculty of Medicine, Masaryk University, Brno, Czechia.,First Department of Internal Medicine/Cardioangiology, St. Anne's Hospital, Masaryk University, Brno, Czechia
| | - Jorge Oliver-De La Cruz
- International Clinical Research Center of the St. Anne's University Hospital Brno (FNUSA-ICRC), Center for Translational Medicine, Brno, Czechia
| | - Giorgia Nardone
- International Clinical Research Center of the St. Anne's University Hospital Brno (FNUSA-ICRC), Center for Translational Medicine, Brno, Czechia
| | - Petr Skladal
- Central European Institute of Technology of Masaryk University, Nanobiotechnology, Brno, Czechia
| | - Giancarlo Forte
- International Clinical Research Center of the St. Anne's University Hospital Brno (FNUSA-ICRC), Center for Translational Medicine, Brno, Czechia.,Department of Biomaterials Science, Institute of Dentistry, University of Turku, Turku, Finland
| |
Collapse
|
14
|
Abstract
We envision that electrodeformation of biological cells through dielectrophoresis as a new technique to elucidate the mechanistic details underlying membrane failure by electrical and mechanical stresses. Here we demonstrate the full control of cellular uniaxial deformation and tensile recovery in biological cells via amplitude-modified electric field at radio frequency by an interdigitated electrode array in microfluidics. Transient creep and cyclic experiments were performed on individually tracked human erythrocytes. Observations of the viscoelastic-to-viscoplastic deformation behavior and the localized plastic deformations in erythrocyte membranes suggest that electromechanical stress results in irreversible membrane failure. Examples of membrane failure can be separated into different groups according to the loading scenarios: mechanical stiffening, physical damage, morphological transformation from discocyte to echinocyte, and whole cell lysis. These results show that this technique can be potentially utilized to explore membrane failure in erythrocytes affected by other pathophysiological processes.
Collapse
Affiliation(s)
- E Du
- Correspondence: ; Tel.: +1-561-297-3441
| | | | | |
Collapse
|
15
|
Grasland-Mongrain P, Zorgani A, Nakagawa S, Bernard S, Paim LG, Fitzharris G, Catheline S, Cloutier G. Ultrafast imaging of cell elasticity with optical microelastography. Proc Natl Acad Sci U S A 2018; 115:861-6. [PMID: 29339488 DOI: 10.1073/pnas.1713395115] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In wave physics, and especially seismology, uncorrelated vibrations could be exploited using “noise correlation” tools to reconstruct images of a medium. By using a high-frequency vibration, a high-speed tracking device, and a reconstruction technique based on temporal correlations of travelling waves we conceptualized an optical microelastography technique to map elasticity of internal cellular structures. This technique, unlike other methods, can provide an elasticity image in less than a millisecond, thus opening the possibility of studying dynamic cellular processes and elucidating new mechanocellular properties. We call this proposed technique “cell quake elastography.” Elasticity is a fundamental cellular property that is related to the anatomy, functionality, and pathological state of cells and tissues. However, current techniques based on cell deformation, atomic force microscopy, or Brillouin scattering are rather slow and do not always accurately represent cell elasticity. Here, we have developed an alternative technique by applying shear wave elastography to the micrometer scale. Elastic waves were mechanically induced in live mammalian oocytes using a vibrating micropipette. These audible frequency waves were observed optically at 200,000 frames per second and tracked with an optical flow algorithm. Whole-cell elasticity was then mapped using an elastography method inspired by the seismology field. Using this approach we show that the elasticity of mouse oocytes is decreased when the oocyte cytoskeleton is disrupted with cytochalasin B. The technique is fast (less than 1 ms for data acquisition), precise (spatial resolution of a few micrometers), able to map internal cell structures, and robust and thus represents a tractable option for interrogating biomechanical properties of diverse cell types.
Collapse
|
16
|
Babahosseini H, Strobl JS, Agah M. Using nanotechnology and microfluidics in search of cell biomechanical cues for cancer progression. Nanomedicine (Lond) 2015; 10:2635-8. [PMID: 26328619 DOI: 10.2217/nnm.15.104] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Affiliation(s)
- Hesam Babahosseini
- Department of Mechanical Engineering, Virginia Tech, Blacksburg, VA 24061, USA
| | - Jeannine S Strobl
- The Bradley Department of Electrical & Computer Engineering, Virginia Tech, Blacksburg, VA 24061, USA
| | - Masoud Agah
- The Bradley Department of Electrical & Computer Engineering, Virginia Tech, Blacksburg, VA 24061, USA
| |
Collapse
|
17
|
Louw TM, Budhiraja G, Viljoen HJ, Subramanian A. Mechanotransduction of ultrasound is frequency dependent below the cavitation threshold. Ultrasound Med Biol 2013; 39:1303-19. [PMID: 23562015 PMCID: PMC4183372 DOI: 10.1016/j.ultrasmedbio.2013.01.015] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Revised: 01/18/2013] [Accepted: 01/27/2013] [Indexed: 05/11/2023]
Abstract
This study provides evidence that low-intensity ultrasound directly affects nuclear processes, and the magnitude of the effect varies with frequency. In particular, we show that the transcriptional induction of first load-inducible genes, which is independent of new protein synthesis, is frequency dependent. Bovine chondrocytes were exposed to low-intensity (below the cavitational threshold) ultrasound at 2, 5 and 8 MHz. Ultrasound elevated the expression of early response genes c-Fos, c-Jun and c-Myc, maximized at 5 MHz. The phosphorylated ERK inhibitor PD98059 abrogated any increase in c-series gene expression, suggesting that signaling occurs via the MAPPK/ERK pathway. However, phosphorylated ERK levels did not change with ultrasound frequency, indicating that processes downstream of ERK phosphorylation (such as nuclear transport and chromatin reorganization) respond to ultrasound with frequency dependence. A quantitative, biphasic mathematical model based on Biot theory predicted that cytoplasmic and nuclear stress is maximized at 5.2 ± 0.8 MHz for a chondrocyte, confirming experimental measurements.
Collapse
Affiliation(s)
- Tobias M Louw
- Department of Chemical & Biomolecular Engineering, University of Nebraska-Lincoln, Lincoln, NE, USA
| | | | | | | |
Collapse
|
18
|
Byun H, Hillman TR, Higgins JM, Diez-Silva M, Peng Z, Dao M, Dasari RR, Suresh S, Park Y. Optical measurement of biomechanical properties of individual erythrocytes from a sickle cell patient. Acta Biomater 2012; 8:4130-8. [PMID: 22820310 PMCID: PMC3576574 DOI: 10.1016/j.actbio.2012.07.011] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.6] [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: 11/29/2011] [Revised: 06/10/2012] [Accepted: 07/11/2012] [Indexed: 11/19/2022]
Abstract
Sickle cell disease (SCD) is characterized by the abnormal deformation of red blood cells (RBCs) in the deoxygenated condition, as their elongated shape leads to compromised circulation. The pathophysiology of SCD is influenced by both the biomechanical properties of RBCs and their hemodynamic properties in the microvasculature. A major challenge in the study of SCD involves accurate characterization of the biomechanical properties of individual RBCs with minimum sample perturbation. Here we report the biomechanical properties of individual RBCs from a SCD patient using a non-invasive laser interferometric technique. We optically measure the dynamic membrane fluctuations of RBCs. The measurements are analyzed with a previously validated membrane model to retrieve key mechanical properties of the cells: bending modulus; shear modulus; area expansion modulus; and cytoplasmic viscosity. We find that high cytoplasmic viscosity at ambient oxygen concentration is principally responsible for the significantly decreased dynamic membrane fluctuations in RBCs with SCD, and that the mechanical properties of the membrane cortex of irreversibly sickled cells (ISCs) are different from those of the other types of RBCs in SCD.
Collapse
Affiliation(s)
- HeeSu Byun
- Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Republic of Korea
| | - Timothy R. Hillman
- George R. Harrison Spectroscopy Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - John M. Higgins
- Center for Systems Biology and Department of Pathology, Massachusetts General Hospital, Boston, MA 02114, USA
- Department of Systems Biology, Harvard Medical School, Boston, MA 02114, USA
| | - Monica Diez-Silva
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Zhangli Peng
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Ming Dao
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Ramachandra R. Dasari
- George R. Harrison Spectroscopy Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Subra Suresh
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - YongKeun Park
- Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Republic of Korea
| |
Collapse
|
19
|
Abstract
Chondrocytes and osteoblasts experience multiple stresses in vivo. The optimum mechanical conditions for cell health are not fully understood. This paper describes the optical and microfluidic mechanical manipulation of single suspended cells enabled by the μPIVOT, an integrated micron resolution particle image velocimeter (μPIV) and dual optical tweezers instrument (OT). In this study, we examine the viability and trap stiffness of cartilage cells, identify the maximum fluid-induced stresses possible in uniform and extensional flows, and compare the deformation characteristics of bone and muscle cells. These results indicate cell photodamage of chondrocytes is negligible for at least 20 min for laser powers below 30 mW, a dead cell presents less resistance to internal organelle rearrangement and deforms globally more than a viable cell, the maximum fluid-induced shear stresses are limited to ~15 mPa for uniform flows but may exceed 1 Pa for extensional flows, and osteoblasts show no deformation for shear stresses up to 250 mPa while myoblasts are more easily deformed and exhibit a modulated response to increasing stress. This suggests that global and/or local stresses can be applied to single cells without physical contact. Coupled with microfluidic sensors, these manipulations may provide unique methods to explore single cell biomechanics.
Collapse
Affiliation(s)
- Nathalie Nève
- Department of Mechanical & Materials Engineering, Portland State University, P.O. Box 751, Portland, OR 97201, USA
| | - Sean S. Kohles
- Department of Mechanical & Materials Engineering, Portland State University, P.O. Box 751, Portland, OR 97201, USA
- Department of Surgery, Oregon Health & Science University, Portland, OR 97239, USA
| | - Shelley R. Winn
- Department of Restorative Dentistry, Oregon Health & Science University, Portland, OR 97239, USA
- Department of Molecular & Medical Genetics, Oregon Health & Science University, Portland, OR 97239, USA
| | - Derek C. Tretheway
- Department of Mechanical & Materials Engineering, Portland State University, P.O. Box 751, Portland, OR 97201, USA
| |
Collapse
|
20
|
Nève N, Lingwood JK, Zimmerman J, Kohles SS, Tretheway DC. The μPIVOT: an integrated particle image velocimeter and optical tweezers instrument for microenvironment investigations. Meas Sci Technol 2008; 19:95403. [PMID: 18953424 PMCID: PMC2572229 DOI: 10.1088/0957-0233/19/9/095403] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
A novel instrument to manipulate and characterize the mechanical environment in and around microscale objects in a fluidic environment has been developed by integrating two laser-based techniques: micron-resolution particle image velocimetry (μPIV) and optical tweezers (OT). This instrument, the μPIVOT, enables a new realm of microscale studies, yet still maintains the individual capabilities of each optical technique. This was demonstrated with individual measurements of optical trap stiffness (∼70 pN μm(-1) for a 20 μm polystyrene sphere and a linear relationship between trap stiffness and laser power) and fluid velocities within 436 nm of a microchannel wall. The integrated device was validated by comparing computational flow predictions to the measured velocity profile around a trapped particle in either a uniform flow or an imposed, gravity-driven microchannel flow (R(2) = 0.988, RMS error = 13.04 μm s(-1)). Interaction between both techniques is shown to be negligible for 15 μm to 35 μm diameter trapped particles subjected to fluid velocities from 50 μm s(-1) to 500 μm s(-1) even at the highest laser power (1.45 W). The integrated techniques will provide a unique perspective toward understanding microscale phenomena including single-cell biomechanics, non-Newtonian fluid mechanics and single particle or particle-particle hydrodynamics.
Collapse
Affiliation(s)
- N Nève
- Department of Mechanical & Materials Engineering, Portland State University, PO Box 751, Portland, OR 97207-0751, USA
| | | | | | | | | |
Collapse
|
21
|
Abstract
The structure and function of each individual mammary epithelial cell (MEC) is largely controlled by a bidirectional interchange of chemical and mechanical signals with the microenvironment. Most of these signals are tissue-specific, since they arise from the three-dimensional (3D) tissue organization and are modulated during mammary gland development, maturation, pregnancy, lactation, and involution. Although the important role played by structural and mechanical signals in mammary cell and tissue function is being increasingly recognized, quantitative biomechanical approaches are still scarce. Here we review currently available biomechanical tools that allow quantitative examination of individual cells, groups of cells or full monolayers in two-dimensional cultures, and cells in 3D cultures. Current technological limitations and challenges are discussed, with special emphasis on their potential applications in MEC biology. We argue that the combination of biomechanical tools with current efforts in mathematical modeling and in cell and molecular biology applied to 3D cultures provides a powerful approach to unravel the complexity of tissue-specific structure-function relationships.
Collapse
Affiliation(s)
- Jordi Alcaraz
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California
- To whom correspondence should be addressed at Life Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, MS 83-101, Berkeley, California 94720; ;
| | - Celeste M. Nelson
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California
| | - Mina J. Bissell
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California
- To whom correspondence should be addressed at Life Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, MS 83-101, Berkeley, California 94720; ;
| |
Collapse
|