Evgeny Gladilin

Universität Heidelberg, Heidelburg, Baden-Württemberg, Germany

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Publications (47)20.05 Total impact

  • Evgeny Gladilin, Paula Gonzalez, Roland Eils
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    ABSTRACT: Mechanical cell properties play an important role in many basic biological functions, including motility, adhesion, proliferation and differentiation. There is a growing body of evidence that the mechanical cell phenotype can be used for detection and, possibly, treatment of various diseases, including cancer. Understanding of pathological mechanisms requires investigation of the relationship between constitutive properties and major structural components of cells, i.e., the nucleus and cytoskeleton. While the contribution of actin und microtubules to cellular rheology has been extensively studied in the past, the role of intermediate filaments has been scarcely investigated up to now. Here, for the first time we compare the effects of drug-induced disruption of actin and vimentin intermediate filaments on mechanical properties of suspended NK cells using high-throughput deformability measurements and computational modeling. Although, molecular mechanisms of actin and vimentin disruption by the applied cytoskeletal drugs, Cytochalasin-D and Withaferin-A, are different, cell softening in both cases can be attributed to reduction of the effective density and stiffness of filament networks. Our experimental data suggest that actin and vimentin deficient cells exhibit, in average, 41% and 20% higher deformability in comparison to untreated control. 3D Finite Element simulation is performed to quantify the contribution of cortical actin and perinuclear vimentin to mechanical phenotype of the whole cell. Our simulation provides quantitative estimates for decreased filament stiffness in drug-treated cells and predicts more than two-fold increase of the strain magnitude in the perinuclear vimentin layer of actin deficient cells relatively to untreated control. Thus, the mechanical function of vimentin becomes particularly essential in motile and proliferating cells that have to dynamically remodel the cortical actin network. These insights add functional cues to frequently observed overexpression of vimentin in diverse types of cancer and underline the role of vimentin targeting drugs, such as Withaferin-A, as a potent cancerostatic supplement.
    Journal of biomechanics. 06/2014;
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    ABSTRACT: Mechanical properties of the cell nucleus play an important role in maintaining the integrity of the genome and controlling the cellular force balance. Irregularities in these properties have been related to disruption of a variety of force-dependent processes in the cell, such as migration, division, growth or differentiation. Characterizing mechanical properties of the cell nucleus in situ and relating these parameters to cellular phenotypes remain challenging tasks, as conventional micromanipulation techniques do not allow direct probing of intracellular structures. Here, we present a framework based on light microscopic imaging and automated mechanical modeling that enables characterization of the compressibility of the nuclear interior in situ. Based entirely on optical methods, our approach does not require application of destructive or contacting techniques and it enables measurements of a significantly larger number of cells. Compressibility, in this paper represented by Poisson's ratio ν, is determined by fitting a numerical model to experimentally observed time series of microscopic images of fluorescent cell nuclei in which bleached patterns are introduced. In a proof-of-principle study, this framework was applied to estimate ν in wild type cells and cells lacking important structural proteins of the nuclear envelope (LMNA(-/-)). Based on measurements of a large number of cells, our study revealed distinctive changes in compressibility of the nuclear interior between these two cell types. Our method allows an automated, contact-free estimation of mechanical properties of intracellular structures. Combined with knockdown and overexpression screens, it paves the way towards a high-throughput measurement of intracellular mechanical properties in functional phenotyping screens.
    Journal of biomechanics 09/2011; 44(15):2642-8. · 2.66 Impact Factor
  • Biophysical Journal 01/2011; 100(3). · 3.67 Impact Factor
  • E Gladilin, M Schulz, C Kappel, R Eils
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    ABSTRACT: Mechanical properties of the chromatin-bearing nucleus in normal and pathological cells are of general interest for epigenetics and medicine. Conventional techniques for quantitative measurements of material properties of cellular matter are based on application of controlled forces onto the cellular or nuclear boundary and do not allow probing intracellular structures that are not directly accessible for physical contact inside the living cell. In this work, we present a novel approach for contactless determination of the nuclear compressibility (i.e. the Poisson's ratio ν) in living cells by means of image- and model-based analysis of drug-induced cell deformation. The Poisson's ratio of the HeLa cell nucleus is determined from time-series of 3D images as a parameter of constitutive model that minimizes the dissimilarity between the numerically predicted and experimentally observed images.
    Journal of Microscopy 12/2010; 240(3):216-26. · 1.63 Impact Factor
  • Evgeny Gladilin, Roland Eils
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    ABSTRACT: Determination of constitutive properties of cells is important for quantitative description of cellular mechanics. Existing approaches to mechanical cell manipulation are based on experimental techniques that do not allow unsupervised analysis of large number of cells and/or probing of intracellular structures that are not directly exposed to external loads. Alternatively, mechanical behavior of cellular matter can be studied in time-series of microscopic images. In this work, we present an image- and model-based framework for determination of constitutive properties of living cells. Our experimental studies demonstrate application of this approach for quantitative analysis of cellular mechanics on the basis of image data assessed by different experimental techniques, including microplate stretching, optical stretching and contactless cellular deformation induction using cytoskeleton-disrupting drugs.
    Proc SPIE 03/2010;
  • E. Gladilin, R. Eils
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    ABSTRACT: Determination of constitutive properties plays a key role in quantitative description of cellular mechanics. Existing methods of experimental cell mechanics have one of the following drawbacks: they do not allow unsupervised analysis of large number of cells and/or probing of intracellular structures that are not directly exposed to boundary forces. Alternatively, mechanical behavior of cellular matter can be studied in time-series of microscopic images that capture successive deformation of cellular matter. In this work, we present an image- and model-based framework for determination of constitutive properties of living cells and subcellular structures. Our experimental studies demonstrate application of this approach for quantitative analysis of cellular mechanics on the basis of image data assessed by different experimental techniques, including microplate and optical stretchers as well as fully contactless procedures based on optical monitoring of drug-induced cellular deformation.
    01/2010;
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    ABSTRACT: Apart from storing most of the DNA in eukaryotic cells, the cell nucleus provides mechanical protection through its nuclear envelope to ensure the integrity of the genome. The nuclear lamina is known to play an important role in this respect by supplying a structural framework for the nucleus [1]. The severe diseases arising from mutations in the LMNA gene confirm the importance of the lamin proteins for normal cell functionality [2]. Most experimental techniques for investigation of the cell mechanics are based on the application of external forces onto the cell boundary [3]. Thus, the quantitative determination of the mechanical properties of intracellular structures in situ, still represents a challenging task. In our previous works, we proposed a 3D image- and model-based framework for analysis of intracellular mechanics [4]. In this work, we extend this approach to a fully contactless investigation of nuclear mechanics of normal and LMNA–/– mutant cells. Differently from previous approaches, cellular deformation was induced by chemical agents, i.e., without any mechanical contact with the cell boundary. In particular, we focus on (i) comparative analysis of 3D structural response of nuclear matter with respect to external forces in normal and pathological cell, as well as (ii) determination of the scarcely-investigated nuclear compressibility (i.e. the Poisson’s ratio).
    ASME 2009 Summer Bioengineering Conference; 06/2009
  • Source
    Evgeny Gladilin, Roland Eils
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    ABSTRACT: Unsupervised analysis of time-series of live-cell images is one of the important tools of quantitative biology. Due to permanent cell motility or displacements of subcellular structures, microscopic images exhibit intrinsic non-uniform motion. In this article, we present a novel approach for detection of non-uniform multi-body motion which is based on combination of the Fourier-phase correlation with iterative probing target and background image regions similar to the strategy known from saccadic eye movements. We derive theoretical expressions that yield plausible explanation why this strategy turns out to be advantageous for tracking particular image pattern. Our experiments with synthetic and live-cell images demonstrate that the proposed approach is capable of accurately detecting non-uniform motion in synthetic and live-cell images.
    Proc SPIE 02/2009;
  • Evgeny Gladilin, Alexander Ivanov
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    ABSTRACT: Cranio-maxillofacial (CMF) surgery operations are associated with rearrangement of facial hard and soft tissues, leading to dramatic changes in facial geometry. Often, correction of the aesthetical patient's appearance is the primary objective of the surgical intervention. Due to the complexity of the facial anatomy and the biomechanical behaviour of soft tissues, the result of the surgical impact cannot always be predicted on the basis of surgeon's intuition and experience alone. Computational modelling of soft tissue outcome using individual tomographic data and consistent numerical simulation of soft tissue mechanics can provide valuable information for surgeons during the planning stage. In this article, we present a general framework for computer-assisted planning of CMF surgery interventions that is based on the reconstruction of patient's anatomy from 3D computer tomography images and finite element analysis of soft tissue deformations. Examples from our clinical case studies that deal with the solution of direct and inverse surgical problems (i.e. soft tissue prediction, inverse implant shape design) demonstrate that the developed approach provides a useful tool for accurate prediction and optimisation of aesthetic surgery outcome.
    Computer Methods in Biomechanics and Biomedical Engineering 12/2008; 12(3):305-18. · 1.39 Impact Factor
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    ABSTRACT: Topological analysis of cells and subcellular structures on the basis of image data, is one of the major trends in modern quantitative biology. However, due to the dynamic nature of cell biology, the optical appearance of different cells or even time-series of the same cell is undergoing substantial variations in shape and texture, which makes a comparison of shapes and distances across different cells a nontrivial task. In the absence of canonical invariances, a natural approach to the normalization of cells consists of spherical mapping, enabling the analysis of targeted regions in terms of canonical spherical coordinates, that is, radial distances and angles. In this work, we present a physically-based approach to spherical mapping, which has been applied for topological analysis of multichannel confocal laser scanning microscopy images of human fibroblast nuclei. Our experimental results demonstrate that spherical mapping of entire nuclear domains can automatically be obtained by inverting affine and elastic transformations, performed on a spherical finite element template mesh.
    Journal of Microscopy 07/2008; 231(Pt 1):105-14. · 1.63 Impact Factor
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    Evgeny Gladilin, Roland Eils
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    ABSTRACT: Linear elastic model widely applied for simulation of soft tissue deformations in biomedical imaging applications is basically limited to the range of small deformations and rotations. Thus, computation of large deformations and rotations using linear elastic approximation and its derivatives is associated with substantial error. More realistic modeling of mechanical behavior of soft tissue requires handling of different types of nonlinearities. This paper presents a framework for more accurate modeling of deformable structures based on the St. Venant-Kirchhoff law with the nonlinear Green-Lagrange strain tensor and variable material constants, which considers both material and geometric nonlinearities. We derive the governing partial differential equation of nonlinear elasticity, which represents consistent extension of the Lame-Navier PDE of linear elasticity, and describe two alternative numerical schemes for solving this nonlinear PDE via the Newton's and fixed point method, respectively. The results of our comparative studies demonstrate the advantages of nonlinear elastic model for accurate computing of large deformations and rotations in comparison to the linear elastic approximation.
    Proc SPIE 04/2008;
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    ABSTRACT: Mechanical forces play an important role in many microbiological phenomena such as embryogenesis, regeneration, cell proliferation and differentiation. Micromanipulation of cells in a controlled environment is a widely used approach for understanding cellular responses with respect to external mechanical forces. While modern micromanipulation and imaging techniques provide useful optical information about the change of overall cell contours under the impact of external loads, the intrinsic mechanisms of energy and signal propagation throughout the cell structure are usually not accessible by direct observation. This work deals with the computational modelling and simulation of intracellular strain state of uniaxially stretched cells captured in a series of images. A nonlinear elastic finite element method on tetrahedral grids was applied for numerical analysis of inhomogeneous stretching of a rat embryonic fibroblast 52 (REF 52) using a simplified two-component model of a eukaryotic cell consisting of a stiffer nucleus surrounded by a softer cytoplasm. The difference between simulated and experimentally observed cell contours is used as a feedback criterion for iterative estimation of canonical material parameters of the two-component model such as stiffness and compressibility. Analysis of comparative simulations with varying material parameters shows that (i) the ratio between the stiffness of cell nucleus and cytoplasm determines intracellular strain distribution and (ii) large deformations result in increased stiffness and decreased compressibility of the cell cytoplasm. The proposed model is able to reproduce the evolution of the cellular shape over a sequence of observed deformations and provides complementary information for a better understanding of mechanical cell response.
    Physical Biology 07/2007; 4(2):104-13. · 2.62 Impact Factor
  • Evgeny Gladilin, Roland Eils
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    ABSTRACT: External forces, cell adhesion and soluble signaling molecules influence fundamental functions of cells like shape, migration, proliferation or differentiation. Thus, investigating how mechanical forces affect 3D cell structure and function is of crucial significance in order to gain a better understanding healthy and malignant cell behavior during embryogenesis, regeneration or malignancy [1]. Micromanipulation of cells in a controlled environment is a widely used approach for understanding cellular responses with respect to external mechanical forces. While experimental data provide optical information about the overall cell shape, the 3D deformation state of intracellular structures is not accessible by direct observations and measurements. However, the continuous description of the intracellular deformation state can be calculated as a numerical solution of the boundary value problem given by the partial differential equations of structural mechanics, including a set of canonic material constants (stiffness, compressibility), and the boundary conditions derived from time series of images, e.g. change of visible cell contours. The main idea of our approach is to reformulate the problem of finding optimal modeling parameters as an image registration problem. That is the optimal set of modeling parameters corresponds to the minimum of a suitable similarity measure between computationally predicted and experimentally observed deformations. In this article, we focus on the numerical analysis of uniaxial stretching of a rat embryonic fibroblast 52 (REF 52) based on a series of 2D images reflecting the successive alteration of cell contours during deformation. The goal of this study consists in finding an optimal set of material constants within a non-linear hyperelastic material law, which is able to reproduce results of experimental observations.
    ASME 2007 Summer Bioengineering Conference; 06/2007
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    ABSTRACT: Investigation of 3D chromatin structure in interphase cell nuclei is important for the understanding of genome function. For a reconstruction of the 3D architecture of the human genome, systematic fluorescent in situ hybridization in combination with 3D confocal laser scanning microscopy is applied. The position of two or three genomic loci plus the overall nuclear shape were simultaneously recorded, resulting in statistical series of pair and triple loci combinations probed along the human chromosome 1 q-arm. For interpretation of statistical distributions of geometrical features (e.g. distances, angles, etc.) resulting from finite point sampling experiments, a Monte-Carlo-based approach to numerical computation of geometrical probability density functions (PDFs) for arbitrarily-shaped confined spatial domains is developed. Simulated PDFs are used as bench marks for evaluation of experimental PDFs and quantitative analysis of dimension and shape of probed 3D chromatin regions. Preliminary results of our numerical simulations show that the proposed numerical model is capable to reproduce experimental observations, and support the assumption of confined random folding of 3D chromatin fiber in interphase cell nuclei.
    05/2007: pages 104-118;
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    ABSTRACT: Investigation of 3D chromatin structure in interphase cell nuclei is important for the understanding of genome function. For a reconstruction of the 3D architecture of the human genome, systematic fluorescent in situ hybridization in combination with 3D confocal laser scanning microscopy is applied. The position of two or three genomic loci plus the overall nuclear shape were simultaneously recorded, resulting in statistical series of pair and triple loci combinations probed along the human chromosome 1 q-arm. For interpretation of statistical distributions of geometrical features (e.g. distances, angles, etc.) resulting from finite point sampling experiments, a Monte-Carlo-based approach to numerical computation of geometrical probability density functions (PDFs) for arbitrarily-shaped confined spatial domains is developed. Simulated PDFs are used as bench marks for evaluation of experimental PDFs and quantitative analysis of dimension and shape of probed 3D chromatin regions. Preliminary results of our numerical simulations show that the proposed numerical model is capable to reproduce experimental observations, and support the assumption of confined random folding of 3D chromatin fiber in interphase cell nuclei
    Computational Intelligence and Bioinformatics and Computational Biology, 2007. CIBCB '07. IEEE Symposium on; 05/2007
  • Evgeny Gladilin, Constantin Kappel, Roland Eils
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    ABSTRACT: High-throughput live-cell imaging is one of the important tools for the investigation of cellular structure and functions in modern experimental biology. Automatic processing of time series of microscopic images is hampered by a number of technical and natural factors such as permanent movements of cells in the optical field, alteration of optical cell appearance and high level of noise. Detection and compensation of global motion of groups of cells or relocation of a single cell within a dynamical multi-cell environment is the first indispensable step in the image analysis chain. This article presents an approach for detection of global image motion and single cell tracking in time series of confocal laser scanning microscopy images using an extended Fourier-phase correlation technique, which allows for analysis of non-uniform multi-body motion in partially-similar images. Our experimental results have shown that the developed approach is capable to perform cell tracking and registration in dynamical and noisy scenes, and provides a robust tool for fully-automatic registration of time-series of microscopic images.
    Proc SPIE 03/2007;
  • Bioinformatics Research and Development, First International Conference, BIRD 2007, Berlin, Germany, March 12-14, 2007, Proceedings; 01/2007
  • Source
    Evgeny Gladilin, Karl Rohr, Roland Eils
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    ABSTRACT: Non-physical techniques for elastic image registration such as difierent spline-based optimization methods are often applied in biomedi- cal applications for image normalization w.r.t. non-rigid transformations. Since mechanical properties of biological structures to be registered are usually unknown, a "ground truth" validation of the results of image registration is not possible. This article presents a framework for the val- idation of elastic image registration techniques by a direct comparison of displacement flelds vs analytical or numerical reference solutions of customizable boundary value problems. The proposed procedure enables an easy handling of material parameters, domain shapes and boundary conditions, and provides a ∞exible benchmark-tool for quantitative vali- dation of elastic image registration algorithms.
    Bildverarbeitung für die Medizin 2007, Algorithmen, Systeme, Anwendungen, Proceedings des Workshops vom 25.-27. März 2007 in München; 01/2007
  • Vladimir Pekar, Evgeny Gladilin, Karl Rohr
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    ABSTRACT: Deformable registration is an important application in medical image analysis and processing. We propose a physics-based parametric approach for deformable image registration, where non-rigid transformations are computed using an irregular grid of control points distributed within the image domain. The image is modelled as a three-dimensional (3D) homogeneous infinite elastic medium. It is assumed that a Gaussian-shaped force is applied at every control point, where the strengths, directions and influence areas of the forces as well as the positions of the control points are considered as free parameters whose optimization leads to maximization of the similarity measure between the images to be registered. For optimization, a computationally efficient Levenberg-Marquardt method is used. The proposed approach has certain advantages over traditional landmark-based methods or the registration methods based on regular grids, for example B-splines, since comparable results can be achieved by using less control points. Experimental results with 3D clinical images demonstrate that our method is capable of successfully coping with complex registration tasks.
    Physics in Medicine and Biology 02/2006; 51(2):361-77. · 2.70 Impact Factor
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    ABSTRACT: Topological analysis of cells and subcellular structures on the basis of image data is one of the major trends in modern quantitative biology. However, due to the dynamic nature of cell biology, the optical appearance of different cells or even time series of the same cell is undergoing substantial variations in shape and texture which makes the analysis of image data a non-trivial task. In the absence of canonical invariances, a natural approach to the normalization of cell images consists in dimension reduction of the 3D problem by means of spherical mapping which enables the analysis of targeted regions in terms of radial distances. In this work, we present a finite element template-based approach for physically-base spherical mapping which has been applied for topological analysis of confocal laser scanning microscopy images of cell nuclei.
    Proc SPIE 01/2006; 6144:1557-1566.

Publication Stats

209 Citations
20.05 Total Impact Points

Institutions

  • 2006–2011
    • Universität Heidelberg
      Heidelburg, Baden-Württemberg, Germany
  • 2007–2009
    • German Cancer Research Center
      • Division of Theoretical Bioinformatics
      Heidelburg, Baden-Württemberg, Germany
  • 2001–2004
    • Zuse-Institut Berlin
      • Department of Visualization and Data Analysis
      Berlín, Berlin, Germany