전단유동으로 제어되는 세포부착분자의 경사도생성

박정열(Jungyul Park),김덕호(Deok-Ho Kim),Andre Levchenko 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5

This paper describes a simple, versatile method of generating gradients of cell adhesion molecules and of a mechanical force induced by varying shear flow speeds using microtluidic channel with triangular cross-section. This fabricated microchannel allows varying shear flow speeds in microchannel by just dispensing fluids using a mcrosyringe pump, which makes the different cell adhesion molecule be deposited. We model this phenomenon with analytical mathematical model, analyze with computational fluid dynamics (CFD), and verify it by observing intensity of FN-rhodamine deposition in microchanel. We demonstrate the assessment of cell migration to fibronectin (FN) coated substrates as a function of varying FN concentration in microchannels due to varying shear flow speeds. Using this device, we will demonstrate that FN gradients could induce haptotaxis of CHO cells, while not affecting the overall rate of cell migration. Cells in the higher FN concentrations are more likely to diverge around its area of high FN concentration, while cells in the less FN concentration areas migrate with a direction towards the higher FN concentration. Compared to previous microtludic chip related to generation of gradients, this device can be also used to investigate how cell migration responds to the interactions between haptotaxis and mechanotaxis, which mimic the real in vivo circumstance

Guided Cell Migration on Microtextured Substrates with Variable Local Density and Anisotropy

Kim, Deok-Ho,Seo, Chang-Ho,Han, Karam,Kwon, Keon Woo,Levchenko, Andre,Suh, Kahp-Yang WILEY-VCH Verlag 2009 Advanced functional materials Vol.19 No.10

<P>This work reports the design of and experimentation with a topographically patterned cell culture substrate of variable local density and anisotropy as a facile and efficient platform to guide the organization and migration of cells in spatially desirable patterns. Using UV-assisted capillary force lithography, an optically transparent microstructured layer of a UV curable poly(urethane acrylate) resin is fabricated and employed as a cell-culture substrate after coating with fibronectin. With variable local pattern density and anisotropy present in a single cell-culture substrate, the differential polarization of cell morphology and movement in a single experiment is quantitatively characterized. It is found that cell shape and velocity are exquisitely sensitive to variation in the local anisotropy of the two-dimensional rectangular lattice arrays, with cell elongation and speed decreasing on symmetric lattice patterns. It is also found that cells could integrate orthogonal spatial cues when determining the direction of cell orientation and movement. Furthermore, cells preferentially migrate toward the topographically denser areas from sparser ones. Consistent with these results, it is demonstrated that systematic variation of local densities of rectangular lattice arrays enable a planar assembly of cells into a specified location. It is envisioned that lithographically defined substrates of variable local density and anisotropy not only provide a new route to tailoring the cell-material interface but could serve as a template for advanced tissue engineering.</P> <B>Graphic Abstract</B> <P>Microtextured substrates with variable local density and anisotropy (see image) are designed to guide the organization and migration of fibroblasts in spatially desirable locations. Cell motility is sensitive to variation in the local density and anisotropy of rectangular lattice, with cell elongation and speed decreasing on symmetric lattice. Also, cells integrate orthogonal spatial cues when determining the direction of their orientation and movement. <img src='wiley_img/1616301X-2009-19-10-ADFM200801174-content.gif' alt='wiley_img/1616301X-2009-19-10-ADFM200801174-content'> </P>

Simple haptotactic gradient generation within a triangular microfluidic channel

Park, Jungyul,Kim, Deok-Ho,Kim, Gabriel,Kim, Younghoon,Choi, Eunpyo,Levchenko, Andre Royal Society of Chemistry 2010 Lab on a chip Vol.10 No.16

<P>Most microfluidic devices developed to date for the analysis of live cells incorporate channels with relatively simple constant rectangular or semi-circular cross-sections, relying on complex channel network geometries rather than alteration of the shapes of the channels themselves for development of diverse functional fluidic controls, <I>e.g.</I>, spatial gradients of bioactive ligands. In this study we describe a simple alternative method to create highly defined and predictable gradients of surface bound molecules. This method relies on the generation of a considerable variation in the spatial distribution of flow velocities within a channel with a triangular cross-section. The triangular shape can be easily implemented by using bulk wet etching and polydimethylsiloxane (PDMS) replica molding techniques. By analytical modeling and simulation, we predict that the deposition of the solute onto a channel boundary depends on the local flow rate values, yielding gradient spanning the whole width of the channel. This prediction was validated by direct visualization of the flow rate and fibronectin–rhodamine deposition in a fabricated microchannel. Using this experimental platform, we assessed cell migration in response to a fibronectin gradient deposited in the microchannels. We find that this gradient could induce robust haptotaxis of Chinese Hamster Ovary (CHO) cells towards the areas of higher fibronectin surface density. We propose that the described simple gradient generation method can help to avoid complexity present in many current device designs, allowing to introduce more easily other potentially useful design features.</P> <P>Graphic Abstract</P><P>In this study we describe a simple alternative method to create highly defined and predictable gradients of surface bound molecules. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=b924222h'> </P>

Biomimetic Nanopatterns as Enabling Tools for Analysis and Control of Live Cells

Kim, Deok‐,Ho,Lee, Hyojin,Lee, Young Kwang,Nam, Jwa‐,Min,Levchenko, Andre WILEY‐VCH Verlag 2010 Advanced Materials Vol.22 No.41

<P><B>Abstract</B></P><P>It is becoming increasingly evident that cell biology research can be considerably advanced through the use of bioengineered tools enabled by nanoscale technologies. Recent advances in nanopatterning techniques pave the way for engineering biomaterial surfaces that control cellular interactions from the nano‐ to the microscale, allowing more precise quantitative experimentation capturing multi‐scale aspects of complex tissue physiology <I>in vitro</I>. The spatially and temporally controlled display of extracellular signaling cues on nanopatterned surfaces (e. g., cues in the form of chemical ligands, controlled stiffness, texture, etc.) that can now be achieved on biologically relevant length scales is particularly attractive enabling experimental platform for investigating fundamental mechanisms of adhesion‐mediated cell signaling. Here, we present an overview of bio‐nanopatterning methods, with the particular focus on the recent advances on the use of nanofabrication techniques as enabling tools for studying the effects of cell adhesion and signaling on cell function. We also highlight the impact of nanoscale engineering in controlling cell‐material interfaces, which can have profound implications for future development of tissue engineering and regenerative medicine.</P>

Directed migration of cancer cells guided by the graded texture of the underlying matrix

Park, JinSeok,Kim, Deok-Ho,Kim, Hong-Nam,Wang, Chiaochun Joanne,Kwak, Moon Kyu,Hur, Eunmi,Suh, Kahp-Yang,An, Steven S.,Levchenko, Andre Nature Publishing Group, a division of Macmillan P 2016 Nature materials Vol.15 No.7

<P>Living cells and the extracellular matrix (ECM) can exhibit complex interactions that define key developmental, physiological and pathological processes. Here, we report a new type of directed migration-which we term 'topotaxis'-guided by the gradient of the nanoscale topographic features in the cells' ECM environment. We show that the direction of topotaxis is reflective of the effective cell stiffness, and that it depends on the balance of the ECM-triggered signalling pathways PI(3)K-Akt and ROCK-MLCK. In melanoma cancer cells, this balance can be altered by different ECM inputs, pharmacological perturbations or genetic alterations, particularly a loss of PTEN in aggressive melanoma cells. We conclude that topotaxis is a product of the material properties of cells and the surrounding ECM, and propose that the invasive capacity of many cancers may depend broadly on topotactic responses, providing a potentially attractive mechanism for controlling invasive and metastatic behaviour.</P>

Mechanochemical feedback underlies coexistence of qualitatively distinct cell polarity patterns within diverse cell populations

Park, JinSeok,Holmes, William R.,Lee, Sung Hoon,Kim, Hong-Nam,Kim, Deok-Ho,Kwak, Moon Kyu,Wang, Chiaochun Joanne,Edelstein-Keshet, Leah,Levchenko, Andre National Academy of Sciences 2017 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.114 No.28

<P>Cell polarization and directional cell migration can display random, persistent, and oscillatory dynamic patterns. However, it is not clear whether these polarity patterns can be explained by the same underlying regulatory mechanism. Here, we show that random, persistent, and oscillatory migration accompanied by polarization can simultaneously occur in populations of melanoma cells derived from tumors with different degrees of aggressiveness. We demonstrate that all of these patterns and the probabilities of their occurrence are quantitatively accounted for by a simple mechanism involving a spatially distributed, mechanochemical feedback coupling the dynamically changing extracellular matrix (ECM)-cell contacts to the activation of signaling downstream of the Rho-family small GTPases. This mechanism is supported by a predictive mathematical model and extensive experimental validation, and can explain previously reported results for diverse cell types. In melanoma, this mechanism also accounts for the effects of genetic and environmental perturbations, including mutations linked to invasive cell spread. The resulting mechanistic understanding of cell polarity quantitatively captures the relationship between population variability and phenotypic plasticity, with the potential to account for a wide variety of cell migration states in diverse pathological and physiological conditions.</P>