Document Detail

Structure-function relationships in the stem cell's mechanical world B: emergent anisotropy of the cytoskeleton correlates to volume and shape changing stress exposure.
MedLine Citation:
PMID:  22338708     Owner:  NLM     Status:  MEDLINE    
In the preceding study (Part A), we showed that prescribed seeding conditions as well as seeding density can be used to subject multipotent stem cells (MSCs) to volume changing stresses and that changes in volume of the cell are associated with changes in shape, but not volume, of the cell nucleus. In the current study, we aim to control the mechanical milieu of live cells using these prescribed seeding conditions concomitant to delivery of shape changing stresses via fluid flow, while observing adaptation of the cytoskeleton, a major cellular transducer that modulates cell shape, stiffness and remodeling. We hypothesize that the spatiotemporal organization of tubulin and actin elements of the cytoskeleton changes in response to volume and shape changing stresses emulating those during development, prior to the first beating of the heart or twitching of muscle. Our approach was to quantify the change over baseline in spatiotemporal distribution of actin and tubulin in live C3H/10T1/2 model stem cells subjected to volume changing stresses induced by seeding at density as well as low magnitude, short duration, shape changing (shear) stresses induced by fluid flow (0.5 or 1.0 dyne/cm2 for 30/60/90 minutes). Upon exposure to fluid flow, both tubulin thickness (height) and concentration (fluorescence intensity) change significantly over baseline, as a function of proximity to neighboring cells (density) and the substrate (apical-basal height). Given our recently published studies showing amplification of stress gradients (flow velocity) with increasing distance to nearest neighbors and the substrate, i.e. with decreasing density and toward the apical side of the cell, tubulin adaptation appears to depend significantly on the magnitude of the stress to which the cell is exposed locally. In contrast, adaptation of actin to the changing mechanical milieu is more global, exhibiting less significant differences attributable to nearest neighbors or boundaries than differences attributable to magnitude of the stress to which the cell is exposed globally (0.5 versus 1.0 dyne/cm2). Furthermore, changes in the actin cytoskeletal distribution correlate positively with one pre-mesenchymal condensation marker (Msx2) and negatively with early markers of chondrogenesis (ColIIaI alone, indicative of pre-hypertrophic chondrogenesis) and osteogenesis (Runx2). Changes in the tubulin cytoskeletal distribution correlate positively with a marker of pericondensation (Sox9 alone), negatively with chondrogenesis (ColIIaI) and positively with adipogenesis (Ppar-gamma 2). Taken as a whole, exposure of MSCs to volume and shape changing stresses results in emergent anisotropy of cytoskeletal architecture (structure), which relate to emergent cell fate (function).
Hana Chang; Melissa L Knothe Tate
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Molecular & cellular biomechanics : MCB     Volume:  8     ISSN:  1556-5297     ISO Abbreviation:  Mol Cell Biomech     Publication Date:  2011 Dec 
Date Detail:
Created Date:  2012-02-17     Completed Date:  2012-03-20     Revised Date:  2013-06-26    
Medline Journal Info:
Nlm Unique ID:  101253756     Medline TA:  Mol Cell Biomech     Country:  United States    
Other Details:
Languages:  eng     Pagination:  297-318     Citation Subset:  IM    
Department of Biomedical Engineering, Case Western Reserve University, 2071 Martin Luther King Drive, Cleveland, OH 44106-7207, USA.
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MeSH Terms
Actins / genetics,  metabolism
Cell Culture Techniques / methods
Cell Line
Cell Shape*
Cell Size*
Cytoskeleton / chemistry*,  metabolism,  ultrastructure*
Imaging, Three-Dimensional / methods
Mesenchymal Stromal Cells / chemistry,  cytology*,  metabolism
Mice, Inbred C3H
Stress, Mechanical*
Tubulin / genetics,  metabolism
Grant Support
Reg. No./Substance:
0/Actins; 0/Tubulin

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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