title: Viscoelastic behaviour of human mesenchymal stem cells.
abstract: BACKGROUND
  In this study, we have investigated the viscoelastic behaviour of individual human adult bone marrow-derived mesenchymal stem cells (hMSCs) and the role of F-actin filaments in maintaining these properties, using micropipette aspiration technique together with a standard linear viscoelastic solid model.
  
  
  RESULTS
  Under a room temperature of 20 degrees C, the instantaneous and equilibrium Young's modulus, E0 and Einfinity, were found to be 886 +/- 289 Pa and 372 +/- 125 Pa, respectively, while the apparent viscosity, mu, was 2710 +/- 1630 Pa.s. hMSCs treated with cytochalasin D up to 20 microM at 20 degrees C registered significant drop of up to 84% in stiffness and increase of up to 255% in viscosity. At the physiological temperature of 37 degrees C, E0 and Einfinity have decreased by 42-66% whereas mu has increased by 95%, compared to the control. Majority of the hMSCs behave as viscoelastic solid with a rapid initial increase in aspiration length and it gradually levels out with time. Three other types of non-typical viscoelastic behavior of hMSCs were also seen.
  
  
  CONCLUSIONS
  hMSCs behave as viscoelastic solid. Its viscoelstic behaviour are dependent on the structural integrity of the F-actin filaments and temperature.
authors.affiliation: Division of Bioengineering, School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore 637457, Singapore. tanc0101@ntu.edu.sg
authors.forename: Samuel C W
authors.initials: SC
authors.lastname: Tan
authors.forename: Wen X
authors.initials: WX
authors.lastname: Pan
authors.forename: Gang
authors.initials: G
authors.lastname: Ma
authors.forename: Ning
authors.initials: N
authors.lastname: Cai
authors.forename: Kam W
authors.initials: KW
authors.lastname: Leong
authors.forename: Kin
authors.initials: K
authors.lastname: Liao
mesh_terms: D000199:Actins / Q000737:chemistry / Q000378:metabolism; D000328:Adult; D001854:Bone Marrow Cells / Q000737:chemistry* / Q000166:cytology / Q000378:metabolism; D002460:Cell Line; D015638:Cytochalasin D / Q000378:metabolism; D003599:Cytoskeleton / Q000737:chemistry / Q000378:metabolism; D004548:Elasticity; D006801:Humans; D059630:Mesenchymal Stem Cells / Q000737:chemistry* / Q000166:cytology* / Q000378:metabolism; D008962:Models, Theoretical; D019384:Nucleic Acid Synthesis Inhibitors / Q000378:metabolism; D013314:Stress, Mechanical; D013696:Temperature; D014783:Viscosity
chemical_list: D000199:Actins; D019384:Nucleic Acid Synthesis Inhibitors; D015638:Cytochalasin D