title: Changes in the stiffness of human mesenchymal stem cells with the progress of cell death as measured by atomic force microscopy.
abstract: This note reports observations of the change of stiffness of human mesenchymal stem cells (hMSCs) with the progress of cell death as measured by AFM. hMSC with impaired membrane, dead and viable cells were labelled with Annexin V and Propidium Iodide after 24h cold storage, followed by AFM measurement and Young's modulus of cells was derived. Viable hMSCs have a Young's modulus (E) in the range of 0.81-1.13kPa and consistent measurement was observed when different measurement locations were chosen. E of cells with partially impaired membrane was 0.69±0.17kPa or in the range of 2.04-4.74kPa, depending upon the measurement locations. With the loss of membrane integrity, though there was no variation on measured E between different locations, a mixed picture of cell stiffness was observed as indicated by cells with E as low as 0.09±0.03kPa, in a mid-range of 4.62±0.67kPa, and the highest of up to 48.98±19.80kPa. With the progress of cell death, the highest stiffness was noticed for cells showing a more granular appearance; also the lowest stiffness for cells with vacuole appearance. Findings from this study indicate that cell stiffness is significantly altered with the progress of cell death.
authors.affiliation: Centre of Biological Engineering, Wolfson School of Mechanical & Manufacturing Engineering, Loughborough University, Loughborough LE11 3TU, UK.
authors.forename: Nikolay I
authors.initials: NI
authors.lastname: Nikolaev
authors.affiliation: JPK Instruments Limited, Unit 7223, Cambridge Research Park, Waterbeach, Cambridge CB25 9TL, UK.
authors.forename: Torsten
authors.initials: T
authors.lastname: Müller
authors.affiliation: Centre of Biological Engineering, Wolfson School of Mechanical & Manufacturing Engineering, Loughborough University, Loughborough LE11 3TU, UK.
authors.forename: David J
authors.initials: DJ
authors.lastname: Williams
authors.affiliation: Centre of Biological Engineering, Wolfson School of Mechanical & Manufacturing Engineering, Loughborough University, Loughborough LE11 3TU, UK. Electronic address: y.liu3@lboro.ac.uk.
authors.forename: Yang
authors.initials: Y
authors.lastname: Liu
mesh_terms: D016923:Cell Death / Q000502:physiology*; D002462:Cell Membrane / Q000502:physiology; D002470:Cell Survival / Q000502:physiology; D002478:Cells, Cultured; D015925:Cryopreservation; D055119:Elastic Modulus / Q000502:physiology*; D006801:Humans; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000502:physiology*; D018625:Microscopy, Atomic Force / Q000379:methods*; D008954:Models, Biological
keywords: Atomic Force Microscopy (AFM); Cell death; Elastic modulus; Nanoindentation; Stem cells