Mechanical stiffness as an improved single-cell indicator of osteoblastic human mesenchymal stem cell differentiation

• Authors: Barbara Boyan, Emory University; Todd McDevitt, Emory University; Tom Bongiorno, Georgia Institute of Technology; Jacob Kazlow, Georgia Institute of Technology; Roman Mezencev, Georgia Institute of Technology; Sarah Griffiths, Georgia Institute of Technology; Rene Olivares-Navarrete, Virginia Commonwealth University; John F McDonald, Georgia Institute of Technology; Zvi Schwartz, Virginia Commonwealth University; Todd Sulchek, Georgia Institute of Technology
• Journal Title: Journal of Biomechanics
• Volume: Volume 47, Number 9
• Publisher: Elsevier | 2014-06-27, Pages 2197-2204
• Type of Work: Article | Post-print: After Peer Review
• Publisher DOI: http://doi.org/10.1016/j.jbiomech.2013.11.017
• Subjects: Engineering, Biomedical; Engineering, Mechanical
• Keywords: Science & Technology; Life Sciences & Biomedicine; Technology; Biophysics; Engineering, Biomedical; Engineering; MSC; Atomic force microscopy; Bone sialoprotein; Cell stiffness; Osteoblast differentiation; Osteocalcin; ACTIN-FILAMENT NETWORKS; ATOMIC-FORCE MICROSCOPY; OSTEOGENIC DIFFERENTIATION; PROPERTIES REFLECT; ALPHA-ACTININ; EXPRESSION; ROLES; PLAY

Abstract

Although it has been established that cellular stiffness can change as a stem cell differentiates, the precise relationship between cell mechanics and other phenotypic properties remains unclear. Inherent cell heterogeneity and asynchronous differentiation complicate population analysis; therefore, single-cell analysis was employed to determine how changes in cell stiffness correlate with changes in molecular biomarkers during differentiation. Design of a custom gridded tissue culture dish facilitated single-cell comparisons between cell mechanics and other differentiation biomarkers by enabling sequential measurement of cell mechanics and protein biomarker expression at the single cell level. The Young's modulus of mesenchymal stem cells was shown not only to decrease during chemically-induced osteoblast differentiation, but also to correlate more closely with the day of differentiation than did the relative expression of the traditional osteoblast differentiation markers, bone sialoprotein and osteocalcin. Therefore, cell stiffness, a measurable property of individual cells, may serve as an improved indicator of single-cell osteoblast differentiation compared to traditional biological markers. Revelation of additional osteoblast differentiation indicators, such as cell stiffness, can improve identification and collection of starting cell populations, with applications to mesenchymal stem cell therapies and stem cell-based tissue engineering. © 2013 Elsevier Ltd.