The effect of equiaxial stretching on the osteogenic differentiation and mechanical properties of human adipose stem cells. (August 2017)

• Record Type: Journal Article
• Authors: Virjula, Sanni; Zhao, Feihu; Leivo, Joni; Vanhatupa, Sari; Kreutzer, Joose; Vaughan, Ted J.; Honkala, Anna-Maija; Viehrig, Marlitt; Mullen, Conleth A.; Kallio, Pasi; McNamara, Laoise M.; Miettinen, Susanna
• Is Part Of: Journal of the mechanical behavior of biomedical materials. Volume 72(2017)
• Page Start: 38
• Page End: 48
• Publication Date: 2017-08
• Subjects: Mesenchymal stem cell -- Dynamic cell culture -- Mechanical stimulation -- Atomic force microscopy indentation -- PDMS -- mechanobiology; Biomedical materials -- Periodicals; Biomedical materials -- Mechanical properties -- Periodicals; Biomedical materials; Biomedical materials -- Mechanical properties; Periodicals; Electronic journals; 610.28
• DOI: 10.1016/j.jmbbm.2017.04.016
• Languages: English
• ISSNs: 1751-6161

Abstract

Abstract: Although mechanical cues are known to affect stem cell fate and mechanobiology, the significance of such stimuli on the osteogenic differentiation of human adipose stem cells (hASCs) remains unclear. In this study, we investigated the effect of long-term mechanical stimulation on the attachment, osteogenic differentiation and mechanical properties of hASCs. Tailor-made, pneumatic cell stretching devices were used to expose hASCs to cyclic equiaxial stretching in osteogenic medium. Cell attachment and focal adhesions were visualised using immunocytochemical vinculin staining on days 3 and 6, and the proliferation and alkaline phosphatase activity, as a sign of early osteogenic differentiation, were analysed on days 0, 6 and 10. Furthermore, the mechanical properties of hASCs, in terms of apparent Young's modulus and normalised contractility, were obtained using a combination of atomic force microscopy based indentation and computational approaches. Our results indicated that cyclic equiaxial stretching delayed proliferation and promoted osteogenic differentiation of hASCs. Stretching also reduced cell size and intensified focal adhesions and actin cytoskeleton. Moreover, cell stiffening was observed during osteogenic differentiation and especially under mechanical stimulation. These results suggest that cyclic equiaxial stretching modifies cell morphology, focal adhesion formation and mechanical properties of hASCs. This could be exploited to enhance osteogenic differentiation. Graphical abstract: Highlights: Equiaxial stretching enhances osteogenic differentiation of adipose stem cells. Stretching reduces cell size and intensifies focal adhesions and actin cytoskeleton. Cellular Young's modulus increases during osteogenic differentiation.