Laminar shear stress delivers cell cycle arrest and anti-apoptosis to mesenchymal stem cells

Abstract

Biomechanical forces are emerging as critical regulators of cell function and fluid flow is a potent mechanical stimulus. Although the mechanisms of osteoblasts and osteocytes responding to fluid flow are being elucidated, little is known about how the osteoprogenitors, mesenchymal stem cells (MSCs), respond to fluid flow. Here, we examined the effects of laminar shear stress (LSS) on MSCs in vitro. MSCs from bone marrow of Sprague-Dawley rats were isolated, purified, and subjected to physiological levels of LSS. DNA synthesis and cell cycle were measured through [(3)H]thymidine and by flow cytometry, respectively, to detect the cellular proliferation. Annexin V immunostaining and Bcl-2/Bax mRNA expression were evaluated to determine the effect of LSS on MSCs apoptosis. Results showed that fluid shear stress caused a dose-related reduction of MSCs' proliferation rate with the majority of cells being arrested in the G(0) or G(1) phase. Moreover, it was found that physiological levels of LSS exerted a potent suppression effect on MSC apoptosis. In summary, these data revealed a critical role of LSS in maintaining the quiescence of MSCs.

Agitation and aeration of stirred-bioreactors for the microcarrier culture of human mesenchymal stem cells and potential implications for large-scale bioprocess development

“…BM-hMSC growth kinetics due to changes in impeller speed are therefore not attributed to cellular damage by membrane disruption in this instance. It has been demonstrated previously however, that increasing the shear stress in flow chambers during BM-hMSC culture leads to the inhibition of proliferation, in association with maintaining cells in the G0/G1 phase of the cell cycle [22]. Additionally, the reduction in growth kinetics at higher impeller speeds could be caused by an inhibition of BM-hMSC attachment and re-attachment to the microcarriers during the growth phase.…”

Transient DNMT3L Expression Reinforces Chromatin Surveillance to Halt Senescence Progression in Mouse Embryonic Fibroblast

“…Senescence can be activated by reaching the Hayflick limit (telomere shortening to a critical length) (Hayflick and Moorhead, 1961;Hayflick, 1965) or stressors (Serrano et al, 1997;Wang et al, 2009;Luo et al, 2011;Suram et al, 2012;de Magalhaes and Passos, 2018). In addition to the continuous attrition of telomere length accompanied by cell division, aging cells approaching senescence display a lessstringent chromatin architecture and epigenetic control (Pal and Tyler, 2016;Xie et al, 2018;Benayoun et al, 2019), and these features can be accelerated by stress induced by stochastic replication mistakes, environmental stimuli, oncogene activation or signals produced by pre-existing senescent cells (Hodny et al, 2010;Nelson et al, 2012;Benayoun et al, 2015).…”

Hydrodynamics and bioprocess considerations in designing bioreactors for cardiac tissue engineering

“…Other studies have also shown that shear stress higher than 2.5 dyn/cm 2 would cause cellular damage and reduce cell expansion; this is true for both human ESC and neonatal rat cardiomyocyte cultures [71,96,97]. In the case of rat BM-MSC expansion, proliferation would only decrease at higher levels under laminar shear stress conditions [98,99]; when BM-MSCs were exposed to 5 dyn/cm 2 of shear for 4 hours, proliferation decreased significantly [99]. However, shear conditions of 1 dyn/cm 2 did not affect cell proliferation, indicating that BM-MSCs could still be cultured under a mild shear environment.…”