Low Intensity Vibration Restores Nuclear YAP Levels and Acute YAP Nuclear Shuttling in Mesenchymal Stem Cells Subjected to Simulated Microgravity

AbstractReducing the bone deterioration that astronauts experience in microgravity requires countermeasures that can improve the effectiveness of rigorous and time-expensive exercise regimens under microgravity. The ability of low intensity vibrations (LIV) to activate force-responsive signaling pathways in cells suggests LIV as a potential countermeasure to improve cell responsiveness to subsequent mechanical challenge. Mechanoresponse of mesenchymal stem cells (MSC) which maintain bone-making osteoblasts is in part controlled by the “mechanotransducer” protein YAP (Yes-associated protein) which is shuttled into the nucleus in response cyto-mechanical forces. Here, using YAP nuclear shuttling as a measure of MSC mechanoresponse, we tested the effect of 72 hours of simulated microgravity (SMG) and daily LIV application (LIVDT) on the YAP nuclear entry driven by either acute LIV (LIVAT) or Lysophosphohaditic acid (LPA), applied at the end of the 72h period. We hypothesized that SMG-induced impairment of acute YAP nuclear entry will be alleviated by daily application of LIVDT. Results showed that while both acute LIVAT and LPA treatments increased nuclear YAP entry by 50% and 87% over the basal levels in SMG-treated MSCs, nuclear YAP levels of all SMG groups were significantly lower than non-SMG controls. Daily dosing of LIVDT, applied in parallel to SMG, restored the SMG-driven decrease in basal nuclear YAP to control levels as well as increased the LPA-induced but not LIVAT-induced YAP nuclear entry over the non-LIVDT treated, SMG only, counterparts. These cell level observations suggest that utilizing daily LIV treatments is a feasible countermeasure for increasing the YAP-mediated anabolic responsiveness of MSCs to subsequent mechanical challenge under SMG.

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Low-intensity vibration restores nuclear YAP levels and acute YAP nuclear shuttling in mesenchymal stem cells subjected to simulated microgravity

npj Microgravity ◽

10.1038/s41526-020-00125-5 ◽

2020 ◽

Vol 6 (1) ◽

Author(s):

Matthew Thompson ◽

Kali Woods ◽

Joshua Newberg ◽

Julia Thom Oxford ◽

Gunes Uzer

Keyword(s):

Stem Cells ◽

Mesenchymal Stem Cells ◽

Simulated Microgravity ◽

Mechanical Forces ◽

Cell Level ◽

Nuclear Entry ◽

Low Intensity ◽

Nuclear Shuttling ◽

Low Intensity Vibration ◽

Daily Application

AbstractReducing the musculoskeletal deterioration that astronauts experience in microgravity requires countermeasures that can improve the effectiveness of otherwise rigorous and time-expensive exercise regimens in space. The ability of low-intensity vibrations (LIV) to activate force-responsive signaling pathways in cells suggests LIV as a potential countermeasure to improve cell responsiveness to subsequent mechanical challenge. Mechanoresponse of mesenchymal stem cells (MSC), which maintain bone-making osteoblasts, is in part controlled by the “mechanotransducer” protein YAP (Yes-associated protein), which is shuttled into the nucleus in response to cyto-mechanical forces. Here, using YAP nuclear shuttling as a measurement outcome, we tested the effect of 72 h of clinostat-induced simulated microgravity (SMG) and daily LIV application (LIVDT) on the YAP nuclear entry driven by either acute LIV (LIVAT) or Lysophosphohaditic acid (LPA), applied after the 72 h period. We hypothesized that SMG-induced impairment of acute YAP nuclear entry would be alleviated by the daily application of LIVDT. Results showed that while both acute LIVAT and LPA treatments increased nuclear YAP entry by 50 and 87% over the basal levels in SMG-treated MSCs, nuclear YAP levels of all SMG groups were significantly lower than non-SMG controls. LIVDT, applied in parallel to SMG, restored the SMG-driven decrease in basal nuclear YAP to control levels as well as increased the LPA-induced but not LIVAT-induced YAP nuclear entry over SMG only, counterparts. These cell-level observations suggest that daily LIV treatments are a feasible countermeasure for restoring basal nuclear YAP levels and increasing the YAP nuclear shuttling in MSCs under SMG.

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Low Intensity Vibrations Restore Nuclear YAP Levels and Acute YAP Nuclear Shuttling in Mesenchymal Stem Cells Subjected to Simulated Microgravity

10.18122/td/1689/boisestate ◽

2020 ◽

Author(s):

Matt Thompson

Keyword(s):

Stem Cells ◽

Mesenchymal Stem Cells ◽

Simulated Microgravity ◽

Mechanical Forces ◽

Altered Gravity ◽

Nuclear Entry ◽

Soluble Factors ◽

Low Intensity ◽

Proliferation And Differentiation ◽

Nuclear Shuttling

The bone deterioration that astronauts experience in microgravity environments is known to occur in response to the lack of gravity-based tissue stress. Mechanical forces are crucial to maintain healthy bone mass by regulating the function of bone-making osteoblasts as well as the proliferation and differentiation of their progenitors, mesenchymal stem cells (MSC) which replenish osteoblastic cells. Regulation of proliferative function of MSCs in response to mechanical force is in part controlled by the "mechanotransducer" protein YAP (Yes-associated protein) which is shuttled into the nucleus in response to mechanical challenge to induce gene expression necessary for cell proliferation. Our group had recently reported that altered gravity conditions under simulated microgravity (SMG) decreases proliferation of MSCs and that application of daily low intensity vibrations (LIV) during SMG reverses this effect on proliferation. While these findings suggest that LIV may be a promising countermeasure for altered loading, the specific SMG and LIV effects on YAP mechanosignaling are unknown. Therefore, here we tested the effects of SMG and daily LIV treatment on basal nuclear YAP levels as well as on the acute YAP nuclear entry in response to both mechanical and soluble factors in MSCs. MSCs subjected to 72h of SMG, despite decreased nuclear YAP levels across all groups, responded to both LIV and Lysophosphohaditic acid (LPA) treatments by increasing nuclear YAP levels within 6hrs by 49.52% and 87.34%, respectively. Additionally, daily LIV restored the basal decrease seen in SMG as well as nuclear YAP levels as well as restored in part the YAP nuclear entry response to subsequently applied acute LIV and LPA treatments. These results show that rescue of basal YAP levels by LIV may explain previously found proliferative effects of MSCs under SMG and demonstrates that daily LIV is capable of alleviating the inhibition caused by SMG of YAP nuclear shuttling in response to subsequent mechanical and soluble challenge.

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Low-intensity vibrations normalize adipogenesis-induced morphological and molecular changes of adult mesenchymal stem cells

Proceedings of the Institution of Mechanical Engineers Part H Journal of Engineering in Medicine ◽

10.1177/0954411916687338 ◽

2017 ◽

Vol 231 (2) ◽

pp. 160-168 ◽

Cited By ~ 19

Author(s):

Oznur Baskan ◽

Gulistan Mese ◽

Engin Ozcivici

Keyword(s):

Stem Cells ◽

Bone Marrow ◽

Mesenchymal Stem Cells ◽

Mouse Bone Marrow ◽

Vibration Signals ◽

Force Microscopy ◽

Low Intensity ◽

Adult Mesenchymal Stem Cells ◽

Marrow Mesenchymal Stem Cells ◽

Low Intensity Vibration

Bone marrow mesenchymal stem cells that are committed to adipogenesis were exposed daily to high-frequency low-intensity mechanical vibrations to understand molecular, morphological and ultrastructural adaptations to mechanical signals during adipogenesis. D1-ORL-UVA mouse bone marrow mesenchymal stem cells were cultured with either growth or adipogenic medium for 1 week. Low-intensity vibration signals (15 min/day, 90 Hz, 0.1 g) were applied to one group of adipogenic cells, while the other adipogenic group served as a sham control. Cellular viability, lipid accumulation, ultrastructure and morphology were determined with MTT, Oil-Red-O staining, phalloidin staining and atomic force microscopy. Semiquantitative reverse transcription polymerase chain reaction showed expression profile of the genes responsible for adipogenesis and ultrastructure of cells. Low-intensity vibration signals increased viability of the cells in adipogenic culture that was reduced significantly compared to quiescent controls. Low-intensity vibration signals also normalized the effects of adipogenic condition on cell morphology, including area, perimeter, circularization and actin cytoskeleton. Furthermore, low-intensity vibration signals reduced the expression of some adipogenic markers significantly. Mesenchymal stem cells are sensitive and responsive to mechanical loads, but debilitating conditions such as aging or obesity may steer mesenchymal stem cells toward adipogenesis. Here, daily application of low-intensity vibration signals partially neutralized the effects of adipogenic induction on mesenchymal stem cells, suggesting that these signals may provide an alternative and/or complementary option to reduce fat deposition.

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