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Probing Single-Cell Mechanical Allostasis Using Ultrasound Tweezers



In response to external stress, cells alter their morphology, metabolic activity, and functions to mechanically adapt to the dynamic, local environment through cell allostasis. To explore mechanotransduction in cellular allostasis, we applied an integrated micromechanical system that combines an ‘ultrasound tweezers’-based mechanical stressor and a Förster resonance energy transfer (FRET)-based molecular force biosensor, termed “actinin-sstFRET,” to monitor in situ single-cell allostasis in response to transient stimulation in real time.


The ultrasound tweezers utilize 1 Hz, 10-s transient ultrasound pulses to acoustically excite a lipid-encapsulated microbubble, which is bound to the cell membrane, and apply a pico- to nano-Newton range of forces to cells through an RGD-integrin linkage. The actinin-sstFRET molecular sensor, which engages the actin stress fibers in live cells, is used to map real-time actomyosin force dynamics over time. Then, the mechanosensitive behaviors were examined by profiling the dynamics in Ca2+ influx, actomyosin cytoskeleton (CSK) activity, and GTPase RhoA signaling to define a single-cell mechanical allostasis.


By subjecting a 1 Hz, 10-s physical stress, single vascular smooth muscle cells (VSMCs) were observed to remodeled themselves in a biphasic mechanical allostatic manner within 30 min that caused them to adjust their contractility and actomyosin activities. The cellular machinery that underscores the vital role of CSK equilibrium in cellular mechanical allostasis, includes Ca2+ influx, remodeling of actomyosin CSK and contraction, and GTPase RhoA signaling. Mechanical allostasis was observed to be compromised in VSMCs from patients with type II diabetes mellitus (T2DM), which could potentiate an allostatic maladaptation.


By integrating tools that simultaneously permit localized mechanical perturbation and map actomyosin forces, we revealed distinct cellular mechanical allostasis profiles in our micromechanical system. Our findings of cell mechanical allostasis and maladaptation provide the potential for mechanophenotyping cells to reveal their pathogenic contexts and their biophysical mediators that underlie multi-etiological diseases such as diabetes, hypertension, or aging.

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We acknowledge financial support from the Department of Mechanical and Aerospace Engineering at New York University, the American Heart Association Scientist Development Grant (16SDG31020038), the National Science Foundation (CBET 1701322), and the National Institute of Health (R21EB025406).

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Weiyi Qian and Weiqiang Chen declare that they have no conflicts of interest.

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Weiqiang Chen is an Assistant Professor in the Departments of Mechanical and Aerospace Engineering and Biomedical Engineering at New York University. He received his B.S. in Physics from Nanjing University and M.S. degrees from Shanghai Jiao Tong University and Purdue University, both in Electrical Engineering. He earned his Ph.D. in Mechanical Engineering from the University of Michigan in 2014. Research in the Chen’s lab focuses on developing new biomaterials, microfluidics, and organ-on-a-chip systems to address emerging biomedical problems in cell mechanobiology, cancer biology, immune engineering, and stem cell-based regenerative medicine. He is the recipient of the American Heart Association Scientist Development Award, the Lab on a Chip Emerging Investigator Award, the New York University Whitehead Fellowship in Biomedical and Biological Sciences, the Goddard Junior Faculty Fellowship, the Baxter Young Investigator Award, the University of Michigan Richard F. & Eleanor A. Towner Prize for Outstanding PhD Research, and the ProQuest Distinguished Dissertation Award.


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Qian, W., Chen, W. Probing Single-Cell Mechanical Allostasis Using Ultrasound Tweezers. Cel. Mol. Bioeng. 12, 415–427 (2019).

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  • Cellular allostasis
  • Acoustic tweezers
  • FRET
  • Mechanotransduction
  • Diabetes