Mechanical characterization of living and dead undifferentiated human adipose-derived stem cells by using atomic force microscopy

Abstract

In this article, to map the mechanical properties of undifferentiated human adipose-derived stem cells, local mechanical characterization is carried out on the adipose-derived stem cells. In addition, to distinguish the living and dead human adipose-derived stem cells, mechanical characterization is also implemented on both living and dead adipose-derived stem cells. In this study, Young's modulus of the cell membrane is used for representing the mechanical properties of cells. To obtain Young's modulus of cell membrane, the force-spectroscopy mode of atomic force microscopy is employed to measure the atomic force microscopy tip indentation depth and force on the cells. Then, Young's modulus is obtained through fitting these experimental data to the Hertzian contact mechanics model. The global Young's moduli of living and dead undifferentiated adipose-derived stem cells are about 1.27 and 18.61 kPa, respectively. This displays obvious gap of Young's modulus between the living and dead undifferentiated adipose-derived stem cells. Finally, comparison of the local Young's modulus shows deviation of the local Young's modulus for either living or dead undifferentiated adipose-derived stem cells, and the root-mean-square errors of the global Young's modulus of living and dead undifferentiated adipose-derived stem cells are about 0.48 and 5.05 kPa, respectively.

Elucidating nanoscale mechanical properties of diabetic human adipose tissue using atomic force microscopy

“…Atomic force microscopy (AFM) nanoindentation measures tissue mechanics with nanoscale resolution by applying a small compressive force and extracting the Young's, or elastic, modulus 13 . Only a few studies have applied AFM to cells derived from adipose tissue [14][15][16][17][18][19] , several of which attempted to directly measure mechanical properties, but none of these studies applied AFM to intact adipose tissue or investigated disease correlations. Related to this point, AFM has been utilized to investigate the mechanical properties of whole human tissues, including those from the brain 20 , eye 21 , and heart 22,23 , providing important insights for sample preparation and mechanical property analyses of our human adipose tissues.…”

The Roles of Cellular Nanomechanics in Cancer

“…Deriving the mechanical properties from such stem cells will delineate important information. A clear enhancement (∼10–17 times) in Young's moduli between living and dead undifferentiated adipose‐derived stem cells was observed by Hu et al Another study demonstrated that an increased compliance of cancerous and precancerous cells may behave in a “crumble and yield” manner . This study revealed the order of Young's moduli at 1 nN stiffness of indentation force: normal squamous cells (EPC2) (4.7 kPa live and 9.9 kPa fixed) > metastatic (CP‐A) (3.1 kPa live and 2.9 kPa fixed) > dysmoplastic esophageal cells (2.6 kPa live and 2.1 kPa fixed) …”

“…Combining CTC isolation technology and nanoindentation hybrid platform will result in high recovery rates as well as information on the state of cancers for superior diagnostics . Another group investigated nanoindentation experiments and drug–target interactions directly on patient cancer cells, which mimic human in vivo conditions . The Gaussian fit of the histogram of nanoindentation binding force of CD20‐rituximab on B‐cell lymphomas was much higher than normal cells .…”

Cardiomyocyte contractile force changes in response to AGRWE detected by AFM

“…The vertical force of the AFM cantilever tip used to monitor changes in cardiomyocyte set at 0.4 nN. Different probing locations could lead to the variations of the measured beating forces [21]. To reduce the effect, the AFM probe was placed in the central region of the cell and ten positions were measured/averaged for each cell in the experiments.…”

“…One of the most important factors for evaluating the activities of cardiomyocytes is the mechanical contraction [18][19][20]. Atomic force microscope (AFM) technique has been widely applied in the mechanical characterisation of cells due to its high resolution on the nanoscale [21,22]. Its application on characterising the nanomechanical properties of single cells and molecules has broadened the insights into cellular structures and biology functions.…”