Tracking Traction Force Changes of Single Cells on the Liquid Crystal Surface

YesCell migration is a key contributor to wound repair. This study presents findings indicating that the liquid crystal based cell traction force transducer (LCTFT) system can be used in conjunction with a bespoke cell traction force mapping (CTFM) software to monitor cell/surface traction forces from quiescent state in real time. In this study, time-lapse photo microscopy allowed cell induced deformations in liquid crystal coated substrates to be monitored and analyzed. The results indicated that the system could be used to monitor the generation of cell/surface forces in an initially quiescent cell, as it migrated over the culture substrate, via multiple points of contact between the cell and the surface. Future application of this system is the real-time assaying of the pharmacological effects of cytokines on the mechanics of cell migration

Characterization and Biocompatibility Study of Nematic and Cholesteryl Liquid Crystals.

noIntensive research in bio-engineering has been conducted in the search for flexible biomaterials that could support cell growth and cells attachment. Flexible synthetic materials that support cell growth without the aid of synthetic extracellular matrix proteins are still rare. Cholesteryl liquid crystal containing cholesteryl moieties may have suitable biological affinity. Human keratinocytes (HaCat) were cultured with a nematic liquid crystal and three cholesteryl liquid crystals of different formulation. Subsequently, the trypan blue dye exclusion assay was used to determine cell viability in the liquid crystals. The two classes of liquid crystal were characterized by Differential Scanning Calorimeter (DSC) and polarizing microscope (POM) to understand the nature of the interface material. The cell viability study in medium containing liquid crystals verified that liquid crystals had no effects on cell viability. However, only the surface of cholesteryl liquid crystal has shown affinity to HaCat cells. In addition, cells continued to proliferate in the presence of liquid crystals without a change of medium for eight days. No sign of exothermic and endothermic activities at 370C were observed from the DSC test results for the three samples. Biological and mechanical test result of the cholesteryl liquid crystals has shown that cholesteryl liquid crystals are non toxic and support cell attachment without extracellular matrix protein at very low elasticity

Comparison of two different indentation techniques in studying the in-situ viscoelasticity behavior of liquid crystals

YesLiquid crystal is a new emerging biomaterial. The physical property of liquid crystal plays a role in supporting the adhesion of cells. Nano and microball indentation techniques were applied to determine the elastic modulus or viscoelasticity of the cholesteryl ester liquid crystals in the culture media. Nano-indentation results (108 ± 19.78 kPa, N = 20) agreed well with the microball indentation (110 ± 19.95 kPa, N = 60) for the liquid crystal samples incubated for 24 hours at 37o C, respectively. However, nanoindentation could not measure the modulus of the liquid crystal (LC) incubated more than 24 hours. This is due to the decreased viscosity of the liquid crystal after immersion in the cell culture media for more than 24 hours. Alternatively, microball indentation was used and the elastic modulus of the LC immersed for 48 hours was found to decrease to 55 ± 9.99 kPa (N = 60). The microball indentation indicated that the LC did not creep after 40 seconds of indentation. However, the elastic modulus of the LC was no longer measurable after 72 hours of incubation due to the lost of elasticity. Microball indentation seemed to be a reliable technique in determining the elastic moduli of the cholesteryl ester liquid crystals.Science Fund Vot. No. S024 or Project No. 02- 01-13-SF0104 and FRGS Vot. No. 1482 awarded by Malaysia Ministry of Educatio

A novel algorithm for human fall detection using height, velocity and position of the subject from depth maps

YesHuman fall detection systems play an important role in our daily life, because falls are the main obstacle for elderly people to live independently and it is also a major health concern due to aging population. Different approaches are used to develop human fall detection systems for elderly and people with special needs. The three basic approaches include some sort of wearable devices, ambient based devices or non-invasive vision-based devices using live cameras. Most of such systems are either based on wearable or ambient sensor which is very often rejected by users due to the high false alarm and difficulties in carrying them during their daily life activities. This paper proposes a fall detection system based on the height, velocity and position of the subject using depth information from Microsoft Kinect sensor. Classification of human fall from other activities of daily life is accomplished using height and velocity of the subject extracted from the depth information. Finally position of the subject is identified for fall confirmation. From the experimental results, the proposed system was able to achieve an average accuracy of 94.81% with sensitivity of 100% and specificity of 93.33%.Partly sponsored by Center for Graduate Studies. This work is funded under the project titled “Biomechanics computational modeling using depth maps for improvement on gait analysis”. Universiti Tun Hussein Onn Malaysia for provided lab components and GPPS (Project Vot No. U462) sponsor

Single cell traction force mapping software

N

Compressive forces of cell induced longitudinal deformation to the liquid crystal surface

NoThe ability of a cell to contract plays an important role in determining the ability of the cell to migrate, proliferate and associating with other cells. The transduction of the force in soft substrate such as the liquid crystal surface is a method proposed to study the traction forces of single cells. In this work, finite element method was used to study the compressive forces induced by the keratinocyte to the liquid crystal surface via the anchorage of focal contacts. The constitutive finite element model of the liquid crystal-focal contacts was established. The stress and displacement were analyzed using linear static stress analysis for a quiescent cell. The data for lateral displacements obtained from the experiment were provided as inputs to develop the model and verified through the output acquired for both simulation and experiment. The simulation results indicated that the cell compressive stresses were in the range of 14.93 ± 1.9 nN/μm2 per focal contact. Based on the result obtained, it was suggested to model focal contact-liquid crystal interface with a compressive model that can better approximate the mechanism observe

Biological Imaging with a Near-Field Optical Setup.

NoNoncontact scanning near-field optical microscope (SNOM) systems can be used to optically resolve samples in atmospheric conditions at theoretical resolutions comparable to those of transmission electron microscope and atomic force microscope systems. SNOM systems are also increasingly used to image biological samples. In this study we custom built a SNOM system with the aim of further demonstrating the potential applications of near-field optical examination of biological material. In this study we were able to image both fixed whole-cell samples in air and liquid environments and live whole-cell samples in liquids. The images acquired were of a relatively low resolution, but this work has shown that SNOM systems can be used to monitor the dynamics of living cells at subnanometric resolutions in the z axis and for fluorescent imaging of whole cells in a liquid medium

Cell Traction Force Mapping in MG63 and HaCaTs

NoThe ability of a cell to adhere and transmit traction forces to a surface reveals the cytoskeleton integrity of a cell. Shear sensitive liquid crystals were discovered with new function in sensing cell traction force recently. This liquid crystal has been previously shown to be non-toxic, linear viscoelastic and sensitive to localized exerted forces. This paper reports the possibility of extending the application of the proposed liquid crystal based cell force sensor in sensing traction forces of osteoblast-like (MG-63) and human keratinocyte (HaCaT) cell lines exerted to the liquid crystal sensor. Incorporated with cell force measurement software, force distributions of both cell types were represented in force maps. For these lowly contractile cells, chondrocytes expressed regular forces (10 – 90 nN, N = 200) around the circular cell body whereas HaCaT projected forces (0 – 200 nN, N = 200) around the perimeter of poly-hedral shaped body. These forces are associated with the organisation of the focal adhesion expressions and stiffness of the LC substrate. From the results, liquid crystal based cell force sensor system is shown to be feasible in detecting forces of both MG63 and HaCaT

The Effect of Transforming Growth Factor Beta (TGF-β3) and Sanicle on Wound Healing.

noThere is evidence that both the herb Sanicle and the cytokine TGF- β3 can be beneficial in enhancing wound repair. In this study 3T3 fibroblast cells were cultured and the confluent monolayers were wounded (scarred) using a disposable plastic pipette. Various amounts of TGF-β3 (a growth factor) and Sanicle extract were applied to the cell monolayers. TGF-β3 was applied at concentrations of 50ng/ml, 5ng/ml, 500pg/ml, 50pg/ml and 5pg/ml to five different culture flasks with one additional flask acting as control. Sanicle was applied at concentrations of 100μg/ml, 10μg/ml, 1μg/ml, 100ng/ml and 10ng/ml with one additional flask as a control. The cells were imaged over a period of 20 hours with or without presence of TGF-β3 and Sanicle. The results indicated that although there were no significant increases in the rate of wound closure in relation to application of TGF-β3, there is an indication that TGF-β3 may enhance model wound closure at optimum working concentration between 5ng/ml and 50ng/ml. However, the sanicle extract did not stimulate enhanced repair of the model in vitro wound, but instead seemed to promote cell death along the wound margin. These results indicate that sanicle may be used in the care of wounds, but not as a growth promoter, but because it acts as an antibiotic agent, and possibly because it aids wound debridement

Interactions of Cells with Elastic Cholesteryl Liquid Crystals

noNo Abstrac