Interferometric Measurement of TGF-β Induced Epithelial-Mesenchymal Transition of Tumor Cells

A three-dimensional profile reconstruction of live cells in dynamic cell cultures is a challenging problem due to the highly scattering nature of cell mediums. Furthermore, it is an interesting problem since these cultures present the optimal in vitro conditions that most closely resemble the cells’ natural conditions. In this paper, we report a holographic method used for imaging during the process of treatment of dynamic cell cultures with transforming growth factor beta (TGF-β) and the subsequent epithelial-mesenchymal transition (EMT). The imaging of dynamic cell cultures presents many challenges for holographic techniques due to the highly scattering and high speed nature of the environment. Here we report the algorithmic workflow we used for decreasing the imaging noise due to the presence of cell medium and achieving high speed reconstruction rates in real time. We also report the prominent morphological features we extracted from the obtained depth maps throughout the experiment. We conducted experiments on four different cell lines: ONCO-DG1, HCT-116, MDA-MB-231, and HUVEC. We observed the EMT process throughout a 48 h period after treatment with TGF-β with 6 h intervals for each sample. We show some examples of the reconstructed depth maps of tumor cells during the EMT phase. From these depth maps we extract some morphological parameters and report how they change after the EMT process is completed. The obtained results indicate that the proposed method presents certain advantages from an optical perspective particularly for applications where a dynamical medium is present. These advantages are lower signal-to-noise ratio (SNR) values and a simple setup compared to the setups used in similar studies. Future studies on this application could lead to the development of a model for the EMT process and its effects on cell to cell interactions

MobileSkin: Classification of Skin Lesion Images Acquired Using Mobile Phone-Attached Hand-Held Dermoscopes

Dermoscopy is the visual examination of the skin under a polarized or non-polarized light source. By using dermoscopic equipment, many lesion patterns that are invisible under visible light can be clearly distinguished. Thus, more accurate decisions can be made regarding the treatment of skin lesions. The use of images collected from a dermoscope has both increased the performance of human examiners and allowed the development of deep learning models. The availability of large-scale dermoscopic datasets has allowed the development of deep learning models that can classify skin lesions with high accuracy. However, most dermoscopic datasets contain images that were collected from digital dermoscopic devices, as these devices are frequently used for clinical examination. However, dermatologists also often use non-digital hand-held (optomechanical) dermoscopes. This study presents a dataset consisting of dermoscopic images taken using a mobile phone-attached hand-held dermoscope. Four deep learning models based on the MobileNetV1, MobileNetV2, NASNetMobile, and Xception architectures have been developed to classify eight different lesion types using this dataset. The number of images in the dataset was increased with different data augmentation methods. The models were initialized with weights that were pre-trained on the ImageNet dataset, and then they were further fine-tuned using the presented dataset. The most successful models on the unseen test data, MobileNetV2 and Xception, had performances of 89.18% and 89.64%. The results were evaluated with the 5-fold cross-validation method and compared. Our method allows for automated examination of dermoscopic images taken with mobile phone-attached hand-held dermoscopes

Micro-UFO (Untethered Floating Object): A Highly Accurate Microrobot Manipulation Technique

A new microrobot manipulation technique with high precision (nano level) positional accuracy to move in a liquid environment with diamagnetic levitation is presented. Untethered manipulation of microrobots by means of externally applied magnetic forces has been emerging as a promising field of research, particularly due to its potential for medical and biological applications. The purpose of the presented method is to eliminate friction force between the surface of the substrate and microrobot. In an effort to achieve high accuracy motion, required magnetic force for the levitation of the microrobot was determined by finite element method (FEM) simulations in COMSOL (version 5.3, COMSOL Inc., Stockholm, Sweden) and verified by experimental results. According to position of the lifter magnet, the levitation height of the microrobot in the liquid was found analytically, and compared with the experimental results head-to-head. The stable working range of the microrobot is between 30 µm to 330 µm, and it was confirmed in both simulations and experimental results. It can follow the given trajectory with high accuracy (<1 µm error avg.) at varied speeds and levitation heights. Due to the nano-level positioning accuracy, desired locomotion can be achieved in pre-specified trajectories (sinusoidal or circular). During its locomotion, phase difference between lifter magnet and carrier magnet has been observed, and relation with drag force effect has been discussed. Without using strong electromagnets or bulky permanent magnets, our manipulation approach can move the microrobot in three dimensions in a liquid environment

Determination of Cell Stiffness Using Polymer Microbeads as Reference

Knowing the mechanical properties of cells is very important in cell detection, analysis of cell activities, diagnosis and drug treatment. The determination of cell stiffness, which used effectively in cell analysis, is carried out with different measurement techniques. In this study, the stiffness of cells is determined by comparison to the displacement of polystyrene microparticles induced by vibration generated by piezoelectric transducers. The difference of stiffness of the cells and polystyrene microparticles is measured using a digital holographic imaging technique

Classification of Cells Based on Their Drifting Velocity under Acoustic Radiation Pressure

© 2020 IEEE.This study reports a novel cell classification method based on the observation of trajectories that cells inside a fluidic chamber follow under an externally applied acoustic field. Proposed method is significant both as a cell classification method and as a method for characterising the motion of various cell lines under different surface acoustic wave patterns. The difference is mainly due to the characteristic differences of cells such as mass, surface adhesiveness and cellular volume. We discuss the mechanisms that affect the interaction between cells and surface waves. Classification performance is tested using using support vector machine (SVM), max-likelihood and multilayer perceptron (MLP) methods and accuracy, sensitivity and specificity values are reported for each. The results indicate that the method can be used as a powerful classifier particularly for cells that are hard to distinguish visually. It is observed that for a given frequency, the motion characteristics of different cell lines differ due to the difference between dominant adhesion mechanism for that particular cell line. This observation can be utilized for the development of a frequency based cell manipulation method that is able to target specific cells using their characteristic frequencies. We discuss the potential of the proposed acoustic stimulation method as a cell manipulation technique particularly for uncoupling the motion of different cell lines

Microfluidic wound scratching platform based on an untethered microrobot with magnetic actuation

Cell migration is closely associated with various pathological conditions such as tumor invasion and metastasis as well as cell proliferation. The in vitro wound healing assay involves a simple and affordable technique and is used to examine the migration abilities of cells in a wound area created on confluent cell culture. Although this technique is easy to implement, it is not suitable for microfluidic chips. Microfluidic systems offer advantages such as examining the microenvironment of the cells and performing an analysis closer to the living system in a continuous flow setting. However, they are not compatible with the classical wound healing assay since they are closed systems, and their small channels are not suitable for wound creating via a micropipette tip. This work presents a functional system, which can be used to create wounds in a microfluidic platform without causing any negative effects on the cells and requiring the use of any chemicals. In this system, an untethered magnetic microrobot, which can be manipulated in 4 degrees of freedom (DOF) to create wounds with uniform sizes and different shapes within a closed microfluidic system was used. In addition, the effect of different wound geometries on wound healing was investigated. According to the results, triangle-shaped wound healed the slowest, while the plus-shaped wound healed the fastest. This study could open new lanes in the use of microrobots in lab-on-a-chip devices and can be extended to 3D cell cultures in the near future

Manipulation of Cell Cultures by Means of Holographic Visual Feedback

© 2020 IEEE.In this study we present a novel untethered micro tool that is able to accomplish minimally invasive micro manipulation tasks in 2D and 3D cell cultures. We demonstrate the proposed system for targeted drug delivery, cell translation and mechanical cell stimulation applications. Due to the ability of the proposed system to control the motion of the micro tool in 6 DOF and obtain depth information through holographic visual feedback, we show that the microtool can be manipulated in a way such that the sample cell culture will go negligible mechanical stress. We show that the proposed system can be used for a variety of micro manipulation tasks without effecting the sample in question

Interferometric Investigation of Cell Stiffness and Morphology on Oxidative Stress- Induced Human Umbilical Vein Endothelial Cells (HUVEC)

Cell stiffness that can be measured accordingly elasticity modulus is an important biomechanical feature that plays a one-to-one role on the basic features of the cell, such as migration and proliferation, and this feature is significantly affected by the characteristic of the cytoskeleton. Reactive Oxygen Species (ROS) are side-products formed as a result of the cell's general metabolic activities. Cells have a very effective antioxidant defense to deactivate the toxic effect of ROS however, oxidative stress at abnormal levels significantly damages cellular balance. Many conditions such as inflammation, neurodegenerative and cardiovascular diseases and aging are associated with oxidative stress. Besides, oxidative stress is one of the parameters that affect the biomechanical behavior of the cell, but the mechanism of this effect still remains a mystery. In this study, oxidative stress was mimicked on Human Umbilical Vein Endothelial (HUVEC) cells by using H2O2 and the effect of this situation on cell stiffness and morphological structure was investigated interferometrically for the first time. The changes that occurred in the cell stiffness were determined by calculating the elasticity modules of the cells. Cells were exposed to H2O2 for 24 hours at 0.5 mM and 1 mM concentrations, and as a result, cell stiffness was shown to decrease due to increased H2O2 concentration