Tip of the Month - Don’t forget capacitance

As pointed out below, capacitance at high frequency can be used to determine the percentage of substrate covered with cells – a very useful quantity measured using ECIS without even opening the door of the cell incubator.

For those researchers using the ECIS ZTheta instrumentation or its forerunner, the ECIS 1600R, the impedance (Z) is automatically broken down into components of resistance [R] and capacitance [C] that would be obtained if the instrument were measuring a simple RC series circuit.

In most research papers presenting ECIS data, one sees the resistance and sometimes the impedance but rarely the measured capacitance reported. The likely reason for this is that at the intermediate AC frequency range where most ECIS resistance measurements are made, the capacitance undergoes relatively small changes. This is not true, however, at high AC frequencies (32 kHz and higher).

Under these high frequency conditions there is very noticeable drop in the measured capacitance that is related to cell coverage.

To give some perspective to this measurement, let’s consider capacitance of the 10E+ electrodes at 32 kHz. Without cells, the measured C of a well is ~ 60 nF (nanofarad). As cells attach and spread upon the electrodes and ultimately form a confluent layer, the capacitance drops usually to less than 10 nF. Furthermore the relationship between the drop in capacitance measured at high frequency and the amount of substrate coverage is, for many cell lines, a linear one. In other words, the capacitance at 32 kHz can be used to measure the degree of cell coverage.

Consider an example where the 32 kHz capacitance of the cell free electrode(s) is 60 nF and that of the fully confluent electrode is 10 nF; then when a partially cell-covered electrode has a capacitance of 30 nF, the amount of substrate coverage can be calculated as shown below:

% cell coverage = 100% (Ccell free – Cmeasured) /(Ccell free – Cconfluence)

% cell coverage = 100% (60-30)/(60-10) = 100% (30/50) = 60% cell coverage

Knowing the degree of cell coverage is very useful when doing wound healing assays and is especially important when modeling cell data. The ECIS model requires a confluent cell layer to be valid, and this can be quickly verified by checking the value of the high frequency capacitance.
ECIS Application Webinars

ECIS application webinars review the topics listed below in 20 to 30 minute, web-based, interactive seminars presented by Applied BioPhysics President and co-founder, Dr. Charles Keese.

All webinars are held at 11:00 am EST. To register for a webinar, please go to: https://appliedbiophysics.webex.com and scroll to the webinar date of interest.  

Barrier Function Assays – November 21, 2017

Real-time Electroporation and Monitoring – December 5, 2017
Latest ECIS Software   
The latest version of the software is v1.2.215, which can be downloaded from Help | Check for Updates, or:

Software Tip: Append and Combine

Append Datasets

If an experiment is interrupted and must be restarted as a new file, then the two files can be joined using the ‘Append Dataset’ command from the ‘Edit’ menu. Select the first (earlier) file from the Data Manager, then ‘Append Dataset’ and select the second (later) file to be appended. The datasets must have the same electrodes and experiment type. The time points for the second dataset will be offset with respect to the start time of the first dataset. This process can be repeated for multiple datasets. To save the resulting dataset, go to File | Export data| All data and select the .ABP file format.

Combine Datasets

Multiple 8/16 well datasets can be easily compared on 1 graph using the ‘Combine datasets’ command from the ‘Edit’ menu. The first dataset will transform into a 96 well format, and up to 6 datasets can be combined. Each 8 well array will appear as one column in the Well Configuration. The datasets should have the same experiment type and time point interval. The original data is unchanged, and the new dataset can be saved as described above.

Tradeshows & Events 

2017 ASCB / EMBO
Dec 2 – 6, 2017
Philadelphia, PA

SOT Annual Meeting 2018
March 11 – 15, 2018
San Antonio, TX

AACR Annual Meeting 2018
April 14 – 18, 2018
Chicago, IL

Experimental Biology 2018
April 21 – 25, 2018
San Diego, CA
ECIS School Graduates - August 2017

From left to right: Gary McCollum - Vanderbilt University, Tillie Hackett - University of British Columbia, G. Cristina Brailoiu - Thomas Jefferson University, May Al-Fouadi - University of British Columbia, Alok Bhushan - Thomas Jefferson University (not shown in image).
New Publications

Many new publications have been added to the Applied BioPhysics ECIS publications database.  The following are just a selection of those added.

Baumer, Yvonne et al. “Hyperlipidemia-Induced Cholesterol Crystal Production by Endothelial Cells Promotes Atherogenesis.” Nature Communications 8.1 (2017): 1129. Web.

Mehta, Nehal N. et al. “IFN-γ and TNF-α Synergism May Provide a Link between Psoriasis and Inflammatory Atherogenesis.” Scientific Reports 7.1 (2017): 13831. Web.

Doijen, Jordi et al. “Signaling Properties of the Human Chemokine Receptors CXCR4 and CXCR7 by Cellular Electric Impedance Measurements.” Ed. Edward E. Schmidt. PLOS ONE 12.9 (2017): e0185354. Web.

Singla, Sunit et al. “Hemin Causes Lung Microvascular Endothelial Barrier Dysfunction by Necroptotic Cell Death.” American Journal of Respiratory Cell and Molecular Biology 57.3 (2017): 307–314. Web.

Hung, Chi-Feng et al. “18ß-Glycyrrhetinic Acid Derivative Promotes Proliferation, Migration and Aquaporin-3 Expression in Human Dermal Fibroblasts.” Ed. Paula B. Andrade. PLOS ONE 12.8 (2017): e0182981. Web.

Ungewiß, Hanna et al. “Desmoglein 2 Regulates the Intestinal Epithelial Barrier via p38 Mitogen-Activated Protein Kinase.” Scientific Reports 7.1 (2017): 6329. Web.

Kho, Dan Ting et al. “ECIS Technology Reveals That Monocytes Isolated by CD14+ve Selection Mediate Greater Loss of BBB Integrity than Untouched Monocytes, Which Occurs to a Greater Extent with IL-1β Activated Endothelium in Comparison to TNFα.” Ed. Stefan Liebner. PLOS ONE 12.7 (2017): e0180267. Web.

Cui, Yu-Xin et al. “MicroRNA-7 Suppresses the Homing and Migration Potential of Human Endothelial Cells to Highly Metastatic Human Breast Cancer Cells.” British Journal of Cancer 117.1 (2017): 89–101. Web.

Doggett, Travis M. et al. “Sphingosine-1-Phosphate Treatment Can Ameliorate Microvascular Leakage Caused by Combined Alcohol Intoxication and Hemorrhagic Shock.” Scientific Reports 7.1 (2017): 4078. Web.

Tramontini Gomes de Sousa Cardozo, Francielle et al. “Serum from Dengue Virus-Infected Patients with and without Plasma Leakage Differentially Affects Endothelial Cells Barrier Function in Vitro.” Ed. Dong-Yan Jin. PLOS ONE 12.6 (2017): e0178820. Web.

Jung, Mira et al. “IL-10 Improves Cardiac Remodeling after Myocardial Infarction by Stimulating M2 Macrophage Polarization and Fibroblast Activation.” Basic Research in Cardiology 112.3 (2017): 33. Web.

Kathiriya, Jaymin J et al. “Galectin-1 Inhibition Attenuates Profibrotic Signaling in Hypoxia-Induced Pulmonary Fibrosis.” Cell Death Discovery 3 (2017): 17010. Web.

Mohamed, Riyaz et al. “Hyperhomocysteinemia Alters Retinal Endothelial Cells Barrier Function and Angiogenic Potential via Activation of Oxidative Stress.” Scientific Reports 7.1 (2017): 11952. Web.

ECIS Humor

Need a good laugh? Visit the ECIS Cartoons page of our website to view cartoons by Catherine, our in-house cartoonist, to start your day with a smile.

Are you the creative type? Submit one of your own cartoons; if we post it on our website we will send you a free array!