Novel label-free microscopy enables dynamic, high-resolution imaging of cell interactions

December 07, 2016

Researchers from the University of Illinois at Urbana-Champaign have invented a novel live-cell imaging method that could someday help biologists better understand how stem cells transform into specialized cells and how diseases like cancer spread. The Photonic Crystal Enhanced Microscope (PCEM) is capable of monitoring and quantitatively measuring cell adhesion, a critical process involved cell migration, cell differentiation, cell division, and cell death.

"Our approach is important because there are not currently label-free and high-resolution imaging tools that allow cell-surface interactions to be quantified and imaged dynamically, although these processes are fundamental to things like wound healing, tissue development, tumor invasion, and cancer metastasis," said Brian Cunningham, a professor electrical and computer engineering and of bioengineering at Illinois.

Most conventional imaging methods rely on fluorescent dyes, which attach to and illuminate the cell components so they are visible under a microscope. However, fluorescent tagging has its limitations--namely that it is invasive, difficult for quantitative measurement, and only provides a short-term window of time for cell examination and measurement due to photo bleaching.

By using the PCEM, the researchers have successfully measured the effective mass density of cell membranes during stem cell differentiation, and cancer cell response to drugs in an extended period. Their results, "Quantitative imaging of cell membrane-associated effective mass density using Photonic Crystal Enhanced Microscopy," were reported in the journal Progress in Quantum Electronics, (November 2016, Volume 50).

According to PCEM lead researcher Yue Zhuo, a post-doctoral Beckman Institute Fellow, fluorescent tagging doesn't allow scientists to see how a protein or cell changes over time.

"You can see the cell for maybe a few hours maximum before the fluorescent light dies out, but it takes several days to conduct a stem cell experiment," said Zhuo. "Scientists commonly use fluorescent tagging because there's no better way to monitor live cells due to their low imaging contrast among cellular organelles. That urges us to develop a label-free and high-resolution imaging method for live cell study."

The Illinois team's microscope functions with an LED light source and a photonic crystal biosensor made from inexpensive materials like titanium dioxide and plastic using a fabrication method like nanoreplica molding.

"Our sensor can be massively fabricated easily, and our cost to make the sensor is less than $1 each." noted Zhuo.

In Zhuo's apparatus, the photonic crystal biosensor is an optical sensor which can apply to any attachable cells. The sensor surface is coated with extracellular matrix materials to facilitate cellular interactions, which are then viewed through a normal objective lens and recorded with a CCD camera.

"The advantage of our PCEM system is you can see as the [live] cell is beginning to attach to our sensor, and we can quantitatively and dynamically measure what happened at that time," Zhuo said. "We're able to actually measure a very thin layer on the bottom of the cell that's about 100 nanometers, which is beyond the diffraction limit for visible light."

In the future, Zhuo plans to outfit the microscope with higher imaging resolution and someday hopes to be able to build a library of cell adhesion data for scientists.

"Different types of cells will have different dynamic attachment profiles." she explained. "We can use this library to screen different types of cells for tissue regeneration, disease diagnostic, or drug treatment, for example, see how diseased cells spread, or see how the cancer cells respond to different drug treatment."
-end-
Cunningham is the Donald Biggar Willett Professor of Engineering and director of the Micro + Nanotechnology Lab at Illinois. This project was funded by grants from the National Science Foundation and National Institutes of Health. Research collaborators include associate professor Brendan Harley and post-doctoral researcher Ji Sun Choi (chemical and biomolecular engineering), and graduate student Hojeong Yu (electrical computer engineering).

University of Illinois College of Engineering

Related Stem Cell Articles from Brightsurf:

Fat cell hormone boosts potential of stem cell therapy
Mesenchymal stem cell (MSC) therapy has shown promising results in the treatment of conditions ranging from liver cirrhosis to retinal damage, but results can be variable.

Oncotarget Characterization of iPS87, a prostate cancer stem cell-like cell line
Oncotarget Volume 11, Issue 12 reported outside its natural niche, the cultured prostate cancer stem cells lost their tumor-inducing capability and stem cell marker expression after approximately 8 transfers at a 1:3 split ratio.

Stem cell identity unmasked by single cell sequencing technology
Scientists from The University of Queensland's Diamantina Institute have revealed the difference between a stem cell and other blood vessel cells using gene-sequencing technology.

It's all about the (stem cell) neighborhood
Researchers at Duke-NUS Medical School have now identified how the stem cell neighbourhood, known as a niche, keeps stem cells in the gut alive.

Spaceflight activates cell changes with implications for stem cell-based heart repair
A new study of the effects of spaceflight on the development of heart cells identified changes in calcium signaling that could be used to develop stem cell-based therapies for cardiac repair.

Not just a stem cell marker
The protein CD34 is predominantly regarded as a marker of blood-forming stem cells but it helps with migration to the bone marrow too.

Interferon-beta producing stem cell-derived immune cell therapy on liver cancer
Induced pluripotent stem (iPS) cell-derived myeloid cells (iPS-ML) that produce the anti-tumor protein interferon-beta (IFN-beta) have been produced and analyzed by researchers from Kumamoto University, Japan.

Scientists aim to create the world's largest sickle cell disease stem cell library
Scientists at the Center for Regenerative Medicine at Boston Medical Center and Boston University School of Medicine are creating an induced pluripotent stem cell (iPSC)-based research library that opens the door to invaluable sickle cell disease research and novel therapy development.

Designer switches of cell fate could streamline stem cell biology
Researchers at the University of Wisconsin-Madison have developed a novel strategy to reprogram cells from one type to another in a more efficient and less biased manner than previous methods.

Allen Institute for cell science releases gene edited human stem cell lines
The Allen Institute for Cell Science has released the Allen Cell Collection: the first publicly available collection of gene edited, fluorescently tagged human induced pluripotent stem cells that target key cellular structures with unprecedented clarity.

Read More: Stem Cell News and Stem Cell Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.