Fluorescence microscopy / Photo by: ZEISS Microscopy via Wikimedia Commons
A new imaging technique has been developed to see real-time action in living cells.The researchers at Northwestern University developed the Ultrasound Bioprobe, an imaging technique that uses ultrasound waves and atomic force microscopy, to know the cell's behaviors.
Normally, scientists must slice, dehydrate, apply stains, and embed resin in cells to get high-resolution imaging.Microscope cell staining is used to get a better visualization of cells and their parts under a microscope.It is also used to highlight biological processes, such as metabolism, or to distinguish live cells from dead ones.
There are many stains used for non-living cells that can also be applied to living cells.Commonly used stains include crystal violet in Gram staining, eosin for red blood cells, and fuchsin for collagen or smooth muscle.Unfortunately, the cell dies after the application of stain.
"Sub-cellular components and structures have a profound influence on the behavior of the complex cellular machinery and systems biology.However, unraveling the structures and components inside the cell is very challenging because they are so fragile," said Gajendra Shekhawat of the Northwestern's Engineering.
Traditional methods, such as fluorescent and confocal microscopy, are used to obtain high-resolution and high-sensitivity images from living structures inside cells.
- A fluorescence microscope is similar to a traditional light microscope that features extra capabilities.A fluorescence microscope uses the higher intensity of a light source to produce a magnified image.It is commonly used to capture images of small specimens like cells and microbes, determine if the specimen is alive or dead, and provide images of DNA and RNA.
- A confocal microscope has more features compared to a conventional optical microscope.It can control the depth of field, remove out-of-focus light or flare, and collect optical sections of thick specimens.
These two microscopy techniques can see the biological mechanisms inside cells, but need dyes or labels to improve contrast or to highlight specific parts of cells.Other cell imaging techniques such as light and acoustic waves have limited viewing range, scanning probe microscopy is limited to viewing the cell's surface only, and electron microscopy ultimately kills living cells and tissues just to capture details.
"Characterization of the complex dynamics of biological processes, especially signal pathways at nanoscale resolution, has remained a challenge," said Vinayak Dravid, the director of the Northwestern University of Atomic and Nanoscale Characterization Experimental.
With the Ultrasound Bioprobe, the ultrasound waves can capture images of the intracellular features in the deepest parts of cells without being invasive.The atomic force microscopy, meanwhile, provides the high sensitivity and contrast for the ultrasound waves.The technique can view nanoscale parts of a living cell or tissue without resulting in tissue or cell death.
"This could provide clues for early diagnostics and potential pathways for developing therapeutic strategies," said Shekhawat.
Importance of Cell Imaging
Live-cell imaging is an essential tool needed by scientists to study many aspects of cells.It includes the understanding of cell biology, neurobiology, drug interaction, and cell development.When scientists culture cells, they must put them in favorable cell culture media to grow.Culture media contain several elements to sustain cells, such as amino acids, vitamins, minerals, sugars, lipids, and co-enzymes.For tissue culture media, other factors must be controlled as well, including pH balance, viscosity, surface tension, and concentration of oxygen.
One important application of live-cell imaging techniques is the management of cancer.Every detail a clinician can obtain from cell imaging may be used for medical decision-making.
- Offers essential details about cancer cells, such as form, structure, function, and metabolism.
- Guides invasive therapies to reduce side effects and improve the patient's outcome.
- Early detection of cancer cells from live tissues can reduce the rate of mortality.
- Helps determine the correct type of therapy to treat the disease.Certain therapies like hormone therapy and stem cells require accurate imaging results.
- Improves the development of new therapies in the future.Scientists can quickly create new treatment options if they get more important information on how cancer cells work in real-time.
Live-cell imaging is also used on bacteria and viruses.On November 16, NeoVirTech studied the replication of adenovirus, a common pathogen that causes respiratory diseases, in living cells.Meanwhile, scientists from Northwestern Medicine used such imaging to track down HIV infection and studied individual virions, infectious particles of HIV.
Color coded image of actin filaments in a cancer cell taken on a confocal microscope / Photo by: Howard Vindin via Wikipedia
Cell Imaging in Pharmacology
Aside from studying the tiny structures in cells and the interaction of pathogens, cell imaging is also used in pharmacology, the study of drug action in an organism.In Oxford University, scientists used advanced imaging techniques to analyze the cellular and intracellular structure of the heart and its microcirculation.They studied many aspects of the heart through cell imaging, such as the mechanism of the heart at the cellular level, the microcirculation in small arteries, functions of tissues in certain conditions, and chemicals that affect blood flow and blood pressure.Cell imaging can also determine the pharmacokinetics and pharmacodynamics of drugs in cells.Pharmacokinetics reflects the reaction of an organism to a drug, while pharmacodynamics reflects how a drug can affect an organism.