Newly developed fluorescent protein makes internal organs visible

July 18, 2011
Newly developed fluorescent protein makes internal organs visible
Liver cells in this mouse contain the fluorescent protein iRFP. The mouse was exposed to near-infrared light, which has caused iRFP to emit light waves that are also near-infrared. The composite image shows these fluorescent near-infrared waves passing readily through the animal’s tissues to reveal its brightly glowing liver. (credit: Albert Einstein College of Medicine)

Researchers at Albert Einstein College of Medicine of Yeshiva University have developed the first fluorescent protein that enables scientists to clearly "see" the internal organs of living animals without the need for a scalpel or imaging techniques that can have side effects or increase radiation exposure.

The new probe could prove to be a breakthrough in whole-body imaging – allowing doctors, for example, to noninvasively monitor the growth of tumors in order to assess the effectiveness of anti-cancer therapies. In contrast to other body-scanning techniques, imaging does not involve or require the use of contrast agents. The findings are described in the July 17 online edition of Nature Biotechnology.

For the past 20 years, scientists have used a variety of colored fluorescent proteins, derived from jellyfish and corals, to visualize cells and their organelles and molecules. But using fluorescent probes to peer inside live mammals has posed a major challenge. The reason: hemoglobin in an animal''s blood effectively absorbs the blue, green, red and other wavelengths used to stimulate standard fluorescent proteins along with any wavelengths emitted by the proteins when they do light up.

To overcome that roadblock, the laboratory of Vladislav Verkhusha, Ph.D., associate professor of anatomy and structural biology at Einstein and the study''s senior author, engineered a fluorescent from a bacterial phytochrome (the pigment that a species of bacteria uses to detect light). This new phytochrome-based fluorescent protein, dubbed iRFP, both absorbs and emits light in the near-infrared portion of the electromagnetic spectrum – the spectral region in which mammalian The researchers targeted their fluorescent protein to the liver – an organ particularly difficult to visualize because of its high blood content. Adenovirus particles containing the gene for iRFP were injected into mice. Once the viruses and their gene cargoes infected liver cells, the infected cells expressed the gene and produced iRFP protein. The mice were then exposed to near-infrared light and it was possible to visualize the resulting emitted fluorescent light using a whole-body imaging device. Fluorescence of the liver in the infected mice was first detected the second day after infection and reached a peak at day five. (See accompanying image.) Additional experiments showed that the iRFP fluorescent protein was nontoxic.

"Our study found that iRFP was far superior to the other fluorescent proteins that reportedly help in visualizing the livers of live animals," said Grigory Filonov, Ph.D., a postdoctoral fellow in Dr. Verkhusha''s laboratory at Einstein, and the first author of the Nature Biotechnology paper. "iRFP not only produced a far brighter image, with higher contrast than the other fluorescent proteins, but was also very stable over time. We believe it will significantly broaden the potential uses for noninvasive whole-body imaging."

Dr. Filonov noted that fluorescent-protein imaging involves no radiation risk, which can occur with standard x-rays and computed tomography (CT) scanning. And unlike magnetic resonance imaging (MRI), in which contrasting agents must sometimes be swallowed or injected to make internal body structures more visible, the contrast provided by iRFP is so vibrant that contrasting agents are not needed.

Explore further: Genetically engineered yeast soak up heavy metal pollution

More information: "Bright and stable near-infrared fluorescent protein for in vivo imaging," July 17 online edition of Nature Biotechnology

Related Stories

Genetically engineered yeast soak up heavy metal pollution

July 21, 2017
Environmental contamination with heavy metals is often the result of various types of industrial processes. Because heavy metals can be dangerous to humans and other wildlife, contaminated sites need to be cleaned up. This ...

Illuminating neural pathways in the living brain

July 24, 2017
Using light alone, scientists from the Max Planck Institute of Neurobiology in Martinsried are now able to reveal pairs or chains of functionally connected neurons under the microscope. The new optogenetic method, named Optobow, ...

'Expansion pathology' method could mean earlier intervention

July 21, 2017
(HealthDay)—A new method, called expansion pathology (ExPath), which is a clinically optimized form of expansion microscopy (ExM), can be used for pathology and clinical research, according to a report published online ...

Heart tissues of different origins can 'beat' in sync

July 19, 2017
Researchers from MIPT and the University of Bonn have shown that heart tissues of different origins can contract in sync. In a series of experiments, they first merged two rat tissues of different ages and then combined rat ...

New tool offers snapshots of neuron activity

June 26, 2017
Many cognitive processes, such as decision-making, take place within seconds or minutes. Neuroscientists have longed to capture neuron activity during such tasks, but that dream has remained elusive—until now.

Novel viral vectors deliver useful cargo to neurons throughout the brain and body

June 26, 2017
Viruses have evolved to be highly effective vehicles for delivering genes into cells. Seeking to take advantage of these traits, scientists can reprogram viruses to function as vectors, capable of carrying their genetic cargo ...

Recommended for you

Post-stroke patients reach terra firma with new exosuit technology

July 26, 2017
Upright walking on two legs is a defining trait in humans, enabling them to move very efficiently throughout their environment. This can all change in the blink of an eye when a stroke occurs. In about 80% of patients post-stroke, ...

Molecular hitchhiker on human protein signals tumors to self-destruct

July 24, 2017
Powerful molecules can hitch rides on a plentiful human protein and signal tumors to self-destruct, a team of Vanderbilt University engineers found.

Researchers develop new method to generate human antibodies

July 24, 2017
An international team of scientists has developed a method to rapidly produce specific human antibodies in the laboratory. The technique, which will be described in a paper to be published July 24 in The Journal of Experimental ...

New vaccine production could improve flu shot accuracy

July 24, 2017
A new way of producing the seasonal flu vaccine could speed up the process and provide better protection against infection.

A sodium surprise: Engineers find unexpected result during cardiac research

July 20, 2017
Irregular heartbeat—or arrhythmia—can have sudden and often fatal consequences. A biomedical engineering team at Washington University in St. Louis examining molecular behavior in cardiac tissue recently made a surprising ...

Want to win at sports? Take a cue from these mighty mice

July 20, 2017
As student athletes hit training fields this summer to gain the competitive edge, a new study shows how the experiences of a tiny mouse can put them on the path to winning.

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

gmurphy
not rated yet Jul 18, 2011
Very very impressive. I'm surprised there's not any negative consequences from the introduction of the fluorescent protein to the phenotype.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.