NOV 18, 2015 7:39 AM PST

Let There Be Light... To Repair Neurons?

WRITTEN BY: Xuan Pham
The human brain may not look like much, composed of about three pounds of soft mushy matter. But we all know that our brain is the most intricate organic computer with power that’s unparalleled by any other manmade machine. Despite this extraordinary power though, the brain is quite a fragile organ susceptible to a variety of diseases and traumas. Because of its fragility, injuries to the brain can carry a permanence, affecting cognition that may have taken a lifetime to acquire.
 
Instead of lamenting the brain’s inability to self-renew, researchers at the Research Unit Sensory Biology and Organogenesis at Helmholtz Zentrum München are taking a new approach. They want to repair damages to the brain cells, and they want to do so with light!
 
Optogenetics to repair neurons

Led by Dr. Hernán López-Schier, the team reported to have succeeded in using optogenetics to promote the repair of an injured neural circuit. The team focused on a messenger molecular called cyclic adenosine monophosphate (cAMP) that’s known to promote axonal regrowth. Adenylyl cyclase is the enzyme responsible for producing the cAMP molecule.
 
To increase the levels of cAMP and thus axon repair, the researchers looked to increase adenylyl cyclase. They used a special version of this enzyme from the soil bacterium Beggiatoa that’s modified to activate upon exposure to blue light. This allowed the researchers to systematically increase cAMP levels in cells that expressed the modified blue light activated enzyme.
 
The team tested their optogenetics work in a zebrafish larvae model that was genetically modified to express the photo-sensitive adenylyl cyclase. The control line did not express the modified enzyme. Additionally, the zebrafish larvae also had interrupted sensory lateralis nerves that mimicked neuronal damage. In this live vertebrate system, they reported increased repair of the severed nerves that expressed the modified light-sensitive enzymes with the stimulation of blue light.
 
"While untreated nerve terminals only made synapses again in five percent of the cases, about 30% did after photostimulation." - Yan Xiao, first author of study.
 
Zebrafish neurons repaired by photo-sensitive adenylyl cyclase

In addition, they noted that nearly 100% of the severed peripheral axons regenerated and re-innervated neuromasts within 3 days after sustaining the injury. In contrast, only 5% of the central axons regenerated within the same period. Though the differences in effect are not known, the researchers speculate that it central glia cells may have inhibitory effects on regeneration.
 
While cAMP has been known to promote axonal regrowth, this study claims to be the first one that’s combined cAMP and optogenetics to repair neurons in a living vertebrate. Other light-independent approaches to increase cAMP levels have so far been too imprecise at its targets. This study, however, has the potential to facilitate the repair of neurons in a location and time specific manner. 
 
It’s a proof-of-principle study with desirable outcomes, but the researchers are aiming higher. "Our results are a first step. Now we would like to investigate, whether these results can be extrapolated beyond single neurons in zebrafish, to more complex neuronal circuits of higher animals,” says Dr. López-Schier, senior author.
 

Additional Sources: Science Daily
About the Author
  • I am a human geneticist, passionate about telling stories to make science more engaging and approachable. Find more of my writing at the Hopkins BioMedical Odyssey blog and at TheGeneTwist.com.
You May Also Like
OCT 24, 2020
Clinical & Molecular DX
Software Flags Elevated Cerebral Palsy Risk in Premies
OCT 24, 2020
Software Flags Elevated Cerebral Palsy Risk in Premies
Diagnostic imaging scientists have developed a software tool for predicting the future onset of cerebral palsy in babies ...
NOV 15, 2020
Neuroscience
Hearing Test Can Predict Autism in Newborns
NOV 15, 2020
Hearing Test Can Predict Autism in Newborns
For some time now, researchers have been aware that children and adults with autism tend to have different sensory syste ...
DEC 29, 2020
Clinical & Molecular DX
Injectable Heart Health Tracker Now Picks Up COVID Red Flags
DEC 29, 2020
Injectable Heart Health Tracker Now Picks Up COVID Red Flags
The statistics are a real eye-opener: in the United States, one person dies every 36 seconds from cardiovascular disease ...
JAN 12, 2021
Clinical & Molecular DX
Portable Sequencer Ensures All the Cancer Cells Are Gone
JAN 12, 2021
Portable Sequencer Ensures All the Cancer Cells Are Gone
Surgeons remove a tumor from the abdominal cavity of a patient. But how can they be certain that all the cancer cells we ...
JAN 19, 2021
Clinical & Molecular DX
Fathers' Sperm Linked to Autism in Offspring
JAN 19, 2021
Fathers' Sperm Linked to Autism in Offspring
Researchers at Washington State University have uncovered a genetic link between fathers and children with autism spectr ...
FEB 02, 2021
Immunology
Pumping the Brakes on Stomach Cancer Progression
FEB 02, 2021
Pumping the Brakes on Stomach Cancer Progression
By the time stomach cancer is diagnosed, it’s often bad news for patients. The disease often presents with relativ ...
Loading Comments...