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
NOV 05, 2019
Clinical & Molecular DX
NOV 05, 2019
Meningitis and Encephalitis: Testing & Diagnosis Strategies for Effective Treatment
Meningitis is an inflammation of the membranes surrounding the brain (meninges) and spinal cord. Encephalitis, on the other hand, refers to inflammation of...
NOV 13, 2019
Health & Medicine
NOV 13, 2019
Sherlock's DNA biosensors set to make diagnostics elementary
The anxious wait to receive results from expensive diagnostic laboratory tests could soon be a thing of the past thanks to a technological breakthrough. En...
NOV 14, 2019
Cell & Molecular Biology
NOV 14, 2019
Scientists Find a Non-Invasive Way to Detect Prions
Misfolded proteins, also called prions, can cause a host of problems, including neurodegenerative disorders....
DEC 04, 2019
Clinical & Molecular DX
DEC 04, 2019
Genetic platform takes the guesswork out of catching infections
A physician is faced with 3 patients: an elderly person with a chronic cough, a child being wheeled out of surgery and a young mother with a high fever. Ho...
FEB 19, 2020
Immunology
FEB 19, 2020
Testing the Immune Response to Ovarian Cancer Treatment
There is a new diagnostic test for the deadliest form of gynecological cancer – ovarian cancer. Better tests mean better diagnostics, and better diag...
MAR 28, 2020
Drug Discovery & Development
MAR 28, 2020
FDA Approves 5-Minute Coronavirus Test
In recent weeks, the US has struggled to supply enough tests to detect the coronavirus. Now, however, this may change thanks to the FDA’s approval of...
Loading Comments...