(a) An illustration of how a femtosecond laser pulse is delivered to the target point between an axon and a neuronal soma. (b) An illustration of the phospholipid bilayers of the neuron soma and axon. Note that the attachment region, where the phospholipid layers are attaching, is designated with a circular spot. This does not represent the laser focal spot. (c) The laser pulse high intensity causes a reversible destabilization of both phospholipid layers. A depiction of the femtosecond laser pulse induced axon-soma attachment. Here, the generated free ions (shown in red) and free electrons (shown in orange) cross the center nonpolar region and break bonds between the fatty acid hydrophobic tails. (d) The relaxation process results in the formation of new stable bonds and formation of singular, hemifused, cell membrane only at the targeted connection point.
Broken neuronal connections are the cause of paralysis, organ failure, and other serious conditions. There have been attempts to bypass such injuries, with limited success, but now researchers at the University of Alberta in Canada have developed a technique that uses lasers to essentially weld neurons together. There’s still a ways to go in using the technology in clinical applications, but the breakthrough is certainly very promising for treating chronic disabilities and various debilitating conditions.
The laboratory work involved placing pairs of neurons in a solution that keeps them separated from each other. Then the neuronal axon and soma of the two neurons were pushed against each other as femtosecond laser pulses were fired at the site. The laser raised the temperature of the neurons to their melting point, which caused the neurons to fuse and form a common membrane.
Because the laser purses were so short, they did not heat up the interior of the neurons enough to cause visible damage. The researchers tried the technique on three different cell types, demonstrating the applicability of it in different applications. Because the new method can be used to precisely target the exact location where fusion is to take place, researchers now have a powerful tool for lab use, which we hope they will be able to soon transfer into clinical practice.
From the study introduction:
By physically connecting single axons and neurons right after injury, it will allow researchers to develop new methods of studying the effects of neuron connection on neuronal regeneration, progression of Wallerian degeneration, and the existence of cellular communication, to further our understandings of these phenomena. This effective neuronal connection method should allow the user to select single cells for isolation, connection, and cutting. The technique is shown to be universal and applicable to multiple cell types and their media.
We developed a novel neuron connection method using ultrashort femtosecond laser pulses. Precise tuning of the laser parameters allowed us to induce a process called hemifusion at the contact point of two phospholipid membranes. To achieve neuron connection, the laser intensity and aiming accuracy required are 1.7(±0.08)×1012 W/cm2, and ±0.5 μm, respectively, within the membranes hemifusion location. Exposure to near infrared femtosecond laser pulses induces molecular rearrangement of the phospholipid bilayers via multiphoton and avalanche ionization processes. The high electron and ion density at the laser beam focal point leads to an ultrafast reversible destabilization of the phospholipid molecules.
Study in Nature Scientific Reports: Novel Method for Neuronal Nanosurgical Connection…
More from University of Alberta: Engineering researchers use laser to “weld” neurons, creating new medical research possibilities…
