Phototherapy and nerve tissue repair

Background: Posttraumatic nerve repair continues to be a major challenge of restorative medicine. Numerous attempts have been made to enhance and/or accelerate the recovery of injured peripheral nerves. One of the methods studied is the use of laser phototherapy. Laser phototherapy was applied as a supportive factor for accelerating and enhancing axonal growth and regeneration after injury or reconstructive peripheral nerve procedure. Methods: I - These studies summarize our experience with 632 and 780 nm low power laser irradiation for treatment of peripheral nerve injury using a rat sciatic nerve model after crush injury, neurorraphy or neurotube reconstruction. II - A clinical double-blind, placebo-controlled randomized study was performed to measure the effectiveness of laser phototherapy on patients who had been suffering from incomplete peripheral nerve injuries for 6 months up to several years. III - 780 nm laser irradiation was investigated on the growth of embryonic rat brain cultures embedded in neurogel (cross-linked hyaluronic acid with adhesive molecule laminin). Neuronal cells attached to microcarriers (MCs) were laser treated, and their growth in stationary cultures was detected. Results: I - Animal studies show that laser phototherapy has a protective immediate effect, maintains functional activity of the injured nerve over time, prevents or decreases scar tissue formation at the injured site, prevents or decreases degeneration in corresponding motor neurons of the spinal cord and significantly increases axonal growth and myelinization. Moreover, direct laser irradiation of the spinal cord improves recovery of the corresponding injured peripheral nerve. II - A clinical double-blind, placebo-controlled randomized study shows that in long-term peripheral nerve injured patients low power laser irradiation can progressively improve peripheral nerve function, which leads to significant functional recovery. III - Cell therapy: 780 nm laser irradiation accelerated migration and fiber sprouting of neuronal cells aggregates. The irradiated cultures contained a higher number of large neurons than the controls. Neurons in the irradiated cultures developed a dense branched interconnected network of neuronal fibers. Conclusions: I - The animal and clinical studies on the promoting action of phototherapy on peripheral nerve regeneration make it possible to suggest that the time for broader clinical trials has come. II - 780 nm laser treatment of embryonic rat brain cultures embedded in neurogel and attached to positively charged cylindrical MCs, stimulated migration and fiber sprouting of neuronal cells aggregates and, therefore, can be considered as potential therapy for neuronal injury.