The work of the diaphragm after a fracture of the cervical vertebrae can be restored

Researchers at Case Western Reserve University (Cleveland, Ohio) have developed a procedure that restores the functioning of the respiratory muscles of the diaphragm, even if they were paralyzed more than a year ago. This approach will allow patients with severe spinal cord injuries to breathe without an artificial respiration device.

As part of their study, the scientists worked with a group of nerves descending from the respiratory center of the brain stem through the C3-C5 vertebrae located in the middle of the cervical spine. Any damage to the spinal cord above the C3 vertebra can lead to extensive muscle paralysis, causing respiratory disorders, motor function, regulation of cardiac output and sexual function. Unfortunately, such injuries to the cervical spine are the most common cause of spinal cord injuries.

Spinal cord injury is accompanied by the death of injured nerve fibers, which leads to the loss of a large number of nerve connections between the brain and muscles. The normal reaction of the body to injury is the formation of a scar, represented by dense cartilaginous tissue that prevents the growth of new neurons, the formation of new nerve contacts and the restoration of muscle functioning.

Paralysis of the respiratory muscles caused by spinal cord injuries leads to a decrease in the level of oxygen in the blood and forces all the functional respiratory muscles to work more intensively. However, this is often not enough to maintain the patient's life.

The researchers proposed an approach to solve this problem using a two-step procedure that has shown promising results in animal experiments (Sprague–Dawley rats with an average life expectancy of less than three years).

At the first stage, they injected into the area of spinal cord injury that occurred about a year and a half ago, the enzyme chondroitinase, which removes its main component from the scar tissue – chondroitin sulfate-proteoglycans. This simultaneously enabled the formation of new nerve contacts and stimulation of motor neurons innervating the respiratory muscles. At the second stage, the animals were subjected to short periods of hypoxia (low oxygen content in the medium), which enhanced and accelerated breathing for the rehabilitation of respiratory muscles.

This combined effect increased the level of serotonin in the animals. Known for its ability to alleviate the symptoms of anxiety disorders, this neurotransmitter also has a broader function of stimulating neurons. An increase in the concentration of serotonin in the interneuronal contacts and around specific receptors on muscle fibers ensured the restoration of the functions of the animals' diaphragm to almost normal parameters.

However, despite promising results, the developed method needs improvement. Despite the fact that in about 70% of cases, therapy ensured the restoration of normal breathing, the rest of the animals developed respiratory rhythm disorders. As it turned out, the reason for this was an excess of serotonin, easily eliminated by the introduction of a drug that blocks the receptor for this neurotransmitter.

Currently, the authors are studying the phenomenon of hyperproduction of serotonin, which develops when using the combination therapy developed by them. They note that before being introduced into the clinic, this technique should be tested on large animals whose spinal cord size is comparable to the size of a human spinal cord.

At the same time, experts recognize the uniqueness of the experimental approach, since it not only completely restores the functioning of paralyzed muscles, but also allows you to do it a year and a half after the injury.

The results of the study were presented by the lead performer of the work Philippa Warren (Philippa M. Warren) at the 44th Annual Congress of the Society of Neuroscience Neuroscience 2014, held on November 15-19 in Washington.

Evgeniya Ryabtseva
Portal "Eternal youth" http://vechnayamolodost.ru based on the materials of Case Western Reserve University:
Laboratory Breakthrough Offers Promise for Spinal Cord Injury Patients to Breathe on Their Own Again. 

19.11.2014