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By: Andre Fallavollita
This is a summary of a paper published by a research group from Ohio, USA in the journal Nature.
Original article: Alilain WJ, Horn KP, Hu H, Dick TE, Silver J. Functional regeneration of respiratory pathways after spinal cord injury. Nature. 2011 Jul 14;475(7355):196–200.
Improving breathing function is a very high priority for treatment after SCI. People with high SCI often need ventilators to breathe, which is associated with unique challenges and health risks. Even patients who can breathe without a ventilator sometimes experience impaired breathing, which increases their risk of infections. In fact, the negative effects of impaired breathing are among the leading causes of death after SCI.
Restoring normal breathing after high SCI involves regrowing connections, across the injury site to the diaphragm. The diaphragm is crucial to breathing: it is the muscle that moves the majority of air in and out of the lungs. But there are two reasons that these connections are very difficult to regrow. First, the injured spinal cord is a very unfavorable location for growing nerves. Second, it is difficult to study a process that is so essential to life! However, scientists working in Cleveland, Ohio, recently demonstrated that they could succeed in regrowing injured nerves to a paralyzed diaphragm. Working in a rat model of cervical SCI, they combined a chemical treatment with a surgical graft: the chemical digested stop signals, to clear a path for growing nerves, while the graft made a bridge for the nerves, guiding them past the injury to reconnect with the diaphragm.
What was the most important finding?
Regrowth of nerves restored function to the paralyzed diaphragm. This recovery persisted for at least 6 months: in a rat, this represents a very significant time period, the equivalent of years to decades in humans.
What are some things we need to consider?
In order to succeed, the researchers had to combine chemical treatment with a complex surgery – the chemical alone had little benefit. Because the treatment is so complex, it will be challenging to move from laboratory experiments to clinical treatment.
What does this mean for people with SCI?
Although it is still experimental, this work demonstrates that we can bypass the site of SCI to restore breathing. Patients who presently need a ventilator may be able to regain the ability to breathe without it. Regaining the function of a single muscle could have a dramatic impact on the quality of peoples’ lives.
