You may have experience low back pain that seemed to come out of nowhere; or heard old people in your family or neighbors went to hospital because of feeling painful in the back, but the doctor could not draw any conclusion of the cause.
The low back pain is like an invisible army, influencing people’s daily lives. While doctors are trying to find the reason behind it, recent research showed that low back pain was caused by an overgrowth of pain-sensing nerves into spinal cartilaginous tissue.
80% of people
An estimated 80% of people worldwide will experience low back pain in their lifetimes worldwide. Although some of them may have strain or injury, researchers say the vast majority of low back pain emerges in the absence of injury, especially in older age.
Xu Cao, Ph.D., wanted to figure out the cause of low back pain. Cao and his team analyzed samples of the bony end plates of vertebrae from mice aged more than 20 months, the human equivalent of about 70-80 years old. The results showed that the soft cartilaginous tissue, normally serving as the “cushion on a seat” to protect the bones, became hardened and resembled diffuse bone with a Swiss cheese-like structure.
This made Cao’s team wonder what may cause the abnormal nerve growth and the resulting back pain. Through a little experiment, they found that the osteoclasts could be signaling the nerve growth in some way, perhaps with netrin-1.
Experiment in mice
The team designed an experiment in mice to see whether they could stop the nerve growth in the cartilaginous tissue and the accompanying pain.
They genetically engineered mice to lack the gene that codes for osteoclast formation, and performed a surgery on the mice to destabilize the joints between their vertebrae—mimicking similar instability seen in people with low back pain. The researchers found that the mice lacking osteoclast cells had fewer pain-sensing nerves in the endplates of their vertebrae than mice with the gene.
The team is trying to develop methods using compounds that slow the abnormal bone growth to test their potential to treat low back pain.