Researchers in California say stem cell therapy could one day be used to relieve – and possibly even cure – chronic neuropathic pain.
Neuropathic pain from an illness or injury damages the nerves, is difficult to treat, and is often unresponsive to non-steroidal pain relievers (NSAIDs) or narcotics. But researchers at the University of California, San Francisco found that cell transplant therapy using embryonic stem cells may not only help silence the pain, but can also cure the very condition that caused the pain in the first place.
“We are working toward the possibility of potential treatments that might eliminate the source of neuropathic pain, and that may be much more effective than drugs that aim only to treat symptomatically the pain that results from chronic, painful conditions,” said Allan Basbaum, PhD, chair of the Department of Anatomy at UCSF.
Pain from an injury usually goes away, but in some cases it persists long after the injury heals – leading to chronic neuropathic pain. Neurons may be lost or the central nervous system may change, compromising signals that normally help dampen pain. A state of hypersensitivity to pain results from these changes, causing even a light touch to be perceived as painful. Many people suffer from neuropathic pain for years or decades after a bout of shingles.
Working with mice, scientists transplanted embryonic, immature nerve cells from the brain cortex of a mouse, and used them to replace non-functioning spinal cord neurons that would normally dampen pain signals.
The researchers found that a small number of the transplanted cells survived — and developed into functioning neurons. Once mature, the cells became integrated into the spinal cord, formed synapses and signaled nerve pathways with other neurons. Hypersensitivity to pain caused by nerve injury was essentially eliminated, without the side effects of movement disturbances often caused by drugs.
“This research is at a very early stage, and we’re a long way from thinking about it in human trials, but we do have a method of making cells that are like these inhibitory neurons, starting with human embryonic stem cells,” said Arnold Kriegstein, Director of Developmental and Stem Cell Biology Program at UCSF. “Unlike drugs, the transplanted cells can have very focused effects, depending on where they are transplanted.”
To move toward future therapies, the UCSF researchers plan to graft fetal cells made from human embryonic stem cells into a rodent to determine if human cells will also alleviate chronic neuropathic pain.
The UCSF study is being published in the journal Neuron. The study was funded by the National Institutes of Health, the Association for the Study of Pain and the Canadian Institutes of Health Research.
Below is a video in which two of the study authors, Allan Basbaum and Joao Braz, explain and demonstrate their research and findings.