Under normal circumstances, pain receptors react to painful stimuli such as burns or lacerations. Pain receptors from the body then send that information along nerves to the brain via electrical signals. Once that electrical information reaches the brain (which happens almost immediately), it is perceived as pain. This type of pain is a nociceptive pain.
Neuropathic pain, however, is different. Neuropathic pain is caused by a condition of the nerves themselves. Patients with neuropathic pain experience chronic pain without any specific injury. Neuropathic pain may be felt as a burning sensation, tingling, or a “pins and needles” sensation, or these combined. Neuropathic pain most often occurs in people with diabetes, certain vitamin deficiencies, and shingles. It may also occur after people receive certain cancer treatments following a stroke.
While it is rather simple to treat pain caused by a burn or laceration (nociceptive pain), it is very difficult to effectively treat neuropathic pain. Standard treatments for neuropathic pain include anti-epilepsy medications such as phenytoin, gabapentin, or carbamazepine and antidepressants such as venlafaxine, duloxetine, or amitriptyline. Usually, these treatments are only modestly effective. Eventually, many patients need powerful opioid medications like morphine and oxycodone to control their pain.
Researchers at the Cleveland Clinic published research that strongly suggests that stem cells may be able to improve those battling neuropathic pain. Dr. Jianguo Cheng and his research group have shown that mesenchymal stem cell transplantation into the spinal fluid can reduce pain and pain sensitivity in an animal model of neuropathic pain. In one series of experiments, they showed that mesenchymal stem cells could relieve pain in rats who had experimental nerve damage. Researchers confirmed the benefit of stem cells for neuropathic pain in several different sets of experiments. The results have been so encouraging that Dr. Cheng and the Cleveland Clinic have applied to patent the technology.
Dr. Cheng’s group also showed intravenously administered mesenchymal stem cells are just as effective as cells administered into the spinal fluid (intrathecally). This is good news for patients since it is less invasive to put stem cells into a vein than it is to infuse them into the cerebrospinal fluid. Amazingly, the research group showed that stem cells injected through either route (vein or spinal fluid) ended up finding their way to damaged nerves where they could provide maximum benefit.
While this work in animals must be performed in humans to confirm the results, this preclinical research establishes a strong foundation for those clinical studies. These results provide hope to those who struggle with daily neuropathic pain.