Concise Review: Stem Cell Therapies for Neuropathic Pain

Neuropathic pain is a chronic condition that is heterogeneous in nature and has different causes. Different from and more burdensome than nociceptive pain, neuropathic pain more severely affects people’s quality of life. Understanding the various mechanisms of the onset and progression of neuropathic pain is important in the development of an effective treatment. Research is being done to replace current pharmacological treatments with cellular therapies that will have longer lasting effects. Stem cells present an exciting potential therapy for neuropathic pain. In this review, we describe the neuroprotective effects of stem cells along with special emphasis on the current translational research using stem cells to treat neuropathic pain.

In 2008, the International Association for the Study of Pain formed a special interest group to redefine neuropathic pain as “pain arising as a direct consequence of a lesion or disease affecting the somatosensory system” [1]. Neuropathy is heterogeneous in nature; however, neuropathic lesions may be characterized into four broad categories: focal or multifocal lesions of the peripheral nervous system, generalized lesions of the peripheral nervous system (polyneuropathies), lesions of the central nervous system, and complex neuropathic disorders (Table 1) [2].

Although categorized as chronic pain, neuropathic pain is regarded as more severe than other types of chronic pain. This is due to the increased disruption of both physical and mental quality of life when compared with other chronic pain syndromes. People with chronic neuropathic pain report a higher severity of pain and significantly worse scores for all interference items of the Brief Pain Inventory than non-neuropathic chronic pain patients. Also, those with chronic neuropathic pain report mean scores for the Neuropathic Pain Scale significantly higher than those with non-neuropathic chronic pain, even after adjusting for pain severity, age, and sex [3].