The International Association for the Study of Pain defines neuropathic pain as “pain arising as a direct consequence of a lesion or disease affecting the somatosensory system”. While general neuropathy is diverse by nature, neuropathic lesions generally fall into four categories: focal or multifocal lesions of the peripheral system, general lesions of the peripheral nervous systems, lesions of the central nervous system, and complex neuropathic disorders.
Although neuropathic pain is typically characterized as chronic pain, it is also considered more severe than other types of chronic pain; this is in large part due to the increased disruption to overall quality of life when compared with other chronic pain syndromes.
As part of this review, Fortino, Pelaez, and Cheung review specific types of neuropathic pain and summarize current research being done to replace pharmacological treatments with cellular therapies, including stem cells, designed to have a longer-lasting effect on the treatment of neuropathic pain.
Neuropathic pain presents itself in many different forms, including spontaneous sensations and superficial pain. These forms of neuropathic pain differ from nociceptive pain in that nociceptive pain occurs as a result of tissue damage while neuropathic pain is the product of damage to the peripheral or central nervous system. Neuropathic pain also differs from nociceptive pain in its proportion to the intensity of the stimuli; in other words, while nociceptive pain is proportional to the intensity of the stimuli, neuropathic pain is not.
Considering that uninjured fibers that intermingle with degenerating nerve fibers participate in pain signaling, it is important for the environment surrounding these uninjured nerve fibers to be able to protect them from degeneration and exacerbation associated with neuropathic pain. Since growth factors have proven critical in promoting neuron development and survival and since neurotrophic factors are secreted by stem cells, researchers hypothesize that stem cells present a potential therapy for longer lasting treatment of neuropathic pain.
Clinical studies have demonstrated that neurotrophic factors offered by stem cells when in direct or indirect contact with the lesioned nerve, appear to provide neuroprotection and neuroregenerative effects.
Despite the potential for stem cell therapies to provide protection from neurodegeneration and to promote neuroregeneration, the authors raise several issues that need to be addressed, including determining an optimal dose for stem cell transplantation and obtaining a better understanding of the homing capabilities of stem cells.
In addition to exploring the benefits of neurotrophic factors of stem cells in treating neuropathic pain, transplantation of human mesenchymal stem cells (hMSCs) to explore potential benefits in treating diabetic peripheral neuropathy and spinal cord injuries are also currently being evaluated.
While the role of stem cells in the treatment of neuropathic pain is not yet fully understood, the authors find their ability to modify cellular processes to provide protective and restorative environments that can reverse the causes of neuropathic pain a promising therapy for the long-term treatment of this condition.
Source: “Concise Review: Stem Cell Therapies for Neuropathic Pain – PMC.” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3667564/.
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