Download the full article

hronic neuropathic pain is estimated to be on the rise, particularly with the expected increase in patients with diabetes within the US. Diabetic and nondiabetic patients were surveyed for sick days from
work due to neuropathic pain; approximately two-thirds of these patients were found to consistently be taking days from work, and only one-fifth of those were satisfied with their current therapy.8,24 Unlike nociceptive pain (tissueinjury induced), neuropathic pain is specific to injury of either the central or peripheral nervous system and can be a combination of both. For this reason, several diseases manifest with neuropathy including SCI, stroke, multiple sclerosis, diabetes, infectious related, nutrient deficient,
immune related, and oncological. Interestingly, adjuvant therapies for these disorders including chemotherapy and radiation therapy can also lead to chronic neuropathy. Treatments have largely depended on anticonvulsants and antidepressants because of their analgesic effects; however, the nature of neuropathic pain is its chronicity and as such often becomes recalcitrant to these pharmacological strategies. Intractable neuropathic pain has gained increasing awareness due to its prevalence and the technological advancements in surgical neuromodulation. Electrical stimulation via spinal cord, peripheral nerve, and deep brain targeting has begun to show some early efficacy.18 To date, chronic neuropathic pain is largely considered a heterogeneous pain syndrome that remains with limited efficacious treatment modalities. Also, there is no treatment strategy that is effective for pain management while promoting nervous system repair.

ABSTRACT

Mesenchymal stem cells (MSCs) are very attractive candidates in cell-based strategies that target
inflammatory diseases. Preclinical animal studies and many clinical trials have demonstrated that
human MSCs can be safely administered and that they modify the inflammatory process in the
targeted injured tissue. Our laboratory developed a novel method that optimizes the anti-inflammatory effects of MSCs. We termed the cells prepared by this method MSC2. In this study, we
determined the effects of MSC2-based therapies on an inflammation-linked painful diabetic peripheral neuropathy (pDPN) mouse model. Streptozotocin-induced diabetic mice were treated with
conventionally prepared MSCs, MSC2, or vehicle at three specific time points. Prior to each treatment, responses to radiant heat (Hargreaves) and mechanical stimuli (von Frey) were measured.
Blood serum from each animal was collected at the end of the study to compare levels of inflammatory markers between the treatment groups. We observed that MSC2-treated mice had significant
improvement in behavioral assays compared with the vehicle and MSC groups, and moreover these
responses did not differ from the observations seen in the healthy wild-type control group. Mice
treated with conventional MSCs showed significant improvement in the radiant heat assay, but not
in the von Frey test. Additionally, mice treated with MSC2 had decreased serum levels in many
proinflammatory cytokines compared with the values measured in the MSC- or vehicle-treated
groups. These findings indicate that MSC2-based therapy is a new anti-inflammatory treatment to
consider in the management of pDPN. STEM CELLS TRANSLATIONAL MEDICINE 2012;1:
557–565

Objective:

Mesenchymal stem cells (MSCs) have been shown in animal models to attenuate
chronic neuropathic pain. This preliminary study investigated if: i) injections of autologous
MSCs can reduce human neuropathic pain and ii) evaluate the safety of the procedure.

Methods:

Ten subjects with symptoms of neuropathic trigeminal pain underwent liposuction.
The lipoaspirate was digested with collagenase and washed with saline three times. Following
centrifugation, the stromal vascular fraction was resuspended in saline, and then transferred to
syringes for local injections into the pain fields. Outcome measures at 6 months assessed reduction in: i) pain intensity measured by standard numerical rating scale from 0–10 and ii) daily
dosage requirements of antineuropathic pain medication.

Results:

Subjects were all female (mean age 55.3 years ± standard deviation [SD] 14.67; range
27–80 years) with pain symptoms lasting from 4 months to 6 years and 5 months. Lipoaspirate
collection ranged from 102–214 g with total cell numbers injected from 33 million to 162 million
cells. Cell viability was 62%–91%. There were no systemic or local tissue side effects from the
stem cell therapy (n=41 oral and facial injection sites). Clinical pain outcomes showed that at 6
months, 5/9 subjects had reduced both pain intensity scores and use of antineuropathic medication. The mean pain score pre-treatment was 7.5 (SD 1.58) and at 6 months had decreased to 4.3
(SD 3.28), P=0.018, Wilcoxon signed-rank test. Antineuropathic pain medication use showed
5/9 subjects reduced their need for medication (gabapentin, P=0.053, Student’s t-test).
Conclusion: This preliminary open-labeled study showed autologous administration of stem
cells for neuropathic trigeminal pain significantly reduced pain intensity at 6 months and is a
safe and well tolerated intervention.

Keywords: adipose, stem cells, neuropathic, orofacial, trigeminal

A nonphysiological repair of the lesioned nerve leading to the formation of neurinomas, altered nerve
conduction, and spontaneous firing is considered the main cause of the events underlying neuropathic
pain. It was investigated whether neural stem cell (NSCs) administration could lead to a physiological
nerve repair, thus to a reduction of neuropathic pain symptoms such as hyperalgesia and allodynia in
a well-established model of this pain (sciatic nerve chronic constriction injury [CCI]). Moreover, since
we and others showed that the peripheral nerve lesion starts a cascade of neuroinflammation-related
events that may maintain and worsen the original lesion, the effect of NSCs on sciatic nerve pro- and antiinflammatory cytokines in CCI mice was investigated. NSCs injected intravenously, when the pathology
was already established, induced a significant reduction in allodynia and hyperalgesia already 3 days
after administration, demonstrating a therapeutic effect that lasted for at least 28 days. Responses changed with the number of administered NSCs, and the effect on hyperalgesia could be boosted by a new NSC
administration. Treatment significantly decreased proinflammatory, activated antiinflammatory cytokines in the sciatic nerve, and reduced spinal cord Fos expression in laminae I-VI. Moreover, in NSC-treated animals, a reparative process and an improvement of nerve morphology is present at a later time.
Since NSC effect on pain symptoms preceded nerve repair and was maintained after cells had disappeared
from the lesion site, we suggest that regenerative, behavioral, and immune NSC effects are largely due to microenvironmental changes they might induce at the lesion site