Research
Potential role of stem cells for neuropathic pain disorders
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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.
Anti-Inflammatory Mesenchymal Stem Cells (MSC2)Attenuate Symptoms of Painful Diabetic PeripheralNeuropathy
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
A preliminary report on stem cell therapy for neuropathic pain in humans
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
Intravenous neural stem cells abolish nociceptive hypersensitivity and trigger nerve regeneration in experimental neuropathy
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
Cell-therapy for Parkinson’s disease: a systematic review and meta-analysis
Abstract
Background: Cell-based strategies focusing on replacement or protection of dopaminergic neurons have been considered as a potential approach to treat Parkinson’s disease (PD) for decades. However, despite promising preclinical results, clinical trials on cell-therapy for PD reported mixed outcomes and a thorough synthesis of these findings is lacking. We performed a systematic review and meta-analysis to evaluate cell-therapy for PD patients.
Methods: We systematically identified all clinical trials investigating cell- or tissue-based therapies for PD published before July 2023. Out of those, studies reporting transplantation of homogenous cells (containing one cell type) were included in meta-analysis. The mean difference or standardized mean difference in quantitative neurological scale scores before and after cell-therapy was analyzed to evaluate treatment effects.
Results: The systematic literature search revealed 106 articles. Eleven studies reporting data from 11 independent trials (210 patients) were eligible for meta-analysis. Disease severity and motor function evaluation indicated beneficial effects of homogenous cell-therapy in the ‘of’ state at 3-, 6-, 12-, or 24-month follow-ups, and for motor function even after 36 months. Most of the patients were levodopa responders (61.6–100% in different follow-ups). Cell-therapy was also effective in improving the daily living activities in the ‘of’ state of PD patients. Cells from diverse sources were used and multiple transplantation modes were applied. Autografts did not improve functional outcomes, while allografts exhibited beneficial effects. Encouragingly, both transplantation into basal ganglia and to areas
outside the basal ganglia were effective to reduce disease severity. Some trials reported adverse events potentially related to the surgical procedure. One confirmed and four possible cases of graft-induced dyskinesia were reported in two trials included in this meta-analysis.
Conclusions: This meta-analysis provides preliminary evidence for the beneficial effects of homogenous cell-therapy for PD, potentially to the levodopa responders. Allogeneic cells were superior to autologous cells, and the effective transplantation sites are not limited to the basal ganglia.
PROSPERO registration number: CRD42022369760
Keywords Parkinson’s disease, Cell-therapy, Homogenous cell, Transplantation, Meta-analysis
The potential use of mesenchymal stem cells and their exosomes in Parkinson’s disease treatment
Abstract
Parkinson’s disease (PD) is the second most predominant neurodegenerative disease worldwide. It is recognized clinically by severe complications in motor function caused by progressive degeneration of dopaminergic neurons (DAn) and dopamine depletion. As the current standard of treatment is focused on alleviating symptoms through Levodopa, developing neuroprotective techniques is critical for adopting a more pathology-oriented therapeutic approach. Regenerative cell therapy has provided us with an unrivaled platform for evaluating potentially effective novel methods for treating neurodegenerative illnesses over the last two decades. Mesenchymal stem cells (MSCs)
are most promising, as they can differentiate into dopaminergic neurons and produce neurotrophic substances. The precise process by which stem cells repair neuronal injury is unknown, and MSC-derived exosomes are suggested to be responsible for a significant portion of such effects. The present review discusses the application of mesenchymal stem cells and MSC-derived exosomes in PD treatment.
Keywords: Mesenchymal stem cell, Exosome, Parkinson’s disease, Therapeutic application
Clinical efficacy and safety of stem cell therapy for knee osteoarthritis
Abstract
Background: We performed a meta-analysis of the efficacy and safety of stem cell therapy as a clinical treatment of knee osteoarthritis. This meta-analysis is expected to provide evidence of the efficacy of stem cell therapy, which is currently controversial, as a conservative treatment for knee osteoarthritis.
Methods: An online search for relevant articles was conducted in the PubMed, EMBASE, and Cochrane Library databases. The search terms were “stem cells” and “osteoarthritis.” We conducted a quality assessment of the included articles and extracted the following indicators: Visual Analogue Scale (VAS) score, Subjective International Knee Documentation Committee (IKDC) score, Western Ontario and McMaster Universities (WOMAC) subscales, and adverse events. The RevMan5.3 software was used for
determining effect sizes.
Results: Nine randomized controlled trials involving 339 patients were included. VAS score and IKDC score from baseline to 24 months were improved in the stem cell therapy group compared to those in the control group. However, no significant difference was observed between the 2 groups in IKDC score changes from baseline to 6 and 12 months, as well as in WOMAC-Pain, WOMACStiffness, and WOMAC-Physical Function score changes at each visit point.
Conclusion: Stem cell therapy is certainly superior to traditional treatments in the conservative treatment of KOA; it considerably reduces pain with no obvious additional side effects.
Abbreviations: AD-MSCs = adipose-derived mesenchymal stem cells, BMAC = bone marrow aspirate concentrate, BM-MSCs = bone marrow mesenchymal stromal cells, Cl = confidence interval, HA = hyaluronic acid, HTO = high tibial osteotomy, IKDC = International Knee Documentation Committee, IL-1RA = IL-1 receptor antagonist, MSCs = mesenchymal stem cells, PBSC = peripheral blood stem cells, PRG = progenza, PRISMA = Preferred Reporting Items for Systematic Reviews and Meta-Analysis, PRP
= platelet-poor plasma, RCTs = randomized controlled trials, SMD = standardized mean difference, VAS = Visual Analogue Scale, WOMAC = Western Ontario and McMaster Universities.
Keywords: knee osteoarthritis, meta-analysis, stem cell therapy
Umbilical cord-derived Wharton’s jelly for regenerative medicine applications
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Abstract
Background: The last decade has seen an explosion in the interest in using biologics for regenerative medicine applications, including umbilical cord-derived Wharton’s Jelly. There is insufficient literature assessing the amount of growth factors, cytokines, hyaluronic acid, and extracellular vesicles including exosomes in these products. The present study reports the development of a novel Wharton’s jelly formulation and evaluates the presence of growth factors, cytokines, hyaluronic acid, and extracellular vesicles including exosomes.
Methods: Human umbilical cords were obtained from consenting caesarian section donors. The Wharton’s jelly was then isolated from the procured umbilical cord and formulated into an injectable form. Randomly selected samples from different batches were analyzed for sterility testing and to quantify the presence of growth factors, cytokines, hyaluronic acid, and extracellular vesicles.
Results: All samples passed the sterility test. Growth factors including IGFBP 1, 2, 3, 4, and 6, TGF-α, and PDGF-AA were detected. Several immunomodulatory cytokines, such as RANTES, IL-6R, and IL-16, were also detected. Proinflammatory cytokines MCSFR, MIP-1a; anti-inflammatory cytokines TNF-RI, TNF-RII, and IL-1RA; and homeostatic cytokines TIMP-1 and TIMP-2 were observed. Cytokines associated with wound healing, ICAM-1, G-CSF, GDF-15, and regenerative properties, GH, were also expressed. High concentrations of hyaluronic acid were observed. Particles in the extracellular vesicle size range were also detected and were enclosed by the membrane, indicative of true extracellular vesicles.
Conclusion: There are numerous growth factors, cytokines, hyaluronic acid, and extracellular vesicles present in the Wharton’s jelly formulation analyzed. The amount of these factors in Wharton’s jelly is higher compared with other biologics and may play a role in reducing inflammation and pain and augment healing of musculoskeletal injuries.
Keywords: Regenerative medicine, Musculoskeletal injuries, Osteoarthritis, Biologics, Umbilical cord, Wharton’s jelly, Growth factors, cytokines, Hyaluronic acid, Exosomes
Exosomes from acellular Wharton’s jelly of the human umbilical cord promote skin wound healing
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Abstract
Background: Compromised wound healing has become a global public health challenge which presents a significant psychological, financial, and emotional burden on patients and physicians. We recently reported that acellular gelatinous Wharton’s jelly of the human umbilical cord enhances skin wound healing in vitro and in vivo in a murine model; however, the key player in the jelly which enhances wound healing is still unknown.
Methods: We performed mass spectrometry on acellular gelatinous Wharton’s jelly to elucidate the chemical structures of the molecules. Using an ultracentrifugation protocol, we isolated exosomes and treated fibroblasts with these exosomes to assess their proliferation and migration. Mice were subjected to a full-thickness skin biopsy experiment and treated with either control vehicle or vehicle containing exosomes. Isolated exosomes were subjected to further mass spectrometry analysis to determine their cargo.
Results: Subjecting the acellular gelatinous Wharton’s jelly to proteomics approaches, we detected a large amount of proteins that are characteristic of exosomes. Here, we show that the exosomes isolated from the acellular gelatinous Wharton’s jelly enhance cell viability and cell migration in vitro and enhance skin wound healing in the punch biopsy wound model in mice. Mass spectrometry analysis revealed that exosomes of Wharton’s jelly umbilical cord contain a large amount of alpha-2-macroglobulin, a protein which mimics the effect of acellular gelatinous Wharton’s jelly exosomes on wound healing.
Conclusions: Exosomes are being enriched in the native niche of the umbilical cord and can enhance wound healing in vivo through their cargo. Exosomes from the acellular gelatinous Wharton’s jelly and the cargo protein alpha-2- macroglobulin have tremendous potential as a noncellular, off-the-shelf therapeutic modality for wound healing.
Keywords: Skin, Umbilical cord, Wound healing, Wharton’s jelly, Exosomes, Stem cells