Intrathecal Spinal Progenitor Cell Transplantation for the Treatment of Neuropathic Pain

Fe3O4@Polydopamine-Labeled MSCs Targeting the Spinal Cord to Treat Neuropathic Pain Under the Guidance of a Magnetic Field

Purpose

Neuropathic pain causes great distress among patients; however, its response to traditional analgesia techniques remains sub-optimal. There has been progress in stem cell research for neuropathic pain treatment; however, effective homing remains problematic. This study aimed to establish Fe₃O₄@polydopamine(PDA)-labeled mesenchymal stem cells (MSCs); moreover, we aimed to guide MSCs using a magnetic field to the spinal cord segments showing pain-related responses to allow MSC homing and gathering, in advance, in order to fully employ their repair function.

Materials and Methods

Fe₃O₄@PDA-labeled MSCs were characterized using transmission electron microscopy. We analyzed the characteristics of MSCs, as well as the nanoparticle effects on MSC activity, differentiation, and proliferation, using the CCK-8 method, flow cytometry, and staining. Using rats, we performed behavioral tests of mechanical and thermal pain hypersensitivity. Serum inflammatory markers were detected using ELISA. Finally, changes in proteins associated with spinal cord pain were detected through quantitative reverse transcription PCR, histology, and immunohistochemistry.

Results

Fe₃O₄@PDA did not affect the characteristics and viability of MSCs. The magnetic field guidance improved the therapeutic effect of Fe₃O₄@PDA-labeled MSCs as indicated by the paw withdrawal threshold. Fe₃O₄@PDA-labeled MSCs decreased spinal nerve demyelination and c-Fos expression (a pain molecule); moreover, they inhibited microglia and astrocyte activation.

Conclusion

Fe₃O₄@PDA-labeled MSCs showed better homing to the spinal cord under magnetic field guidance. Moreover, they inhibited microglial and astrocyte activation, as well as played an early and continuous role in neuropathic pain treatment.

The effect of human mesenchymal stem cell injection on pain behavior in chronic post-ischemia pain mice

Background

Neuropathic pain (NP) is considered a clinically incurable condition despite various treatment options due to its diverse causes and complicated disease mechanisms. Since the early 2000s, multipotent human mesenchymal stem cells (hMSCs) have been used in the treatment of NP in animal models. However, the effects of hMSC injections have not been studied in chronic post-ischemia pain (CPIP) mice models. Here, we investigated whether intrathecal (IT) and intrapaw (IP) injections of hMSCs can reduce mechanical allodynia in CPIP model mice.

Methods

Seventeen CPIP C57/BL6 mice were selected and randomized into four groups: IT sham (n = 4), IT stem (n = 5), IP sham (n = 4), and IP stem (n = 4). Mice in the IT sham and IT stem groups received an injection of 5 μL saline and 2 × 10⁴ hMSCs, respectively, while mice in the IP sham and IP stem groups received an injection of 5 μL saline and 2 × 10⁵ hMSCs, respectively. Mechanical allodynia was assessed using von Frey filaments from pre-injection to 30 days post-injection. Glial fibrillary acidic protein (GFAP) expression in the spinal cord and dorsal root ganglia were also evaluated.

Results

IT and IP injections of hMSCs improved mechanical allodynia. GFAP expression was decreased on day 25 post-injection compared with the sham group. Injections of hMSCs improved allodynia and GFAP expression was decreased compared with the sham group.

Conclusions

These results suggested that hMSCs may be also another treatment modality in NP model by ischemia-reperfusion.

Antinociceptive Effect of Intrathecal Injection of Genetically Engineered Human Bone Marrow Stem Cells Expressing the Human Proenkephalin Gene in a Rat Model of Bone Cancer Pain

Background. This study aimed to investigate the use of human bone marrow mesenchymal stem cells (hBMSCs) genetically engineered with the human proenkephalin (hPPE) gene to treat bone cancer pain (BCP) in a rat model. Methods. Primary cultured hBMSCs were passaged and modified with hPPE, and the cell suspensions (6 × 10⁶) were then intrathecally injected into a rat model of BCP. Paw mechanical withdrawal threshold (PMWT) was measured before and after BCP. The effects of hPPE gene transfer on hBMSC bioactivity were analyzed in vitro and in vivo. Results. No changes were observed in the surface phenotypes and differentiation of hBMSCs after gene transfer. The hPPE-hBMSC group showed improved PMWT values on the ipsilateral side of rats with BCP from day 12 postoperatively, and the analgesic effect was reversed by naloxone. The levels of proinflammatory cytokines such as IL-1β and IL-6 were ameliorated, and leucine-enkephalin (L-EK) secretion was augmented, in the hPPE-engineered hBMSC group. Conclusion. The intrathecal administration of BMSCs modified with the hPPE gene can effectively relieve pain caused by bone cancer in rats and might be a potentially therapeutic tool for cancer-related pain in humans.

The Effect of Bone Marrow-Derived Mesenchymal Stem Cell Transplantation on Allodynia and Hyperalgesia in Neuropathic Animals: A Systematic Review with Meta-Analysis

Stem cell transplantation has been considered a possible therapeutic method for neuropathic pain. However, no quantitative data synthesis of stem cell therapy for neuropathic pain exists. Therefore, the present systematic review and meta-analysis assessed the efficacy of bone marrow mesenchymal stem cell (BMMSC) transplantation on alleviating pain symptoms in animal models of neuropathic pain. In the present meta-analysis, controlled animal studies assessing the effect of administrating BMMSC on neuropathic pain were included through an extensive literature search of online databases. After collecting data, effect sizes were computed and the standardized mean difference (SMD) with 95% confidence interval (CI) was entered in all analyses. Random-effects models were used for data analysis. Sensitivity and subgroup analyses were performed to investigate expected or measured heterogeneity. Finally, 14 study were included. The analyses showed that BMMSC transplantation lead to significant improvement on allodynia (SMD = 2.06; 95% CI, 1.09 to 3.03; I(2) = 99.7%; P < .001). The type of neuropathy (P = .036), time between injury and intervention (P = .02), and the number of transplanted cells (P = .023) influence the improvement of allodynia after BMMSC transplantation. BMMSC transplantation has no effect on hyperalgesia (SMD = .3; 95% CI, -1.09 to 1.68; I(2) = 100%; P < .001) unless it occurs during the first 4 days after injury (P = .02). The present systematic review with meta-analysis suggests that BMMSC transplantation improves allodynia but does not have any significant effect on hyperalgesia unless it is given during the first 4 days after injury.

Cell transplantation as a pain therapy targets both analgesia and neural repair

Cell transplantation is a potentially powerful approach for the alleviation of chronic pain. The strategy of cell transplantation for the treatment of pain is focused on cell-based analgesia and neural repair. (1) Adrenal medullary chromaffin cells and the PC12 cell line have been used to treat cancer pain and neuropathic pain in both animal models and human cases. As biological or living minipumps, these cells produce and secrete pain-reducing neuroactive substances if administered directly into the spinal subarachnoid space. (2) Cell implantation for pain neurorestorative therapy is a new concept and an emerging research field for pain control along with neural repair. Possible neurorestorative mechanisms include neuroprotective, neurotrophic, neuroreparative, neuroregenerative, neuromodulation, or neuroconstructive interventions, as well as immunomodulation and enhancing the microcirculation. These factors may ultimately restore the damaged or irritated condition of the lesioned nerves. The growing preclinical and clinical data show that neural stem/progenitor cells, olfactory ensheathing cells, mesenchymal stromal cells, and CD34(+) cells have the capacity to manage intractable pain and improve neurological functions. Cell delivery routes include local, intrathecal, or intravascular implants. Although these strategies are still in their infancy phase for pain neurorestoratology, cell-based therapies could open up new avenues for the relief of pain. In this review, these aspects are critically analyzed based on our own investigations. This manuscript is published as part of the International Association of Neurorestoratology (IANR) supplement issue of Cell Transplantation.

Improvement of contusive spinal cord injury in rats by co-transplantation of gamma-aminobutyric acid-ergic cells and bone marrow stromal cells

BACKGROUND AIMS

Cell therapy is considered a promising option for treatment of spinal cord injury (SCI). The purpose of this study is to use combined therapy of bone marrow stromal cells (BMSCs) and BMSC-derived gamma-aminobutyric acid (GABA)ergic inhibitory neurotransmitter cells (BDGCs) for the contusion model of SCI in rats.

METHODS

BDGCs were prepared from BMSCs by pre-inducing them with β-mercaptoethanol followed by retinoic acid and then inducing them by creatine. They were immunostained with BMSC, proneuronal, neural and GABA markers. The BDGCs were intraspinally transplanted into the contused rats, whereas the BMSCs were delivered intravenously. The animals were sacrificed after 12 weeks.

RESULTS

The Basso, Beattie and Bresnahan test showed improvement in the animals with the combined therapy compared with the untreated animals, the animals treated with GABAergic cells only and the animals that received BMSCs. The immunohistochemistry analysis of the tissue sections prepared from the animals receiving the combined therapy showed that the transplanted cells were engrafted and integrated into the injured spinal cord; in addition, a significant reduction was seen in the cavitation.

CONCLUSIONS

The study shows that the combination of GABAergic cells with BMSCs can improve SCI.

Review of the history and current status of cell-transplant approaches for the management of neuropathic pain

Treatment of sensory neuropathies, whether inherited or caused by trauma, the progress of diabetes, or other disease states, are among the most difficult problems in modern clinical practice. Cell therapy to release antinociceptive agents near the injured spinal cord would be the logical next step in the development of treatment modalities. But few clinical trials, especially for chronic pain, have tested the transplant of cells or a cell line to treat human disease. The history of the research and development of useful cell-transplant-based approaches offers an understanding of the advantages and problems associated with these technologies, but as an adjuvant or replacement for current pharmacological treatments, cell therapy is a likely near future clinical tool for improved health care.

Co-transplantation of olfactory ensheathing glia and mesenchymal stromal cells does not have synergistic effects after spinal cord injury in the rat

BACKGROUND AIMS

Olfactory ensheathing glia (OEG) and mesenchymal stromal cells (MSC) are suitable candidates for transplantation therapy of spinal cord injury (SCI). Both facilitate functional improvement after SCI by producing trophic factors and cytokines. In this study, the co-transplantation of both types of cells was studied to clarify their additive and/ or synergistic effects on SCI.

METHODS

A balloon-induced compression lesion was used to produce SCI in rats. OEG, MSC or both OEG and MSC (3 x 10(5) cells of each cell type) were implanted by intraspinal injection 1 week after SCI. The effect of transplantation was assessed using behavioral, electrophysiologic and histologic methods.

RESULTS

Hindlimb function was examined with Basso, Beattie and Bresnahan (BBB) and Plantar tests. Improvement was found in all three groups of transplanted rats with different time-courses, but there was no significant difference among the groups at the end of the experiment. Motor-evoked potentials after SCI decreased in amplitude from 7 mV to 10 microV. Linear regression analysis showed a modest recovery in amplitude following transplantation, but no change in the control rats. Histologic findings showed that the white and gray matter were significantly spared by transplantation after SCI.

CONCLUSIONS

Functional improvement was achieved with transplantation of OEG and/or MSC, but the co-transplantation of OEG and MSC did not show synergistic effects. The poor migration of OEG and MSC might prevent their concerted action. Pre-treatment with a Rho antagonist and a combination of intraspinal and intravenous injection of the cells might be beneficial for SCI therapy.

Predifferentiated embryonic stem cells prevent chronic pain behaviors and restore sensory function following spinal cord injury in mice

Embryonic stem (ES) cells have been investigated in repair of the CNS following neuronal injury and disease; however, the efficacy of these cells in treatment of postinjury pain is far from clear. In this study, we evaluated the therapeutic potential of predifferentiated mouse ES cells to restore sensory deficits following spinal cord injury (SCI) in mice. The pain model used unilateral intraspinal injection of quisqualic acid (QUIS) into the dorsal horn between vertebral levels T13 and L1. Seven days later, 60,000 predifferentiated ES cells or media were transplanted into the site of the lesion. Histological analysis at 7, 14, and 60 days post-transplantation revealed that animals receiving ES cell transplants suffered significantly less tissue damage than animals receiving media alone. Transplanted cells provided immediate effects on both spontaneous and evoked pain behaviors. Treatment with ES cells resulted in 0% (n = 28) excessive grooming behavior versus 60% (18 of 30) in media-treated animals. In the acetone test (to assess thermal allodynia), mice recovered to preinjury levels by 12 days after ES cell transplant, whereas control animals injected with media after SCI did not show any improvement up to 60 days. Similarly, the von Frey test (to assess mechanical allodynia) and the formalin test (to assess nociceptive hyperalgesia) showed that transplantation of predifferentiated ES cells significantly reduced these pain behaviors following injury. Here we show that predifferentiated ES cells act in a neuroprotective manner and provide antinociceptive and therapeutic effects following excitotoxic SCI.

[A case of a second cancer of metachronous multiple primary non-small cell lung cancer successfully treated with TS-1 and CDDP chemotherapy]

The patient was a 66-year-old man who had undergone right upper lobectomy and ND 2a systematic lymph node dissection for lung cancer (M/D adenocarcinoma, p-stage IB) in March of 1999 . On November 2003, postoperative routine chest computed tomography(CT) demonstrated a mass in left S6, and pathological diagnosis revealed P/D squamous cell carcinoma (cT1N2M0, stage IIIA) by CT-guided needle biopsy and mediastinoscopy. At first, we tried two courses of a combination chemotherapy consisting of carboplatin (CBDCA) and paclitaxel every 3 weeks. After 2 courses, the regimen was stopped because of grade 3 arthritis. Then, two courses of CBDCA and gemcitabine were performed. The evaluation of the response was SD by the guidelines of Response Evaluation Criteria in Solid Tumor Groups. Next, gefitinib was orally administered for 6 months but the tumor and mediastinal lymph nodes were growing. In January 2005, oral administration of TS-1 (60 mg/1, 2 courses, 75 mg/3-6 courses) was begun twice a day for 21 consecutive days while cisplatin (60 mg/m(2)) was administered intravenously on day 8. The response was PR (the tumor decreased by 46%), no serious adverse effect was observed, and the patient maintained good quality of life throughout the chemotherapy. This case suggests that TS-1+CDDP chemotherapy may be an effective treatment in patients with advanced lung cancer even after many protocols of chemotherapy.

Cell and Molecular Approaches to the Attenuation of Pain after Spinal Cord Injury

Recent experimental research to treat spinal cord injury (SCI) pain has greatly increased our understanding of how such chronic pain might be modulated in the human population. Neuropathic pain is caused by the structural and biochemical changes associated with the peripheral and central nervous system damage associated with nervous system trauma, often leading to an imbalance in endogenous excitatory and inhibitory spinal systems that modulate sensory processing. But current pharmacological therapies are often ineffective over time for the greater number of patients. Although there are a variety of useful surgical and pharmacologic interventions (including electric stimulation, implantable mechanical pumps and a myriad of drugs for pain relief) cell and molecular technologies are a new frontier in pain medicine. These other potential therapeutic agents of pain are based on current and developing treatment strategies elucidated from recent research, especially concerning central spinal sensitization, and the spinal mechanisms that are thought to be the origin and ongoing cause of chronic pain, even when the injury is peripheral in location. Newly developing translational strategies such as molecular agents, viral-mediated gene transfer or cellular transplants to treat chronic pain are being evaluated in a variety of peripheral and central injury models. They seek to address both the causes of neuropathic pain, to interfere with its development and maintenance over time, and give the injured person with pain an improved quality-of-life that allows them to better deal with the larger tasks of daily life and the strenuous rehabilitation that might also improve motor function after SCI.

Gene therapy: can neural stem cells deliver?

Neural stem cells are a self-renewing population that generates the neurons and glia of the developing brain. They can be isolated, proliferated, genetically manipulated and differentiated in vitro and reintroduced into a developing, adult or pathologically altered CNS. Neural stem cells have been considered for use in cell replacement therapies in various neurodegenerative diseases, and an unexpected and potentially valuable characteristic of these cells has recently been revealed--they are highly migratory and seem to be attracted to areas of brain pathology such as ischaemic and neoplastic lesions. Here, we speculate on the ways in which neural stem cells might be exploited as delivery vehicles for gene therapy in the CNS.

New targets for neuropathic pain therapeutics

Neuropathic pain (NeP) is initiated by a lesion or dysfunction in the nervous system. Unlike physiological pain it serves no useful purpose and is usually sustained and chronic. NeP encompasses a wide range of pain syndromes of diverse aetiologies which together account for > 12 million sufferers in the US. Currently, there are a number of therapies available for NeP, including gabapentin, pregabalin, anticonvulsants (tiagabine HCl), tricyclic antidepressants (amitriptyline, nortriptyline) and acetaminophen/opioid combination products (Vicodin, Tylenol #3). However, these products do not provide sufficient pain relief and a significant proportion of sufferers are refractory (60%). Therefore, there is a need for new therapies that provide more predictable efficacy in all patients with improved tolerability. Over the last decade, understanding of the basic mechanisms contributing to the generation of NeP in preclinical animal models has greatly improved. Together with the completion of the various genome sequencing projects and significant advances in microarray and target validation strategies, new therapeutic approaches are being rigourously pursued. This article reviews the rationale behind a number of these mechanism-based approaches, briefly discusses specific challenges that they face, and finally, speculates on the potential of emerging technologies as alternative therapeutic strategies to the traditional 'small-molecule' approach.

Cell therapy for neuropathic pain in spinal cord injuries

Cell therapy to treat neuropathic pain after spinal cord injury (SCI) is in its infancy. However, the development of cellular strategies that would replace or be used as an adjunct to existing pharmacological treatments for neuropathic pain have progressed tremendously over the past 20 years. The earliest cell therapy studies for pain relief tested adrenal chromaffin cells from rat or bovine sources, placed in the subarachnoid space, near the spinal cord pain- processing pathways. These grafts functioned as cellular minipumps, secreting a cocktail of antinociceptive agents around the spinal cord for peripheral nerve injury, inflammatory or arthritic pain. These initial animal, and later clinical, studies suggested that the spinal intrathecal space was a safe and accessible location for the placement of cell grafts. However, one major problem was the lack of a homogeneous, expandable cell source to supply the antinociceptive agents. Cell lines that can be reversibly immortalised are the next phase for the development of a practical, homogenous cell source. These technologies have been modelled with a variety of murine cell lines, derived from embryonic adrenal medulla or CNS brainstem, in which cells are transplanted, which downregulate their proliferative, oncogenic phenotype either before or after transplant. An alternative approach for existing human cell lines is the use of neural or adrenal precursors, in which the antinociceptive properties are induced by in vitro treatment with molecules that move the cells to an irreversible neural or chromaffin, and non-oncogenic, phenotype. Although such human cell lines are at an early stage of investigation, their clinical antinociceptive potential is significant given the daunting problem of difficult-to-treat neuropathic SCI pain.

Regulated, electroporation-mediated delivery of pro-opiomelanocortin gene suppresses chronic constriction injury-induced neuropathic pain in rats

We previously reported that intrathecal pro-opiomelanocortin gene electroporation could reduce pain sensitivity induced by chronic constriction injury (CCI) of the sciatic nerve. For optimal use of antinociceptive gene therapy, it might be important to control the expression of the transfected gene extrinsically. For this purpose, a doxycycline-controlled transrepressor system composed of two plasmids coding, respectively, for pro-opiomelanocortin gene (pTRE2-POMC) and the silencer (pTel-off) was employed. The regulation of beta-endorphin expression was first assessed in spinal neuronal culture, then we electrotranfected this plasmid into the spinal cord of mononeuropathic rats and evaluated the analgesic potential of this therapy in vivo by thermal and mechanical withdrawal latency. Intraperitoneal injections of various doses of doxycycline were made to elucidate the possible exogenous downregulation of transfected beta-endorphin gene expression in vivo. The levels of beta-endorphin were analyzed by intrathecal microdialysis and radioimmunoassay. Intrathecal pTRE2-POMC/pTel-off electroporation elevated spinal beta-endorphin levels, as manifested in a significantly elevated pain threshold for chronic constriction injury limbs. Intraperitoneal doxycycline decreased the antinociceptive effect and spinal beta-endorphin levels in a dose-dependent manner. We concluded that intrathecal pTRE2-POMC/pTel-off electroporation alleviates CCI-induced limb pain, and can be controlled by intraperitoneal doxycycline administration.