Pulsed magnetic field enhances therapeutic efficiency of mesenchymal stem cells in chronic neuropathic pain model

Potential Plausible Role of Stem Cell for Treating Depressive Disorder: a Retrospective Review

Depression poses a significant threat to global physical and mental health, impacting around 3.8% of the population with a rising incidence. Current treatment options primarily involve medication and psychological support, yet their effectiveness remains limited, contributing to high relapse rates. There is an urgent need for innovative and more efficacious treatment modalities. Stem cell therapy, a promising avenue in regenerative medicine for a spectrum of neurodegenerative conditions, has recently garnered attention for its potential application in depression. While much of this work remains preclinical, it has demonstrated considerable promise. Identified mechanisms underlying the antidepressant effects of stem cell therapy encompass the stimulation of neurotrophic factors, immune function modulation, and augmented monoamine levels. Nonetheless, these pathways and other undiscovered mechanisms necessitate further investigation. Depression fundamentally manifests as a neurodegenerative disorder. Given stem cell therapy's success in addressing a range of neurodegenerative pathologies, it opens the door to explore its application in depression treatment. This exploration may include repairing damaged nerves directly or indirectly and inhibiting neurotoxicity. Nevertheless, significant challenges must be overcome before stem cell therapies can be applied clinically. Successful resolution of these issues will ultimately determine the feasibility of incorporating stem cell therapies into the clinical landscape. This narrative review provides insights into the progress of research, potential avenues for exploration, and the prevailing challenges in the implementation of stem cell therapy for treatment of depression.

Imbalance of Th1 and Th2 Cytokines and Stem Cell Therapy in Pathological Pain

The pathophysiological importance of T helper 1 (Th1) and Th2 cell cytokines in pathological pain has been highly debated in recent decades. However, the analgesic strategy targeting individual cytokines still has a long way to go for clinical application. In this review, we focus on the contributions of Th1 cytokines (TNF-α, IFN-γ, and IL-2) and Th2 cytokines (IL-4, IL-5, IL-10, and IL-13) in rodent pain models and human pain-related diseases. A large number of studies have shown that Th1 and Th2 cytokines have opposing effects on pain modulation. The imbalance of Th1 and Th2 cytokines might determine the final effect of pain generation or inhibition. However, increasing evidence indicates that targeting the individual cytokine is not sufficient for the treatment of pathological pain. It is practical to suggest a promising therapeutic strategy against the combined effects of Th1 and Th2 cytokines. We summarize the current advances in stem cell therapy for pain-related diseases. Preclinical and clinical studies show that stem cells inhibit proinflammatory cytokines and release enormous Th2 cytokines that exhibit a strong analgesic effect. Therefore, a shift of the imbalance of Th1 and Th2 cytokines induced by stem cells will provide a novel therapeutic strategy against intractable pain. It is extremely important to reveal the cellular and molecular mechanisms of stem cell-mediated analgesia. The efficiency and safety of stem cell therapy should be carefully evaluated in animal models and patients with pathological pain.

Pain Management in Osteoporosis

The most prevalent metabolic bone disease, osteoporosis, is characterized by a decrease in bone mineral density and alterations to the bone's microstructure, both of which can result in fragility fractures. It affects a significant section of the population. Acute or chronic pain from these fractures is typical in elderly adults with other coexisting conditions. Since the antiresorptive medication only partially reduces pain, other analgesics are required for effective pain management. NSAIDs or selective COX-2 inhibitors can reduce acute pain, but persistent neuropathic pain is difficult to manage with these drugs. Opioids have their adverse effects and safety concerns, although they can be used to address acute or chronic pain. Hence, a multifaceted approach is to be implemented, including pharmacological and nonpharmacological therapy and surgical treatment in a selected number of cases. This chapter briefly describes the etiology of pain, its mechanism, and pain management in osteoporotic patients.

Magnetic-Based Strategies for Regenerative Medicine and Tissue Engineering

The fabrication of biological substitutes to repair, replace, or enhance tissue- and organ-level functions is a long-sought goal of tissue engineering (TE). However, the clinical translation of TE is hindered by several challenges, including the lack of suitable mechanical, chemical, and biological properties in one biomaterial, and the inability to generate large, vascularized tissues with a complex structure of native tissues. Over the past decade, a new generation of "smart" materials has revolutionized the conventional medical field, transforming TE into a more accurate and sophisticated concept. At the vanguard of scientific development, magnetic nanoparticles (MNPs) have garnered extensive attention owing to their significant potential in various biomedical applications owing to their inherent properties such as biocompatibility and rapid remote response to magnetic fields. Therefore, to develop functional tissue replacements, magnetic force-based TE (Mag-TE) has emerged as an alternative to conventional TE strategies, allowing for the fabrication and real-time monitoring of tissues engineered in vitro. This review addresses the recent studies on the use of MNPs for TE, emphasizing the in vitro, in vivo, and clinical applications. Future perspectives of Mag-TE in the fields of TE and regenerative medicine are also discussed.

Current advances in stem cell therapy in the treatment of multiple sclerosis

Multiple sclerosis (MS) is an inflammatory disease related to the central nervous system (CNS) with a significant global burden. In this illness, the immune system plays an essential role in its pathophysiology and progression. The currently available treatments are not recognized as curable options and, at best, might slow the progression of MS injuries to the CNS. However, stem cell treatment has provided a new avenue for treating MS. Stem cells may enhance CNS healing and regulate immunological responses. Likewise, stem cells can come from various sources, including adipose, neuronal, bone marrow, and embryonic tissues. Choosing the optimal cell source for stem cell therapy is still a difficult verdict. A type of stem cell known as mesenchymal stem cells (MSCs) is obtainable from different sources and has a strong immunomodulatory impact on the immune system. According to mounting data, the umbilical cord and adipose tissue may serve as appropriate sources for the isolation of MSCs. Human amniotic epithelial cells (hAECs), as novel stem cell sources with immune-regulatory effects, regenerative properties, and decreased antigenicity, can also be thought of as a new upcoming contender for MS treatment. Overall, the administration of stem cells in different sets of animal and clinical trials has shown immunomodulatory and neuroprotective results. Therefore, this review aims to discuss the different types of stem cells by focusing on MSCs and their mechanisms, which can be used to treat and improve the outcomes of MS disease.

Human PMSCs-derived small extracellular vesicles alleviate neuropathic pain through miR-26a-5p/Wnt5a in SNI mice model

BACKGROUND

Mesenchymal stem cell (MSCs)-derived small Extracellular Vesicles (sEVs) are considered as a new cell-free therapy for pain caused by nerve injury, but whether human placental mesenchymal stem cell-derived sEVs relieve pain in sciatic nerve injury and its possible mechanism are still unclear. In this study, we investigated the roles of hPMSCs-derived sEVs and related mechanisms in neuropathic pain.

METHODS

The spared nerve injury (SNI) mouse model was employed. Intrathecal injection of sEVs or miR-26a-5p agomir was performed on the seventh day of modeling, to study its anti-nociceptive effect. sEVs' miRNA sequencing (miRNA-Seq) and bioinformatics analysis were performed to study the downstream mechanisms of miRNAs. RT-qPCR, protein assay and immunofluorescence were used for further validation.

RESULTS

A single intrathecal injection of sEVs durably reversed mechanical hypersensitivity in the left hind paw of mice with partial sciatic nerve ligation. Immunofluorescence studies found that PKH26-labeled sEVs were visible in neurons and microglia in the dorsal horn of the ipsilateral L4/5 spinal cord and more enriched in the ipsilateral. According to miRNA-seq results, we found that intrathecal injection of miR-26a-5p agomir, the second high counts microRNA in hPMSCs derived sEVs, significantly suppressed neuropathic pain and neuroinflammation in SNI mice. Bioinformatics analysis and dual-luciferase reporter gene analysis identified Wnt5a as a direct downstream target gene of miR-26a-5p. The results showed that overexpression of miR-26a-5p in vivo could significantly reduce the expression level of Wnt5a. In addition, Foxy5, a mimetic peptide of Wnt5a, can significantly reverse the inhibitory effect of miR-26a-5p on neuroinflammation and neuropathic pain, and at the same time, miR-26a-5p can rescue the effect of Foxy5 by overexpression.

CONCLUSIONS

We reported that hPMSCs derived sEVs as a promising therapy for nerve injury induced neuropathic pain. In addition, we showed that the miR-26a-5p in the sEVs regulated Wnt5a/Ryk/CaMKII/NFAT partly take part in the analgesia through anti-neuroinflammation, which suggests an alleviating pain effect through non-canonical Wnt signaling pathway in neuropathic pain model in vivo.

Magnetic field effects in biology from the perspective of the radical pair mechanism

Hundreds of studies have found that weak magnetic fields can significantly influence various biological systems. However, the underlying mechanisms behind these phenomena remain elusive. Remarkably, the magnetic energies implicated in these effects are much smaller than thermal energies. Here, we review these observations, and we suggest an explanation based on the radical pair mechanism, which involves the quantum dynamics of the electron and nuclear spins of transient radical molecules. While the radical pair mechanism has been studied in detail in the context of avian magnetoreception, the studies reviewed here show that magnetosensitivity is widespread throughout biology. We review magnetic field effects on various physiological functions, discussing static, hypomagnetic and oscillating magnetic fields, as well as isotope effects. We then review the radical pair mechanism as a potential unifying model for the described magnetic field effects, and we discuss plausible candidate molecules for the radical pairs. We review recent studies proposing that the radical pair mechanism provides explanations for isotope effects in xenon anaesthesia and lithium treatment of hyperactivity, magnetic field effects on the circadian clock, and hypomagnetic field effects on neurogenesis and microtubule assembly. We conclude by discussing future lines of investigation in this exciting new area of quantum biology.

Immunomodulatory effects of mesenchymal stem cells in peripheral nerve injury

Various immune cells and cytokines are present in the aftermath of peripheral nerve injuries (PNI), and coordination of the local inflammatory response is of great significance for the recovery of PNI. Mesenchymal stem cells (MSCs) exhibit immunosuppressive and anti-inflammatory abilities which can accelerate tissue regeneration and attenuate inflammation, but the role of MSCs in the regulation of the local inflammatory microenvironment after PNI has not been widely studied. Here, we summarize the known interactions between MSCs, immune cells, and inflammatory cytokines following PNI with a focus on the immunosuppressive role of MSCs. We also discuss the immunomodulatory potential of MSC-derived extracellular vesicles as a new cell-free treatment for PNI.

Mesenchymal stem cells and extracellular vesicles for the treatment of pain: Current status and perspectives

Mesenchymal stem/stromal cells (MSCs) are multipotent progenitor cells of mesodermal origin. Due to their capacity for self-renewal and differentiation into several cell types, MSCs have been extensively studied in experimental biology and regenerative medicine in recent years. Moreover, MSCs release extracellular vesicles (EVs), which might be partly responsible for their regenerative properties. MSCs regulate several processes in target cells via paracrine signalling, such as immunomodulation, anti-apoptotic signalling, tissue remodelling, angiogenesis and anti-fibrotic signalling. The aim of this review is to provide a detailed description of the functional properties of MSCs and EVs and their potential clinical applications, with a special focus on pain treatment. The analgesic, anti-inflammatory and regenerative properties of MSCs and EVs will be discussed for several diseases, such as neuropathic pain, osteoarthritis and spinal cord injury.

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.

Stem Cell Therapy for Modulating Neuroinflammation in Neuropathic Pain

Neuropathic pain (NP) is a complex, debilitating, chronic pain state, heterogeneous in nature and caused by a lesion or disease affecting the somatosensory system. Its pathogenesis involves a wide range of molecular pathways. NP treatment is extremely challenging, due to its complex underlying disease mechanisms. Current pharmacological and nonpharmacological approaches can provide long-lasting pain relief to a limited percentage of patients and lack safe and effective treatment options. Therefore, scientists are focusing on the introduction of novel treatment approaches, such as stem cell therapy. A growing number of reports have highlighted the potential of stem cells for treating NP. In this review, we briefly introduce NP, current pharmacological and nonpharmacological treatments, and preclinical studies of stem cells to treat NP. In addition, we summarize stem cell mechanisms—including neuromodulation in treating NP. Literature searches were conducted using PubMed to provide an overview of the neuroprotective effects of stem cells with particular emphasis on recent translational research regarding stem cell-based treatment of NP, highlighting its potential as a novel therapeutic approach.

Effects of varying degrees of ligation in a neuropathic pain model induced by chronic constriction injury

AIM

Ligature tightness of chronic constriction injury (CCI) model remains inconsistent and controversial, presenting barriers for researchers.

METHODS

We summarized the different ligation criteria in literature and attempted to clarify their effects. To assess constriction under different criteria, we calculated the radial strain (ε_R) of ligated nerves from digital photographs. The mechanical withdrawal thresholds (MWT), thermal withdrawal latency (TWL) and sciatic functional index (SFI) were observed in rats of different groups to assess the state of model. Changes of myelin sheath were detected by pathological staining and immunohistochemistry.

RESULTS

The median ε_R values in the Loose, Medium and Tight groups were 13.6%, 15.2% and 21.7%, respectively. Ligated groups had lower MWT than Sham group and the TWL of rats in the Loose approached to rats with sham operation, while that of the Tight group was higher than Medium group 14 days after surgery. Medium and Tight groups showed more abnormal in SFI, compared with the other two groups 14 days. Pathological staining revealed demyelination in three CCI groups, especially in the sciatic nerves. Myelin protein zero levels decreased in the sciatic nerves as the degree of constriction increased, but myelin basic protein of the Medium group was lowest abundant in the spinal cords of all rats.

CONCLUSIONS

Our study demonstrated that the surrounding muscles briefly twitched when the diameter of the sciatic nerves was constricted by approximately 14-15%, which may provide a reference for other researchers for establishing CCI models.

A Review on Stem Cell Therapy for Neuropathic Pain

Neuropathic pain is a complex, chronic pain state that is heterogeneous in nature and caused by the consequence of a lesion or disease affecting the somatosensory system. Current medications give a long-lasting pain relief only in a limited percentage of patients also associated with numerous side effects. Stem cell transplantation is one of the attractive therapeutic platforms for the treatment of a variety of diseases, such as neuropathic pain. Here, the authors review the therapeutic effects of stem cell transplantation of different origin and species in different models of neuropathic pain disorders. Stem cell transplantation could alleviate the neuropathic pain; indeed, stem cells are the source of cells, which differentiate into a variety of cell types and lead trophic factors to migrate to the lesion site opposing the effects of damage. In conclusion, this review suggests that stem cell therapy can be a novel approach for the treatment of neuropathic pain.

Adipose-Derived Mesenchymal Stromal Cells in Regenerative Medicine: State of Play, Current Clinical Trials, and Future Prospects

Significance: Wound healing is a complex process involving pain and inflammation, where innervation plays a central role. Managing wound healing and pain remains an important issue, especially in pathologies such as excessive scarring (often leading to fibrosis) or deficient healing, leading to chronic wounds. Recent Advances: Advances in therapies using mesenchymal stromal cells offer new insights for treating indications that previously lacked options. Adipose-derived mesenchymal stromal cells (AD-MSCs) are now being used to a much greater extent in clinical trials for regenerative medicine. However, to be really valid, these randomized trials must imperatively follow strict guidelines such as consolidated standards of reporting trials (CONSORT) statement. Indeed, AD-MSCs, because of their paracrine activities and multipotency, have potential to cure degenerative and/or inflammatory diseases. Combined with their relatively easy access (from adipose tissue) and proliferation capacity, AD-MSCs represent an excellent candidate for allogeneic treatments. Critical Issues: The success of AD-MSC therapy may depend on the robustness of the biological functions of AD-MSCs, which requires controlling source heterogeneity and production processes, and development of biomarkers that predict desired responses. Several studies have investigated the effect of AD-MSCs on innervation, wound repair, or pain management separately, but systematic evaluation of how those effects could be combined is lacking. Future Directions: Future studies that explore how AD-MSC therapy can be used to treat difficult-to-heal wounds, underlining the need to thoroughly characterize the cells used, and standardization of preparation processes are needed. Finally, how this a priori easy-to-use cell therapy treatment fits into clinical management of pain, improvement of tissue healing, and patient quality of life, all need to be explored.

Stem Cells in the Treatment of Neuropathic Pain: Research Progress of Mechanism

Neuropathic pain (NP) is pain caused by somatosensory nervous system injury or disease. Its prominent symptoms are spontaneous pain, hyperalgesia, and allodynia, and the sense of pain is extremely strong. Owing to the complex mechanism, conventional painkillers lack effectiveness. Recently, research on the treatment of NP by stem cells is increasing and promising results have been achieved in preclinical research. In this review, we briefly introduce the neuropathic pain, the current treatment strategy, and the development of stem cell therapy, and we collected the experimental and clinical trial articles of many kinds of stem cells in the treatment of neuropathic pain from the past ten years. We analyzed and summarized the general efficacy and mechanism of stem cells in the treatment of neuropathic pain. We found that the multiple-mechanism approach was different from the single mechanism of routine clinical drugs; stem cells play a role in peripheral mechanism, central mechanism, and disinhibition of spinal cord level that lead to neuropathic pain, so they are more effective in analgesia and treatment of neuropathic pain.

Autologous fat grafting for nerve regeneration and neuropathic pain: current state from bench-to-bedside

Despite recent advances in microsurgical techniques, functional recovery following peripheral nerve injury remains slow and inadequate. Poor peripheral nerve regeneration not only leaves patients with significant impairments, but also commonly leads to the development of debilitating neuropathic pain. Recent research has demonstrated the potential therapeutic benefits of adipose-derived stem cells, to enhance nerve regeneration. However, clinical translation remains limited due to the current regulatory burdens of the US FDA. A reliable and immediately translatable alternative is autologous fat grafting, where native adipose-derived stem cells present in the transferred tissue can potentially act upon regenerating axons. This review presents the scope of adipose tissue-based therapies to enhance outcomes following peripheral nerve injury, specifically focusing on their role in regeneration and ameliorating neuropathic pain.

Neural Regenerative Potential of Stem Cells Derived from the Tooth Apical Papilla

The regenerative effects of stem cells derived from dental tissues have been previously investigated. This study assessed the potential of human tooth stem cells from apical papilla (SCAP) on nerve regeneration. The SCAP collected from nine individuals were characterized and polarized by exposure to interferon-γ (IFN-γ). IFN-γ increased kynurenine and interleukin-6 (IL-6) production by SCAP, without affecting the cell viability. IFN-γ-primed SCAP exhibited a decrease of brain-derived neurotrophic factor (BDNF) mRNA levels, followed by an upregulation of glial cell-derived neurotrophic factor mRNA. Ex vivo, the co-culture of SCAP with neurons isolated from the rat dorsal root ganglion induced neurite outgrowth, accompanied by increased BDNF secretion, irrespective of IFN-γ priming. In vivo, the local application of SCAP reduced the mechanical and thermal hypersensitivity in Wistar rats that had been submitted to sciatic chronic constriction injury. The SCAP also reduced the pain scores, according to the evaluation of the Grimace scale, partially restoring the myelin damage and BDNF immunopositivity secondary to nerve lesion. Altogether, our results provide novel evidence about the regenerative effects of human SCAP, indicating their potential to handle nerve injury-related complications.

Mesenchymal Stem Cells Transplantation for Neuropathic Pain Induced By Peripheral Nerve Injury in Animal Models: A Systematic Review

Neuropathic pain is defined as a lesion or disease of the somatosensory system, currently remaining a challenging condition to treat. Mesenchymal stem cells (MSCs) transplantation is emerging as a promising strategy to alleviate the neuropathic pain conditions induced by peripheral nerve injury. The aim of this systematic review was to assess the efficacy and safety of MSCs transplantation in neuropathic pain induced by peripheral nerve injury in controlled animal studies, and thus to yield evidence-based decision making. Following the PRISMA guidelines, PubMed, Cochrane Central Library, Embase, and CINAHL were searched for preclinical controlled animal studies from the inception to April 16, 2020. Seventeen studies are included in this review. Substantial heterogeneity is observed regarding the animal's species, models of neuropathic pain, regimen of MSCs transplantation, and outcome of measures across the included studies. Both mechanical allodynia and thermal hyperalgesia could be significantly attenuated by transplanted MSCs. The MSCs-elicited analgesic effect is independent of the type of MSCs, time of administration, and route of delivery, and is efficiently enhanced by genetic transfection with fibroblast growth factor, proenkephalin, and glial cell line-derived neurotrophic factor. The migration of MSCs after intrathecal or intravenous injection has been shown to be directed toward the surface of dorsal spinal cord or dorsal root ganglions on the ipsilateral side of injury. No adverse effects have been reported. The accumulating evidence demonstrates the therapeutic effect of MSCs-based cell therapy on prevention and alleviation of the neuropathic pain induced by peripheral nerve injury in rat or mouse models. The robust preclinical studies are deserved to optimize the regimen of MSCs transplantation and to promote the translation of the MSCs-based therapy into clinical studies.

Pro-inflammatory or anti-inflammatory effects of pulsed magnetic field treatments in rats with experimental acute inflammation

In this study, we evaluated the possible effects of sequenced pulsed magnetic fields (PMF) of 1-mT treatments with designed different frequencies (PMF-1-1, 3, 5, 7 Hz or PMF-2-7, 9, 12, 14 Hz) on the inflammatory signs such as abnormal pain behaviors, hyperalgesia and allodynia, edema, and fever in carrageenan (CG)-induced hind paw inflammation model in rats. Paw tissues were also histologically examined. PMF exposure was applied 3 times in 24 h. CG injection gradually decreased the thermal latencies and mechanical threshold and caused significant increases in temperature and mass of paw. PMF treatments significantly reduced the temperature and mass in the paw of rats with inflammation. PMF-1 treatments caused significant increases in the latencies and thresholds. However, administration of PMF-2 treatment was significantly decreased the latency and threshold. Furthermore, the histological pieces of evidence also suggested the anti-inflammatory effects of PMF-1 treatments or inflammatory actions of PMF-2 treatments. Findings presented in this paper suggest that 1-mT PMF treatments may have anti-edematous and antipyretics activities in inflamed rats. However, the effects of PMF treatments on abnormal pain hypersensitivities may be different. PMF treatments may make inflammatory pain relief or worse in inflamed rats depending on the PMF frequencies in sequence.

Pain in Osteoporosis: From Pathophysiology to Therapeutic Approach

The high worldwide prevalence of osteoporosis means it is considered a serious public health concern, possibly leading to physical disability and an increased mortality rate. Although osteoporosis is known as a silent disease affecting aging populations, its primary symptom remains pain. Acute pain is reported by patients with osteoporosis-related fractures, but chronic pain, mainly back pain, is also a characteristic of severe osteoporosis. Pain is associated not only with fractures but also with bodily changes in patients with osteoporosis that may include sensory, affective, and cognitive aspects. Chronic pain leads to progressive loss of independence and the need for long-term care, especially in the elderly. Pain prevention is linked to the appropriate treatment of osteoporosis, and pain management in patients with osteoporosis requires a multidimensional approach to preserve and improve quality of life. Our aim was to review and discuss the main causes of pain in patients with osteoporosis and suggest possible strategies for its management and prevention.