Repairing and Analgesic Effects of Umbilical Cord Mesenchymal Stem Cell Transplantation in Mice with Spinal Cord Injury

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.

Partially brain effects of injection of human umbilical cord mesenchymal stem cells at injury sites in a mouse model of thoracic spinal cord contusion

Purpose

The pain caused by spinal cord injury (SCI) poses a major burden on patients, and pain management is becoming a focus of treatment. Few reports have described changes in the brain after SCI. Particularly, the exact mechanism through which brain regions affect post-injury pain remains unclear. In this study, we aimed to determine the potential therapeutic mechanisms of pain. A mouse model of spinal cord contusion was established, and molecular expression in the anterior cingulate cortex (ACC) and periaqueductal gray (PAG) in the brain and animal behavior was observed after local injection of human umbilical cord mesenchymal stem cells (HU-MSCs) at the site of SCI.

Method

Sixty-three female C57BL/6J mice were divided into four groups: a sham operation group (n = 15); a spinal injury group (SCI, n = 16); an SCI + HU-MSCs group (n = 16) and an SCI + PBS group (n = 16), in which the SCI site was injected with HU-MSCs/phosphate buffer. The BMS score was determined, and the von Frey test and Hargreaves test were used to assess behavior every week after surgery. Mice were sacrificed in the fourth week after operation, and samples were collected. The expression of CGRP, Substance P, C-Fos and KCC2 in the ACC and PAG were observed with immunohistochemistry. Chromic cyanine staining was used to observe transverse sections of the injured spinal cord.

Result

In the ACC and PAG after SCI, the expression of CGRP, SP and C-Fos increased, and the expression of KCC2 decreased, whereas after HU-MSC injection, the expression of CGRP, SP and C-Fos decreased, and the expression of KCC2 increased. The SCI + HU-MSC group showed better exercise ability from 2 to 4 weeks after surgery than the SCI/SCI + PBS groups (P < 0.001). Local injection of HU-MSCs significantly improved the mechanical hyperalgesia caused by SCI in the fourth week after surgery (P < 0.0001), and sensation was significantly recovered 2 weeks after surgery (P < 0.0001); no improvement in thermal hypersensitivity was observed (P > 0.05). The HU-MSC group retained more white matter than the SCI/SCI + PBS groups (P < 0.0001).

Conclusion

Local transplantation of HU-MSCs at the site of SCI partially relieves the neuropathic pain and promotes recovery of motor function. These findings suggest a feasible direction for the future treatment of SCI.

Cell therapy for neuropathic pain

Neuropathic pain (NP) is caused by a lesion or a condition that affects the somatosensory system. Pathophysiologically, NP can be ascribed to peripheral and central sensitization, implicating a wide range of molecular pathways. Current pharmacological and non-pharmacological approaches are not very efficacious, with over half of NP patients failing to attain adequate pain relief. So far, pharmacological and surgical treatments have focused primarily on symptomatic relief by modulating pain transduction and transmission, without treating the underlying pathophysiology. Currently, researchers are trying to use cell therapy as a therapeutic alternative for the treatment of NP. In fact, mounting pre-clinical and clinical studies showed that the cell transplantation-based therapy for NP yielded some encouraging results. In this review, we summarized the use of cell grafts for the treatment of NP caused by nerve injury, synthesized the latest advances and adverse effects, discussed the possible mechanisms to inform pain physicians and neurologists who are endeavoring to develop cell transplant-based therapies for NP and put them into clinical practice.

Current Status of Mesenchymal Stem/Stromal Cells for Treatment of Neurological Diseases

Neurological disorders include a wide spectrum of clinical conditions affecting the central and peripheral nervous systems. For these conditions, which affect hundreds of millions of people worldwide, generally limited or no treatments are available, and cell-based therapies have been intensively investigated in preclinical and clinical studies. Among the available cell types, mesenchymal stem/stromal cells (MSCs) have been widely studied but as yet no cell-based treatment exists for neurological disease. We review current knowledge of the therapeutic potential of MSC-based therapies for neurological diseases, as well as possible mechanisms of action that may be explored to hasten the development of new and effective treatments. We also discuss the challenges for culture conditions, quality control, and the development of potency tests, aiming to generate more efficient cell therapy products for neurological disorders.

Effects of mesenchymal stem cell transplantation on spinal cord injury patients

Spinal cord injury (SCI) is a traumatic injury with sensory and motor deficits that more than 1 million patients worldwide suffer from disability due to it. Many pharmacological therapies help reduce SCI-related injury and protect CNS from more damage but no current therapy could improve the axonal repair. In this regard, stem cell therapy is considered a regenerative method for SCI patient treatment. The neurotrophic and immunomodulatory factor secretion, differentiation, neuroprotecting, and remyelinating properties have made mesenchymal stem cells (MSCs) principally useful in this field. There are studies on the role of MSCs in patients suffering from SCI. However, low number of SCI patients and the lack of control groups in these studies, the cell transplantation appropriate methods, including cell source, dose, route of delivery, and transplantation timing, are various in trials. This study reviews the beneficial effects of MSC transplantation in SCI clinical studies with a special focus on the MSC properties and limitations of MSC transplantation.

Efficacy of transcutaneous electrical nerve stimulation in people with pain after spinal cord injury: a meta-analysis

Study Design

Meta-analysis.

Objectives

This study aimed to evaluate the effect of transcutaneous electrical nerve stimulation in people with pain after spinal cord injury by meta-analysis.

Methods

Reviewed PubMed, Embase, Cochrane library, as well as China National Knowledge Infrastructure (CNKI), Wanfang, and Vip databases to search the randomized controlled trials of pain after spinal cord injury through transcutaneous electrical nerve stimulation from the beginning of the library to March 2021, and analyze the literature with RevMan 5.3 software and the bias in the literature with STATA 12.0 software.

Results

There are six randomized controlled trials in the study with 165 cases. 83 cases in the test group were given transcutaneous electrical nerve stimulation, and 82 cases in the control group used sham stimulation or other treatments. Meta-analysis results showed the experimental group’s visual analog scale (MD = −1.52, 95%CI, −2.44 to −0.60, P = 0.001) and short-form McGill pain questionnaire scores (MD = −0.70, 95% CI, −1.03 to −0.25, P = 0.002) were lower than those of the control group.

Conclusions

Transcutaneous electrical nerve stimulation has some clinical therapeutic effects on persons with pain after spinal cord injury, but due to the lack of literature, the sample size is not large, and clinical trials need to be further improved later.

Neuroinflammation and Scarring After Spinal Cord Injury: Therapeutic Roles of MSCs on Inflammation and Glial Scar

Transected axons are unable to regenerate after spinal cord injury (SCI). Glial scar is thought to be responsible for this failure. Regulating the formation of glial scar post-SCI may contribute to axonal regrow. Over the past few decades, studies have found that the interaction between immune cells at the damaged site results in a robust and persistent inflammatory response. Current therapy strategies focus primarily on the inhibition of subacute and chronic neuroinflammation after the acute inflammatory response was executed. Growing evidences have documented that mesenchymal stem cells (MSCs) engraftment can be served as a promising cell therapy for SCI. Numerous studies have shown that MSCs transplantation can inhibit the excessive glial scar formation as well as inflammatory response, thereby facilitating the anatomical and functional recovery. Here, we will review the effects of inflammatory response and glial scar formation in spinal cord injury and repair. The role of MSCs in regulating neuroinflammation and glial scar formation after SCI will be reviewed as well.

The Conditioned Medium of Lactobacillus rhamnoides GG Regulates Microglia/Macrophage Polarization and Improves Functional Recovery after Spinal Cord Injury in Rats

Lactobacillus rhamnoides, a human intestinal colonizer, can act through various pathways to induce microglia/macrophages to produce cytokines and to polarize microglia/macrophages to different phenotypes to reduce the inflammatory response. In this article, we evaluated the treatment potential of the Lactobacillus rhamnoides GG conditioned medium (LGG-CM) in rat model with SCI (acute spinal cord injury), including functional, neurophysiological, and histological outcomes and the underlying neuroprotective mechanisms. In our experiment, LGG-CM (30 mg/kg) was injected directly into the injury site in rats immediately after SCI. Measured by the BBB scale (Basso, Beattie, and Bresnahan locomotor rating scale) and inclined plane test, rats in the LGG-CM-treated group showed better locomotor scores. Moreover, compared to the vehicle treatment group, LGG-CM increased the mRNA level of the M2 marker (CD206), and decreased that of the M1 marker (iNOS). Western blot assays showed that LGG-CM-treated SCI rats had a higher grayscale ratio of p65 and a lower ratio of p-IκBα/IκBα. Our study shows that local injection of LGG-CM after acute SCI can inhibit inflammatory responses and improve motor function recovery. These effects may be related with the inhibition to the NF-κB (The nuclear factor-kappa B) signal pathway which leads to M2 microglia/macrophage polarization.

hiPSC-derived NSCs effectively promote the functional recovery of acute spinal cord injury in mice

Background

Spinal cord injury (SCI) is a common disease that results in motor and sensory disorders and even lifelong paralysis. The transplantation of stem cells, such as embryonic stem cells (ESCs), induced pluripotent stem cells (iPSCs), mesenchymal stem cells (MSCs), or subsequently generated stem/progenitor cells, is predicted to be a promising treatment for SCI. In this study, we aimed to investigate effect of human iPSC-derived neural stem cells (hiPSC-NSCs) and umbilical cord-derived MSCs (huMSCs) in a mouse model of acute SCI.

Methods

Acute SCI mice model were established and were randomly treated as phosphate-buffered saline (PBS) (control group), repaired with 1 × 10⁵ hiPSC-NSCs (NSC group), and 1 × 10⁵ huMSCs (MSC group), respectively, in a total of 54 mice (n = 18 each). Hind limb motor function was evaluated in open-field tests using the Basso Mouse Scale (BMS) at days post-operation (dpo) 1, 3, 5, and 7 after spinal cord injury, and weekly thereafter. Spinal cord and serum samples were harvested at dpo 7, 14, and 21. Haematoxylin-eosin (H&E) staining and Masson staining were used to evaluate the morphological changes and fibrosis area. The differentiation of the transplanted cells in vivo was evaluated with immunohistochemical staining.

Results

The hiPSC-NSC-treated group presented a significantly smaller glial fibrillary acidic protein (GFAP) positive area than MSC-treated mice at all time points. Additionally, MSC-transplanted mice had a similar GFAP+ area to mice receiving PBS. At dpo 14, the immunostained hiPSC-NSCs were positive for SRY-related high-mobility-group (HMG)-box protein-2 (SOX2). Furthermore, the transplanted hiPSC-NSCs differentiated into GFAP-positive astrocytes and beta-III tubulin-positive neurons, whereas the transplanted huMSCs differentiated into GFAP-positive astrocytes. In addition, hiPSC-NSC transplantation reduced fibrosis formation and the inflammation level. Compared with the control or huMSC transplanted group, the group with transplantation of hiPSC-NSCs exhibited significantly improved behaviours, particularly limb coordination.

Conclusions

HiPSC-NSCs promote functional recovery in mice with acute SCI by replacing missing neurons and attenuating fibrosis, glial scar formation, and inflammation.

Graphical abstract

Ultrashort Wave Combined with Human Umbilical Cord Mesenchymal Stem Cell (HUC-MSC) Transplantation Inhibits NLRP3 Inflammasome and Improves Spinal Cord Injury via MK2/TTP Signalling Pathway

Objective

To investigate the curative effects of HUC-MSCs combined with USW on spinal cord injury (SCI) and the effects on inflammatory microenvironment and to explore the regulatory mechanisms of MK2/TTP signalling pathway and NLRP3 inflammasome.

Methods

The SCI rat model was established using the modified Allen method; rats were administered with USW, HUC-MSCs, and combination therapy of USW and HUC-MSCs; the therapeutic efficacies in each group of rats were monitored and represented in BBB score. SCI levels were observed using HE staining and IF. The microglia polarisation state and released contents of inflammatory factors were detected. IF and Western Blotting were performed on to detect the expression levels of MK2/TTP signalling pathway and NLRP3 inflammasome-related proteins. Furthermore, the regulatory mechanisms of MK2/TTP pathway and NLRP3 were explored by performing on the in vitro study.

Results

Combination therapy of USW and HUC-MSCs was found of significant efficacy on improving motor functions of SCI rats, and it was further proved that this combination therapy can reduce spinal cord injury in SCI rats, of which USW plays a more important role. While transplantation of HUC-MSCs can promote microglial cells developing to SCI repair, and M2 microglial cells were taking advantages gradually. The combination therapy can inhibit the expression of MK2; downregulate NLRP3 inflammasome; suppress the expression levels of pro-caspase-1, pro-IL-1β, and pro-IL-18; and simultaneously suppress the release of IL-1β and IL-18, thereby reducing spinal cord neurons apoptosis. It was found that the steady state of microglial polarisation maintained by combined treatment of USW and HUC-MSCs was destroyed with the upregulation of MK2 expression in cells, of which, M1 type microglial cell was dominant and the increased contents of inflammatory factors were detected. However, overexpressed MK2 relieved the inhibition of NLRP3 expression by TTP.

Conclusions

Combination therapy of USW and HUC-MSCs can downregulate NLRP3 expression, relieve inflammatory responses, improve immune microenvironment, and rescue spinal cord injury via suppressing phosphorylation level of MK2.

What is the impact of human umbilical cord mesenchymal stem cell transplantation on clinical treatment?

Background

Human umbilical cord mesenchymal stem cells (HUC-MSCs) present in the umbilical cord tissue are self-renewing and multipotent. They can renew themselves continuously and, under certain conditions, differentiate into one or more cell types constituting human tissues and organs. HUC-MSCs differentiate, among others, into osteoblasts, chondrocytes, and adipocytes and have the ability to secrete cytokines. The possibility of noninvasive harvesting and low immunogenicity of HUC-MSCs give them a unique advantage in clinical applications. In recent years, HUC-MSCs have been widely used in clinical practice, and some progress has been made in their use for therapeutic purposes.

Main body

This article describes two aspects of the clinical therapeutic effects of HUC-MSCs. On the one hand, it explains the benefits and mechanisms of HUC-MSC treatment in various diseases. On the other hand, it summarizes the results of basic research on HUC-MSCs related to clinical applications. The first part of this review highlights several functions of HUC-MSCs that are critical for their therapeutic properties: differentiation into terminal cells, immune regulation, paracrine effects, anti-inflammatory effects, anti-fibrotic effects, and regulating non-coding RNA. These characteristics of HUC-MSCs are discussed in the context of diabetes and its complications, liver disease, systemic lupus erythematosus, arthritis, brain injury and cerebrovascular diseases, heart diseases, spinal cord injury, respiratory diseases, viral infections, and other diseases. The second part emphasizes the need to establish an HUC-MSC cell bank, discusses tumorigenicity of HUC-MSCs and the characteristics of different in vitro generations of these cells in the treatment of diseases, and provides technical and theoretical support for the clinical applications of HUC-MSCs.

Conclusion

HUC-MSCs can treat a variety of diseases clinically and have achieved good therapeutic effects, and the development of HUC-MSC assistive technology has laid the foundation for its clinical application.