The treatment of spinal cord injury in rats using bone marrow-derived neural-like cells induced by cerebrospinal fluid

Brain-derived neurotrophic factor (BDNF) as biomarker in stem cell-based therapies of preclinical spinal cord injury models: A systematic review

Stem cell-based therapies offer promising treatment for spinal cord injury (SCI) by reducing inflammation, restoring plasticity, and supporting neuroprotection and nerve regeneration. Brain-derived neurotrophic factor (BDNF) is crucial in SCI pathophysiology. This study reviews the impact of stem cells on BDNF expression in preclinical SCI models. A thorough search was performed in PubMed, Scopus, and Web of Science until June 2023, identifying studies on the effects of stem cells on BDNF in SCI. Two researchers reviewed and extracted data from relevant studies. This review is registered in the Prospective Register of Systematic Reviews (PROSPERO) with the registration number [CRD42023441466]. Out of 923 records, 51 studies met the inclusion criteria, involving rats (46 studies) and mice (5 studies). The contusion or compression model was used in 40 studies, and the transection model in 11. The most common stem cell types were bone marrow mesenchymal stem cells (BM-MSCs), neural stem cells (NSCs), and adipose-derived stem cells (ADSCs). BM-MSCs increased BDNF expression in 16 studies, NSCs in 9 studies, and ADSCs in only one study. This review highlights that BM-MSCs and NSCs are effective in enhancing BDNF expression in preclinical SCI models, while other stem cell types may not significantly affect BDNF levels. These findings suggest variability in the effectiveness of different stem cell therapies in modulating BDNF production for SCI treatment.

Spinal cord injury: molecular mechanisms and therapeutic interventions

Spinal cord injury (SCI) remains a severe condition with an extremely high disability rate. The challenges of SCI repair include its complex pathological mechanisms and the difficulties of neural regeneration in the central nervous system. In the past few decades, researchers have attempted to completely elucidate the pathological mechanism of SCI and identify effective strategies to promote axon regeneration and neural circuit remodeling, but the results have not been ideal. Recently, new pathological mechanisms of SCI, especially the interactions between immune and neural cell responses, have been revealed by single-cell sequencing and spatial transcriptome analysis. With the development of bioactive materials and stem cells, more attention has been focused on forming intermediate neural networks to promote neural regeneration and neural circuit reconstruction than on promoting axonal regeneration in the corticospinal tract. Furthermore, technologies to control physical parameters such as electricity, magnetism and ultrasound have been constantly innovated and applied in neural cell fate regulation. Among these advanced novel strategies and technologies, stem cell therapy, biomaterial transplantation, and electromagnetic stimulation have entered into the stage of clinical trials, and some of them have already been applied in clinical treatment. In this review, we outline the overall epidemiology and pathophysiology of SCI, expound on the latest research progress related to neural regeneration and circuit reconstruction in detail, and propose future directions for SCI repair and clinical applications.

Derivation of Stem Cell-like Cells From Spherical Culture of Astrocytes for Enhanced Neural Repair After Middle Cerebral Artery Occlusion

Neural precursor cells (NPCs) tend to aggregate and develop into three-dimensional (3D) spheres, which in turn help maintain the stemness of the cells. This close relationship between spherical environments and cell stemness direct us to assume that 3D spheres of astrocytes (ASTs) may facilitate the acquisition of stem cell-like features and generate sufficient seed cells for the regeneration of neurons. In vitro results confirmed that mouse ASTs cultured on agarose surfaces spontaneously formed cell spheres and exhibited molecular features similar to stem cells, particularly capable of further differentiating into neurons and forming functional synaptic networks with synchronous burst activities. RNA-sequencing results revealed the similarity between AST-derived stem cells (A-iSCs) and NPCs in global gene expression profiles. The potency of A-iSCs in repairing neural injuries was evaluated in a mouse model of middle cerebral artery occlusion. It was observed that the transplanted A-iSCs expressed a series of markers related to neural differentiation, such as NeuN, Tuj1, and Map2, indicating the conversion of the transplanted A-iSCs into neurons in the scenario. We also found that the injured mice injected with A-iSCs exhibited significant improvements in sensorimotor functions after 8 weeks compared with the sham and control mice. Taken together, mouse ASTs form cell spheres on agarose surfaces and acquire stem cell-associated features; meanwhile, the derived A-iSCs possess the capacity to differentiate into neurons and facilitate the regeneration of damaged nerves.

Human Muse cells-derived neural precursor cells as the novel seed cells for the repair of spinal cord injury

At present, stem cell transplantation has a significant therapeutic effect on spinal cord injury (SCI), however, it is still challenging for the seed cells selection. In this study, in order to explore cells with wide neural repair potentials, we selected the pluripotent stem cells multilineage-differentiating stress-enduring (Muse) cells, inducing the in vitro differentiation of human Muse cells into neural precursor cells (Muse-NPCs) by applying neural induction medium. Here, we found induced Muse-NPCs expressed neural stem cell markers Nestin and NCAM, capable of differentiating into three types of neural cells (neuron, astrocyte and oligodendrocyte), and have certain biological functions. When Muse-NPCs were transplanted into rats suffering from T10 SCI, motor function was improved. These results provide an insight for application of Muse-NPCs in cell therapy or tissue engineering for the repair of SCI in future.

MicroRNA124 and microRNA21-5p regulate migration, proliferation and differentiation of rat bone marrow mesenchymal stem cells

Mesenchymal stem cells (MSCs) are multipotent stromal cells that can be a useful source of cells for the treatment of many diseases, including neurologic diseases. The curative effect of MSCs relies mostly on cell’s capacity of migration, proliferation and differentiation. MicroRNAs (miRNAs) are small non-coding RNAs that play important roles on regulating various cell behaviors. Here, we report that miRNA-124 (miR124) and miRNA-21-5p (miR21-5p) display different regulatory roles on migration, proliferation and neuron differentiation of MSCs. MiR124 was shown greatly promoting MSCs migration and neuronal differentiation. MiR21-5p could significantly enhance the proliferation and neuronal differentiation ability of MSCs. MiR124 and miR21-5p synergistically promote differentiation of MSCs into neurons. Collectively, miR124 and miR21-5p can functionally regulate cell migration, proliferation and neuronal differentiation of MSCs. Therefore, miR124 and miR21-5p may be promising tools to improve transplantation efficiency for neural injury.

Spinal cord injury regeneration using autologous bone marrow-derived neurocytes and rat embryonic stem cells: A comparative study in rats

BACKGROUND

Spinal cord injury (SCI) is an important cause of traumatic paralysis and is mainly due to motor vehicle accidents. However, there is no definite treatment for spinal cord damage.

AIM

To assess the outcome of rat embryonic stem cells (rESC) and autologous bone marrow-derived neurocytes (ABMDN) treatment in iatrogenic SCI created in rats, and to compare the efficacy of the two different cell types.

METHODS

The study comprised 45 male Wistar rats weighing between 250 and 300 g, which were divided into three groups, the control, rESC and ABMDN groups. The anesthetized animals underwent exposure of the thoracic 8th to lumbar 1st vertebrae. A T10-thoracic 12th vertebrae laminectomy was performed to expose the spinal cord. A drop-weight injury using a 10 g weight from a height of 25 cm onto the exposed spinal cord was conducted. The wound was closed in layers. The urinary bladder was manually evacuated twice daily and after each evacuation Ringer lactate 5 mL/100 g was administered, twice daily after each bladder evacuation for the first 7 postoperative days. On the 10th day, the rats underwent nerve conduction studies and behavioral assessment [Basso, Beattie, Brenham (BBB)] to confirm paraplegia. Rat embryonic stem cells, ABMDN and saline were injected on the 10th day. The animals were euthanized after 8 wk and the spinal cord was isolated, removed and placed in 2% formalin for histopathological analysis to assess the healing of neural tissues at the axonal level.

RESULTS

All the animals tolerated the procedure well. The BBB scale scoring showed that at the end of the first week no recovery was observed in the groups. Post-injection, there was a strong and significant improvement in rats receiving rESC and ABMDN as compared to the control group based on the BBB scale, and the Train-of-four-Watch SX acceleromyography device exhibited statistically significant (P < 0.0001) regeneration of neural tissue after SCI. Histological evaluation of the spinal cord showed maximum vacuolization and least gliosis in the control group compared to the rESC and ABMDN treated animals. In the ABMDN group, limited vacuolization and more prominent gliosis were observed in all specimens as compared to the control and rESC groups.

CONCLUSION

This study provided strong evidence to support that transplantation of rESC and ABMDN can improve functional recovery after iatrogenic SCI. The transplanted cells showed a beneficial therapeutic effect when compared to the control group.

Clinical Trials of Stem Cell Treatment for Spinal Cord Injury

There are more than one million patients worldwide suffering paralysis caused by spinal cord injury (SCI). SCI causes severe socioeconomic problems not only to the patients and their caregivers but also to society; therefore, the development of innovative treatments is crucial. Many pharmacological therapies have been attempted in an effort to reduce SCI-related damage; however, no single therapy that could dramatically improve the serious long-term sequelae of SCI has emerged. Stem cell transplantation therapy, which can ameliorate damage or regenerate neurological networks, has been proposed as a promising candidate for SCI treatment, and many basic and clinical experiments using stem cells for SCI treatment have been launched, with promising results. However, the cell transplantation methods, including cell type, dose, transplantation route, and transplantation timing, vary widely between trials, and there is no consensus regarding the most effective treatment strategy. This study reviews the current knowledge on this issue, with a special focus on the clinical trials that have used stem cells for treating SCI, and highlights the problems that remain to be solved before the widespread clinical use of stem cells can be adopted.

Polypyrrole/polylactic acid nanofibrous scaffold cotransplanted with bone marrow stromal cells promotes the functional recovery of spinal cord injury in rats

AIMS

The objective of this study was to analyze the efficacy of polypyrrole/polylactic acid (PPy/PLA) nanofibrous scaffold cotransplanted with bone marrow stromal cells (BMSCs) in promoting the functional recovery in a rat spinal cord injury (SCI).

METHODS

Female Sprague-Dawley rats were randomly divided into three groups (n = 18/group): control group, PPy/PLA group, and PPy/PLA/BMSCs group. The SCI was induced in all rats. Consequently, rats in PPy/PLA/BMSCs group were transplanted with 1 × 105 BMSCs after implantation of PPy/PLA, while those in the PPy/PLA group were implanted with PPy/PLA only; no implantation was performed in the control group. Six weeks after surgery, immunofluorescence microscopy, electron microscope, and polymerase chain reaction (PCR) techniques were performed to assess the changes in the injured spinal cord tissues.

RESULTS

Electrophysiology and locomotor function testing suggested that PPy/PLA nanofibrous scaffold cotransplanted with BMSCs could promote the functional recovery of the spinal cord. Six weeks after the operation, lower amount of scar tissue was found in the PPy/PLA group compared with the control group. Abundant neurofilament (NF) and neuron-specific marker (NeuN) positive staining, and myelin formations were detected in the injured area. In addition, the transplantation of BMSCs not only improved the efficacy of PPy/PLA but also managed to survive well and was differentiated into neural and neuroglial cells.

CONCLUSIONS

The implantation of PPy/PLA nanofibrous scaffold and BMSCs has a great potential to restore the electrical conduction and to promote functional recovery by inhibiting the scar tissue formation, promoting axon regeneration, and bridging the gap lesion.

The cell repair research of spinal cord injury: a review of cell transplantation to treat spinal cord injury

Through retrospective analysis of the literature on the cell repair of spinal cord injury worldwide, it is found that the mechanism of cell transplantation repairing spinal cord injury is mainly to replace damaged neurons, protect host neurons, prevent apoptosis, promote axonal regeneration and synapse formation, promote myelination, and secrete trophic factors or growth factors to improve microenvironment. A variety of cells are used to repair spinal cord injury. Stem cells include multipotent stem cells, embryonic stem cells, and induced pluripotent stem cells. The multipotent stem cells are mainly various types of mesenchymal stem cells and neural stem cells. Non-stem cells include olfactory ensheathing cells and Schwann cells. Transplantation of inhibitory interneurons to alleviate neuropathic pain in patients is receiving widespread attention. Different types of cell transplantation have their own advantages and disadvantages, and multiple cell transplantation may be more helpful to the patient’s functional recovery. These cells have certain effects on the recovery of neurological function and the improvement of complications, but further exploration is needed in clinical application. The application of a variety of cell transplantation, gene technology, bioengineering and other technologies has made the prospect of cell transplantation more extensive. There is a need to find a safe and effective comprehensive treatment to maximize and restore the patient’s performance.

Semaphorin 3A promotes osteogenic differentiation of BMSC from type 2 diabetes mellitus rats

Bone regeneration is impaired in patients with type 2 diabetes mellitus (T2DM), which leads to non-healing after bone loss. The decreased osteogenic capacity of bone mesenchymal stem cells (BMSCs) might be a main reason. Sema3A, as a powerful protein promoting osteocyte differentiation, shows potential for bone regeneration treatment. BMSCs may be a therapeutic solution. In this study, we divided BMSCs from T2DM rats (BMSCs-D) and normal rats (BMSCs-N), identified their ability to differentiate into different cell types. Then we found decreased expression of Sema3A in BMSCs-D compared with BMSCs-N. Stimulating with Sema3A showed no influence in the proliferation or migration of BMSCs. However, Sema3A stimulation significantly increased the expression of osteogenic‑related genes, including type I collagen, alkaline phosphatase, Runt-related transcription factor 2 (RUNX2), bone morphogenetic protein and osteocalcin. Besides, the osteogenic capacity of BMSCs was also increased by Sema3A stimulation. In conclusion, we proved that exogenous Sema3A stimulation might repair the osteogenic capacity of BMSCs-D, thus providing a new strategy for restoring the impaired bone regeneration ability for T2DM patients.