Differentiation of Motor Neuron-Like Cells from Tonsil-Derived Mesenchymal Stem Cells and Their Possible Application to Neuromuscular Junction Formation

Preclinical Efficacy of Peripheral Nerve Regeneration by Schwann Cell-like Cells Differentiated from Human Tonsil-Derived Mesenchymal Stem Cells in C22 Mice

Charcot-Marie-Tooth disease (CMT) is a hereditary disease with heterogeneous phenotypes and genetic causes. CMT type 1A (CMT1A) is a type of disease affecting the peripheral nerves and is caused by the duplication of the peripheral myelin protein 22 (PMP22) gene. Human tonsil-derived mesenchymal stem cells (TMSCs) are useful for stem cell therapy in various diseases and can be differentiated into Schwann cell-like cells (TMSC-SCs). We investigated the potential of TMSC-SCs called neuronal regeneration-promoting cells (NRPCs) for peripheral nerve and muscle regeneration in C22 mice, a model for CMT1A. We transplanted NRPCs manufactured in a good manufacturing practice facility into the bilateral thigh muscles of C22 mice and performed behavior and nerve conduction tests and histological and ultrastructural analyses. Significantly, the motor function was much improved, the ratio of myelinated axons was increased, and the G-ratio was reduced by the transplantation of NRPCs. The sciatic nerve and gastrocnemius muscle regeneration of C22 mice following the transplantation of NRPCs downregulated PMP22 overexpression, which was observed in a dose-dependent manner. These results suggest that NRPCs are feasible for clinical research for the treatment of CMT1A patients. Research applying NRPCs to other peripheral nerve diseases is also needed.

Biochemical and functional characterization of skeletal muscle cells differentiated from tonsil-derived mesenchymal stem cells

INTRODUCTION/AIMS

Human tonsils are a readily accessible source of stem cells for the potential treatment of skeletal muscle disorders. We reported previously that tonsil-derived mesenchymal stem cells (TMSCs) can differentiate into skeletal muscle cells (SKMCs), which renders TMSCs promising candidates for cell therapy for skeletal muscle disorders. However, the functional properties of the myocytes differentiated from mesenchymal stem cells have not been clearly evaluated. In this study we investigated whether myocytes differentiated from TMSCs (skeletal muscle cells derived from tonsil mesenchymal stem cells [TMSC-SKMCs]) exhibit the functional characteristics of SKMCs.

METHODS

To test the insulin reactivity of TMSC-SKMCs, the expression of glucose transporter 4 (GLUT4) and phosphatidylinositol 3-kinase/Akt was analyzed after the cells were treated for 30 minutes with 100 nmol/L insulin in normal or high-glucose medium. We also examined whether these cells formed a neuromuscular junction (NMJ) when cocultured with motor neurons, and whether they were stimulated by electrical signals using whole-cell patch clamping.

RESULTS

Skeletal muscle cells derived from tonsil mesenchymal stem cells expressed SKMC markers, such as MYOD, MYH3, MYH8, TNNI1, and TTN, at high levels, and exhibited a multinucleated cell morphology and a myotube-like shape. The expression of the acetylcholine receptor and GLUT4 was confirmed in TMSC-SKMCs. In addition, these cells exhibited insulin-mediated glucose uptake, NMJ formation, and transient changes in cell membrane action potential, all of which are representative functions of human SKMCs.

DISCUSSION

Tonsil-derived mesenchymal stem cells can be functionally differentiated into SKMCs and may have potential for clinical application for the treatment of skeletal muscle disorders.

Study on the Mechanism of BMSCs in Regulating NF-κB Signal Pathway by Targeting miR-449a to Improve the Inflammatory Response to Peripheral Nerve Injury

OBJECTIVE

To evaluate the mechanism of Bone Marrow Mesenchymal Stem Cells (BMSCs) in regulating NF-κB signal pathway by targeting miR-449a.

METHODS

Stem cells were transfected by over-expressing and inhibiting miR-449a to detect the levels and viability of miR-449a in stem cells after transfection. Stem cells and neurons were co-cultured in vitro to evaluate the in vitro mechanism of stem cells over-expressing miR-449a on neurons.

RESULTS

After the addition of neurons, the neuronal activity of miR-449a over-expression group increased significantly, the expression of NF-κB signal pathway proteins (IκBα, p50, and p65) decreased, and the inflammatory cytokines (TNF-α and IL-1β) decreased significantly (P<0.05). In vivo experiments in rats also showed that rats were unresponsive, did not chirp or elude after being stimulated. After stem cell therapy, the weight and response of rats gradually returned to normal levels. miR-449a expression significantly increased in the stem cell + miR-449a over-expression group, expression of NF-κB signal pathway proteins (IκBα, p50, and p65) decreased, inflammatory cytokines (TNF-α and IL-1β) significantly decreased, and cell activity significantly increased (P<0.05).

CONCLUSIONS

BMSCs can modulate NF-κB signaling pathway by targeting miR-449a, so as to reduce the inflammatory response to peripheral nerve injury and repair nerve injury.

Improving motor neuron-like cell differentiation of hEnSCs by the combination of epothilone B loaded PCL microspheres in optimized 3D collagen hydrogel

Spinal cord regeneration is limited due to various obstacles and complex pathophysiological events after injury. Combination therapy is one approach that recently garnered attention for spinal cord injury (SCI) recovery. A composite of three-dimensional (3D) collagen hydrogel containing epothilone B (EpoB)-loaded polycaprolactone (PCL) microspheres (2.5 ng/mg, 10 ng/mg, and 40 ng/mg EpoB/PCL) were fabricated and optimized to improve motor neuron (MN) differentiation efficacy of human endometrial stem cells (hEnSCs). The microspheres were characterized using liquid chromatography-mass/mass spectrometry (LC-mas/mas) to assess the drug release and scanning electron microscope (SEM) for morphological assessment. hEnSCs were isolated, then characterized by flow cytometry, and seeded on the optimized 3D composite. Based on cell morphology and proliferation, cross-linked collagen hydrogels with and without 2.5 ng/mg EpoB loaded PCL microspheres were selected as the optimized formulations to compare the effect of EpoB release on MN differentiation. After differentiation, the expression of MN markers was estimated by real-time PCR and immunofluorescence (IF). The collagen hydrogel containing the EpoB group had the highest HB9 and ISL-1 expression and the longest neurite elongation. Providing a 3D permissive environment with EpoB, significantly improves MN-like cell differentiation and maturation of hEnSCs and is a promising approach to replace lost neurons after SCI.

Direct differentiation of tonsillar biopsy-derived stem cells to the neuronal lineage

BACKGROUND

Neurological disorders are considered one of the greatest burdens to global public health and a leading cause of death. Stem cell therapies hold great promise for the cure of neurological disorders, as stem cells can serve as cell replacement, while also secreting factors to enhance endogenous tissue regeneration. Adult human multipotent stem cells (MSCs) reside on blood vessels, and therefore can be found in many tissues throughout the body, including palatine tonsils. Several studies have reported the capacity of MSCs to differentiate into, among other cell types, the neuronal lineage. However, unlike the case with embryonic stem cells, it is unclear whether MSCs can develop into mature neurons.

METHODS

Human tonsillar MSCs (T-MSCs) were isolated from a small, 0.6-g sample, of tonsillar biopsies with high viability and yield as we recently reported. Then, these cells were differentiated by a rapid, multi-stage procedure, into committed, post-mitotic, neuron-like cells using defined conditions.

RESULTS

Here we describe for the first time the derivation and differentiation of tonsillar biopsy-derived MSCs (T-MSCs), by a rapid, multi-step protocol, into post-mitotic, neuron-like cells using defined conditions without genetic manipulation. We characterized our T-MSC-derived neuronal cells and demonstrate their robust differentiation in vitro.

CONCLUSIONS

Our procedure leads to a rapid neuronal lineage commitment and loss of stemness markers, as early as three days following neurogenic differentiation. Our studies identify biopsy-derived T-MSCs as a potential source for generating neuron-like cells which may have potential use for in vitro modeling of neurodegenerative diseases or cell replacement therapies.

Loss of FEZ1, a gene deleted in Jacobsen syndrome, causes locomotion defects and early mortality by impairing motor neuron development

FEZ1-mediated axonal transport plays important roles in central nervous system development but its involvement in the peripheral nervous system is not well-characterized. FEZ1 is deleted in Jacobsen syndrome (JS), an 11q terminal deletion developmental disorder. JS patients display impaired psychomotor skills, including gross and fine motor delay, suggesting that FEZ1 deletion may be responsible for these phenotypes, given its association with the development of motor-related circuits. Supporting this hypothesis, our data show that FEZ1 is selectively expressed in the rat brain and spinal cord. Its levels progressively increase over the developmental course of human motor neurons (MN) derived from embryonic stem cells. Deletion of FEZ1 strongly impaired axon and dendrite development, and significantly delayed the transport of synaptic proteins into developing neurites. Concurring with these observations, Drosophila unc-76 mutants showed severe locomotion impairments, accompanied by a strong reduction of synaptic boutons at neuromuscular junctions. These abnormalities were ameliorated by pharmacological activation of UNC-51/ATG1, a FEZ1-activating kinase, with rapamycin and metformin. Collectively, the results highlight a role for FEZ1 in MN development and implicate its deletion as an underlying cause of motor impairments in JS patients.

A transcriptomic analysis of serial-cultured, tonsil-derived mesenchymal stem cells reveals decreased integrin α3 protein as a potential biomarker of senescent cells

Background

Mesenchymal stem cells (MSCs) have been widely used for stem cell therapy, and serial passage of stem cells is often required to obtain sufficient cell numbers for practical applications in regenerative medicine. A long-term serial cell expansion can potentially induce replicative senescence, which leads to a progressive decline in stem cell function and stemness, losing multipotent characteristics. To improve the therapeutic efficiency of stem cell therapy, it would be important to identify specific biomarkers for senescent cells.

Methods

Tonsil-derived mesenchymal stem cells (TMSCs) with 20–25 passages were designated as culture-aged TMSCs, and their mesodermal differentiation potentials as well as markers of senescence and stemness were compared with the control TMSCs passaged up to 8 times at the most (designated as young). A whole-genome analysis was used to identify novel regulatory factors that distinguish between the culture-aged and control TMSCs. The identified markers of replicative senescence were validated using Western blot analyses.

Results

The culture-aged TMSCs showed longer doubling time compared to control TMSCs and had higher expression of senescence-associated (SA)-β-gal staining but lower expression of the stemness protein markers, including Nanog, Oct4, and Sox2 with decreased adipogenic, osteogenic, and chondrogenic differentiation potentials. Microarray analyses identified a total of 18,614 differentially expressed genes between the culture-aged and control TMSCs. The differentially expressed genes were classified into the Gene Ontology categories of cellular component (CC), functional component (FC), and biological process (BP) using KEGG (Kyoto encyclopedia of genes and genomes) pathway analysis. This analysis revealed that those genes associated with CC and BP showed the most significant difference between the culture-aged and control TMSCs. The genes related to extracellular matrix-receptor interactions were also shown to be significantly different (p < 0.001). We also found that culture-aged TMSCs had decreased expressions of integrin α3 (ITGA3) and phosphorylated AKT protein (p-AKT-Ser⁴⁷³) compared to the control TMSCs.

Conclusions

Our data suggest that activation of ECM-receptor signaling, specifically involved with integrin family-mediated activation of the intracellular cell survival-signaling molecule AKT, can regulate stem cell senescence in TMSCs. Among these identified factors, ITGA3 was found to be a representative biomarker of the senescent TMSCs. Exclusion of the TMSCs with the senescent TMSC markers in this study could potentially increase the therapeutic efficacy of TMSCs in clinical applications.

Nerve guide conduits for peripheral nerve injury repair: A review on design, materials and fabrication methods

Peripheral nerves can sustain injuries due to loss of structure and/or function of peripheral nerves because of accident, trauma and other causes, which leads to partial or complete loss of sensory, motor, and autonomic functions and neuropathic pain. Even with the extensive knowledge on the pathophysiology and regeneration mechanisms of peripheral nerve injuries (PNI), reliable treatment methods that ensure full functional recovery are scant. Nerve autografting is the current gold standard for treatment of PNI. Given the limitations of autografts including donor site morbidity and limited supply, alternate treatment methods are being pursued by the researchers. Neural guide conduits (NGCs) are increasingly being considered as a potential alternative to nerve autografts. The anatomy of peripheral nerves, classification of PNI, and current treatment methods are briefly yet succinctly reviewed. A detailed review on the various designs of NGCs, the different materials used for making the NGCs, and the fabrication methods adopted is presented in this work. Much progress had been made in all the aspects of making an NGC, including the design, materials and fabrication techniques. The advent of advanced technologies such as additive manufacturing and 3D bioprinting could be beneficial in easing the production of patient-specific NGCs. NGCs with supporting cells or stem cells, NGCs loaded with neurotropic factors and drugs, and 4D printed NGCs are some of the futuristic areas of interest. STATEMENT OF SIGNIFICANCE: Neural guide conduits (NGCs) are increasingly being considered as a potential alternative to nerve autografts in the treatment of peripheral nerve injuries. A detailed review on the various designs of NGCs, the different materials used for making the NGCs, and the fabrication methods (including Additive Manufacturing) adopted is presented in this work.