In Vitro Differentiation of Bone Marrow Mesenchymal Stem Cells into Neuron-Like Cells by Cerebrospinal Fluid Improves Motor Function of Middle Cerebral Artery Occlusion Rats

Comparison of compositional MRI techniques to quantify the regenerative potential of articular cartilage: a preclinical minipig model after osteochondral defect treatments with autologous mesenchymal stromal cells and unseeded scaffolds

Background

The field of orthopedics seeks effective, safer methods for evaluating articular cartilage regeneration. Despite various treatment innovations, non-invasive, contrast-free full quantitative assessments of hyaline articular cartilage's regenerative potential using compositional magnetic resonance (MR) sequences remain challenging. In this context, our aim was to investigate the effectiveness of different MR sequences for quantitative assessment of cartilage and to compare them with the current gold standard delayed gadolinium-enhanced MR imaging of cartilage (dGEMRIC) measurements.

Methods

We employed ex vivo imaging in a preclinical minipig model to assess knee cartilage regeneration. Standardized osteochondral defects were drilled in the proximal femur of the specimens (n=14), which were divided into four groups. Porcine collagen scaffolds seeded with autologous adipose-derived stromal cells (ASC), autologous bone marrow stromal cells (BMSC), and unseeded scaffolds (US) were implanted in femoral defects. Furthermore, there was a defect group which received no treatment. After 6 months, the specimens were examined using different compositional MR methods, including the gold standard dGEMRIC as well as T1, T2, T2*, and T1ρ techniques. The statistical evaluation involved comparing the defect region with the uninjured tibia and femur cartilage layers and all measurements were performed on a clinical 3T MR Scanner.

Results

In the untreated defect group, we observed significant differences in the defect region, with dGEMRIC values significantly lower (404.86±64.2 ms, P=0.018) and T2 times significantly higher (44.24±2.75 ms, P<0.001). Contrastingly, in all three treatment groups (ASC, BMSC, US), there were no significant differences among the three regions in the dGEMRIC sequence, suggesting successful cartilage regeneration. However, T1, T2*, and T1ρ sequences failed to detect such differences, highlighting their lower sensitivity for cartilage regeneration.

Conclusions

As expected, dGEMRIC is well suited for monitoring cartilage regeneration. Interestingly, T2 imaging also proved to be a reliable cartilage imaging technique and thus offers a contrast agent-free alternative to the former gold standard for subsequent in vivo studies investigating the cartilage regeneration potential of different treatment modalities.

Pain Alleviating Effect of Adipose-Derived Stem Cells Transplantation on the Injured Spinal Cord: A Behavioral and Electrophysiological Evaluation

Few studies are conducted on the efficacy of human adipose-derived stem cells (ADSCs) in spinal cord injury (SCI) management and electrophysiological changes in the spinal cord. Therefore, the present study aimed to determine the effect of ADSCs on neuropathic pain, motor function recovery, and electrophysiology assessment. For the purpose of this study, adult male Wistar rats (weight: 140-160 gr, n = 42) were randomly allocated into five groups namely intact animals, sham-operated, SCI non-treated animals, vehicle-treated (culture media), and ADSCs treated groups. One week after clips compression SCI induction, about 1×10⁶ cells were transplanted into the spinal cord. As well, both neuropathic pain (allodynia and hyperalgesia) and motor function were measured weekly. Cavity size, ADSCs survival, and electrophysiology assessments were measured at the end of the eighth week. The transplantation of ADSCs resulted in a significant improvement in the locomotion of SCI animals (p<0.0001), mechanical allodynia (p<0.0001), cold allodynia (p<0.0001), mechanical hyperalgesia (p<0.0001), and thermal hyperalgesia (p<0.0001). The cavity size was significantly smaller among the ADSCs-treated animals (p <0.0001). The single-unit recording showed that the transplantation of ADSCs decreased wide dynamic range (WDR) in neurons and it evoked potential in response to receiving signals from Aβ (p<0.0001) and Aδ (p=0.003) C-fiber (p<0.0001) neurons. Post-discharge recorded from WDR neurons decreased after the transplantation of ADSCs (p<0.0001) and wind up in the ADSCs-treated group was lower than that of the SCI group (p=0.003). Our results showed that the transplantation of ADSCs could significantly alleviate neuropathic pain, enhance motor function recovery, and improve electrophysiology findings after SCI.

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.

Neuroprotective response and efficacy of intravenous administration of mesenchymal stem cells in traumatic brain injury mice

Cellular transplantation of stem cells can be a beneficial treatment approach for neurodegenerative diseases such as traumatic brain injury (TBI). In this study, we investigated the proliferation and differentiation potential of infused mesenchymal stem cells (MSCs) after localisation at the injury site. We evaluated the appropriate homing of infused MSCs through immunohistochemistry, followed by Y-chromosome-specific polymerase chain reaction and fluorescent in situ hybridisation analyses. The proliferation and differentiation of infused MSCs were analysed using exogenous cell tracer 5'-bromo-2'-deoxyuridine (BrdU) labelling and neuronal specific markers, respectively. Structural and functional recovery in TBI mice were examined by performing magnetic resonance imaging and different behavioural assessments, respectively. Results demonstrated a significantly high number of BrdU-positive cells in the lesion region in the MSC-infused group compared with control and TBI groups. Infused MSCs were well differentiated into neural-like cells and expressed significantly more neural markers (neuronal nuclear antigen [NeuN], microtubule-associated protein 2 [MAP2] and glial fibrillary acid protein [GFAP]). Improved tissue abnormalities as well as functional behaviours were observed in MSC-infused TBI mice, implying the substantial proliferation and differentiation of infused MSCs. Our findings support the neuroprotective response and efficacy of MSCs after transplantation in TBI mice, and MSCs may serve as potential therapeutic candidates in regenerative medicine.

Therapeutic Advancement in Neuronal Transdifferentiation of Mesenchymal Stromal Cells for Neurological Disorders

Neurodegenerative disorders have become the leading cause of chronic pain and death. Treatments available are not sufficient to help the patients as they only alleviate the symptoms and not the cause. In this regard, stem cells therapy has emerged as an upcoming option for the replacement of dead and damaged neurons. Stem cells, in general, are characterized as cells exhibiting potency properties, i.e., on being subjected to specific conditions they transform into cells of another lineage. Of all the types, mesenchymal stem cells (MSCs) are known for their pluripotent nature without the obstacle of ethical concern surrounding the procurement of other cell types. Although fibroblasts are quite similar to MSCs morphologically, certain markers like CD73, CD 90 are specific to MSCs, making both the cell types distinguishable from each other. This is implemented while procuring MSCs from a plethora of sources like umbilical cord blood, adipose tissue, bone marrow, etc. Among these, bone marrow MSCs are the most widely used type for neural regeneration. Neural regeneration is achieved via transdifferentiation. Several studies have either transplanted the stem cells into rodent models or have carried out transdifferentiation in vitro. The process involves a combination of growth factors, pre-treatment factors, and neuronal differentiation inducing mediums. The results obtained are characterized by neuron-like morphology, expression of markers, along with electrophysical activity in some. Recent attempts involve exploring biomaterials that may mimic the native ECM and therefore can be directly introduced at the site of interest. The review gives a brief description of MSCs, their sources and markers, and the different attempts that have been made towards achieving the goal of differentiating MSCs into neurons.

Mesenchymal stromal cell secretome as a therapeutic strategy for traumatic brain injury

Traumatic brain injury (TBI) is a global health problem that is a common cause of disability and mortality. Despite the availability of many treatment options, none is capable of restoring functional and structural recovery of the damaged brain. Both the results of preclinical and clinical studies suggest the use of mesenchymal stromal cells (MSCs) as a therapeutic strategy for structural and functional recovery in TBI. However, recent evidence shows that the neuroprotective potential of MSCs is due to multiple secretions of bioactive molecules that modulate tissue microenvironment for tissue repair and regeneration. The results of preclinical studies indicate the therapeutic benefits of MSC secretome in TBI. Soluble bioactive molecules and extracellular vesicles are the various factors secreted by MSCs that can induce neurogenesis, angiogenesis, neovascularization, and anti-inflammatory activities. This review highlights the neuroprotective effect of MSC secretome for the treatment of TBI. In addition, the possible challenges of secretome as biotherapeutics are identified and how some of the issues raised could be overcome for effective clinical application are also discussed.

Xeno-free trans-differentiation of adipose tissue-derived mesenchymal stem cells into glial and neuronal cells

Mesenchymal stem cells (MSCs) are undifferentiated cells that have the ability of self-renewal and trans-differentiation into other cell types. They hold out hope for finding a cure for many diseases. Nevertheless, there are still some obstacles that limit their clinical transplantation. One of these obstacles are the xenogeneic substances added in either proliferation or differentiation media with subsequent immunogenic and infectious transmission problems. In this study, we aimed to replace fetal bovine serum (FBS), the main nutrient source for MSC proliferation with xeno-free blood derivatives. We tested the effect of human activated pure platelet-rich plasma (P-PRP) and advanced platelet-rich fibrin (A-PRF) on the proliferation of human adipose derived-MSCs (AD-MSCs) at different concentrations. For the induction of MSC neural differentiation, we used human cerebrospinal fluid (CSF) at different concentrations in combination with P-PRP to effect xeno-free/species-specific neuronal/glial differentiation and we found that media with 10% CSF and 10% PRP promoted glial differentiation, while media with only 10% PRP induced a neuron-like phenotype.

Differentiation of human adipose-derived stem cells into neuron/motoneuron-like cells for cell replacement therapy of spinal cord injury

Human adipose-derived stem cells (hADSCs) are increasingly presumed to be a prospective stem cell source for cell replacement therapy in various degenerative and/or traumatic diseases. The potential of trans-differentiating hADSCs into motor neuron cells indisputably provides an alternative way for spinal cord injury (SCI) treatment. In the present study, a stepwise and efficient hADSC trans-differentiation protocol with retinoic acid (RA), sonic hedgehog (SHH), and neurotrophic factors were developed. With this protocol hADSCs could be converted into electrophysiologically active motoneuron-like cells (hADSC-MNs), which expressed both a cohort of pan neuronal markers and motor neuron specific markers. Moreover, after being primed for neuronal differentiation with RA/SHH, hADSCs were transplanted into SCI mouse model and they survived, migrated, and integrated into injured site and led to partial functional recovery of SCI mice. When ablating the transplanted hADSC-MNs harboring HSV-TK-mCherry overexpression system with antivirial Ganciclovir (GCV), functional relapse was detected by motor-evoked potential (MEP) and BMS assays, implying that transplanted hADSC-MNs participated in rebuilding the neural circuits, which was further confirmed by retrograde neuronal tracing system (WGA). GFP-labeled hADSC-MNs were subjected to whole-cell patch-clamp recording in acute spinal cord slice preparation and both action potentials and synaptic activities were recorded, which further confirmed that those pre-conditioned hADSCs indeed became functionally active neurons in vivo. As well, transplanted hADSC-MNs largely prevented the formation of injury-induced cavities and exerted obvious immune-suppression effect as revealed by preventing astrocyte reactivation and favoring the secretion of a spectrum of anti-inflammatory cytokines and chemokines. Our work suggests that hADSCs can be readily transformed into MNs in vitro, and stay viable in spinal cord of the SCI mouse and exert multi-therapeutic effects by rebuilding the broken circuitry and optimizing the microenvironment through immunosuppression.

Cerebrospinal fluid-stem cell interactions may pave the path for cell-based therapy in neurological diseases

Recent studies have suggested that the regulation of endogenous neural stem cells (NSCs) or transplanting of exogenous nerve cells are the newest and most promising methods for the treatment of dementia and other neurological diseases. The special location and limited number of endogenous NSCs, however, restrict their clinical application. The success in directional differentiation of exogenous stem cells from other tissue sources into neural cells has provided a novel source for NSCs. Study on the relative mechanisms is still at the preliminary stage. Currently the induction methods include: 1) cell growth factor induction; 2) chemical induction; 3) combined growth factor-chemical induction; or 4) other induction methods such as traumatic brain tissue homogenate, gene transfection, traditional Chinese medicine, and coculture induction. Cerebrospinal fluid (CSF), as a natural medium under physiological conditions, contains a variety of progrowth peptide factors that can promote the proliferation and differentiation of mesenchymal stromal cells (MSCs) into neural cells through the corresponding receptors on the cell surface. This suggests that CSF can not only nourish the nerve cells, but also become an effective and suitable inducer to increase the yield of NSCs. However, some other studies believed that CSF contained certain inhibitory components against the differentiation of primary stem cells into mature neural cells. Based on the above background, here we review the relative literature on the influence of the CSF on stem cells in order to provide a more comprehensive reference for the wide clinical application of NSCs in the future.

Comparison of the neuronal differentiation abilities of bone marrow‑derived and adipose tissue‑derived mesenchymal stem cells

Bone marrow-derived mesenchymal stem cells (BMSCs) and adipose tissue-derived mesenchymal stem cells (ADSCs) are able to differentiate into neuron-like cells when exposed to small molecule compounds, however the specific differences in their neuronal differentiation abilities remain to be fully elucidated. The present study aimed to compare the neuronal differentiation abilities of BMSCs and ADSCs. BMSCs and ADSCs from the same Sprague Dawley rats were isolated and cultured for use. The proliferation capacity was revealed using a cell counting method. Following BMSCs and ADSCs induction by four types of small-molecular compounds, the expression of various neuronal markers and the secretion of several neurotrophic factors were detected by immunofluorescence, western blotting, reverse transcription-quantitative polymerase chain reaction and ELISA. It was demonstrated that the ADSCs exhibited an increased proliferation capacity compared with BMSCs, according to cumulative population doubling analyses. Following a 7-day neuronal induction period, BMSCs and ADSCs exhibited a neuron-like morphology, and were termed neuronal induced (NI)-BMSCs and NI-ADSCs. They expressed neuronal markers including β-tubulin III, microtubule associated protein 2 and choline acetyltransferase. The number of NI-BMSCs that positively expressed the neuronal markers was significantly decreased compared with NI-ADSCs, and the expression and secretion of the neurotrophic factors nerve growth factor and 3′-nucleotidase in NI-BMSCs were additionally decreased compared with NI-ADSCs. The findings of the present study indicated that the neuronal differentiation abilities and neurotrophic factor secretion abilities of ADSCs were increased compared with BMSCs. ADSCs may therefore act as efficient candidates in cell transplantation therapy for diseases and injuries of the nervous system.