Cytoplasmic extracts from adipose tissue stromal cells alleviates secondary damage by modulating apoptosis and promotes functional recovery following spinal cord injury

Spinal Cord Injury: A Systematic Review and Network Meta-Analysis of Therapeutic Strategies Based on 15 Types of Stem Cells in Animal Models

Objective: The optimal therapeutic strategies of stem cells for spinal cord injury (SCI) are fully explored in animal studies to promote the translation of preclinical findings to clinical practice, also to provide guidance for future animal experiments and clinical studies.

Methods: PubMed, Web of Science, Embase, CNKI, Wangfang, VIP, and CBM were searched from inception to September 2021. Screening of search results, data extraction, and references quality evaluation were undertaken independently by two reviewers.

Results and Discussion: A total of 188 studies were included for data analysis. Results of traditional meta-analysis showed that all 15 diverse types of stem cells could significantly improve locomotor function of animals with SCI, and results of further network meta-analysis showed that adipose-derived mesenchymal stem cells had the greatest therapeutic potential for SCI. Moreover, a higher dose (≥1 × 106) of stem cell transplantation had better therapeutic effect, transplantation in the subacute phase (3–14 days, excluding 3 days) was the optimal timing, and intralesional transplantation was the optimal route. However, the evidence of current animal studies is of limited quality, and more high-quality research is needed to further explore the optimal therapeutic strategies of stem cells, while the design and implementation of experiments, as well as measurement and reporting of results for animal studies, need to be further improved and standardized to reduce the risk when the results of animal studies are translated to the clinic.

Systematic Review Registration: [website], identifier [registration number].

Regenerative medicine for spinal cord injury: focus on stem cells and biomaterials

INTRODUCTION

Spinal cord injury (SCI) is a dramatic medical pathology consequence of a trauma (primary injury). However, most of the post-traumatic degeneration of the tissue is caused by the so-called secondary injury, which is known to be a multifactorial process. This, indeed, includes a wide spectrum of events: blood-brain barrier dysfunction, local inflammation, neuronal death, demyelination and disconnection of nerve pathways.

AREAS COVERED

Cell therapy represents a promising cure to target diseases and disorders at the cellular level, by restoring cell population or using cells as carriers of therapeutic cargo. In particular, regenerative medicine with stem cells represents the most appealing category to be used, thanks to their peculiar features.

EXPERT OPINION

Many preclinical research studies demonstrated that cell treatment can improve animal sensory/motor functions and so demonstrated to be very promising for clinical trials. In particular, recent advances have led to the development of biomaterials aiming to promote in situ cell delivery. This review digs into this topic discussing the possibility of cell treatment to improve medical chances in SCI repair.

microRNA-196a promotes osteogenic differentiation and inhibit adipogenic differentiation of adipose stem cells via regulating β-catenin pathway

microRNAs play important roles in proliferation and differentiation of stem cells, but mechanisms by which microRNAs regulate osteogenic or adipogenic differentiation of adipose stem cells (ASCs) are still poorly understood. In the present study, results showed up-regulation of microRNA-196a was able to promote the osteogenic differentiation of ACSs, but down-regulation of microRNA-196a induced adipogenic differentiation. Further investigation indicated microRNA-196a could regulate Wnt signaling pathway to affect osteogenic or adipogenic differentiation of ASCs, addition of Wnt agonist 1 was able to reverse the down-regulated osteogenic differentiation of ASCs caused by microRNA-196a deficiency and inhibition of Wnt signaling pathway with XAV939 promoted the adipogenic differentiation of ASCs. Taken together, microRNA-196a may regulate Wnt signaling pathway to promote the osteogenic differentiation and inhibit the adipogenic differentiation of ASCs.

Stem cell paracrine effect and delivery strategies for spinal cord injury regeneration

Spinal cord injury (SCI) is a complicated neuropathological condition that results in functional dysfunction and paralysis. Various treatments have been proposed including drugs, biological factors and cells administered in several ways. Stem cell therapy offers a potentially revolutionary mode to repair the damaged spinal cord after injury. Initially, stem cells were considered promising for replacing cells and tissue lost after SCI. Many studies looked at their differentiation to replace neuronal and glial cells for a better functional outcome. However, it is becoming clear that different functional improvements recognized to stem cells are due to biomolecular activities by the transplanted stem cells rather than cell replacement. This review aimed to discuss the paracrine mechanisms for tissue repair and regeneration after stem cell transplantation in SCI. It focuses on stem cell factor production, effect in tissue restoration, and novel delivery strategies to use them for SCI therapy.

MicroRNA‑381/Hes1 is a potential therapeutic target for spinal cord injury

The aim of the present study was to investigate whether microRNA‑381 is a potential therapeutic target for spinal cord injury (SCI) and its possible mechanism. Reverse transcription quantitative polymerase chain reaction (qPCR) for mRNA expression was used to analyze the changes of microRNA-381 expression. Cell viability and cell apoptosis were measured using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and flow cytometry. Caspase‑3 activity was measured using caspase‑3 activity kit, and western blot analysis was used to measure the protein expression of neurogenic locus notch homolog protein 1 (Notch1), notch 1 intracellular domain (NICD) and transcription factor HES-1 (Hes1). The data showed that microRNA‑381 expression of model SCI rats was downregulated compared with that of control rats. Overexpression of microRNA‑381 promoted cell proliferation, and inhibited apoptosis and caspase‑3 and apoptosis regulator BAX (Bax) protein expression in neurocytes. Overexpression of microRNA‑381 also increased Wnt and β‑catenin protein expression, and suppressed the protein expression of Notch1, NICD and Hes1 in neurocytes. Wnt inhibitor, Wnt‑C59 (1 µmol/l), inhibited cell proliferation, promoted apoptosis and caspase‑3 and Bax protein expression, suppressed β‑catenin protein expression and induced Hes1 protein expression in neurocytes following microRNA‑381 overexpression. Notch inhibitor, FLI‑06 (1 µmol/l), promoted cell proliferation, inhibited apoptosis and caspase‑3 and Bax protein expression, and suppressed NICD and Hes1 protein expression in neurocytes following microRNA‑381 overexpression. Thus, this study showed that overexpression of microRNA‑381 promotes cell proliferation of neurocytes in SCI via Hes1 expression, which may be a novel important mechanism for SCI in clinical applications.

Current Options for Cell Therapy in Spinal Cord Injury

Spinal cord injury (SCI) is a complex pathology that evolves after primary acute mechanical injury, causing further damage to the spinal cord tissue that exacerbates clinical outcomes. Based on encouraging results from preclinical experiments, some cell treatments being translated into clinical practice demonstrate promising and effective improvement in sensory/motor function. Combinatorial treatments of cell and drug/biological factors have been demonstrated to be more effective than cell treatments alone. Recent advances have led to the development of biomaterials aiming to promote in situ cell delivery for SCI, together with combinatorial strategies using drugs/biomolecules to achieve a maximized multitarget approach. This review provides an overview of single and combinatorial regenerative cell treatments as well as potential delivery options to treat SCI.

Methylprednisolone promotes recovery of neurological function after spinal cord injury: association with Wnt/β-catenin signaling pathway activation

Some studies have indicated that the Wnt/β-catenin signaling pathway is activated following spinal cord injury, and expression levels of specific proteins, including low-density lipoprotein receptor related protein-6 phosphorylation, β-catenin, and glycogen synthase kinase-3β, are significantly altered. We hypothesized that methylprednisolone treatment contributes to functional recovery after spinal cord injury by inhibiting apoptosis and activating the Wnt/β-catenin signaling pathway. In the current study, 30 mg/kg methylprednisolone was injected into rats with spinal cord injury immediately post-injury and at 1 and 2 days post-injury. Basso, Beattie, and Bresnahan scores showed that methylprednisolone treatment significantly promoted locomotor functional recovery between 2 and 6 weeks post-injury. The number of surviving motor neurons increased, whereas the lesion size significantly decreased following methylprednisolone treatment at 7 days post-injury. Additionally, caspase-3, caspase-9, and Bax protein expression levels and the number of apoptotic cells were reduced at 3 and 7 days post-injury, while Bcl-2 levels at 7 days post-injury were higher in methylprednisolone-treated rats compared with saline-treated rats. At 3 and 7 days post-injury, methylprednisolone up-regulated expression and activation of the Wnt/β-catenin signaling pathway, including low-density lipoprotein receptor related protein-6 phosphorylation, β-catenin, and glycogen synthase kinase-3β phosphorylation. These results indicate that methylprednisolone-induced neuroprotection may correlate with activation of the Wnt/β-catenin signaling pathway.

Therapeutic potential of human adipose-derived stem cells in neurological disorders

Stem cell therapy has been noted as a novel strategy to various diseases including neurological disorders such as Alzheimer's disease, Parkinson's disease, stroke, amyotrophic lateral sclerosis, and Huntington's disease that have no effective treatment available to date. The adipose-derived stem cells (ASCs), mesenchymal stem cells (MSCs) isolated from adipose tissue, are well known for their pluripotency with the ability to differentiate into various types of cells and immuno-modulatory property. These biological features make ASCs a promising source for regenerative cell therapy in neurological disorders. Here we discuss the recent progress of regenerative therapies in various neurological disorders utilizing ASCs.

Neurotrauma and mesenchymal stem cells treatment: From experimental studies to clinical trials

Mesenchymal stem cell (MSC) therapy has attracted the attention of scientists and clinicians around the world. Basic and pre-clinical experimental studies have highlighted the positive effects of MSC treatment after spinal cord and peripheral nerve injury. These effects are believed to be due to their ability to differentiate into other cell lineages, modulate inflammatory and immunomodulatory responses, reduce cell apoptosis, secrete several neurotrophic factors and respond to tissue injury, among others. There are many pre-clinical studies on MSC treatment for spinal cord injury (SCI) and peripheral nerve injuries. However, the same is not true for clinical trials, particularly those concerned with nerve trauma, indicating the necessity of more well-constructed studies showing the benefits that cell therapy can provide for individuals suffering the consequences of nerve lesions. As for clinical trials for SCI treatment the results obtained so far are not as beneficial as those described in experimental studies. For these reasons basic and pre-clinical studies dealing with MSC therapy should emphasize the standardization of protocols that could be translated to the clinical set with consistent and positive outcomes. This review is based on pre-clinical studies and clinical trials available in the literature from 2010 until now. At the time of writing this article there were 43 and 36 pre-clinical and 19 and 1 clinical trials on injured spinal cord and peripheral nerves, respectively.

Mesenchymal stem cells in the treatment of spinal cord injuries: A review

With technological advances in basic research, the intricate mechanism of secondary delayed spinal cord injury (SCI) continues to unravel at a rapid pace. However, despite our deeper understanding of the molecular changes occurring after initial insult to the spinal cord, the cure for paralysis remains elusive. Current treatment of SCI is limited to early administration of high dose steroids to mitigate the harmful effect of cord edema that occurs after SCI and to reduce the cascade of secondary delayed SCI. Recent evident-based clinical studies have cast doubt on the clinical benefit of steroids in SCI and intense focus on stem cell-based therapy has yielded some encouraging results. An array of mesenchymal stem cells (MSCs) from various sources with novel and promising strategies are being developed to improve function after SCI. In this review, we briefly discuss the pathophysiology of spinal cord injuries and characteristics and the potential sources of MSCs that can be used in the treatment of SCI. We will discuss the progress of MSCs application in research, focusing on the neuroprotective properties of MSCs. Finally, we will discuss the results from preclinical and clinical trials involving stem cell-based therapy in SCI.

Compensation of cATSCs-derived TGFβ1 and IL10 expressions was effectively modulated atopic dermatitis

In this study, we found an effective and novel therapeutic approach to atopic dermatitis (AD) therapy via treatment with a canine adipose tissue stem cell (cATSC) extract. We determined that the therapeutic application of cATSC-derived interleukin 10 (IL10) and transforming growth factor β1 (TGFβ1) effectively modulated the overloaded immune response after the induction of AD. In addition, we investigated the molecular role of the cATSC extract during AD treatment. Dogs with naturally occurring AD that was treated at Seoul National University Veterinary Teaching Hospital was enrolled in this study. Owner consent was obtained for privately owned dogs before enrollment. We prepared a primary fat-derived cATSC extract that contained various functional factors, including IL10 and TGFβ1, as a treatment for AD. We found that the cATSC extract significantly ameliorated the pathological symptoms of canine AD. The cATSC extract secreted the immunomodulatory cytokines IL10 and TGFβ1, which modulated the overloaded immune response after the induction of AD. Moreover, these immunomodulatory cytokines modulated AD-induced inflammation and inactivated the pathological signals IL6, INFγ, iNOS, eNOS and Nox4. Additionally, these cytokines protected against apoptotic keratinocyte degeneration. This study demonstrated the novel therapeutic efficacy of the cATSC extract during successive AD treatments, which suggests a potential therapeutic use for human AD patients.

Wnt5a-mediating neurogenesis of human adipose tissue-derived stem cells in a 3D microfluidic cell culture system

In stem cell biology, cell plasticity refers to the ability of stem cells to differentiate into a variety of cell lineages. Recently, cell plasticity has been used to refer to the ability of a given cell type to reversibly de-differentiate, re-differentiate, or transdifferentiate in response to specific stimuli. These processes are regulated by multiple intracellular and extracellular growth and differentiation factors, including low oxygen. Our recent study showed that 3D microfluidic cell culture induces activation of the Wnt5A/β-catenin signaling pathway in hATSCs (human Adipose Tissue-derived Stem Cells). This resulted in self renewal and transdifferentiation of hATSCs into neurons. To improve neurogenic potency of hATSCs in response to low oxygen and other unknown physical factors, we developed a gel-free 3D microfluidic cell culture system (3D-μFCCS). The functional structure was developed for the immobilization of 3D multi-cellular aggregates in a microfluidic channel without the use of a matrix on the chip. Growth of hATSCs neurosphere grown on a chip was higher than the growth of control cells grown in a culture dish. Induction of differentiation in the Chip system resulted in a significant increase in the induction of neuronal-like cell structures and the presentation of TuJ or NF160 positive long neuritis compared to control cells after active migration from the center of the microfluidic channel layer to the outside of the microfluidic channel layer. We also observed that the chip neurogenesis system induced a significantly higher level of GABA secreting neurons and, in addition, almost 60% of cells were GABA + cells. Finally, we observed that 1 month of after the transplantation of each cell type in a mouse SCI lesion, chip cultured and neuronal differentiated hATSCs exhibited the ability to effectively transdifferentiate into NF160 + motor neurons at a high ratio. Interestingly, our CHIP/PCR analysis revealed that HIF1α-induced hATSCs neurogenesis on the chip. This induction was a result of the direct binding of HIF1α to the regulatory regions of the Oct4 and β-catenin genes in nucleus. In the Chip culture of hATSCs that we developed, a low oxygen microenvironment was induced. The low oxygen level induced HIF1α expression, which resulted in increased expression of Wnt5A/β-catenin and Oct4 via the direct binding of HIF1α to the regulatory regions of β-catenin and Oct4.

Long-term in vivo regeneration of peripheral nerves through bioengineered nerve grafts

Although autologous nerve graft is still the first choice strategy in nerve reconstruction, it has the severe disadvantage of the sacrifice of a functional nerve. Cell transplantation in a bioartificial conduit is an alternative strategy to improve nerve regeneration. Nerve fibrin conduits were seeded with various cell types: primary Schwann cells (SC), SC-like differentiated bone marrow-derived mesenchymal stem cells (dMSC), SC-like differentiated adipose-derived stem cells (dASC). Two further control groups were fibrin conduits without cells and autografts. Conduits were used to bridge a 1 cm rat sciatic nerve gap in a long term experiment (16 weeks). Functional and morphological properties of regenerated nerves were investigated. A reduction in muscle atrophy was observed in the autograft and in all cell-seeded groups, when compared with the empty fibrin conduits. SC showed significant improvement in axon myelination and average fiber diameter of the regenerated nerves. dASC were the most effective cell population in terms of improvement of axonal and fiber diameter, evoked potentials at the level of the gastrocnemius muscle and regeneration of motoneurons, similar to the autografts. Given these results and other advantages of adipose derived stem cells such as ease of harvest and relative abundance, dASC could be a clinically translatable route towards new methods to enhance peripheral nerve repair.

Neural differentiation of human adipose tissue-derived stem cells

While adult stem cells can be induced to transdifferentiate into multiple lineages of cells or tissues, their plasticity and utility for human therapy remains controversial. In this chapter, we describe methods for the transdifferentiation of human adipose tissue-derived stem cells (ASCs) along neural lineages using in vitro and in vivo systems. The in vitro neural differentiation of ASCs has been reported by several groups using serum-free cytokine induction, butylated hydroxyanisole (BHA) chemical induction, and neurosphere formation in combination with the cytokines, such as brain-derived neurotrophic factor (BDNF) and basic fibroblast growth factor (bFGF). For in vivo neurogenic induction, ASCs are treated with BDNF and bFGF to form neurospheres in vitro and then delivered directly to the brain. In this chapter, several detailed protocols for the effective neurogenic induction of ASCs in vitro and in vivo are described. The protocols described herein can be applied to further molecular and mechanistic studies of neurogenic induction and differentiation of ASCs. In addition, these methods can be useful for differentiating ASCs for therapeutic intervention in central nervous system disorders.

Generation and characterization of neurospheres from canine adipose tissue-derived stromal cells

Adipose tissue-derived stromal cells (ADSCs) have been identified as a powerful stem cell source for cellular transplantation therapy. The dog is increasingly used as a model of human neurological disease; however, few studies have reported induction of canine ADSCs to neural lineages. We characterized canine ADSCs and investigated whether they could be induced to differentiate into neural lineages. Subcutaneous adipose tissue collected from the dorsal epaxial region of adult dogs aged from 1 to 6 years was cultured to produce ADSCs that were then induced to neural lineages. RT-PCR, flow cytometry, and immunocytochemistry were performed to characterize these cell populations. Morphologically fibroblast-like ADSCs were isolated and had similar characteristics to mesenchymal stem cells. Under neurogenic conditions containing basic fibroblast growth factor and epidermal growth factor, ADSCs formed spherical cellular aggregates that resembled neurospheres. RT-PCR confirmed expression of Sox2 and CD90 by these aggregates. Expression of neural stem/progenitor markers (Nestin, Sox2, Vimentin) and neural lineage markers (A2B5, GFAP, Tuj1) was shown on immunocytochemistry. After differentiation, 60% of the cells were Tuj1 positive. In conclusion, we isolated and generated neural progenitor cells from canine ADSCs. ADSCs have potential for future autologous cell transplantation therapy for neurological disorders.

Functional recovery after the transplantation of neurally differentiated mesenchymal stem cells derived from bone marrow in a rat model of spinal cord injury

This study was designed to investigate functional recovery after the transplantation of mesenchymal stem cells (MSCs) or neurally differentiated MSCs (NMSCs) derived from bone marrow in a rat model of spinal cord injury (SCI). Sprague-Dawley rats were subjected to incomplete SCI using an NYU impactor to create a free drop contusion at the T9 level. The SCI rats were then classified into three groups; MSCs, NMSCs, and phosphate-buffered saline (PBS)-treated groups. The cells or PBS were administrated 1 week after SCI. Basso-Beattie-Bresnahan (BBB) locomotor rating scores were measured at 1-week intervals for 9 weeks. Somatosensory evoked potentials (SSEPs) and motor evoked potentials (MEPs) were also recorded 8 weeks after transplantation. While transplantation of MSCs led to a clear tendency of motor recovery, NMSC-treated rats had significantly improved BBB scores and showed significantly shortened initial latency, N1 latency, and P1 latency of the SSEPs compared to PBS controls. In addition, 5-bromo-2-deoxyuridine (BrdU)-prelabeled MSCs costained for BrdU and glial fibrillary acidic protein (GFAP) or myelin basic protein (MBP) were found rostrally and caudally 5 mm each from the epicenter of the necrotic cavity 4 weeks after transplantation. These results suggest that neurally differentiated cells might be an effective therapeutic source for functional recovery after SCI.

Effect of freshly isolated autologous tissue resident stromal cells on cardiac function and perfusion following acute myocardial infarction

BACKGROUND

The aim of this study was to investigate the effect of intracoronary administration of freshly isolated, uncultured autologous tissue-derived stromal cells on cardiac function and perfusion after acute infarction in pigs.

METHODS

A transmural myocardial infarction in a porcine model was induced by occlusion of the mid LAD with an angioplasty balloon for 3 h. Upon reperfusion, freshly isolated, uncultured autologous stromal cells (1.5×10⁶ cells/kg) or control solution was injected into the infarct artery. Cardiac function and area at risk were determined by (99m)Tc-SPECT.

RESULTS

Eight weeks after infarction, cell treated pigs showed a 20% smaller myocardial perfusion defect compared to control animals (35±9% vs. 44±5% of LV, treated vs. control, respectively, p<0.05). The reduction of the perfusion defect was associated with a significantly higher myocardial salvage index in the cell group as well as a significant increase in ejection fraction compared to control (EF at 8 weeks 43±7% vs. 35±3%, treated vs. control, respectively, p<0.05). This functional improvement was reflected by an increased wall thickness of the infarct and border zone in the treated group (11.2±2.2 mm) compared to control (8.6±1.6 mm, p<0.05) as well as an increased capillary density in the border zone (treated vs. control; 41.6±17.9 vs. 32.9±12.6 capillaries per 0.1 mm², p<0.05).

CONCLUSIONS

This study demonstrates for the first time that recovery and intracoronary delivery of uncultured autologous tissue derived stromal cells at time of vessel reperfusion is feasible and improves ventricular function.

Recombinant Human Erythropoietin Protects against Experimental Spinal Cord Trauma Injury by Regulating Expression of the Proteins MKP-1 and p-ERK

The present study explored the tissue-protective effect of erythropoietin in rats after experimental spinal cord injury (SCI) produced by dropping a weight onto surgically exposed spinal cord. Sixty rats were randomized to sham operation (spinal cord exposure; control), SCI plus intraperitoneal saline injection, or SCI plus intraperitoneal erythropoietin injection. Locomotor function was evaluated with Basso, Beattie and Bresnahan scores 1 day (24 h) and 7 days later, and rats were then killed for analysis of lesion site tissue. Compared with saline-treated SCI rats, erythropoietin-treated SCI rats showed significantly less locomotor dysfunction and faster locomotor recovery. Immunohistochemistry showed that erythropoietin-treated SCI rats had a significantly lower phospho-extracellular signal-regulated kinase (p-ERK) protein expression and a significantly higher mitogen-activated protein kinase phosphatase-1 (MKP-1) protein expression than saline-treated SCI rats. Haematoxylin–eosin staining showed progressive disruption of dorsal white matter and neuron loss after SCI; lesions were less severe and there was more neuron regeneration in the erythropoietin group than in the saline group. It is concluded that erythropoietin reduces pathological changes and SCI severity via down-regulation of p-ERK and up-regulation of MKP-1.

Stronger expression of CHOP and caspase 12 in diabetic spinal cord injury rats

OBJECTIVES

It is suggested that the injury-induced cell death of neurons within the spinal cord is related with endoplasmic reticulum (ER) stress. In this work, we explored that diabetes induce more severe spinal cord injury (SCI) and stronger ER stress in rats.

METHODS

Forty-five Sprague-Dawley rats were divided into three groups at random (the sham operation control group, SCI group and diabetic SCI group). Streptozotocin was injected into the caudal vein (30 mg/kg) to induce diabetes; 4 weeks after diabetes model induction, using a weight-drop contusion model of SCI in SCI group and diabetic SCI group; then, rats were killed at 24 hours and 7 days, and the level of C/EBP homologous transcription factor protein (CHOP), a proapoptotic protein, and caspase 12 were determined by immunohistochemistry staining and real-time reverse transcription quantitative polymerase chain reaction analysis.

RESULTS

We observe that both CHOP and caspase 12 were higher in diabetic SCI group than in the SCI group. Diabetes also caused severe locomotor dysfunction and slowly recovered as their Basso, Beattie and Bresnaha scores lowered. Pathological hematoxylin-eosin staining observation also showed progressive disruption of the dorsal white and few neurons regeneration in diabetic SCI rats.

DISCUSSION

These results suggest that stronger ER stress in diabetic rats may be the reason for severe SCI observed.