Comparison of transdifferentiated and untransdifferentiated human umbilical mesenchymal stem cells in rats after traumatic brain injury

Systematic review and meta-analysis of preclinical studies testing mesenchymal stromal cells for traumatic brain injury

Mesenchymal stromal cells (MSCs) are widely used in preclinical models of traumatic brain injury (TBI). Results are promising in terms of neurological improvement but are hampered by wide variability in treatment responses. We made a systematic review and meta-analysis: (1) to assess the quality of evidence for MSC treatment in TBI rodent models; (2) to determine the effect size of MSCs on sensorimotor function, cognitive function, and anatomical damage; (3) to identify MSC-related and protocol-related variables associated with greater efficacy; (4) to understand whether MSC manipulations boost therapeutic efficacy. The meta-analysis included 80 studies. After TBI, MSCs improved sensorimotor and cognitive deficits and reduced anatomical damage. Stratified meta-analysis on sensorimotor outcome showed similar efficacy for different MSC sources and for syngeneic or xenogenic transplants. Efficacy was greater when MSCs were delivered in the first-week post-injury, and when implanted directly into the lesion cavity. The greatest effect size was for cells embedded in matrices or for MSC-derivatives. MSC therapy is effective in preclinical TBI models, improving sensorimotor, cognitive, and anatomical outcomes, with large effect sizes. These findings support clinical studies in TBI.

Cell-Based Therapies for Traumatic Brain Injury: Therapeutic Treatments and Clinical Trials

Traumatic brain injury (TBI) represents physical damage to the brain tissue that induces transitory or permanent neurological disabilities. TBI contributes to 50% of all trauma deaths, with many enduring long-term consequences and significant medical and rehabilitation costs. There is currently no therapy to reverse the effects associated with TBI. An increasing amount of research has been undertaken regarding the use of different stem cells (SCs) to treat the consequences of brain damage. Neural stem cells (NSCs) (adult and embryonic) and mesenchymal stromal cells (MSCs) have shown efficacy in pre-clinical models of TBI and in their introduction to clinical research. The purpose of this review is to provide an overview of TBI and the state of clinical trials aimed at evaluating the use of stem cell-based therapies in TBI. The primary aim of these studies is to investigate the safety and efficacy of the use of SCs to treat this disease. Although an increasing number of studies are being carried out, few results are currently available. In addition, we present our research regarding the use of cell therapy in TBI. There is still a significant lack of understanding regarding the cell therapy mechanisms for the treatment of TBI. Thus, future studies are needed to evaluate the feasibility of the transplantation of SCs in TBI.

Intranasal administration of Cytoglobin modifies human umbilical cord‑derived mesenchymal stem cells and improves hypoxic‑ischemia brain damage in neonatal rats by modulating p38 MAPK signaling‑mediated apoptosis

Neonatal hypoxic‑ischemic brain damage (HIBD) is a common clinical syndrome in newborns. Hypothermia is the only approved therapy for the clinical treatment; however, the therapeutic window of hypothermia is confined to 6 h after birth and even then, >40% of the infants either die or survive with various impairments, including cerebral palsy, seizure disorder and intellectual disability following hypothermic treatment. The aim of the present study was to determine whether nasal transplantation of Cytoglobin (CYGB) genetically modified human umbilical cord‑derived mesenchymal stem cells (CYGB‑HuMSCs) exhibited protective effects in neonatal rats with HIBD compared with those treated without genetically modified CYGB. A total of 120 neonatal Sprague‑Dawley rats (postnatal day 7) were assigned to either a Sham, HIBD, HuMSCs or CYGB‑HuMSCs group (n = 30 rats/group). For HIBD modeling, rats underwent left carotid artery ligation and were exposed to 8% oxygen for 2.5 h. A total of 30 min after HI, HuMSCs (or CYGB‑HuMSCs) labeled with enhanced‑green fluorescent protein (eGFP) were intranasally administered. After modeling for 3, 14 and 29 days, five randomly selected rats were sacrificed in each group, and the expression levels of CYGB, ERK, JNK and p38 in brain tissues were determined. Nissl staining of the cortex and hippocampal Cornu Ammonis 1 area of rats in each group were compared after 3 days of modeling. TUNEL assay and immunofluorescence were performed 3 days after modeling. Long term memory in rats was assessed using a Morris‑water maze 29 days after modeling. The HIBD group demonstrated significant deficiencies compared with the Sham group based on Nissl staining, TUNEL assay and the Morris‑water maze test. HuMSC treated rats exhibited improvement on in all the tests, and CYGB‑HuMSCs treatment resulted in further improvements. PCR and western blotting results indicated that the CYGB mRNA and protein levels were increased from day 3 to day 29 after transplantation of CYGB‑HuMSCs. Furthermore, it was identified that CYGB‑HuMSC transplantation suppressed p38 signaling at all experimental time points. Immunofluorescence indicated the scattered presence of HuMSCs or CYGB‑HuMSCs in damaged brain tissue. No eGFP and glial fibrillary acidic protein or eGFP and neuron‑specific enolase double‑stained positive cells were found in the brain tissues. Therefore, CYGB‑HuMSCs may serve as a gene transporter, as well as exert a neuroprotective and antiapoptotic effect in HIBD, potentially via the p38 mitogen‑activated protein kinase signaling pathway.

Potential of mesenchymal stem cells alone, or in combination, to treat traumatic brain injury

Traumatic brain injury (TBI) causes death and disability in the United States and around the world. The traumatic insult causes the mechanical injury of the brain and primary cellular death. While a comprehensive pathological mechanism of TBI is still lacking, the focus of the TBI research is concentrated on understanding the pathophysiology and developing suitable therapeutic approaches. Given the complexities in pathophysiology involving interconnected immunologic, inflammatory, and neurological cascades occurring after TBI, the therapies directed to a single mechanism fail in the clinical trials. This has led to the development of the paradigm of a combination therapeutic approach against TBI. While there are no drugs available for the treatment of TBI, stem cell therapy has shown promising results in preclinical studies. But, the success of the therapy depends on the survival of the stem cells, which are limited by several factors including route of administration, health of the administered cells, and inflammatory microenvironment of the injured brain. Reducing the inflammation prior to cell administration may provide a better outcome of cell therapy following TBI. This review is focused on different therapeutic approaches of TBI and the present status of the clinical trials.

Differentiation of Human Mesenchymal Stem Cells towards Neuronal Lineage: Clinical Trials in Nervous System Disorders

Mesenchymal stem cells (MSCs) have been proposed as an alternative therapy to be applied into several pathologies of the nervous system. These cells can be obtained from adipose tissue, umbilical cord blood and bone marrow, among other tissues, and have remarkable therapeutic properties. MSCs can be isolated with high yield, which adds to their ability to differentiate into non-mesodermal cell types including neuronal lineage both in vivo and in vitro. They are able to restore damaged neural tissue, thus being suitable for the treatment of neural injuries, and possess immunosuppressive activity, which may be useful for the treatment of neurological disorders of inflammatory etiology. Although the long-term safety of MSC-based therapies remains unclear, a large amount of both pre-clinical and clinical trials have shown functional improvements in animal models of nervous system diseases following transplantation of MSCs. In fact, there are several ongoing clinical trials evaluating the possible benefits this cell-based therapy could provide to patients with neurological damage, as well as their clinical limitations. In this review we focus on the potential of MSCs as a therapeutic tool to treat neurological disorders, summarizing the state of the art of this topic and the most recent clinical studies.

Placenta-Derived Cells for Acute Brain Injury

Acute brain injury resulting from ischemic/hemorrhagic or traumatic damage is one of the leading causes of mortality and disability worldwide and is a significant burden to society. Neuroprotective options to counteract brain damage are very limited in stroke and traumatic brain injury (TBI). Given the multifaceted nature of acute brain injury and damage progression, several therapeutic targets may need to be addressed simultaneously to interfere with the evolution of the injury and improve the patient’s outcome. Stem cells are ideal candidates since they act on various mechanisms of protection and repair, improving structural and functional outcomes after experimental stroke or TBI. Stem cells isolated from placenta offer advantages due to their early embryonic origin, ease of procurement, and ethical acceptance. We analyzed the evidence for the beneficial effects of placenta-derived stem cells in acute brain injury, with the focus on experimental studies of TBI and stroke, the engineering strategies pursued to foster cell potential, and characterization of the bioactive molecules secreted by placental cells, known as their secretome, as an alternative cell-free strategy. Results from the clinical application of placenta-derived stem cells for acute brain injury and ongoing clinical trials are summarily discussed.

Role of Human Wharton's Jelly Derived Mesenchymal Stem Cells (WJ-MSCs) for Rescue of d-Galactosamine Induced Acute Liver Injury in Mice

BACKGROUND/AIM

Mesenchymal stem cells (MSCs) are multipotent precursor cells having self-renewal ability making them a candidate for use in regenerative medicine. Acute liver injury results in sudden loss of hepatic function leading to organ failure. Liver transplantation is often required to salvage patients with acute liver failure. Due to shortage of organs, identification of alternate method is the need of the hour. In view of this, an attempt has been made to check the regenerative ability of WJ-MSCs (wharton's jelly derived MSC) in mice models for acute liver injury.

METHODS

Swiss albino mice weighing 25 ± 5 g were used in this study. The control mice (Group I), was given saline. Group II mice received d-Galactosamine (d-GalN-800 mg/kg; i.p). Group III mice similar with Group II, received WJ-MSCs (5 × 105 cells/0.5 ml DMEM) through tail vein, 24 h after d-GalN administration and Group IV mice received MSC alone.

RESULTS

Parameters, indicative of hepatotoxicity and oxidative stress were analyzed. A two-fold elevation in the marker enzymes of liver toxicity such as aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (SAP), and total serum bilirubin (TBIL) confirms hepatocellular injury, while a greater than four-fold increase in malondialdehyde (MDA) formation, along with around 40% fall in superoxide-dis-mutase (SOD) activity was indicative of oxidative stress and loss of hepatocellular membrane integrity induced by d-GalN. The above biochemical and pathological changes were significantly restored in mice that received WJ-MSCs indicating hepatoprotective and probable regenerative property.

CONCLUSION

The present study showed that WJ-MSC treatment is able to rescue/ameliorate the hepatotoxicity induced by d-GalN in mice.

Preclinical progenitor cell therapy in traumatic brain injury: a meta-analysis

BACKGROUND

No treatment is available to reverse injury associated with traumatic brain injury (TBI). Progenitor cell therapies show promise in both preclinical and clinical studies. We conducted a meta-analysis of preclinical studies using progenitor cells to treat TBI.

METHODS

EMBASE, MEDLINE, Cochrane Review, Biosis, and Google Scholar were searched for articles using prespecified search strategies. Studies meeting inclusion criteria underwent data extraction. Analysis was performed using Review Manager 5.3 according to a fixed-effects model, and all studies underwent quality scoring.

RESULTS

Of 430 abstracts identified, 38 met inclusion criteria and underwent analysis. Average quality score was 4.32 of 8 possible points. No study achieved a perfect score. Lesion volume (LV) and neurologic severity score (NSS) outcomes favored cell treatment with standard mean difference (SMD) of 0.86 (95% CI: 0.64-1.09) and 1.36 (95% CI: 1.11-1.60), respectively. Rotarod and Morris water maze outcomes also favored treatment with improvements in SMD of 0.34 (95% CI: 0.02-0.65) and 0.46 (95% CI: 0.17-74), respectively. Although LV and NSS were robust to publication bias assessments, rotarod and Morris water maze tests were not. Heterogeneity (I²) ranged from 74%-85% among the analyses, indicating a high amount of heterogeneity among studies. Precision as a function of quality score showed a statistically significant increase in the size of the confidence interval as quality improved.

CONCLUSIONS

Our meta-analysis study reveals an overall positive effect of progenitor cell therapies on LV and NSS with a trend toward improved motor function and spatial learning in different TBI animal models.

Mesenchymal Stem Cells in the Treatment of Traumatic Brain Injury

Traumatic brain injury (TBI) is characterized by a disruption in the normal function of the brain due to an injury following a trauma, which can potentially cause severe physical, cognitive, and emotional impairment. The primary insult to the brain initiates secondary injury cascades consisting of multiple complex biochemical responses of the brain that significantly influence the overall severity of the brain damage and clinical sequelae. The use of mesenchymal stem cells (MSCs) offers huge potential for application in the treatment of TBI. MSCs have immunosuppressive properties that reduce inflammation in injured tissue. As such, they could be used to modulate the secondary mechanisms of injury and halt the progression of the secondary insult in the brain after injury. Particularly, MSCs are capable of secreting growth factors that facilitate the regrowth of neurons in the brain. The relative abundance of harvest sources of MSCs also makes them particularly appealing. Recently, numerous studies have investigated the effects of infusion of MSCs into animal models of TBI. The results have shown significant improvement in the motor function of the damaged brain tissues. In this review, we summarize the recent advances in the application of MSCs in the treatment of TBI. The review starts with a brief introduction of the pathophysiology of TBI, followed by the biology of MSCs, and the application of MSCs in TBI treatment. The challenges associated with the application of MSCs in the treatment of TBI and strategies to address those challenges in the future have also been discussed.

The Present and Future for Peripheral Nerve Regeneration

Peripheral nerve injury can have a potentially devastating impact on a patient's quality of life, resulting in severe disability with substantial social and personal cost. Refined microsurgical techniques, advances in peripheral nerve topography, and a better understanding of the pathophysiology and molecular basis of nerve injury have all led to a decisive leap forward in the field of translational neurophysiology. Nerve repair, nerve grafting, and nerve transfers have improved significantly with consistently better functional outcomes. Direct nerve repair with epineural microsutures is still the surgical treatment of choice when a tension-free coaptation in a well-vascularized bed can be achieved. In the presence of a significant gap (>2-3 cm) between the proximal and distal nerve stumps, primary end-to-end nerve repair often is not possible; in these cases, nerve grafting is the treatment of choice. Indications for nerve transfer include brachial plexus injuries, especially avulsion type, with long distance from target motor end plates, delayed presentation, segmental loss of nerve function, and broad zone of injury with dense scarring. Current experimental research in peripheral nerve regeneration aims to accelerate the process of regeneration using pharmacologic agents, bioengineering of sophisticated nerve conduits, pluripotent stem cells, and gene therapy. Several small molecules, peptides, hormones, neurotoxins, and growth factors have been studied to improve and accelerate nerve repair and regeneration by reducing neuronal death and promoting axonal outgrowth. Targeting specific steps in molecular pathways also allows for purposeful pharmacologic intervention, potentially leading to a better functional recovery after nerve injury. This article summarizes the principles of nerve repair and the current concepts of peripheral nerve regeneration research, as well as future perspectives. [Orthopedics. 2017; 40(1):e141-e156.].

Repair and regeneration of lumbosacral nerve defects in rats with chitosan conduits containing bone marrow mesenchymal stem cells

OBJECTIVES

Despite the great progress in surgical treatment of lumbosacral nerve injuries caused by high-energy trauma, functional recovery remains poor and insufficient. Bone marrow mesenchymal stem cells (BMSCs), which express neurotrophic factors and can also differentiate into nerve cells, have potential as an effective alternative therapy for lumbosacral nerve defects. The aim of the present study was to evaluate the functional recovery, nerve regeneration, motor neuron survival and apoptosis after lumbosacral nerve transection in rats receiving BMSC transplantation into the chitosan conduit.

METHODS

The right L4-L6 nerve roots of rats were transected and bridged with three 1-cm-long chitosan conduits, which were further injected with the BMSCs (MSC-treated group) or culture medium (DMEM group). The nerve regeneration and motor function recovery were assessed by the sciatic functional index (SFI) and analysed electrophysiologically and morphologically.

RESULTS

At 6 and 12 weeks after surgery, the SFI values in MSC-treated group were significantly higher than those in DMEM group (P≤0.05). The peak amplitude of CMAP (compound muscle action potential) and nerve conduction velocity in MSC-treated group were significantly higher than that in DMEM group (P≤0.01), while the latency of CMAP onset in MSC-treated group was significantly shorter than that in DMEM group (P≤0.01). The diameter of the myelinated fibres and thickness of the myelin sheath in MSC-treated group were significantly higher than those in DMEM group (P≤0.05). There was no difference in the number of motor neurons in the anterior horn of the spinal cord at 6 weeks post-operation (P>0.05), while the number of motor neurons was significantly greater in MSC-treated group than that in DMEM group at 12 weeks post-operation (P≤0.001). The number of apoptotic cells was also significantly lower (P≤0.01).

CONCLUSIONS

The results of the present study showed that BMSCs treatment improved lumbosacral nerve regeneration and motor function. In addition, our data suggested that BMSCs inhibited motor neuron apoptosis, and improved motor neuron function and survival in the anterior horn of the spinal cord.

Cell-based therapy for traumatic brain injury

Traumatic brain injury is a major economic burden to hospitals in terms of emergency department visits, hospitalizations, and utilization of intensive care units. Current guidelines for the management of severe traumatic brain injuries are primarily supportive, with an emphasis on surveillance (i.e. intracranial pressure) and preventive measures to reduce morbidity and mortality. There are no direct effective therapies available. Over the last fifteen years, pre-clinical studies in regenerative medicine utilizing cell-based therapy have generated enthusiasm as a possible treatment option for traumatic brain injury. In these studies, stem cells and progenitor cells were shown to migrate into the injured brain and proliferate, exerting protective effects through possible cell replacement, gene and protein transfer, and release of anti-inflammatory and growth factors. In this work, we reviewed the pathophysiological mechanisms of traumatic brain injury, the biological rationale for using stem cells and progenitor cells, and the results of clinical trials using cell-based therapy for traumatic brain injury. Although the benefits of cell-based therapy have been clearly demonstrated in pre-clinical studies, some questions remain regarding the biological mechanisms of repair and safety, dose, route and timing of cell delivery, which ultimately will determine its optimal clinical use.

Wharton's Jelly-derived mesenchymal stem cells alleviate memory deficits and reduce amyloid-β deposition in an APP/PS1 transgenic mouse model

Alzheimer's disease (AD) is the leading cause of dementia in the elderly and is characterized by amyloid plaques, neurofibrillary tangles, and neuronal loss. Cumulative evidence supports that neuroinflammation is an important factor for the pathogenesis of AD and contributes to amyloid beta (Aβ) generation. However, there has been no effective treatment for AD. Wharton's Jelly-derived mesenchymal stem cells (WJ-MSCs) have a potential therapeutic effect in the treatment for neurological diseases. In the present study, we evaluated the therapeutic effect of WJ-MSC transplantation on the neuropathology and memory deficits in amyloid precursor protein (APP) and presenilin-1 (PS1) double-transgenic mice and discussed the mechanism. WJ-MSCs were intravenously transplanted into the APP/PS1 mice. Four weeks after treatment, WJ-MSCs significantly improved the spatial learning and alleviated the memory decline in the APP/PS1 mice. Aβ deposition and soluble Aβ levels were significantly reduced after WJ-MSC treatment. Furthermore, WJ-MSCs significantly increased the expression of the anti-inflammatory cytokine, IL-10. Meanwhile, pro-inflammatory microglial activation and the expressions of pro-inflammatory cytokines, IL-1β and TNFα, were significantly down-regulated by WJ-MSC treatment. Thus, our findings suggest that WJ-MSCs might produce beneficial effects on the prevention and treatment for AD through modulation of neuroinflammation.

Augmenting peripheral nerve regeneration using stem cells: A review of current opinion

Outcomes following peripheral nerve injury remain frustratingly poor. The reasons for this are multifactorial, although maintaining a growth permissive environment in the distal nerve stump following repair is arguably the most important. The optimal environment for axonal regeneration relies on the synthesis and release of many biochemical mediators that are temporally and spatially regulated with a high level of incompletely understood complexity. The Schwann cell (SC) has emerged as a key player in this process. Prolonged periods of distal nerve stump denervation, characteristic of large gaps and proximal injuries, have been associated with a reduction in SC number and ability to support regenerating axons. Cell based therapy offers a potential therapy for the improvement of outcomes following peripheral nerve reconstruction. Stem cells have the potential to increase the number of SCs and prolong their ability to support regeneration. They may also have the ability to rescue and replenish populations of chromatolytic and apoptotic neurons following axotomy. Finally, they can be used in non-physiologic ways to preserve injured tissues such as denervated muscle while neuronal ingrowth has not yet occurred. Aside from stem cell type, careful consideration must be given to differentiation status, how stem cells are supported following transplantation and how they will be delivered to the site of injury. It is the aim of this article to review current opinions on the strategies of stem cell based therapy for the augmentation of peripheral nerve regeneration.

Human umbilical cord Wharton's jelly-derived oligodendrocyte precursor-like cells for axon and myelin sheath regeneration

Human umbilical mesenchymal stem cells from Wharton's jelly of the umbilical cord were induced to differentiate into oligodendrocyte precursor-like cells in vitro. Oligodendrocyte precursor cells were transplanted into contused rat spinal cords. Immunofluorescence double staining indicated that transplanted cells survived in injured spinal cord, and differentiated into mature and immature oligodendrocyte precursor cells. Biotinylated dextran amine tracing results showed that cell transplantation promoted a higher density of the corticospinal tract in the central and caudal parts of the injured spinal cord. Luxol fast blue and toluidine blue staining showed that the volume of residual myelin was significantly increased at 1 and 2 mm rostral and caudal to the lesion epicenter after cell transplantation. Furthermore, immunofluorescence staining verified that the newly regenerated myelin sheath was derived from the central nervous system. Basso, Beattie and Bresnahan testing showed an evident behavioral recovery. These results suggest that human umbilical mesenchymal stem cell-derived oligodendrocyte precursor cells promote the regeneration of spinal axons and myelin sheaths.

Up-regulation of CXCR4 in rat umbilical mesenchymal stem cells induced by serum from rat with acute liver failure promotes stem cells migration to injured liver tissue

The role of C-X-C chemokine receptor type 4 (CXCR4) in umbilical mesenchymal stem cells (UMSCs) as therapy for liver disease is ill understood. The aim of the study was to evaluate rat UMSCs (rUMSCs) on CXCR4 expression and homing to injured liver tissue. rUMSCs were isolated from umbilical cords of pregnant rats. Acute liver failure (ALF) models were developed using D-galactosamine. CXCR4 expression induction by serum from rats with ALF (LFS), cytokines, growth factors, and LPS was analyzed. CXCR4 expression was analyzed by RT-PCR, western blot, and flow cytometry. rUMSCs were labeled with carboxyfluorescein and pretreated with LFS to induce CXCR4 expression and were transplanted into ALF rats. Animals were sacrificed 48 h and 1 week after transplantation. Liver-homing rUMSCs were observed under fluorescence microscopy. rUMSCs were successfully isolated, expressing CD90 and CD106, but not CD34 and CD45. mRNA and protein expressions of CXCR4 were strongly up-regulated by LFS and by the mixture of cytokines, stem cell factor, and LPS (CM). Expression of cell surface CXCR4 on rUMSCs in groups treated with LFS (42.37 ± 1.60 %) and CM (40.17 ± 1.78 %) was higher than that in the untreated control group (9.67 ± 1.06 %) (both P < 0.001). At 48 h after transplantation, more rUMSCs pretreated with LFS appeared in the portal area, and migrated to the liver parenchyma after 1 week. LFS strongly induced the surface expression of CXCR4 on rUMSCs. Increasing CXCR4 expression on rUMSCs may enhance their homing ability to injured liver tissue, and may eventually be used for treating liver diseases.

IGF-1 enhances cell proliferation and survival during early differentiation of mesenchymal stem cells to neural progenitor-like cells

BACKGROUND

There has been increasing interest recently in the plasticity of mesenchymal stem cells (MSCs) and their potential to differentiate into neural lineages. To unravel the roles and effects of different growth factors in the differentiation of MSCs into neural lineages, we have differentiated MSCs into neural lineages using different combinations of growth factors. Based on previous studies of the roles of insulin-like growth factor 1 (IGF-1) in neural stem cell isolation in the laboratory, we hypothesized that IGF-1 can enhance proliferation and reduce apoptosis in neural progenitor-like cells (NPCs) during differentiation of MSCs into NCPs.We induced MSCs differentiation under four different combinations of growth factors: (A) EGF + bFGF, (B) EGF + bFGF + IGF-1, (C) EGF + bFGF + LIF, (D) EGF + bFGF + BDNF, and (E) without growth factors, as a negative control. The neurospheres formed were characterized by immunofluorescence staining against nestin, and the expression was measured by flow cytometry. Cell proliferation and apoptosis were also studied by MTS and Annexin V assay, respectively, at three different time intervals (24 hr, 3 days, and 5 days). The neurospheres formed in the four groups were then terminally differentiated into neuron and glial cells.

RESULTS

The four derived NPCs showed a significantly higher expression of nestin than was shown by the negative control. Among the groups treated with growth factors, NPCs treated with IGF-1 showed the highest expression of nestin. Furthermore, NPCs derived using IGF-1 exhibited the highest cell proliferation and cell survival among the treated groups. The NPCs derived from IGF-1 treatment also resulted in a better yield after the terminal differentiation into neurons and glial cells than that of the other treated groups.

CONCLUSIONS

Our results suggested that IGF-1 has a crucial role in the differentiation of MSCs into neuronal lineage by enhancing the proliferation and reducing the apoptosis in the NPCs. This information will be beneficial in the long run for improving both cell-based and cell-free therapy for neurodegenerative diseases.

Stem cell therapy for acute cerebral injury: what do we know and what will the future bring?

PURPOSE OF REVIEW

The central nervous system has limited capacity for regeneration after acute and chronic injury. An attractive approach to stimulate neural plasticity in the brain is to transplant stem cells in order to restore function. Here, we discuss potential mechanisms of action, current knowledge and future perspectives of clinical stem cell research for stroke and traumatic brain injury.

RECENT FINDINGS

Preclinical data using various models suggest stem cell therapy to be a promising therapeutic avenue. Progress has been made in elucidating the mechanism of action of various cell types used, shifting the hypothesis from neural replacement to enhancing endogenous repair processes. Translation of these findings in clinical trials is currently being pursued with emphasis on both safety as well as efficacy.

SUMMARY

Clinical trials are currently recruiting patients in phase I and II trials to gain more insight in the therapeutic potential of stem cells in acute cerebral injury. A close interplay between results of these clinical trials and more extensive basic research is essential for future trial design, choosing the optimal transplantation strategy and selecting the right patients.

Functional assessment of long-term deficits in rodent models of traumatic brain injury

Traumatic brain injury (TBI) ranks as the leading cause of mortality and disability in the young population worldwide. The annual US incidence of TBI in the general population is estimated at 1.7 million per year, with an estimated financial burden in excess of US$75 billion a year in the USA alone. Despite the prevalence and cost of TBI to individuals and society, no treatments have passed clinical trial to clinical implementation. The rapid expansion of stem cell research and technology offers an alternative to traditional pharmacological approaches targeting acute neuroprotection. However, preclinical testing of these approaches depends on the selection and characterization of appropriate animal models. In this article we consider the underlying pathophysiology for the focal and diffuse TBI subtypes, discuss the existing preclinical TBI models and functional outcome tasks used for assessment of injury and recovery, identify criteria particular to preclinical animal models of TBI in which stem cell therapies can be tested for safety and efficacy, and review these criteria in the context of the existing TBI literature. We suggest that 2 months post-TBI is the minimum period needed to evaluate human cell transplant efficacy and safety. Comprehensive review of the published TBI literature revealed that only 32% of rodent TBI papers evaluated functional outcome ≥1 month post-TBI, and only 10% evaluated functional outcomes ≥2 months post-TBI. Not all published papers that evaluated functional deficits at a minimum of 2 months post-TBI reported deficits; hence, only 8.6% of overall TBI papers captured in this review demonstrated functional deficits at 2 months or more postinjury. A 2-month survival and assessment period would allow sufficient time for differentiation and integration of human neural stem cells with the host. Critically, while trophic effects might be observed at earlier time points, it will also be important to demonstrate the sustainability of such an effect, supporting the importance of an extended period of in vivo observation. Furthermore, regulatory bodies will likely require at least 6 months survival post-transplantation for assessment of toxicology/safety, particularly in the context of assessing cell abnormalities.

Tackling the physiological barriers for successful mesenchymal stem cell transplantation into the central nervous system

Over the past decade a lot of research has been performed towards the therapeutic use of mesenchymal stem cells (MSCs) in neurodegenerative and neuroinflammatory diseases. MSCs have shown to be beneficial in different preclinical studies of central nervous system (CNS) disorders due to their immunomodulatory properties and their capacity to secrete various growth factors. Nevertheless, most of the transplanted cells die within the first hours after transplantation and induce a neuroinflammatory response. In order to increase the efficacy of MSC transplantation, it is thus imperative to completely characterise the mechanisms mediating neuroinflammation and cell death following MSC transplantation into the CNS. Consequently, different components of these cell death- and neuroinflammation-inducing pathways can be targeted in an attempt to improve the therapeutic potential of MSCs for CNS disorders.

Human umbilical cord mesenchymal stem cell-derived neuron-like cells rescue memory deficits and reduce amyloid-beta deposition in an AβPP/PS1 transgenic mouse model

Introduction

Cell therapy is a potential therapeutic approach for neurodegenerative disorders, such as Alzheimer disease (AD). Neuronal differentiation of stem cells before transplantation is a promising procedure for cell therapy. However, the therapeutic impact and mechanisms of action of neuron-like cells differentiated from human umbilical cord mesenchymal stem cells in AD have not been determined.

Methods

In this study, we used tricyclodecan-9-yl-xanthogenate (D609) to induce human mesenchymal stem cells isolated from Wharton jelly of the umbilical cord (HUMSCs) to differentiate into neuron-like cells (HUMSC-NCs), and transplanted the HUMSC-NCs into an AβPP/PS1 transgenic AD mouse model. The effects of HUMSC-NC transplantation on the cognitive function, synapsin I level, amyloid β-peptides (Aβ) deposition, and microglial function of the mice were investigated.

Results

We found that transplantation of HUMSC-NCs into AβPP/PS1 mice improved the cognitive function, increased synapsin I level, and significantly reduced Aβ deposition in the mice. The beneficial effects were associated with “alternatively activated” microglia (M2-like microglia). In the mice transplanted with HUMSC-NCs, M2-like microglial activation was significantly increased, and the expression of antiinflammatory cytokine associated with M2-like microglia, interleukin-4 (IL-4), was also increased, whereas the expression of proinflammatory cytokines associated with classic microglia (M1-like microglia), including interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α), was significantly reduced. Moreover, the expression of Aβ-degrading factors, insulin-degrading enzyme (IDE) and neprilysin (NEP), was increased substantially in the mice treated with HUMSC-NCs.

Conclusions

HUMSC-NC transplantation decreased Aβ deposition and improved memory in AβPP/PS1 mice by a mechanism associated with activating M2-like microglia and modulating neuroinflammation. Transplantation of neuron-like cells differentiated from mesenchymal stem cells might be a promising cell therapy for Alzheimer disease.

Neural stem-like cells derived from human amnion tissue are effective in treating traumatic brain injury in rat

Although human amnion derived mesenchymal stem cells (AMSC) are a promising source of stem cells, their therapeutic potential for traumatic brain injury (TBI) has not been widely investigated. In this study, we evaluated the therapeutic potential of AMSC using a rat TBI model. AMSC were isolated from human amniotic membrane and characterized by flow cytometry. After induction, AMSC differentiated in vitro into neural stem-like cells (AM-NSC) that expressed higher levels of the neural stem cell markers, nestin, sox2 and musashi, in comparison to undifferentiated AMSC. Interestingly, the neurotrophic factors, brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF), neurotrophin 3 (NT-3), glial cell derived neurotrophic factor (GDNF) and ciliary neurotrophic factor (CNTF) were markedly upregulated after neural stem cell induction. Following transplantation in a rat TBI model, significant improvements in neurological function, brain tissue morphology, and higher levels of BDNF, NGF, NT-3, GDNF and CNTF, were observed in the AM-NSC group compared with the AMSC and Matrigel groups. However, few grafted cells survived with minimal differentiation into neural-like cells. Together, our results suggest that transplantation of AM-NSC promotes functional rehabilitation of rats with TBI, with enhanced expression of neurotrophic factors a likely mechanistic pathway.

Long-term outcome of the repair of 50 mm long median nerve defects in rhesus monkeys with marrow mesenchymal stem cells-containing, chitosan-based tissue engineered nerve grafts

Despite great progress in the fields of tissue engineering and stem cell therapy, the translational and preclinical studies are required to accelerate the clinical application of tissue engineered nerve grafts, as an alternative to autologous nerve grafts, for peripheral nerve repair. Rhesus monkeys (non-human primates) are more clinically relevant and more suitable for scaling up to humans as compared to other mammalians. Based on this premise, and considering a striking similarity in the anatomy and function between human and monkey hands, here we used chitosan/PLGA-based, autologous marrow mesenchymal stem cells (MSCs)-containing tissue engineered nerve grafts (TENGs) for bridging a 50-mm long median nerve defect in rhesus monkeys. At 12 months after grafting, locomotive activity observation, electrophysiological assessments, and FG retrograde tracing tests indicated that the recovery of nerve function by TENGs was more efficient than that by chitosan/PLGA scaffolds alone; histological and morphometric analyses of regenerated nerves further confirmed that the morphological reconstruction by TENGs was close to that by autografts and superior to that by chitosan/PLGA scaffolds alone. In addition, blood test and histopathological examination demonstrated that TENGs featured by addition of autologous MSCs could be safely used in the primate body. These findings suggest the efficacy of our developed TENGs for peripheral nerve regeneration and their promising perspective for clinical applications.

A combination of taxol infusion and human umbilical cord mesenchymal stem cells transplantation for the treatment of rat spinal cord injury

BACKGROUND AND PURPOSE

Studies have shown that the administration of Taxol, an anti-cancer drug, inhibited scar formation, promoted axonal elongation and improved locomotor recovery in rats after spinal cord injury (SCI). We hypothesized that combining Taxol with another promising therapy, transplantation of human umbilical mesenchymal stem cells (hUCMSCs), might further improve the degree of locomotor recovery. The present study examined whether Taxol combined with transplantation of hUCMSCs would produce synergistic effects on recovery and which mechanisms were involved in the effect.

METHODS

A total of 32 rats subjected to SCI procedures were assigned to one of the following four treatment groups: phosphate-buffered saline (PBS, control), hUCMSCs, Taxol, or Taxol+hUCMSCs. Immediately after injury, hUCMSCs were transplanted into the injury site and Taxol was administered intrathecally for 4 weeks. Locomotor recovery was evaluated using the Basso, Beattie and Bresnahan locomotor (BBB) rating scale. Survival of the transplanted human cells and the host glial reaction in the injured spinal cord were studied by immunohistochemistry.

RESULTS

Treatment with Taxol, hUCMSCs or Taxol+hUCMSCs reduced the extent of astrocytic activation, increased axonal preservation and decreased the number of caspase-3(+) and ED-1(+) cells, but these effects were more pronounced in the Taxol+hUCMSCs group. Behavioral analyses showed that rats in the Taxol+hUCMSCs group showed better motor performance than rats treated with hUCMSCs or Taxol only.

CONCLUSIONS

The combination of Taxol and hUCMSCs produced beneficial effects in rats with regard to functional recovery following SCI through the enhancement of anti-inflammatory, anti-astrogliosis, anti-apoptotic and axonal preservation effects.

Improved viability and activity of neutrophils differentiated from HL-60 cells by co-culture with adipose tissue-derived mesenchymal stem cells

Neutropenia is a principal complication of cancer treatment. We investigated the supportive effect of adipose tissue-derived mesenchymal stem cells (AD-MSCs) on the viability and function of neutrophils. Neutrophils were derived from HL-60 cells by dimethylformamide stimulation and cultured with or without AD-MSCs under serum-starved conditions to evaluate neutrophil survival, proliferation, and function. Serum starvation resulted in the apoptosis of neutrophils and decreased cell survival. The co-culture of neutrophils and AD-MSCs resulted in cell survival and inhibited neutrophil apoptosis under serum-starved conditions. The survival rate of neutrophils was prolonged up to 72 h, and the expression levels of interferon (IFN)-α, granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage colony-stimulating factor, and transforming growth factor (TGF)-β in AD-MSCs were increased after co-culture with neutrophils. AD-MSCs promoted the viability of neutrophils by inhibiting apoptosis as well as enhancing respiratory burst, which could potentially be mediated by the increased expression of IFN-α, G-CSF, and TGF-β. Thus, we conclude that the use of AD-MSCs may be a promising cell-based therapy for increasing immunity by accelerating neutrophil function.