Transplantation of mesenchymal stem cells to the brain by topical application in an experimental traumatic brain injury model

Adipose-derived stem cells modified by TWIST1 silencing accelerates rat sciatic nerve repair and functional recovery

The regeneration of peripheral nerves after injury is often slow and impaired, which may be associated with weakened and denervated muscles subsequently leading to atrophy. Adipose-derived stem cells (ADSCs) are often regarded as cell-based therapeutic candidate due to their regenerative potential. The study aims to assess the therapeutic efficacy of gene-modified ADSCs on sciatic nerve injury. We lentivirally transduced ADSCs with shRNA-TWIST1 and transplanted modified cells to rats undergoing sciatic nerve transection and repair. Results showed that TWIST1 knockdown accelerated functional recovery of rats with sciatic nerve injury as faster nerve conduction velocity and higher wire hang scores obtained by rats transplanted with TWIST1-silenced ADSCs than scramble ADSCs. Although the rats experienced degenerated axons and decreased myelin sheath thickness after sciatic nerve injury 8 weeks after operation, those transplanted with TWIST1-silenced ADSCs exhibited more signs of regenerated nerve fibers surrounded by newly formed myelin sheaths than those with scramble ADSCs. The rats transplanted with TWIST1-silenced ADSCs presented increased expressions of neurotrophic factors including neurotrophin-3 (NT-3), brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF), and glial cell line-derived neurotrophic factor (GDNF) in the sciatic nerves than those with scramble ADSCs. These results suggest that genetically modifying TWIST1 in ADSCs could facilitate peripheral nerve repair after injury in a more efficient way than that with ADSCs alone.

Nanowired Delivery of Cerebrolysin with Mesenchymal Stem Cells Attenuates Heat Stress-Induced Exacerbation of Neuropathology Following Brain Blast Injury

Blast brain injury (bBI) following explosive detonations in warfare is one of the prominent causes of multidimensional insults to the central nervous and other vital organs injury. Several military personnel suffered from bBI during the Middle East conflict at hot environment. The bBI largely occurs due to pressure waves, generation of heat together with release of shrapnel and gun powders explosion with penetrating and/or impact head trauma causing multiple brain damage. As a result, bBI-induced secondary injury causes breakdown of the blood-brain barrier (BBB) and edema formation that further results in neuronal, glial and axonal injuries. Previously, we reported endocrine imbalance and influence of diabetes on bBI-induced brain pathology that was significantly attenuated by nanowired delivery of cerebrolysin in model experiments. Cerebrolysin is a balanced composition of several neurotrophic factors, and active peptide fragment is capable of neuroprotection in several neurological insults. Exposure to heat stress alone causes BBB damage, edema formation and brain pathology. Thus, it is quite likely that hot environment further exacerbates the consequences of bBI. Thus, novel therapeutic strategies using nanodelivery of stem cell and cerebrolysin may further enhance superior neuroprotection in bBI at hot environment. Our observations are the first to show that combined nanowired delivery of mesenchymal stem cells (MSCs) and cerebrolysin significantly attenuated exacerbation of bBI in hot environment and induced superior neuroprotection, not reported earlier. The possible mechanisms of neuroprotection with MSCs and cerebrolysin in bBI are discussed in the light of current literature.

Recent Advances in Fluorescence Imaging of Traumatic Brain Injury in Animal Models

Traumatic brain injury (TBI) is one of the top three specific neurological disorders, requiring reliable, rapid, and sensitive imaging of brain vessels, tissues, and cells for effective diagnosis and treatment. Although the use of medical imaging such as computed tomography (CT) and magnetic resonance imaging (MRI) for the TBI detection is well established, the exploration of novel TBI imaging techniques is of great interest. In this review, recent advances in fluorescence imaging for the diagnosis and evaluation of TBI are summarized and discussed in three sections: imaging of cerebral vessels, imaging of brain tissues and cells, and imaging of TBI-related biomarkers. Design strategies for probes and labels used in TBI fluorescence imaging are also described in detail to inspire broader applications. Moreover, the multimodal TBI imaging platforms combining MRI and fluorescence imaging are also briefly introduced. It is hoped that this review will promote more studies on TBI fluorescence imaging, and enable its use for clinical diagnosis as early as possible, helping TBI patients get better treatment and rehabilitation.

Topical application of adipose tissue-derived mesenchymal stem cells (ADMSCs) reduced cerebral edema in experimental traumatic brain injury (TBI)-a preliminary study

Background

Our previous studies showed that topical application of mesenchymal stem cells (MSCs) improved functional recovery in rat traumatic brain injury (TBI) model, and hypoxic precondition further enhanced the therapeutic effects of MSCs. There was no previous study on the attenuation of cerebral edema by MSCs.

We investigated whether topical application of normoxic and hypoxic MSCs could reduce cerebral edema in an experimental TBI model.

Methods

Two million normoxic (N = 24) and hypoxic (N = 24) MSCs were applied topically to exposed the cerebral cortex in a controlled cortical impact (CCI) model. The MSCs were fixed in position with fibrin glue. No treatment was given to control animals (TBI only: n = 24). After surgery, four animals in each group were sacrificed daily (day 1 to day 6) for edema evaluation. Normal animals without TBI were used as reference (n = 4). The expressions of GFAP, AQP4, and MMP9 were also investigated by immunofluorescence staining and RT-PCR at day 3.

Results

The edema peaked within 3 days after TBI. Compared with the control, hypoxic MSCs reduced brain water content significantly (p < 0.05). Both hypoxic and normoxic MSCs downregulated the expression of MMP9 and normalized AQP4 distribution to astrocyte end feet.

Conclusion

Our preliminary study showed that topical application of hypoxic MSCs suppressed both vasogenic and cytotoxic edema formation.

Induced pluripotent stem cell-derived neural progenitor cell transplantation promotes regeneration and functional recovery after post-traumatic stress disorder in rats

Post-traumatic stress disorder (PTSD) is a mental disorder characterized by hippocampal neuron loss and cognitive dysfunction. The aim of the present study was to investigate the potential functional outcomes of transplantation of induced pluripotent stem cell-derived neural progenitor cells (iPSC-NPCs) for treating PTSD. Human induced pluripotent stem cell (iPSCs), differentiated into neural progenitor cells (NPCs) in vitro, were transplanted into the brain of rat. Following iPSC-NPCs transplantation, cognitive function was determined. The open field test and fear condition test indicated that long-term iPSC-NPCs transplantation ameliorated cognitive dysfunction and reduced freezing time in PTSD rats. Following testing, the brain of rat was analyzed using immunocytochemistry and immunofluorescence. The results revealed that iPSC-NPCs differentiated into neurons replacing the loss of hippocampus neurons, and iPSC-NPCs transplantation showed higher expression of glial fibrillary acidic protein (GFAP) and increased number of NeuN compared with the control group. Moreover, western blot analysis suggested enhanced expression of brain-derived neurotrophic factor (BDNF) in hippocampus tissue of iPSC-NPCs transplanted rats in comparison to the PBS group. Collectively, these findings showed that iPSC-NPCs could promote regeneration and motor function recovery in PTSD model.

Potential of mesenchymal stem cells as topical immunomodulatory cell therapies for ocular surface inflammatory disorders

Ocular surface inflammatory disorders (OSIDs) are a group of highly prevalent, heterogeneous diseases that display a variety of aetiologies and symptoms and are risk factors for serious complications, including ocular and cornea impairment. Corneal inflammation is a common factor of all OSIDs, regardless of their cause or symptoms. Current medications include over-the-counter lubricating eye drops, corticosteroids, and ciclosporin, which either do not treat the corneal inflammation or have been associated with multiple side effects leading to alternative treatments being sought. Regenerative medicine cell therapies, particularly mesenchymal stem cells (MSCs), have shown great promise for immunosuppression and disease amelioration across multiple tissues, including the cornea. However, for successful development and clinical translation of MSC therapy for OSIDs, significant problems must be addressed. This review aims to highlight considerations, including whether the source of MSC isolation impacts the efficacy and safety of the therapy, in addition to assessing the feasibility of MSC topical application to the cornea and ocular surface through analysis of potential scaffolds and cell carriers for application to the eye. The literature contains limited data assessing MSCs incorporated into scaffolds for corneal administration, thus here we highlight the necessity of further investigations to truly exploit the potential of an MSC-based cell therapy for the treatment of OSIDs.

Distribution and Migration of Human Placental Mesenchymal Stromal Cells in the Brain of Healthy Rats after Stereotaxic or Intra-Arterial Transplantation

Human placenta mesenchymal stromal cells were injected to healthy rats either stereotaxically into the striatum or intra-arterially through the internal carotid artery. Some cells injected into the brain migrated along the corpus callosum both medially and laterally or concentrated around small blood vessels. A small fraction of MSC injected intra-arterially adhered to the endothelium and stayed inside blood vessels for up to 48 hours mostly in the basin of the middle cerebral artery. Neither stereotaxic, nor intra-arterial transplantation of mesenchymal stromal cells modulated the proliferation of neural stem cells in the subventricular zone of the brain, but stereotaxic transplantation suppressed activation of their proliferation in response to traumatization with the needle.

A Review of Stem Cell Therapy for Acquired Brain Injuries and Neurodegenerative Central Nervous System Diseases

Cell-based therapies have been the subject of much discussion regarding their potential role in enhancing central nervous system function for a number of pathologic conditions. Much of the current research has been in preclinical trials, with clinical trials in the phase I or I/II stage. Nevertheless, there is considerable interest in the public about the potential regenerative role that stem cells may have in improving function for these neurologic conditions. This review will describe the different types of stem cells that are available, review their possible effects, and discuss some of the variables that investigators need to consider when designing their studies. Current clinical research in the areas of stroke, traumatic brain injury, and neurodegenerative diseases (amyotrophic lateral sclerosis and Parkinson disease) will be reviewed. As this article is aimed at a rehabilitation audience, outcome measures, and the role of concurrent rehabilitation therapies will also be mentioned.

Topically applied adipose-derived mesenchymal stem cell treatment in experimental focal cerebral ischemia

In this study, the neuro-modulation effect of topical mesenchymal stem cells (MSCs) was tested in a rodent middle carotid artery occlusion (MCAO) model. Twenty-four hours after MCAO, craniotomy was made and 0.8 × 10⁶ GFP-MSCs were topically applied to the exposed parietal cortex. The MSCs were fixed in position by a thin layer of fibrin glue (N = 30). In the control group, saline were topically applied to the ipsilateral parietal cortex (N = 30). Three days after topical application, few GFP-positive cells were found in the ischemic penumbra. They expressed GFAP and NeuN. Topical MSCs triggered microglial activation, astrocytosis and cellular proliferation at day 3. The recovery of neurological functions were significantly enhanced as determined in Rotarod test and Morris Water Maze test with smaller infarct volume. PCR array showed that expressions of ten genes of neurogenesis were altered in the penumbra region (fold change > 1.25, p < 0.05) in MSCs group: Apoe, Ascl1, Efnb1, Mef2c, Nog, A100a6 and B2m were up-regulated; Pax2, Pax3 and Th were down-regulated. In conclusion, topical application provided a direct and effective transplant method for the delivery of MSCs to the surface of ipsilateral cerebral cortex and the topical MSCs could improve the neurological function from cerebral ischemia resulting from a major cerebral artery occlusion in a rodent experimental model.

The neuroprotection of hypoxic adipose tissue-derived mesenchymal stem cells in experimental traumatic brain injury

Traumatic brain injury is one of the leading causes of mortality and morbidity worldwide. At present there is no effective treatment. Previous studies have demonstrated that topical application of adipose tissue-derived mesenchymal stem cells can improve functional recovery in experimental traumatic brain injury. In this study, we evaluated whether hypoxic preconditioned mesenchymal stem cells could enhance the recovery from traumatic brain injury. Traumatic brain injury was induced with an electromagnetically controlled cortical impact device. Two million mesenchymal stem cells derived from the adipose tissue of transgenic green fluorescent protein Sprague-Dawley rats were cultured under either hypoxic (2.5% O₂ for 18 hours) (N = 30) or normoxic (18% O₂) (N = 30) conditions, then topically applied to the exposed cerebral cortex within 1 hour after traumatic brain injury. A thin layer of fibrin was used to fix the cells in position. No treatment was given to the animals with traumatic brain injury (N = 30). Animals that underwent craniectomy without traumatic brain injury were treated as the sham group (N = 15). Neurological functions were evaluated with water maze, Roto-rod and gait analysis. Animals were sacrificed at days 3, 7, and 14 for microscopic examinations and real-time polymerase chain reaction analysis. The rats treated with hypoxic mesenchymal stem cells showed the greatest improvement in neurological function recovery. More green fluorescent protein-positive cells were found in the injured brain parenchyma treated with hypoxic mesenchymal stem cells that co-expressed glial fibrillary acidic protein, Nestin, and NeuN. Moreover, there was early astrocytosis triggered by the infiltration of more glial fibrillary acidic protein-positive cells and microgliosis was suppressed with fewer ionized calcium binding adapter molecule 1-positive cells in the penumbra region of hypoxic mesenchymal stem cells group at day 3. Compared with normoxic mesenchymal stem cells and traumatic brain injury only groups, there was significantly (p < 0.05) less neuronal death in both the hippocampus and penumbral regions in sections treated with hypoxic mesenchymal stem cells as determined by Cresyl violet and terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling staining respectively. The expression of pro-inflammatory genes (interleukin 6, interleukin 1a, interleukin 1b, tumor necrosis factor α) was upregulated and apoptotic gene (Caspase-3) expression was suppressed at day 3. Anti-inflammatory (interleukin 10) and anti-apoptotic (BCL2 associated agonist of cell death) gene expression was upregulated at days 7 and 14. Our study showed that a hypoxic precondition enhanced the beneficial effects of mesenchymal stem cells on neurological recovery after traumatic brain injury.

An updated review of adipose derived-mesenchymal stem cells and their applications in musculoskeletal disorders

INTRODUCTION

Adipose-derived mesenchymal stem cells (ASCs) represent a new therapeutic strategy in biomedicine with many potential applications, especially in musculoskeletal disorders. Preclinical and clinical studies based on the administration of ASCs support their efficacy in bone regeneration, joint repair, tendon injury and skeletal muscle alterations. Many of these novel treatments may improve patients' quality of life and prognosis. However, several concerns about the use of stem cells remain unsolved, particularly regarding their safety and side effects. The present work aims to review the nature, clinical trials and patents involving the use of ASCs in musculoskeletal disorders.

AREAS COVERED

In this article, we describe ASCs' isolation, culture and differentiation in vivo and in vitro, advances on ASCs' applications in bone, cartilage, muscle and tendon repair, and patents involving the use of ASCs.

EXPERT OPINION

The use of ASCs in musculoskeletal disorders presents significant therapeutic advantages, including limited autoimmune response, potential cell expansion ex vivo, high plasticity to differentiate into several mesodermal cell lineages, and additional effects of therapeutic interest such as secretion of neurotrophic factors and anti-inflammatory properties. For these reasons, ASCs are promising therapeutic agents for clinical applications in musculoskeletal disorders.

Transplantation of Embryonic Neural Stem Cells and Differentiated Cells in a Controlled Cortical Impact (CCI) Model of Adult Mouse Somatosensory Cortex

Traumatic brain injury (TBI) is a major cause of death worldwide. Depending on the severity of the injury, TBI can reflect a broad range of consequences such as speech impairment, memory disturbances, and premature death. In this study, embryonic neural stem cells (ENSC) were isolated from E14 mouse embryos and cultured to produce neurospheres which were induced to generate differentiated cells (DC). As a cell replacement treatment option, we aimed to transplant ENSC or DC into the adult injured C57BL/6 mouse cortex controlled cortical impact (CCI) model, 7 days post-trauma, in comparison to saline injection (control). The effect of grafted cells on neuroinflammation and neurogenesis was investigated at 1 and 4 weeks post-transplantation. Results showed that microglia were activated following mild CCI, but not enhanced after engraftment of ENSC or DC. Indeed, ipsilateral lesioned somatosensory area expressed high levels of Iba-1+ microglia within the different groups after 1 and 4 weeks. On the other hand, treatment with ENSC or DC demonstrated a significant reduction in astrogliosis. The levels of GFAP expressing astrocytes started decreasing early (1 week) in the ENSC group and then were similarly low at 4 weeks in both ENSC and DC. Moreover, neurogenesis was significantly enhanced in ENSC and DC groups. Indeed, a significant increase in the number of DCX expressing progenitor cells was observed at 1 week in the ENSC group, and in DC and ENSC groups at 4 weeks. Furthermore, the number of mature neuronal cells (NeuN+) significantly increased in DC group at 4 weeks whereas they decreased in ENSC group at 1 week. Therefore, injection of ENSC or DC post-CCI caused decreased astrogliosis and suggested an increased neurogenesis via inducing neural progenitor proliferation and expression rather than neuronal maturation. Thus, ENSC may play a role in replacing lost cells and brain repair following TBI by improving neurogenesis and reducing neuroinflammation, reflecting an optimal environment for transplanted and newly born cells.

Combination of drug and stem cells neurotherapy: Potential interventions in neurotrauma and traumatic brain injury

Traumatic brain injury (TBI) has been recognized as one of the major public health issues that leads to devastating neurological disability. As a consequence of primary and secondary injury phases, neuronal loss following brain trauma leads to pathophysiological alterations on the molecular and cellular levels that severely impact the neuropsycho-behavioral and motor outcomes. Thus, to mitigate the neuropathological sequelae post-TBI such as cerebral edema, inflammation and neural degeneration, several neurotherapeutic options have been investigated including drug intervention, stem cell use and combinational therapies. These treatments aim to ameliorate cellular degeneration, motor decline, cognitive and behavioral deficits. Recently, the use of neural stem cells (NSCs) coupled with selective drug therapy has emerged as an alternative treatment option for neural regeneration and behavioral rehabilitation post-neural injury. Given their neuroprotective abilities, NSC-based neurotherapy has been widely investigated and well-reported in numerous disease models, notably in trauma studies. In this review, we will elaborate on current updates in cell replacement therapy in the area of neurotrauma. In addition, we will discuss novel combination drug therapy treatments that have been investigated in conjunction with stem cells to overcome the limitations associated with stem cell transplantation. Understanding the regenerative capacities of stem cell and drug combination therapy will help improve functional recovery and brain repair post-TBI. This article is part of the Special Issue entitled "Novel Treatments for Traumatic Brain Injury".

Neural stem cell therapy-Brief review

Adult mammalian neural stem cells are unique because of their properties, such as differentiation capacity, self-renewal, quiescence, and also because they exist in specific niches, which are the subventricular zone (SVZ) and subgranular zone (SGZ) - the dentate gyrus of the hippocampus. SVZ is situated along the ependymal cell layer, dividing the ventricular area and subventricular zone. There are several sources of neural stem cells such as human embryonic stem cells, human fetal brain-derived neural stem/progenitor cells, human induced pluripotent stem cells, direct reprogrammed astrocytes. Stem cell sciences are a promising tool for research purposes as well as therapy. Induced pluripotent stem cells appear to be very useful for human neuron studies, allowing the creation of defined neuron populations, particularly for neurodevelopmental and neurodegenerative diseases as well as ischemic events. Neural stem cell sciences have a promising future in terms of stem cell therapy as well as research. There is, however, still a great need for further research to overcome obstacles.

[Effect of chitosan porous scaffolds combined with bone marrow mesenchymal stem cells in repair of neurological deficit after traumatic brain injury in rats]

Objective

To investigate the possibility and effect of chitosan porous scaffolds combined with bone marrow mesenchymal stem cells (BMSCs) in repair of neurological deficit after traumatic brain injury (TBI) in rats.

Methods

BMSCs were isolated, cultured, and passaged by the method of bone marrow adherent culture. The 3rd generation BMSCs were identified by the CD29 and CD45 surface antigens and marked by 5-bromo-2-deoxyuridine (BrdU). The chitosan porous scaffolds were produced by the method of freeze-drying. The BrdU-labelled BMSCs were co-cultured in vitro with chitosan porous scaffolds, and were observed by scanning electron microscopy. MTT assay was used to observe the cell growth within the scaffold. Fifty adult Sprague Dawley rats were randomly divided into 5 groups with 10 rats in each group. The rat TBI model was made in groups A, B, C, and D according to the principle of Feeney's free fall combat injury. Orthotopic transplantation was carried out at 72 hours after TBI. Group A was the BMSCs and chitosan porous scaffolds transplantation group; group B was the BMSCs transplantation group; group C was the chitosan porous scaffolds transplantation group; group D was the complete medium transplantation group; and group E was only treated with scalp incision and skull window as sham-operation group. Before TBI and at 1, 7, 14, and 35 days after TBI, the modified neurological severity scores (mNSS) was used to measure the rats' neurological function. The Morris water maze tests were used after TBI, including the positioning voyage test (the incubation period was detected at 31-35 days after TBI, once a day) and the space exploration test (the number of crossing detection platform was detected at 35 days after TBI). At 36 days after TBI, HE staining and immunohistochemistry double staining [BrdU and neurofilament triplet H (NF-H) immunohistochemistry double staining, and BrdU and glial fibrillary acidic protein (GFAP) immunohistochemistry double staining] were carried out to observe the transplanted BMSCs' migration and differentiation in the damaged brain areas.

Results

Flow cytometry test showed that the positive rate of CD29 of the 3rd generation BMSCs was 98.49%, and the positive rate of CD45 was only 0.85%. After co-cultured with chitosan porous scaffolds in vitrofor 48 hours, BMSCs were spindle-shaped and secreted extracellular matrix to adhere in the scaffolds. MTT assay testing showed that chitosan porous scaffolds had no adverse effects on the BMSCs' proliferation. At 35 days after TBI, the mNSS scores and the incubation period of positioning voyage test in group A were lower than those in groups B, C, and D, and the number of crossing detection platform of space exploration test in group A was higher than those in groups B, C, and D, all showing significant differences ( P<0.05); but no significant difference was found between groups A and E in above indexes ( P>0.05). HE staining showed that the chitosan porous scaffolds had partially degraded, and they integrated with brain tissue well in group A; the degree of repair in groups B, C, and D were worse than that of group A. Immunohistochemical double staining showed that the transplanted BMSCs could survive and differentiate into neurons and glial cells, some differentiated neural cells had relocated at the normal brain tissue; the degree of repair in groups B, C, and D were worse than that of group A.

Conclusion

The transplantation of chitosan porous scaffolds combined with BMSCs can improve the neurological deficit of rats following TBI obviously, and also inhabit the glial scar's formation in the brain damage zone, and can make BMSCs survive, proliferate, and differentiate into nerve cells in the brain damage zone.

Docosahexaenoic acid (DHA) enhances the therapeutic potential of neonatal neural stem cell transplantation post-Traumatic brain injury

Traumatic Brain Injury (TBI) is a major cause of death and disability worldwide with 1.5 million people inflicted yearly. Several neurotherapeutic interventions have been proposed including drug administration as well as cellular therapy involving neural stem cells (NSCs). Among the proposed drugs is docosahexaenoic acid (DHA), a polyunsaturated fatty acid, exhibiting neuroprotective properties. In this study, we utilized an innovative intervention of neonatal NSCs transplantation in combination with DHA injections in order to ameliorate brain damage and promote functional recovery in an experimental model of TBI. Thus, NSCs derived from the subventricular zone of neonatal pups were cultured into neurospheres and transplanted in the cortex of an experimentally controlled cortical impact mouse model of TBI. The effect of NSC transplantation was assessed alone and/or in combination with DHA administration. Motor deficits were evaluated using pole climbing and rotarod tests. Using immunohistochemistry, the effect of transplanted NSCs and DHA treatment was used to assess astrocytic (Glial fibrillary acidic protein, GFAP) and microglial (ionized calcium binding adaptor molecule-1, IBA-1) activity. In addition, we quantified neuroblasts (doublecortin; DCX) and dopaminergic neurons (tyrosine hydroxylase; TH) expression levels. Combined NSC transplantation and DHA injections significantly attenuated TBI-induced motor function deficits (pole climbing test), promoted neurogenesis, coupled with an increase in glial reactivity at the cortical site of injury. In addition, the number of tyrosine hydroxylase positive neurons was found to increase markedly in the ventral tegmental area and substantia nigra in the combination therapy group. Immunoblotting analysis indicated that DHA+NSCs treated animals showed decreased levels of 38kDa GFAP-BDP (breakdown product) and 145kDa αII-spectrin SBDP indicative of attenuated calpain/caspase activation. These data demonstrate that prior treatment with DHA may be a desirable strategy to improve the therapeutic efficacy of NSC transplantation in TBI.

Traumatic Brain Injury and Stem Cell: Pathophysiology and Update on Recent Treatment Modalities

Traumatic brain injury (TBI) is a complex condition that presents with a wide spectrum of clinical symptoms caused by an initial insult to the brain through an external mechanical force to the skull. In the United States alone, TBI accounts for more than 50,000 deaths per year and is one of the leading causes of mortality among young adults in the developed world. Pathophysiology of TBI is complex and consists of acute and delayed injury. In the acute phase, brain tissue destroyed upon impact includes neurons, glia, and endothelial cells, the latter of which makes up the blood-brain barrier. In the delayed phase, “toxins” released from damaged cells set off cascades in neighboring cells eventually leading to exacerbation of primary injury. As researches further explore pathophysiology and molecular mechanisms underlying this debilitating condition, numerous potential therapeutic strategies, especially those involving stem cells, are emerging to improve recovery and possibly reverse damage. In addition to elucidating the most recent advances in the understanding of TBI pathophysiology, this review explores two primary pathways currently under investigation and are thought to yield the most viable therapeutic approach for treatment of TBI: manipulation of endogenous neural cell response and administration of exogenous stem cell therapy.

Interactome and reciprocal activation of pathways in topical mesenchymal stem cells and the recipient cerebral cortex following traumatic brain injury

In this study, GFP-MSCs were topically applied to the surface of cerebral cortex within 1 hour of experimental TBI. No treatment was given to the control group. Three days after topical application, the MSCs homed to the injured parenchyma and improved the neurological function. Topical MSCs triggered earlier astrocytosis and reactive microglia. TBI penumbra and hippocampus had higher cellular proliferation. Apoptosis was suppressed at hippocampus at 1 week and reduced neuronal damaged was found in the penumbral at day 14 apoptosis. Proteolytic neuronal injury biomarkers (alphaII-spectrin breakdown products, SBDPs) and glial cell injury biomarker, glial fibrillary acidic protein (GFAP)-breakdown product (GBDPs) in injured cortex were also attenuated by MSCs. In the penumbra, six genes related to axongenesis (Erbb2); growth factors (Artn, Ptn); cytokine (IL3); cell cycle (Hdac4); and notch signaling (Hes1) were up-regulated three days after MSC transplant. Transcriptome analysis demonstrated that 7,943 genes were differentially expressed and 94 signaling pathways were activated in the topical MSCs transplanted onto the cortex of brain injured rats with TBI. In conclusion, topical application offers a direct and efficient delivery of MSCs to the brain.

Topical Application of Mesenchymal Stromal Cells Ameliorated Liver Parenchyma Damage After Ischemia-Reperfusion Injury in an Animal Model

Supplemental digital content is available in the text.

Background

Ischemia-reperfusion injury (IRI) is commonly encountered after liver surgery. This study evaluated the hepatoprotective effects of topically applied adipose-derived mesenchymal stromal cells (ADMSCs) on hepatic IRI in a rat model.

Methods

ADMSCs from transgenic green fluorescent protein Sprague-Dawley rats were topically applied to the liver surface of Sprague-Dawley rats after hepatic IRI and fixed in position by fibrin glue (group A, n = 24). An equivalent amount of ADMSCs were administered through the portal (group B, n = 24) or tail vein (group C, n = 24). In the control group (group D, n = 20), no treatment was given to the IRI liver.

Results

All the rats in group A and group D survived. Within 2 days after hepatic IRI, only 50% of rats survived in group B, and ADMSCs were detected in thromboemboli within large vessels. 62.5% of the rats died in group C because most of the ADMSCs were trapped in the lungs. ADMSCs migrated across the liver capsule and homed to the injured liver parenchyma 3 days after topical application in group A. The homed ADMSCs expressed hepatocyte nuclear factor-4α and hepatocyte nuclear factor-1. Compared with group D, the rate of hepatic regeneration in group A was enhanced with less inflammation, smaller necrotic areas, and improved liver function. Proinflammatory cytokines IL-6, IL-21, and CD70 were significantly downregulated in group A by 6.3-, 2.7-, and 12.7-fold, respectively (P < 0.05). The neurogenic locus NOTCH homolog protein pathway was activated in the topical ADMSCs.

Conclusions

Topically applied adipose-derived mesenchymal stromal cells demonstrated hepatoprotective effects on hepatic IRI in an animal model.

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.

Stem cells and combination therapy for the treatment of traumatic brain injury

TBI is a nondegenerative, noncongenital insult to the brain from an external mechanical force; for instance a violent blow in a car accident. It is a complex injury with a broad spectrum of symptoms and has become a major cause of death and disability in addition to being a burden on public health and societies worldwide. As such, finding a therapy for TBI has become a major health concern for many countries, which has led to the emergence of many monotherapies that have shown promising effects in animal models of TBI, but have not yet proven any significant efficacy in clinical trials. In this paper, we will review existing and novel TBI treatment options. We will first shed light on the complex pathophysiology and molecular mechanisms of this disorder, understanding of which is a necessity for launching any treatment option. We will then review most of the currently available treatments for TBI including the recent approaches in the field of stem cell therapy as an optimal solution to treat TBI. Therapy using endogenous stem cells will be reviewed, followed by therapies utilizing exogenous stem cells from embryonic, induced pluripotent, mesenchymal, and neural origin. Combination therapy is also discussed as an emergent novel approach to treat TBI. Two approaches are highlighted, an approach concerning growth factors and another using ROCK inhibitors. These approaches are highlighted with regard to their benefits in minimizing the outcomes of TBI. Finally, we focus on the consequent improvements in motor and cognitive functions after stem cell therapy. Overall, this review will cover existing treatment options and recent advancements in TBI therapy, with a focus on the potential application of these strategies as a solution to improve the functional outcomes of TBI.

Effect of Erythropoietin and Stem Cells on Traumatic Brain Injury

OBJECTIVE

To investigate the healing effects of erythropoietin (EPO) and stem cells (SCs) in traumatic brain injury (TBI).

METHODS

Twenty-nine Wistar albino rats were used and separated into the following groups: control (C), EPO, SC, and SC+EPO. Group C received a TBI only, with no treatment. In the EPO group, 1000 U/kg EPO was given intraperitoneally at 30 minutes after TBI. In SC group, immediately after formation of TBI, 3 × 10,000 CD34(+) stem cells were injected into the affected area. In the SC+EPO group, half an hour after TBI and the injection of stem cells, 1000 U/kg EPO was injected. Before and after injury, trauma coordination performance was measured by the rotarod and inclined plane tests.

RESULTS

Seven weeks after trauma, rat brains were examined by radiology and histology. Rotarod performance test did not change remarkably, even after the injury. Compared with group C, the SC+EPO group was found to have significant differences in the inclined plane test results.

CONCLUSIONS

Separately given, SCs and EPO have a positive effect on TBI, and our findings suggest that their coadministration is even more powerful.

Topical Therapy with Mesenchymal Stem Cells Following an Acute Experimental Head Injury Has Benefits in Motor-Behavioral Tests for Rodents

BACKGROUND

The neuroprotective effects of mesenchymal stem cells (MSCs) have been reported in rodent and in preliminary clinical studies. MSCs are usually transplanted to patients by systemic infusion. However, only a few of the infused MSCs are delivered to the brain because of pulmonary trapping and the blood-brain barrier. In this study, MSCs were topically applied to the site of traumatic brain injury (TBI) and the neuroprotective effects were assessed.

MATERIALS AND METHODS

TBI was induced in Sprague-Dawley (SD) rats with an electromagnetically controlled cortical impact device after craniotomy was performed between the bregma and lambda, 1 mm lateral to the midline. We applied 1.5 million MSCs, derived from the adipose tissue of transgenic green fluorescent protein (GFP)-SD rats, to the exposed cerebral cortex at the injured site. The MSCs were held in position by a thin layer of fibrin. Neurological function in the test (n = 10) and control (n = 10) animals was evaluated using the rotarod test, the water maze test, and gait analysis at different time points.

RESULTS

Within 5 days following topical application, GFP-positive cells were found in the brain parenchyma. These cells co-expressed with markers of Glial fibrillary acidic protein (GFAP), nestin, and NeuN. There was less neuronal death in CA1 and CA3 of the hippocampus in the test animals. Neurological functional recovery was significantly improved.

CONCLUSION

Topically applied MSCs can migrate to the injured brain parenchyma and offer neuroprotective effects.

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.

Stem cells in neuroinjury and neurodegenerative disorders: challenges and future neurotherapeutic prospects

The prevalence of neurodegenerative diseases and neural injury disorders is increasing worldwide. Research is now focusing on improving current neurogenesis techniques including neural stem cell therapy and other biochemical drug-based approaches to ameliorate these disorders. Unfortunately, we are still facing many obstacles that are rendering current neurotherapies ineffective in clinical trials for reasons that are yet to be discovered. That is why we should start by fully understanding the complex mechanisms of neurogenesis and the factors that affect it, or else, all our suggested therapies would fail since they would not be targeting the essence of the neurological disorder but rather the symptoms. One possible paradigm shift is to switch from neuroprotectant therapies towards neurodegeneration/neurorestorative approaches. In addition, other and our laboratories are increasingly focusing on combining the use of pharmacological agents (such as Rho-associated kinase (ROCK) inhibitors or other growth factors (such as brain-derived neurotrophic factor (BDNF)) and stem cell treatment to enhance the survivability and/or differentiation capacity of transplanted stem cells in neurotrauma or other neurodegeneration animal models. Ongoing stem cell research is surely on the verge of a breakthrough of multiple effective therapeutic options for neurodegenerative disorders. Once, we fully comprehend the process of neurogenesis and its components, we will fully be capable of manipulating and utilizing it. In this work, we discuss the current knowledge of neuroregenerative therapies and their associated challenges.