Do bone marrow stromal cells proliferate after transplantation into mice cerebral infarct?—A double labeling study

Application of Mesenchymal Stem Cells in Targeted Delivery to the Brain: Potential and Challenges of the Extracellular Vesicle-Based Approach for Brain Tumor Treatment

Treating brain tumors presents enormous challenges, and there are still poor prognoses in both adults and children. Application of novel targets and potential drugs is hindered by the function of the blood-brain barrier, which significantly restricts therapeutic access to the tumor. Mesenchymal stem cells (MSCs) can cross biological barriers, migrate to sites of injuries to exert many healing effects, and be engineered to incorporate different types of cargo, making them an ideal vehicle to transport anti-tumor agents to the central nervous system. Extracellular vesicles (EVs) produced by MSCs (MSC-EVs) have valuable innate properties from parent cells, and are being exploited as cell-free treatments for many neurological diseases. Compared to using MSCs, targeted delivery via MSC-EVs has a better pharmacokinetic profile, yet avoids many critical issues of cell-based systems. As the field of MSC therapeutic applications is quickly expanding, this article aims to give an overall picture for one direction of EV-based targeting of brain tumors, with updates on available techniques, outcomes of experimental models, and critical challenges of this concept.

Bone Marrow Stromal Cells Alleviate Secondary Damage in the Substantia Nigra After Focal Cerebral Infarction in Rats

Transplantation of bone marrow stromal cells (BMSCs) is a promising therapy for ischemic stroke. Previously, we had reported that the secondary degeneration occurred in the ipsilateral substantia nigra (SN) after permanent distal branch of middle cerebral artery occlusion (dMCAO) in Sprague-Dawley rats. However, whether BMSCs have neurorestorative effects on the secondary damage in the SN after focal cerebral infarction has not known. In this study, rats were subjected to dMCAO followed by intravenous administration of BMSCs 1 day later. We found that transplanted BMSCs survived and migrated to cortical infarct areas and ipsilateral SN. Furthermore, BMSCs promoted neurogenesis through proliferation and differentiation in the SN after dMCAO. Rats implanted with BMSCs showed significant improvement in their performance of modified neurological severity scores and adhesive-removal test. Engrafted BMSCs enhanced survival of dopaminergic neuron, reduced gliosis in the ipsilateral SN, and increased contents of dopamine (DA) and its metabolites in the ipsilateral striatum after dMCAO. With pseudorabies virus-152 as a retrograde tracer, we also demonstrated that BMSCs could effectively enhance the cortico-striatum-nigral connections. These results suggest that BMSCs transplantation exerts neurorestorative effects after cortical infarction through promoting endogenous neurogenesis, increasing contents of DA and its metabolites, alleviating the secondary neuronal damage in the SN, enhancing the cortico-striatum-nigral projections pathway, and finally improving the neurological functional outcome.

Muse Cell: A New Paradigm for Cell Therapy and Regenerative Homeostasis in Ischemic Stroke

Multilineage-differentiating stress enduring (Muse) cells are one of the most promising donor cells for cell therapy against ischemic stroke, because they can differentiate into any type of cells constructing the central nervous system (CNS), including the neurons. They can easily be isolated from the bone marrow stromal cells (BMSCs), which may also contribute to functional recovery after ischemic stroke as donor cells. In this chapter, we concisely review their biological features and then future perspective of Muse cell transplantation for ischemic stroke. In addition, we briefly refer to the surprising role of Muse cells to maintain the homeostasis in the living body under both physiological and pathological conditions.

Peptide modified mesenchymal stem cells as targeting delivery system transfected with miR-133b for the treatment of cerebral ischemia

Mesenchymal stem cells (MSCs) have been regarded as potential targeting vehicles and demonstrated to exert therapeutic benefits for brain diseases. Direct homing to diseased tissue is crucial for stem cell-based therapy. In this study, a peptide-based targeting approach was established to enhance cell homing to cerebral ischemic lesion. Palmitic acid-peptide painted onto the cell membrane was able to direct MSCs to ischemic tissues without any observed cell cytotoxicity and influence on differentiation, thus reducing accumulation of cells in peripheral organs and increasing engraftment of cells in the targeted tissues. With enhanced cell homing, MSCs were used to deliver miR-133b to increase the expression level of miR-133b in an ischemic lesion and further improve therapeutic effects. This study is the first to develop MSCs co-modified with targeting peptide and microRNAs as potential targeting therapeutic agents. This targeting delivery system is expected to be applicable to other cell types and other diseases aside from stroke.

Current Opinion of Bone Marrow Stromal Cell Transplantation for Ischemic Stroke

This article reviews recent advancement and perspective of bone marrow stromal cell (BMSC) transplantation for ischemic stroke, based on current information of basic and translational research. The author would like to emphasize that scientific approach would enable us to apply BMSC transplantation into clinical situation in near future.

Optimization of the magnetic labeling of human neural stem cells and MRI visualization in the hemiparkinsonian rat brain

BACKGROUND

Magnetic resonance imaging is the ideal modality for non-invasive in vivo cell tracking allowing for longitudinal studies over time. Cells labeled with superparamagnetic iron oxide nanoparticles have been shown to induce sufficient contrast for in vivo magnetic resonance imaging enabling the in vivo analysis of the final location of the transplanted cells. For magnetic nanoparticles to be useful, a high internalization efficiency of the particles is required without compromising cell function, as well as validation of the magnetic nanoparticles behaviour inside the cells.

RESULTS

In this work, we report the development, optimization and validation of an efficient procedure to label human neural stem cells with commercial nanoparticles in the absence of transfection agents. Magnetic nanoparticles used here do not affect cell viability, cell morphology, cell differentiation or cell cycle dynamics. Moreover, human neural stem cells progeny labeled with magnetic nanoparticles are easily and non-invasively detected long time after transplantation in a rat model of Parkinson's disease (up to 5 months post-grafting) by magnetic resonance imaging.

CONCLUSIONS

These findings support the use of commercial MNPs to track cells for short- and mid-term periods after transplantation for studies of brain cell replacement therapy. Nevertheless, long-term MR images should be interpreted with caution due to the possibility that some MNPs may be expelled from the transplanted cells and internalized by host microglial cells.

Bone Marrow-Derived Mesenchymal Stem Cells Repair Necrotic Pancreatic Tissue and Promote Angiogenesis by Secreting Cellular Growth Factors Involved in the SDF-1 α /CXCR4 Axis in Rats

Acute pancreatitis (AP), a common acute abdominal disease, 10%-20% of which can evolve into severe acute pancreatitis (SAP), is of significant morbidity and mortality. Bone marrow-derived mesenchymal stem cells (BMSCs) have been reported to have a potential therapeutic role on SAP, but the specific mechanism is unclear. Therefore, we conducted this experiment to shed light on the probable mechanism. We validated that SDF-1α significantly stimulated the expressions of VEGF, ANG-1, HGF, TGF-β, and CXCR4 in BMSCs, which were inhibited by its receptor agonist, AMD3100. The capacities of proliferation, migration, and repair of human umbilical vein endothelial cells were enhanced by BMSCs supernatant. Meanwhile, BMSCs supernatant could also promote angiogenesis, especially after the stimulation with SDF-1α. In vivo, the migration of BMSCs was regulated by SDF-1α/CXCR4 axis. Moreover, transplanted BMSCs could significantly alleviate SAP, reduce the systematic inflammation (TNF-α↓, IL-1β↓, IL-6↓, IL-4↑, IL-10↑, and TGF-β↑), and promote tissue repair and angiogenesis (VEGF↑, ANG-1↑, HGF↑, TGF-β↑, and CD31↑), compared with the SAP and anti-CXCR4 groups. Taken together, the results showed that BMSCs ameliorated SAP and the SDF-1α/CXCR4 axis was involved in the repair and regeneration process.

Cell-based therapy for acute organ injury: preclinical evidence and ongoing clinical trials using mesenchymal stem cells

Critically ill patients often suffer from multiple organ failures involving lung, kidney, liver, or brain. Genomic, proteomic, and metabolomic approaches highlight common injury mechanisms leading to acute organ failure. This underlines the need to focus on therapeutic strategies affecting multiple injury pathways. The use of adult stem cells such as mesenchymal stem or stromal cells (MSC) may represent a promising new therapeutic approach as increasing evidence shows that MSC can exert protective effects following injury through the release of promitotic, antiapoptotic, antiinflammatory, and immunomodulatory soluble factors. Furthermore, they can mitigate metabolomic and oxidative stress imbalance. In this work, the authors review the biological capabilities of MSC and the results of clinical trials using MSC as therapy in acute organ injuries. Although preliminary results are encouraging, more studies concerning safety and efficacy of MSC therapy are needed to determine their optimal clinical use. (ANESTHESIOLOGY 2014; 121:1099-121).

Short-, middle- and long-term safety of superparamagnetic iron oxide-labeled allogeneic bone marrow stromal cell transplantation in rat model of lacunar infarction

Recently, both basic and clinical studies demonstrated that bone marrow stromal cell (BMSC) transplantation therapy can promote functional recovery of patients with CNS disorders. A non-invasive method for cell tracking using MRI and superparamagnetic iron oxide (SPIO)-based labeling agents has been applied to elucidate the behavior of transplanted cells. However, the long-term safety of SPIO-labeled BMSCs still remains unclear. The aim of this study was to investigate the short-, middle- and long-term safety of the SPIO-labeled allogeneic BMSC transplantation. For this purpose, BMSCs were isolated from transgenic rats expressing green fluorescent protein (GFP) and were labeled with SPIO. The Na/K ATPase pump inhibitor ouabain or vehicle was stereotactically injected into the right striatum of wild-type rats to induce a lacunar lesion (n = 22). Seven days after the insult, either BMSCs or SPIO solution were stereotactically injected into the left striatum. A 7.0-Tesla MRI was performed to serially monitor the behavior of BMSCs in the host brain. The animals were sacrificed after 7 days (n = 7), 6 weeks (n = 6) or 10 months (n = 9) after the transplantation. MRI demonstrated that BMSCs migrated to the damage area through the corpus callosum. Histological analysis showed that activated microglia were present around the bolus of donor cells 7 days after the allogeneic cell transplantation, although an immunosuppressive drug was administered. The SPIO-labeled BMSCs resided and started to proliferate around the route of the cell transplantation. Within 6 weeks, large numbers of SPIO-labeled BMSCs reached the lacunar infarction area from the transplantation region through the corpus callosum. Some SPIO nanoparticles were phagocytized by microglia. After 10 months, the number of SPIO-positive cells was lower compared with the 7-day and 6-week groups. There was no tumorigenesis or severe injury observed in any of the animals. These findings suggest that BMSCs are safe after cell transplantation for the treatment of stroke.

Calvarial defect healing by recruitment of autogenous osteogenic stem cells using locally applied simvastatin

Local statins implant has been shown to promote bone healing, the underlying mechanisms are unclear. The purpose of this study was to test the effect of local simvastatin implant on bone defect healing; to evaluate the mobilization, migration, and homing of bone marrow-derived mesenchymal stem cells (BMSCs) and endothelial progenitor cells (EPCs) induced by simvastatin. We found that local simvastatin implant increased bone formation by 51.8% (week 6) and 64.8% (week 12) compared with polyglycolic acid controls (P < 0.01), as verified by X-ray, CT, and histology. Simvastatin increased migration capacity of BMSCs and EPCs in vitro (P < 0.05). Local simvastatin implant increased mobilization of EPCs to the peripheral blood by 127% revealed by FACS analysis (P < 0.01), and increased osteogenic BMSCs to the peripheral blood dramatically revealed by Alizarin Red-S staining for mineralized nodules formation. Pre-transplanted GFP-transfected BMSCs as a tracing cell and bioluminescence imaging revealed that local simvastatin implant recruited GFP-labeled BMSC. Also, local simvastatin implant induced the HIF-1α and BMP-2 expression. In conclusion, local simvastatin implantation promotes bone defect healing, where the underlying mechanism appears to involve the higher expression of HIF-1α and BMP-2, thus recruit autogenous osteogenic and angiogenetic stem cells to the bone defect area implanted with simvastatin.

The effects of iron oxide incorporation on the chondrogenic potential of three human cell types

Non-invasive monitoring of living cells in vivo provides an important tool in the development of cell-based therapies in cartilage tissue engineering. High-resolution magnetic resonance imaging (MRI) has been used to monitor target cell populations in vivo. However, the side-effects on cell function of the labelling reagents, such as superparamagnetic iron oxide (SPIO), are still unclear. This study investigated the effect of SPIO particles on the chondrogenic differentiation of human bone marrow stromal cells (HBMSCs), neonatal and adult chondrocytes in vitro. Cells were labelled with SPIO for 24 h and chondrogenesis induced in serum-free medium including TGFβ3. For labelled/unlabelled cells, viability, morphology and proliferation were determined using CellTracker™ Green and PicoGreen dsDNA assays. The expression of SOX9, COL2A1 and ACAN was investigated using qRT-PCR after 2, 7 and 14 days. The results showed that viability was unaffected in all of the cells but cell morphology changed towards a 'stretched' phenotype following SPIO uptake. Cell proliferation was reduced only for labelled neonatal chondrocytes. SOX9 and COL2A1 expression decreased at day 2 but not at days 7 and 14 for labelled HBMSCs and adult chondrocytes; ACAN expression was unaffected. In contrast, SOX9 and COL2A1 expression were unaffected in labelled neonatal chondrocytes but a decrease in ACAN expression was seen at day 14. The results suggest that downregulation of chondrogenic genes associated with SPIO labelling is temporary and target cell-dependent. Resovist® can be used to label HBMSCs or mature chondrocytes for MR imaging of cells for cartilage tissue engineering.

Combination of temperature-sensitive stem cells and mild hypothermia: a new potential therapy for severe traumatic brain injury

Stem cell transplantation holds great potential for the treatment of traumatic brain injury (TBI). However, the micro-environment of reduced oxygen and accumulated toxins leads to low survival rates of grafted cells, which dramatically limits their clinical application. Mild hypothermia has been demonstrated to improve the micro-environment after severe TBI. Thus, we speculate that combinational therapy of mild hypothermia may promote survival of grafted cells, especially temperature-sensitive stem cells, which show the most activity in mild temperatures. In this study, we first isolated mesenchymal stem cells from umbilical cord (UCSMCs) and generated the temperature-sensitive UCSMCs (tsUCSMCs) by infection with a retrovirus carrying the temperature-sensitive tsA58 SV40 LT antigen gene. We demonstrated that tsUCSMCs grew and proliferated with more activity at 33°C than at 37°C by counting cell numbers with a hematocytometer, measuring the cell cycle with flow cytometry, and detecting proliferating cell nuclear antigen (PCNA) with immunofluorescence staining. Thereafter, we established the rat severe TBI model by fluid percussion, and injected PBS, UCSMCs, or tsUCSMCs into the injured region, and subject the animals to normothermia or mild hypothermia (33°C). We found that, compared with UCSMC or tsUCSMC treatment alone, their combination with hypothermia could significantly improve motor and cognitive function with more survival of the grafted cells. Furthermore, we observed that combined therapy with hypothermia and tsUCSMCs exerted the most protective effect on the recovery of neurological function of all the tested treatments, with the highest survival and proliferation rates, and the lowest apoptosis rate. Thus this may represent a new therapeutic strategy for the treatment of severe TBI.

Stem cell therapy for cerebral ischemia: from basic science to clinical applications

Recent stem cell technology provides a strong therapeutic potential not only for acute ischemic stroke but also for chronic progressive neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis with neuroregenerative neural cell replenishment and replacement. In addition to resident neural stem cell activation in the brain by neurotrophic factors, bone marrow stem cells (BMSCs) can be mobilized by granulocyte-colony stimulating factor for homing into the brain for both neurorepair and neuroregeneration in acute stroke and neurodegenerative diseases in both basic science and clinical settings. Exogenous stem cell transplantation is also emerging into a clinical scene from bench side experiments. Early clinical trials of intravenous transplantation of autologous BMSCs are showing safe and effective results in stroke patients. Further basic sciences of stem cell therapy on a neurovascular unit and neuroregeneration, and further clinical advancements on scaffold technology for supporting stem cells and stem cell tracking technology such as magnetic resonance imaging, single photon emission tomography or optical imaging with near-infrared could allow stem cell therapy to be applied in daily clinical applications in the near future.

Therapeutic effects of intra-arterial delivery of bone marrow stromal cells in traumatic brain injury of rats--in vivo cell tracking study by near-infrared fluorescence imaging

BACKGROUND

A noninvasive and effective route of cell delivery should be established to yield maximal therapeutic effects for central nervous system (CNS) disorders.

OBJECTIVE

To elucidate whether intra-arterial delivery of bone marrow stromal cells (BMSCs) significantly promotes functional recovery in traumatic brain injury (TBI) in rats.

METHODS

Rat BMSCs were transplanted through the ipsilateral internal carotid artery 7 days after the onset of cortical freezing injury. The BMSCs were labeled with fluorescent dye, and in vivo optical imaging was employed to monitor the behaviors of cells for 4 weeks after transplantation. Motor function was assessed for 4 weeks, and the transplanted BMSCs were examined using immunohistochemistry.

RESULTS

In vivo optical imaging and histologic analysis clearly demonstrated that the intra-arterially injected BMSCs were engrafted during the first pass without systemic circulation, and the transplanted BMSCs started to migrate from the cerebral capillary bed to the injured CNS tissue within 3 hours. Intra-arterial BMSC transplantation significantly promoted functional recovery after cortical freezing injury. A subgroup of BMSCs expressed the phenotypes of neurons, astrocytes, and endothelial cells around the injured neocortex 4 weeks after transplantation.

CONCLUSION

Intra-arterial transplantation may be a valuable option for prompt, noninvasive delivery of BMSCs to the injured CNS tissue, enhancing functional recovery after TBI. In vivo optical imaging may provide important information on the intracerebral behaviors of donor cells by noninvasive, serial visualization.

Human umbilical cord blood mesenchymal stem cells protect mice brain after trauma

OBJECTIVE

To investigate whether human umbilical cord blood mesenchymal stem cells, a novel source of progenitors with multilineage potential: 1) decrease traumatic brain injury sequelae and restore brain function; 2) are able to survive and home to the lesioned region; and 3) induce relevant changes in the environment in which they are infused.

DESIGN

Prospective experimental study.

SETTING

Research laboratory.

SUBJECTS

Male C57Bl/6 mice.

INTERVENTIONS

Mice were subjected to controlled cortical impact/sham brain injury. At 24 hrs postinjury, human umbilical cord blood mesenchymal stem cells (150,000/5 μL) or phosphate-buffered saline (control group) were infused intracerebroventricularly contralateral to the injured side. Immunosuppression was achieved by cyclosporine A (10 mg/kg intraperitoneally).

MEASUREMENTS AND MAIN RESULTS

After controlled cortical impact, human umbilical cord blood mesenchymal stem cell transplantation induced an early and long-lasting improvement in sensorimotor functions assessed by neuroscore and beam walk tests. One month postinjury, human umbilical cord blood mesenchymal stem cell mice showed attenuated learning dysfunction at the Morris water maze and reduced contusion volume compared with controls. Hoechst positive human umbilical cord blood mesenchymal stem cells homed to lesioned tissue as early as 1 wk after injury in 67% of mice and survived in the injured brain up to 5 wks. By 3 days postinjury, cell infusion significantly increased brain-derived neurotrophic factor concentration into the lesioned tissue, restoring its expression close to the levels observed in sham operated mice. By 7 days postinjury, controlled cortical impact human umbilical cord blood mesenchymal stem cell mice showed a nonphagocytic activation of microglia/macrophages as shown by a selective rise (260%) in CD11b staining (a marker of microglia/macrophage activation/recruitment) associated with a decrease (58%) in CD68 (a marker of active phagocytosis). Thirty-five days postinjury, controlled cortical impact human umbilical cord blood mesenchymal stem cell mice showed a decrease of glial fibrillary acidic protein positivity in the scar region compared with control mice.

CONCLUSIONS

These findings indicate that human umbilical cord blood mesenchymal stem cells stimulate the injured brain and evoke trophic events, microglia/macrophage phenotypical switch, and glial scar inhibitory effects that remodel the brain and lead to significant improvement of neurologic outcome.

Autologous bone marrow stromal cell transplantation for central nervous system disorders - recent progress and perspective for clinical application

There is increasing evidence that the transplanted BMSC significantly promote functional recovery after CNS damage in the animal models of various kinds of CNS disorders, including cerebral infarct, traumatic brain injury and spinal cord injury. However, there are several shortages of information when considering clinical application of BMSC transplantation for patients with CNS disorders. In this review, therefore, we discuss what we should clarify to establish cell transplantation therapy as the scientifically proven entity in clinical situation and describe our recent works for this purpose. The BMSC have the ability to alter their gene expression profile and phenotype in response to the surrounding circumstances and to protect the neurons by producing some neurotrophic factors. They also promote neurite extension and rebuild the neural circuits in the injured CNS. The BMSC can be expanded in vitro using the animal serum-free medium. Pharmacological modulation may accelerate the in vitro proliferation of the BMSC. Using in vivo optical imaging technique, the transplanted BMSC can non-invasively be tracked in the living animals for at least 8 weeks after transplantation. It is urgent issues to develop clinical imaging technique to track the transplanted cells in the CNS and evaluate the therapeutic significance of BMSC transplantation in order to establish it as a definite therapeutic strategy in clinical situation in the future.

Nanotechnology for treatment of stroke and spinal cord injury

The use of nanotechnology in cell therapy and tissue engineering offers promising future perspectives for brain and spinal cord injury treatment. Stem cells have been shown to selectively target injured brain and spinal cord tissue and improve functional recovery. To allow cell detection, superparamagnetic iron-oxide nanoparticles can be used to label transplanted cells. MRI is then a suitable method for the in vivo tracking of grafted cells in the host organism. CNS, and particularly spinal cord, injury is accompanied by tissue damage and the formation of physical and biochemical barriers that prevent axons from regenerating. One aspect of nanomedicine is the development of biologically compatible nanofiber scaffolds that mimic the structure of the extracellular matrix and can serve as a permissive bridge for axonal regeneration or as a drug-delivery system. The incorporation of biologically active epitopes and/or the utilization of these scaffolds as stem cell carriers may further enhance their therapeutic efficacy.

Effect of biodegradable fibrin scaffold on survival, migration, and differentiation of transplanted bone marrow stromal cells after cortical injury in rats

Object

In this study the authors' aim was to assess whether fibrin matrix could act as an injectable, valuable scaffold in bone marrow stromal cell (BMSC) transplantation for injured CNS tissue.

Methods

Both clotting time and 3D structure of fibrin matrix were analyzed with various concentrations of fibrinogen and CaCl2. The BMSCs were harvested from green fluorescent protein–transgenic mice and cultured. A cortical lesion was produced in rats by application of a very cold rod to the right cerebral hemisphere. The BMSCs, fibrin matrix, or BMSC–fibrin matrix complex was transplanted into the lesion though a small bur hole 7 days after the insult. Using immunohistochemical analysis, the authors evaluated the survival, migration, and differentiation of the transplanted cells 4 weeks after transplantation.

Results

Based on in vitro observations, the concentrations of fibrinogen and CaCl2 were fixed at 2.5 mg/ml and 2 μM in animal experiments, respectively. Fibrin matrix almost completely disappeared 4 weeks after transplantation. However, immunohistochemical analysis revealed that fibrin matrix exclusively enhanced the retention of the transplanted cells within the lesion, migration toward the lesion boundary zone, and differentiation into the neurons and perivascular cells.

Conclusions

Injectable fibrin matrix enhanced the survival, migration, and differentiation of the BMSCs transplanted into the cortical lesion in rats. The authors believe that it is one of the promising candidates for a potential, minimally invasive scaffold for CNS disorders. The present findings strongly suggest that such a strategy of tissue engineering could be a therapeutic option for CNS regeneration in patients with CNS injuries.

Cellular stroke therapy: from cell replacement to trophic support

Although initially considered as primarily a cell-replacement strategy, researchers today attribute a combination of both cellular repair and trophic support from transplanted cells as mediators of recovery.

Optimizing the success of cell transplantation therapy for stroke

Stem cell transplantation has evolved as a promising experimental treatment approach for stroke. In this review, we address the major hurdles for successful translation from basic research into clinical applications and discuss possible strategies to overcome these issues. We summarize the results from present pre-clinical and clinical studies and focus on specific areas of current controversy and research: (i) the therapeutic time window for cell transplantation; (ii) the selection of patients likely to benefit from such a therapy; (iii) the optimal route of cell delivery to the ischemic brain; (iv) the most suitable cell types and sources; (v) the potential mechanisms of functional recovery after cell transplantation; and (vi) the development of imaging techniques to monitor cell therapy.

Fractalkine and CX3CR1 are involved in the migration of intravenously grafted human bone marrow stromal cells toward ischemic brain lesion in rats

Recent research has shown that transplanted bone marrow stromal cells (MSCs) migrate to the injured regions and exert their therapeutic effects in cases of intracranial trauma, stroke, inflammation and degenerative disease. The specific mechanisms involved in their migration to lesions are still to be fully elucidated. In the present study, a rat model of transient middle cerebral artery occlusion (MCAO) was established. At 24 h after reperfusion, human bone marrow stromal cells (hMSCs) were transplanted by intravenous injection to explore the effects of fractalkine/CX3CR1 on the migration of transplanted MSCs to lesions. In vitro study using real-time PCR and western blot revealed that CX3CR1, the only known receptor of fractalkine, was expressed in cultured hMSCs. The expression of fractalkine in the ischemic brain was significantly increased. The directional migration of transplanted hMSCs to the damaged region was observed through detection of green fluorescence protein (GFP). The results indicated the cells were mainly distributed in the ischemic boundary zone with high fractalkine expression. In a further study, lentivirus-mediated RNA interference of CX3CR1 expression was employed. The results of these experiments indicated that CX3CR1 knock-down dramatically decreased the migration of hMSCs to the ischemic brain. The present study suggests that fractalkine and its specific receptor CX3CR1 are involved in the directional migration of transplanted MSCs to the ischemic damaged brain region.

Synergistic effects of granulocyte-colony stimulating factor on bone marrow stromal cell transplantation for mice cerebral infarct

This study was aimed to assess whether ex vivo treatment with granulocyte-colony stimulating factor (G-CSF) modifies biological properties of bone marrow stromal cells (BMSC) and enhances functional recovery by BMSC transplantation into infarct brain. Immunohistochemistry was conducted to characterize the cultured BMSC. The pharmacological effects of G-CSF on their proliferation, cell cycle, and growth factor production were precisely analyzed, using FACS and ELISA techniques. Non-treated or G-CSF treated BMSC were stereotactically transplanted into the mice brain subjected to cerebral infarct, and its effects on functional and histological aspects were evaluated. The BMSC expressed the receptor for G-CSF. Treatment with 0.1muM of G-CSF significantly enhanced the proliferation of BMSC by increasing their population in S phase, and increased their production of SDF-1alpha, HGF, and NGF. When transplanted into infarct brain, G-CSF treated BMSC significantly improved motor function as early as 2 weeks after transplantation, whereas non-treated BMSC did 4 weeks after transplantation. These findings strongly suggest that G-CSF may enhance the proliferation and growth factor production of the cultured BMSC and accelerate functional restoration by BMSC transplantation. Such pharmacological "activation" of the BMSC may contribute to successful clinical application of BMSC transplantation therapy for ischemic stroke.

In vivo magnetic resonance tracking of Feridex-labeled bone marrow-derived neural stem cells after autologous transplantation in rhesus monkey

Bone marrow stroma cells-derived neural stem cells (BMSCs-D-NSCs) transplantation is a promising strategy for the treatment of nervous system disorders. The development of a non-invasive method to follow the fate of BMSCs-D-NSCs in vivo is very important for the future application of this treatment. In this paper, we show for the first time, that BMSCs-D-NSCs from rhesus monkeys can be labeled in vitro with the superparamagnetic iron oxide (SPIO) contrast agent Feridex and Poly-L-lysine (PLL) without affecting morphology, cell cycle, telomerase activity, proliferation and differentiation ability of the labeled cells. Furthermore, when autografted into the striatum, these cells survived, differentiated and were incorporated into the brain, and could be reliably tracked using MRI, as confirmed by histological examination of the grafting sites with PKH(67) fluorescence. These results suggest that Feridex labeling of BMSCs-D-NSCs is feasible, efficient and safe for MRI tracing following autografting into the rhesus monkey nervous system.

Mesenchymal and neural stem cells labeled with HEDP-coated SPIO nanoparticles: in vitro characterization and migration potential in rat brain

Mesenchymal stem cells (MSC) may transdifferentiate into neural cells in vitro under the influence of matrix molecules and growth factors present in neurogenic niches. However, further experiments on the behavior of such stem cells remain to be done in vivo. In this study, rat MSC (rMSC) have been grafted in a neurogenic environment of the rat brain, the subventricular zone (SVZ), in order to detect and follow their migration using superparamagnetic iron oxide (SPIO) nanoparticles. We sought to characterize the potential effect of iron loading on the behavior of rMSC as well as to address the potential of rMSC to migrate when exposed to the adequate brain microenvironment. 1-hydroxyethylidene-1.1-bisphosphonic acid (HEDP)-coated SPIO nanoparticles efficiently labeled rMSC without significant adverse effects on cell viability and on the in vitro differentiation potential. In opposition to iron-labeled rat neural stem cells (rNSC), used as a positive control, iron-labeled rMSC did not respond to the SVZ microenvironment in vivo and did not migrate, unless a mechanical lesion of the olfactory bulb was performed. This confirmed the known potential of iron-labeled rMSC to migrate toward lesions and, as far as we know, this is the first study describing such a long distance migration from the SVZ toward the olfactory bulb through the rostral migratory stream (RMS).

Bone marrow-derived mesenchymal stem cells for the treatment of ischemic stroke

Bone marrow-derived mesenchymal stem cells (MSCs) have great potential as therapeutic agents in stroke management, since they are easily accessible and can be rapidly expanded ex vivo for autologous transplantation. Increasing evidence suggests that bone marrow cells migrate throughout the brain and differentiate into neurons and glial cells. Both non-human and human MSCs have been used to treat stroke in murine models with satisfactory results. Several factors, such as transdifferentiation, induction of neurogenesis and angiogenesis, neuroprotection, and activation of endogenous neurorestorative processes, contribute to the benefits of MSCs in the ischemic brain. Many variables, including types of MSCs, cell dose, timing of treatment, route of cell delivery, and characteristics of stroke patients, influence the efficacy of MSC treatment of stroke. Although the first trials of autologous MSC therapy in stroke patients showed promising results, the optimal approach for different clinical settings has yet to be determined. The fundamental properties of MSCs and their potential short-term and long-term toxicities also need to be determined before moving forward to use of these cells in clinical practice.

Neural progenitor cells transplanted into the uninjured brain undergo targeted migration after stroke onset

Endogenous neural stem cells normally reside in their niche, the subventricular zone, in the uninjured rodent brain. Upon stroke, these cells become more proliferative and migrate away from the subventricular zone into the surrounding parenchyma. It is not known whether this stroke-induced behavior is due to changes in the niche or introduction of attractive cues in the infarct zone, or both. A related question is how transplanted neural stem cells respond to subsequent insults, including whether exogenous stem cells have the plasticity to respond to subsequent injuries after engraftment. We addressed this issue by transplanting neural progenitor cells (NPCs) into the uninjured brain and then subjecting the animal to stroke. We were able to follow the transplanted NPCs in vivo by labeling them with superparamagnetic iron oxide particles and imaging them via high-resolution magnetic resonance imaging (MRI) during engraftment and subsequent to stroke. We find that transplanted NPCs that are latent can be activated in response to stroke and exhibit directional migration into the parenchyma, similar to endogenous neural NPCs, without a niche environment.

Intravascular cell replacement therapy for stroke

✓ The use of stem cell transplantation to restore neurological function after stroke is being recognized as a potential novel therapy. Before stem cell transplantation can become widely applicable, however, questions remain about the optimal site of delivery and timing of transplantation. In particular, there seems to be increasing evidence that intravascular cell delivery after stroke is a viable alternative to intracerebral transplantation. In this review, the authors focus on the intravascular delivery of stem cells for stroke treatment with an emphasis on timing, transendothelial migration and possible mechanisms leading to neuroprotection, angiogenesis, immunomodulation, and neural plasticity. They also review current concepts of in vivo imaging and tracking of stem cells after stroke.