Intrastriatal transplantation of bone marrow nonhematopoietic cells improves functional recovery after stroke in adult mice

Neuroplasticity and cellular therapy in cerebral infarction

Stroke is the second to third most common cause of death in adults, and more than a third of people who survive a stroke will have severe disability. Therapeutic options currently centre on fibrinolytic treatment, but its limitations restrict use to a small proportion of patients. Although a wide range of neuroprotective substances has been effective in experimental models, they have repeatedly failed in clinical trials because of toxicity or loss of effectiveness. Recent strategies based on neuroplasticity and cellular therapy have shown significant efficacy in improving functional recovery in experimental models, although further study is still necessary to clarify how the brain responds to ischaemic damage and is able to reorganize itself in the long term. Although steps must still be taken to ensure the safety and feasibility of treatments based on neuroplasticity and cellular therapy, neurorepair strategies provide promising future therapeutic options for stroke.

Human umbilical cord blood-derived CD34+ cells cause attenuation of multiorgan dysfunction during experimental heatstroke

Multiorgan dysfunction ensuing from severe heatstroke includes hypotension, hepatic and renal failure, hypercoagulable state, activated inflammation, and cerebral ischemia and injury. We attempted to assess whether human umbilical cord blood-derived CD34+ cell therapy improves survival during experimental heatstroke by attenuating multiorgan dysfunction. Anesthetized rats, immediately after the onset of heatstroke, were divided into 2 major groups and given CD34- or CD34+ cells (1 x 10(5)-5 x 10(5)/mL/kg body weight) i.v. They were exposed to ambient temperature of 43 degrees C to induce heatstroke. Another group of rats were exposed to room temperature (26 degrees C) and used as normothermic controls. Hypotension, hepatic and renal failure (evidenced by increased serum urea nitrogen, creatinine, aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase levels in plasma), hypercoagulable state (evidenced by increased prothrombin time, activated partial thromboplastin time, and D-dimer, and decreased platelet count and protein C in plasma), activated inflammation (evidence by increased TNF-alpha levels in serum), and cerebral dysfunction (evidenced by intracranial hypertension, cerebral hypoperfusion and hypoxia, and cerebral ischemia and injury) were monitored. When the CD34- cell-treated or untreated rats underwent heat stress, their survival time values were found to be 19 to 23 min. Resuscitation with CD34+ cells significantly improved survival time (duration, 63-291 min). As compared with normothermic controls, all CD34- cell-treated heatstroke animals displayed hypotension, hepatic and renal failure, hypercoagulable state, activated inflammation, and cerebral ischemia and injury. However, CD34+ cell therapy significantly caused attenuation of all the above-mentioned heatstroke reactions. In addition, the levels of IL-10 in plasma and glial cell line-derived neurotrophic factors in brain were all significantly increased after CD34+ cell therapy during heatstroke. Our data indicate that CD34+ cell therapy may resuscitate persons who had a heatstroke by reducing multiorgan dysfunction or failure.

Bone marrow-derived mesenchymal stromal cells for the repair of central nervous system injury

Transplantation of bone marrow-derived mesenchymal stromal cells (MSCs) into the injured brain or spinal cord may provide therapeutic benefit. Several models of central nervous system (CNS) injury have been examined, including that of ischemic stroke, traumatic brain injury and traumatic spinal cord injury in rodent, primate and, more recently, human trials. Although it has been suggested that differentiation of MSCs into cells of neural lineage may occur both in vitro and in vivo, this is unlikely to be a major factor in functional recovery after brain or spinal cord injury. Other mechanisms of recovery that may play a role include neuroprotection, creation of a favorable environment for regeneration, expression of growth factors or cytokines, vascular effects or remyelination. These mechanisms are not mutually exclusive, and it is likely that more than one contribute to functional recovery. In light of the uncertainty surrounding the fate and mechanism of action of MSCs transplanted into the CNS, further preclinical studies with appropriate animal models are urgently needed to better inform the design of new clinical trials.

Post-ischemic treatment with erythropoietin or carbamylated erythropoietin reduces infarction and improves neurological outcome in a rat model of focal cerebral ischemia

BACKGROUND AND PURPOSE

Recombinant human erythropoietin (rhEPO; Epoetin-alpha; PROCRITtrade mark) has been shown to exert neuroprotective and restorative effects in a variety of CNS injury models. However, limited information is available regarding the dose levels required for these beneficial effects or the neuronal responses that may underlie them. Here we have investigated the dose-response to rhEPO and compared the effects of rhEPO with those of carbamylated rhEPO (CEPO) in a model of cerebral stroke in rats.

EXPERIMENTAL APPROACH

Rats subjected to embolic middle cerebral artery occlusion (MCAo) were treated with rhEPO or CEPO, starting at 6 h and repeated at 24 and 48 h, after MCAo. Cerebral infarct volumes were assessed at 28 days and neurological impairment at 7, 14, 21 and 28 days, post-MCAo.

KEY RESULTS

rhEPO at dose levels of 500, 1150 or 5000 IU kg(-1) or CEPO at a dose level of 50 microg kg(-1) significantly reduced cortical infarct volume and reduced neurologic impairment. All doses of rhEPO, but not CEPO, produced a transient increase in haematocrit, while rhEPO and CEPO substantially reduced the number of apoptotic cells and activated microglia in the ischemic boundary region.

CONCLUSIONS AND IMPLICATIONS

These data indicate that rhEPO and CEPO have anti-inflammatory and anti-apoptotic effects, even with administration at 6 h following embolic MCAo in rats. Taken together, these actions of rhEPO and CEPO are likely to contribute to their reduction of neurologic impairment following cerebral ischemia.

Bone marrow stromal cells promoting corticospinal axon growth through the release of humoral factors in organotypic cocultures in neonatal rats

OBJECT

The transplantation of bone marrow stromal cells (BMSCs) is considered to be an alternative treatment to promote central nervous system regeneration, but the precise mechanisms of this regeneration after transplantation of BMSCs have not been clarified. In the present study, the authors assessed the effects of BMSC transplantation on corticospinal axon growth quantitatively, and they analyzed the mechanism of central nervous system regeneration in the injured and BMSC-treated spinal cord using the organotypic coculture system.

METHODS

Bone marrow stromal cells derived from green fluorescent protein-expressing transgenic Sprague-Dawley rats were transplanted to the organotypic coculture system in which brain cortex and spinal cord specimens obtained in neonatal Sprague-Dawley rats were used. The axon growth from the cortex to the spinal cord was assessed quantitatively, using anterograde tracing with 1,1 '-ioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate. To identify the differentiation of transplanted BMSCs, immunohistochemical examinations were performed. In addition, BMSCs were analyzed using reverse transcriptase polymerase chain reaction (RT-PCR) for mRNA expression of the growth factors. The transplantation of BMSCs beneath the membrane, where the transplanted cells did not come into direct contact with the cultured tissue, promoted corticospinal axon growth to the same extent as transplantation of BMSCs on the tissues. The RT-PCR showed that the transplanted BMSCs expressed the mRNA of brain-derived neurotrophic factor (BDNF) and vascular endothelial growth factor (VEGF). Con

CONCLUSIONS

ese findings strongly suggest that humoral factors expressed by BMSCs, including BDNF and VEGF, participate in regeneration of the central nervous system after transplantation of these cells.

Development of adult pluripotent stem cell therapies for ischemic injury and disease

Over the past 5 years, adult pluripotent stem cell lines have been isolated from multiple organs and tissues in laboratories worldwide. Adult pluripotent stem cells are capable of regenerating tissues of all three primitive germ layers and express pluripotency markers, such as Oct4 or telomerase, which are associated with the primitive stem cell properties of embryonic stem cells. As our collective understanding of the biology of these unique cells has improved, so has our ability to isolate, expand and subsequently evaluate them as therapeutics in preclinical models of acute injury and disease. Pluripotent adult stem cells, as opposed to tissue-restricted adult stem cells, such as mesenchymal stromal cells; have extensive replicative capacity enabling large-scale clinical expansion. This is essential to achieving consistent clinical response data and enabling the cost-effective production necessary for commercial adoption. In addition, investigators have reported effective use of allogeneic adult pluripotent stem cells in acute ischemic injury models in the heart and brain, supporting the 'off the shelf' product concept for this cellular therapy. In this article, the authors review preclinical animal data demonstrating the benefit of pluripotent adult progenitor cells in the treatment of ischemic injuries of the heart, vascular system and CNS.

Human umbilical cord blood cells or estrogen may be beneficial in treating heatstroke

This current review summarized animal models of heatstroke experimentation that promote our current knowledge of therapeutic effects on cerebrovascular dysfunction, coagulopathy, and/or systemic inflammation with human umbilical cord blood cells (HUCBCs) or estrogen in the setting of heatstroke. Accumulating evidences have demonstrated that HUCBCs provide a promising new therapeutic method against neurodegenerative diseases, such as stroke, traumatic brain injury, and spinal cord injury as well as blood disease. More recently, we have also demonstrated that post- or pretreatment by HUCBCs may resuscitate heatstroke rats with by reducing circulatory shock, and cerebral nitric oxide overload and ischemic injury. Moreover, CD34+ cells sorted from HUCBCs may improve survival by attenuating inflammatory, coagulopathy, and multiorgan dysfunction during experimental heatstroke. Many researchers indicated pro- (e.g. tumor necrosis factor-alpha [TNF-alpha]) and anti-inflammatory (e.g. interleukin-10 [IL-10]) cytokines in the peripheral blood stream correlate with severity of circulatory shock, cerebral ischemia and hypoxia, and neuronal damage occurring in heatstroke. It has been shown that intravenous administration of CD34+ cells can secrete therapeutic molecules, such as neurotrophic factors, and attenuate systemic inflammatory reactions by decreasing serum TNF-alpha but increasing IL-10 during heatstroke. Another line of evidence has suggested that estrogen influences the severity of injury associated with cerebrovascular shock. Recently, we also successfully demonstrated estrogen resuscitated heatstroke rats by ameliorating systemic inflammation. Conclusively, HUCBCs or estrogen may be employed as a beneficial therapeutic strategy in prevention and repair of cerebrovascular dysfunction, coagulopathy, and/or systemic inflammation during heatstroke.

Histone deacetylase inhibitors exhibit anti-inflammatory and neuroprotective effects in a rat permanent ischemic model of stroke: multiple mechanisms of action

The pathophysiology of cerebral ischemia involves multiple mechanisms including neuroinflammation mediated by activated microglia and infiltrating macrophages/monocytes. The present study employed a rat permanent middle cerebral artery occlusion (pMCAO) model to study effects of histone deacetylase (HDAC) inhibition on ischemia-induced brain infarction, neuroinflammation, gene expression, and neurological deficits. We found that post-pMCAO injections with HDAC inhibitors, valproic acid (VPA), sodium butyrate (SB), or trichostatin A (TSA), decreased brain infarct volume. Postinsult treatment with VPA or SB also suppressed microglial activation, reduced the number of microglia, and inhibited other inflammatory markers in the ischemic brain. The reduction in levels of acetylated histone H3 in the ischemic brain was prevented by treatment with VPA, SB, or TSA. Moreover, injections with HDAC inhibitors superinduced heat-shock protein 70 and blocked pMCAO-induced down-regulation of phospho-Akt, as well as ischemia-elicited up-regulation of p53, inducible nitric oxide synthase, and cyclooxygenase-2. The motor, sensory, and reflex performance of pMCAO rats was improved by VPA, SB, or TSA treatment. The beneficial effects of SB and VPA in reducing brain infarct volume and neurological deficits occurred when either drug was administrated at least 3 h after ischemic onset, and the behavioral improvement was long-lasting. Together, our results demonstrate robust neuroprotective effects of HDAC inhibitors against cerebral ischemia-induced brain injury. The neuroprotection probably involves multiple mechanisms including suppression of ischemia-induced cerebral inflammation. Given that there is no effective treatment for stroke, HDAC inhibitors, such as VPA, SB, and TSA, should be evaluated for their potential use for clinical trials in stroke patients.

2', 3'-Cyclic nucleotide 3'-phosphodiesterase cells derived from transplanted marrow stromal cells and host tissue contribute to perineurial compartment formation in injured rat spinal cord

Transdifferentiation of transplanted marrow stromal cells (MSCs) and reactive changes of glial cells in a completely transected rat spinal cord were examined. Marrow stromal cells exhibited 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNP) at the plasma membrane and this has allowed their identification after transplantation by immunoelectron microscopy. In the control rats, the lesion site showed activated microglia/neural macrophages and some elongated cells, whose cytoplasm was immunoreactive for CNP. Cells designated as CNP1 and apparently host-derived expressed CXCR4. In experimental rats receiving MSCs transplantation, CNP1 cells were increased noticeably. This was coupled with the occurrence of a different subset of CNP cells whose plasma membrane was CNP-immunoreactive and expressed CXCR4. These cells, designated as CNP2, enclosed both myelinated and unmyelinated neurites thus assuming a spatial configuration resembling that of Schwann cells. A remarkable feature was the extensive ramifications of CNP1 cells with long filopodia processes delineating the CNP2 cells and their associated neurites, forming many perineurial-like compartments. Present results have shown that CNP2 cells considered to be MSCs-derived can transform into cells resembling Schwann cells based on their spatial relation with the regenerating nerve fibers, whereas the CNP1 glial cells participate in formation of perineurial compartments, probably serving as conduits to guide the nerve fiber growth. The chemotactic migration of CNP cells either derived from host tissue or MSCs bearing CXCR4 may be attracted by stromal derived factor-1alpha (SDF-1alpha) produced locally. The coordinated cellular interaction between transplanted MSCs and local glial cells may promote the growth of nerve fibers through the lesion site.

Bone marrow stromal cells of transgenic mice can improve the cognitive ability of an Alzheimer's disease rat model

This study investigated the effects of bone marrow stromal cells transplantation on Alzheimer's disease (AD). Bone marrow stromal cells (BMSC) were obtained from the bone marrow of transgenic mice expressing green fluorescent protein and transplanted into the hippocampus of rats, which had received an injection of beta amyloid protein into the hippocampus 8 days earlier. Morris Water Maze test was used to observe behavior 2 weeks after transplantation. The survival and differentiation of the grafts were studied immunohistochemically. Behavior improved significantly in the transplanted group. The transplanted BMSC survived and presented ChAT-like neurons, indicating that these transplanted cells might differentiate into cholinergic neurons and the procedure could be a promising therapy for Alzheimer's disease.

Neurogenesis, Angiogenesis, and MRI Indices of Functional Recovery From Stroke

This article analyzes the mechanisms underlying the potentiation of functional recovery poststroke by cell-based and pharmacologic agents, which amplify endogenous neurogenesis in the subventricular zone and angiogenesis in the border of the ischemic lesion in the animal. Discussion of the interaction between angiogenesis and neurogenesis is provided and data are described demonstrating a role for matrix metalloproteinases expressed in periinfarct vasculature as chemotactic for neuroblasts migrating from the subventricular zone. Monitoring angiogenesis and structural changes in the ischemic brain associated with functional recovery by means of MRI is described. We demonstrate that injured brain can be stimulated to promote angiogenesis and neurogenesis, which are coupled restorative processes that contribute to functional recovery from stroke and that MRI indices of these neurorestorative events are highly correlative with neurologic function and may be used in real-time monitoring of recovery from stroke.

Bone marrow-derived stem cells in neurological diseases: stones or masons?

In spite of the commonly held belief that ‘the brain does not regenerate’, it is now accepted that postnatal neurogenesis does occur. Thus, one wonders whether cellular-replacement therapy might be used to heal the brain in diseases caused by neuronal cell loss. The existence of neural stem cells has been demonstrated by many scientists and is now generally accepted. The exact role of these cells, how their numbers are regulated and how they participate in CNS and spinal cord regeneration in postnatal life are still not well known. There are many reviews summarizing work on these cells; consequently, I will focus instead on other cells that may participate in postnatal neurogenesis: bone marrow-derived stem cells. The possibility that bone marrow-derived stem cells populate the CNS and differentiate into various neural elements is certainly not universally accepted.

Autologous adipose tissue-derived stromal cells for treatment of spinal cord injury

Isolated rat adipose tissue-derived stromal cells (rATSCs) contain pluripotent cells that can be differentiated into a variety of cell lineages, including neural cells. Recent work has shown that ATSCs can make neurosphere-like clumps and differentiate into neuron-like cells expressing neuronal markers, but their therapeutic effect is unclear. Here we report that intravenous infusion of oligodendrocyte precursor cells (OPCs) derived from rATSC autograft cells sources improve motor function in rat models of spinal cord injury (SCI). After 4-5 weeks, transplanted rATSC-OPC cells survived and migrated into the injured region of SCI very efficiently (30-35%) and migrated cells were partially differentiated into neurons and oligodendrocyte. Also, we found some of the engrafted OPCs migrated and integrated in the kidney, brain, lung, and liver through the intravenous system. Behavioral analysis revealed the locomotor functions of OPC-autografted SCI rats were significantly restored. Efficient migration of intravenously engrafted rATSC-OPCs cells into SCI lesion suggests that SCI-induced chemotaxic factors facilitate migration of rATSC-OPCs. Here, we verified that engrafted rATSCs and SCI-induced chemotaxic factors indeed play an important role in proliferation, migration, and differentiation of endogeneous spinal cord-derived neural progenitor cells in the injured region. In transplantation paradigms, the interaction between engrafted rATSC-OPCs and endogeneous spinal cord-derived neuronal progenitor cells will be important in promoting healing through fate decisions, resulting in coordinated induction of cell migration and differentiation.

Neural differentiation of human mesenchymal stem cells: evidence for expression of neural markers and eag K+ channel types

OBJECTIVE

Mesenchymal stem cells (MSCs) are multipotent cells that can self-renew, proliferate, and exhibit elevated cellular plasticity. To investigate their possible neural fate, we studied human mesenchymal stem cells (hMSCs) in different cell culture conditions from morphological, immunochemical, gene expression, and physiological points of view.

MATERIALS AND METHODS

We tested hMSCs in three previously reported experimental conditions made of alpha-modified minimum essential medium (alpha-MEM)/1 mM beta-mercaptoethanol (betaME), 10 microM alpha-MEM/retinoic acid (RA) or alpha-MEM/2% dimethylsulfoxide (DMSO) + 200 microM beta-hydroxyanisole (BHA), respectively, and in a new experimental condition with neural progenitor maintenance medium (NPMM).

RESULTS

hMSCs were isolated from bone marrow and expanded for several passages. In betaME, cells became immunoreactive for neuronal nuclear antigen (NeuN), neuron-specific enolase (NSE), Nestin, and glial fibrillary acidic protein (GFAP). In experimental conditions with RA and DMSO/BHA, hMSCs were NeuN and NSE-positive while in NPMM they were positive for GFAP and NSE. Untreated hMSCs showed a weak mRNA expression for microtubule-associated protein, NSE, and neurofilament protein-medium and GFAP, which strongly increased in NPMM-treated hMSCs. In the electrophysiological study, NPMM-differentiated hMSCs expressed two delayed rectifier K+ currents related to two ether-à-go-go K+ channels (eag1, eag2), which are fundamental for setting the negative resting potentials required for neuronal survival and basal cell activity. The two K+ channels were absent in undifferentiated hMSCs. These data were confirmed by real-time polymerase chain reaction.

CONCLUSION

In our new culture condition, hMSCs acquired new morphological characteristics, neural markers, and electrophysiological properties, which are suggestive of neural differentiation. This might lead to clinical use of hMSCs in neural degenerative diseases.

Vascular fate of adipose tissue-derived adult stromal cells in the ischemic murine brain: A combined imaging-histological study

Increasing evidence indicates that fat tissue can provide a novel source of progenitor cells with therapeutic potential. Here, the fate of adipose tissue-derived stromal cells (ADSCs) transplanted into the mouse ischemic cortex was monitored in the long term using in vivo imaging, and subsequently characterized. The left middle cerebral artery (MCA) was occluded in C57BL/6J mice equipped with a closed cranial window chronically implanted over the left parietal cortex (n = 20). ADSCs expressing the green fluorescent protein (GFP) (approximately 18 x 10(3) cells in 0.5 microl) were transplanted into the ipsilateral cortex, 24 h after MCA occlusion. GFP+-ADSCs were monitored through the window using confocal fluorescence microscopy to assess their single fate in vivo. Co-localization of GFP with vascular, neuronal, glial or proliferation markers was investigated immunohistochemically. Repeated in vivo imaging revealed that GFP+-ADSCs migrated over 1 week toward the lesion, survived for at least 4 weeks, and exhibited a particular tropism for vessels. About 5% of the transplanted GFP+-ADSCs were scattered in the peri-ischemic area on histological sections. Immunohistochemistry evidenced that perivascular GFP+-ADSCs enfolded CD31-labeled endothelial cells, always outside their basal lamina, and occasionally expressed smooth muscle alpha-actin. Less than 1% GFP and BrdU co-labeling indicated a low proliferation rate of ADSCs. These results demonstrate that cerebral ischemia induces ADSCs survival, migration toward the lesion, especially toward microvessels, and occasional differentiation into smooth muscle cells.

Bone marrow stromal cells mediate protection through stimulation of PI3-K/Akt and MAPK signaling in neurons

Application of adult bone marrow stromal cells (BMSC) improves functional outcome in animal models of cerebral ischemia, traumatic brain injury, and spinal cord injury. Accumulating evidence suggests that such functional recovery after BMSC treatment is mediated by enhanced trophic support of the injured neurons and improved neuronal plasticity rather than tissue replacement by bone marrow-derived stem cells. Therefore, the aim of the present study was to explore the potential of non-hematopoietic BMSC to stimulate signaling pathways in neurons that mediate trophic effects and neuroprotection. In primary embryonic rat neurons, BMSC conditioned medium (CM) attenuated staurosporine (STS) or amyloid-beta peptide-induced apoptosis in a concentration-dependent manner. The neuroprotective effect of CM required several hours of pretreatment and was abolished by heating over 90 degrees C. Immunoblot analyses revealed that CM enhanced Erk1/2 and Akt phosphorylation in neurons, and the specific MEK1 inhibitor PD98059 or the phosphoinositide-3 kinase (PI3-K) inhibitor Ly294002 abolished the neuroprotective effect of CM. Further, double-conditioned medium (DCM) obtained from BMSC previously stimulated by medium from STS-challenged neurons showed a more potent anti-apoptotic effect compared to the single-conditioned medium. Overall, these findings demonstrate that BMSC trigger endogenous survival signaling pathways in neurons that mediate protection against apoptotic insults. Moreover, the interaction between stressed neurons and BMSC further amplifies the observed neuroprotective effect.

Novel therapeutic strategy for stroke in rats by bone marrow stromal cells and ex vivo HGF gene transfer with HSV-1 vector

Occlusive cerebrovascular disease leads to brain ischemia that causes neurological deficits. Here we introduce a new strategy combining mesenchymal stromal cells (MSCs) and ex vivo hepatocyte growth factor (HGF) gene transferring with a multimutated herpes simplex virus type-1 vector in a rat transient middle cerebral artery occlusion (MCAO) model. Gene-transferred MSCs were intracerebrally transplanted into the rats' ischemic brains at 2 h (superacute) or 24 h (acute) after MCAO. Behavioral tests showed significant improvement of neurological deficits in the HGF-transferred MSCs (MSC-HGF)-treated group compared with the phosphate-buffered saline (PBS)-treated and MSCs-only-treated group. The significant difference of infarction areas on day 3 was detected only between the MSC-HGF group and the PBS group with the superacute treatment, but was detected among each group on day 14 with both transplantations. After the superacute transplantation, we detected abundant expression of HGF protein in the ischemic brain of the MSC-HGF group compared with others on day 1 after treatment, and it was maintained for at least 2 weeks. Furthermore, we determined that the increased expression of HGF was derived from the transferred HGF gene in gene-modified MSCs. The percentage of apoptosis-positive cells in the ischemic boundary zone (IBZ) was significantly decreased, while that of remaining neurons in the cortex of the IBZ was significantly increased in the MSC-HGF group compared with others. The present study shows that combined therapy is more therapeutically efficient than MSC cell therapy alone, and it may extend the therapeutic time window from superacute to acute phase.

Adult hippocampus derived soluble factors induce a neuronal-like phenotype in mesenchymal stem cells

Bone marrow-derived mesenchymal stem cells (MSCs) are not restricted in their differentiation fate to cells of the mesenchymal lineage. They acquire a neural phenotype in vitro and in vivo after transplantation in the central nervous system. Here we investigated whether soluble factors derived from different brain regions are sufficient to induce a neuronal phenotype in MSCs. We incubated bone marrow-derived MSCs in conditioned medium (CM) derived from adult hippocampus (HCM), cortex (CoCM) or cerebellum (CeCM) and analyzed the cellular morphology and the expression of neuronal and glial markers. In contrast to muscle derived conditioned medium, which served as control, conditioned medium derived from the different brain regions induced a neuronal morphology and the expression of the neuronal markers GAP-43 and neurofilaments in MSCs. Hippocampus derived conditioned medium had the strongest activity. It was independent of NGF or BDNF; and it was restricted to the neuronal differentiation fate, since no induction of the astroglial marker GFAP was observed. The work indicates that soluble factors present in the brain are sufficient to induce a neuronal phenotype in MSCs.

Infusion of human umbilical cord blood ameliorates neurologic deficits in rats with hemorrhagic brain injury

Umbilical cord blood is a rich source of hematopoietic stem cells. It is routinely used for transplantation to repopulate cells of the immune system. Recent studies, however, have demonstrated that intravenous infusions of umbilical cord blood can ameliorate neurologic deficits associated with ischemic brain injury in rodents. Moreover, the infused cells penetrate into the parenchyma of the brain and adopt phenotypic characteristics typical of neural cells. In the present study we tested the hypothesis that the administration of umbilical cord blood can also diminish neurologic deficits caused by intracerebral hemorrhage (ICH). Intracerebral hemorrhage is a major cause of morbidity and mortality, and at the present time there are no adequate therapies that can minimize the consequences of this cerebrovascular event. ICH was induced in rats by intrastriatal injections of collagenase to cause bleeding in the striatum. Twenty-four hours after the induction of ICH rats received intravenous saphenous vein infusions of human umbilical cord blood (2.4 x 10(6) to 3.2 to 10(6) cells). Animals were evaluated using a battery of tests at day 1 after ICH, but before the administration of umbilical cord blood, and at days 7, and 14 after ICH (days 6 and 13, respectively, after cord blood administration). These tests included a neurological severity test, a stepping test, and an elevated body-swing test. Animals with umbilical cord blood infusions exhibited significant improvements in (1) the neurologic severity test at 6 and 13 days after cord blood infusion in comparison to saline-treated animals (P < 0.05); (2) the stepping test at day 6 (P < 0.05); and (3) the elevated body-swing test at day 13 (P< 0.05). These results demonstrate that the administration of human umbilical cord blood cells can ameliorate neurologic deficits associated with intracerebral hemorrhage.

Multiple stem cell traits of expanded rat bone marrow stromal cells

Bone marrow stromal cells (BMSC) exhibit many traits of a stem cell population. Knowing that BMSC have the ability to self-renew, proliferate and differentiate into a variety of cell types, questions may arise as to whether these traits differ between the cells that have different expansion times. In this study, we examined the stem cell potentiality of BMSC through their characterization, proliferative capacity and the ability to differentiate into multiple lineages in the cultured 2nd passage cells and 10th passage cells. The results were as follows: (1) the 10th passage cells had a larger and more flatted morphology than the 2nd passage cells and also exhibited a decreased labeling for BMSC-related antigens such as CD90, CD73. (2) The cell proliferative capacity was approximately 2 times greater in the 2nd passage cells, and the apoptosis phenomenon was detected in the 10th passage cells. (3) The ability to differentiate into mesodermal tissue (osteocytes, adipocytes), as well as into ectodermal tissue (neurons) was more effective in the 2nd passage cells. Taken together, early stage BMSC would be a valuable cell source for various in vitro applications, as well as cell therapy.

Neurorepair versus neuroprotection in stroke

Stroke is the second to third leading cause of death and the main cause of severe, long-term disability in adults. However, treatment is almost reduced to fibrinolysis, a therapy useful in a low percentage of patients. Given that the immediate treatment for stroke is often unfeasible in the clinical setting, the need for new therapy strategies is imperative. After stroke, the remaining impairment in functions essential for routine activities, such as movement programming and execution, sensorimotor integration, language and other cognitive functions have a deep and life-long impact on the quality of life. An interesting point is that a slow but consistent recovery can be observed in the clinical practice over a period of weeks and months. Whereas the recovery in the first few days likely results from edema resolution and/or from reperfusion of the ischemic penumbra, a large part of the recovery afterwards is due mainly to brain plasticity, by which some regions of the brain assume the functions previously performed by the damaged areas. Neurogenesis and angiogenesis are other possible mechanisms of recovery after stroke. An understanding of the mechanisms underlying functional recovery may shed light on strategies for neurorepair, an alternative with a wide therapeutic window when compared with neuroprotective strategies.

Infusion of human umbilical cord blood cells protect against cerebral ischemia and damage during heatstroke in the rat

Intravenously delivered human umbilical cord blood cells (HUCBC) have been previously shown to improve both morphologic and functional recovery of heat-stroked rats. To extend these findings, we examined both the morphologic and functional alterations in the presence of HUCBC or human peripheral mononuclear cells (PBMC) 24 h before initiation of heatstroke. Anesthetized rats, 1 day before the initiation of heatstroke, were divided into three major groups and given the following: (a) serum-free lymphocyte medium (0.3 ml) intravenously; (b) PBMC (5 x 10(6) in 0.3 ml serum-free lymphocyte medium); or (c) HUCBC (5 x 10(6) in 0.3 ml serum-free lymphocyte medium). Another group of rats were exposed to room temperature (26 degrees C) and used as normothermic controls. In vehicle-treated heatstroke rats, their mean arterial pressure, cerebral blood flow, and brain PO(2) were all lower than in normothermic controls after the onset of heatstroke. However, their body temperatures and striatal levels of inducible nitric oxide synthase (iNOS)-dependent NO, ischemia and damage markers (e.g., glycerol, glutamate, and lactate/pyruvate ratio), and neuronal damage in the striatum were all greater. The heatstroke-induced arterial hypotension, cerebral ischemia and hypoxia, and increased levels of iNOS-dependent NO in the striatum were all significantly reduced by pretreatment with HUCBC, but not with PBMC. Moreover, HUCBC were localized by immunohistochemistry and PCR analysis in the injured brain structures and spleen. These findings indicate that HUCBC transplantation, in addition to having therapeutic values, can be a good choice for preventing heatstroke occurrence.

Differentiation and neurological benefit of the mesenchymal stem cells transplanted into the rat brain following intracerebral hemorrhage

Spontaneous intracerebral hemorrhage (ICH) is often a fatal event. In a patient who survives the initial ictus, the resulting hematoma within brain parenchyma can trigger a series of events that lead to secondary insults and severe neurological deficits. Great efforts have been focused on searching for new approaches to help patients recover neurological function after ICH. Previous studies indicate that mesenchymal stem cells (MSCs) grafted into the ischemic rat brain can improve neurological function. However, there is no report regarding whether MSCs can be used in the same way to improve the neurological function after ICH. We generated the ICH model by injecting collagenase VII into rat brain. Subsequently, 5-bromo-2-deoxyuridine (BrdU)-labeled mesenchymal stem cells were delivered into the brain through carotid artery, cervical vein or lateral ventricle. The distribution and differentiation of MSCs were investigated by methods of immunohistochemistry. We found that MSCs were able to differentiate into neural cells in vitro as well as in the rat brain after ICH. The injected MSCs were able to migrate into hippocampus, blooding foci and ipsilateral cortex. In the hippocampus, MSCs differentiated into neurons; but in surrounding bleeding foci, they differentiated into neurons and astrocytes. In the ipsilateral cortex, MSCs differentiated into neurons, astrocytes and oligodendrocytes. Notably, the motor function of the rats in the carotid artery (CA) group and the lateral ventricle (LV) group improved significantly. Collectively, our study indicates that MSCs are able to differentiate into neural cells in the rat brain after ICH and can significantly improve motor function.

In vivo imaging with cellular resolution of bone marrow cells transplanted into the ischemic brain of a mouse

The aim of the study was to monitor in vivo and noninvasively the fate of single bone marrow cells (BMCs) transplanted into the ischemic brain of unirradiated mice. In vivo imaging was performed through a closed cranial window, throughout the 2 weeks following cell transplantation, using laser-scanning confocal fluorescence microscopy. The window was chronically implanted above the left parieto-occipital cortex in C57BL/6J adult mice. BMC (3 x 10(5) nucleated cells in 0.5 microL medium) from 5-week-old transgenic mice, ubiquitously expressing green fluorescent protein (GFP), was transplanted into the ipsilateral cortex 24 h after the induction of focal ischemia by coagulation of the left middle cerebral artery (n = 15). Three nonischemic mice served as controls. Repeated in vivo imaging, up to a depth of 200 microm, revealed that BMCs survived within the ischemic and peri-ischemic cortex, migrated significantly towards the lesion, proliferated and adopted a microglia-like morphology over 2 weeks. These results were confirmed using ex vivo imaging after appropriate immunocytochemical treatments. This study indicates that confocal fluorescence microscopy is a reliable and unique tool to repeatedly assess with cellular resolution the in vivo dynamic fate of fluorescent cells transplanted into a mouse brain. These results also provide the first in vivo findings on the fate of single BMCs transplanted into the ischemic brain of unirradiated mice.

Effects of intravenous administration of human bone marrow stromal cells after intracerebral hemorrhage in rats

Object

The goal of this study was to investigate whether human bone marrow stromal cells (hBMSCs) administered by intravenous injection have a beneficial effect on outcome after intracerebral hemorrhage (ICH) in rats.

Methods

An ICH was induced in 54 adult male Wistar rats by a stereotactically guided injection of autologous blood into the right striatum. Intravenous infusion of the hBMSCs (3, 5, or 8 million cells) was performed 1 day after ICH, and for each dose group there was a control group that received injections of vehicle. Neurological function, which was evaluated using the Neurological Severity Score (NSS) and the corner turn test, was tested before and at 1, 7, and 14 days after ICH. After 14 days of survival, the area of encephalomalacia was calculated and histochemical labeling was performed.

For all three groups, there were no statistical differences in either the NSS or corner turn tests after 1 day. After 7 and 14 days, however, the three groups that received the hBMSCs showed significant improvement in functional scores compared with the control group. In addition, after 14 days there was significantly more striatal tissue loss in the placebo groups compared with each of the three treatment groups. The region of injury in the treated animals demonstrated a significantly increased presence of hBMSCs, immature neurons, neuronal migration, synaptogenesis, and newly formed DNA.

Conclusions

Intravenous administration of hBMSCs significantly improves neurological function in rats subjected to ICH. This improvement in the treated animals is associated with reduced tissue loss and increased local presence of the hBMSCs, mitotic activity, immature neurons, synaptogenesis, and neuronal migration.

Behavioral and histological evaluation of a focal cerebral infarction rat model transplanted with neurons induced from bone marrow stromal cells

Neurons can be specifically induced from bone marrow stromal cells (MSCs) with extremely high efficiency using gene transfection of the Notch intracellular domain and subsequent treatment with basic-fibroblast growth factor, forskolin, and ciliary neurotrophic factor. We investigated the behavioral and histologic efficacy of such bone marrow stromal cell-derived neuronal cell (MSDNC) transplantation into a focal cerebral infarction model in rats. A left middle cerebral artery occlusion (MCAO) was performed on adult Wistar rats. MSDNC transplantation into the ipsilateral hemisphere was performed on day 7 after MCAO. The behavioral analyses were conducted on days 14, 21, 28, 35, and 36-40, and a histologic evaluation was performed on day 41. MSDNC-transplanted rats showed significant recovery compared with controls (MCAO without cell transplantation) in beam balance, limb placing, and Morris water maze tests. Histologically, transplanted cells migrated from the injection site into the ischemic boundary area, including the cortex, corpus callosum, striatum, and hippocampus. Transplanted MSDNCs were positive for MAP-2 (84% +/- 8.11%), whereas only a small number of cells were positive for GFAP (1.0% +/- 0.23%). The survival rates of MSDNCs and MSCs 1 month after transplantation were approximately 45% and 10%, respectively. These results suggest that use of MSDNCs may be a promising therapeutic strategy for cerebral infarction.

Transplantation of Undifferentiated, Bone Marrow‐Derived Stem Cells

Stem cell research has known an enormous development, and cellular transplantation holds great promise for regenerative medicine. However, some aspects, such as the mechanisms underlying stem cell plasticity (cell fusion vs true transdifferentiation) and the functional improvement after stem cell transplantation, are highly debated. Furthermore, the great variability in methodology used by several groups, sometimes leads to confusing, contradicting results. In this chapter, we review a number of studies in this area with an eye on possible technical and other difficulties in interpretation of the obtained results.

Bone marrow stromal cells upregulate expression of bone morphogenetic proteins 2 and 4, gap junction protein connexin-43 and synaptophysin after stroke in rats

Bone morphogenetic proteins play a key role in astrocytic differentiation. Astrocytes express the gap junctional protein connexin-43, which permits exchange of small molecules in brain and enhances synaptic efficacy. Bone marrow stromal cells produce soluble factors including bone morphogenetic protein 2 and bone morphogenetic protein 4 (bone morphogenetic protein 2/4) in ischemic brain. Here, we tested whether intra-carotid infusion of bone marrow stromal cells promotes synaptophysin expression and neurological functional recovery after stroke in rats. Adult male Wistar rats were subjected to 2 h of right middle cerebral artery occlusion. Rats were treated with or without bone marrow stromal cells at 24 h after middle cerebral artery occlusion via intra-arterial injection (n=8/group). A battery of functional tests was performed. Immunostaining of 5-bromo-2-deoxyuridine, Ki67, bone morphogenetic protein 2/4, connexin-43, synaptophysin, glial fibrillary acidic protein, neuronal nuclear antigen, and double staining of 5-bromo-2-deoxyuridine/glial fibrillary acidic protein, 5-bromo-2-deoxyuridine/neuronal nuclear antigen, glial fibrillary acidic protein/bone morphogenetic protein 2/4 and glial fibrillary acidic protein/connexin-43 were employed. Rats treated with bone marrow stromal cells significantly (P<0.05) improved functional recovery compared with the controls. 5-Bromo-2-deoxyuridine and Ki67 positive cells in the ipsilateral subventricular zone were significantly (P<0.05) increased in bone marrow stromal cell treatment group compared with the controls, respectively. Administration of bone marrow stromal cells significantly (P<0.05) promoted the proliferating cell astrocytic differentiation, and increased bone morphogenetic protein 2/4, connexin-43 and synaptophysin expression in the ischemic boundary zone compared with the controls, respectively. Bone morphogenetic protein 2/4 expression correlated with the expression of connexin-43 (r=0.84, P<0.05) and connexin-43 expression correlated with the expression of synaptophysin (r=0.73, P<0.05) in the ischemic boundary zone, respectively. Administration of bone marrow stromal cells via an intra-carotid route increases endogenous brain bone morphogenetic protein 2/4 and connexin-43 expression in astrocytes and promotes synaptophysin expression, which may benefit functional recovery after stroke in rats.

Characterization of multipotent mesenchymal stem cells from the bone marrow of rhesus macaques

The isolation and characterization of embryonic and adult stem cells from higher-order mammalian species will enhance the understanding of the biology and therapeutic application of stem cells. The aim of this study was to purify rhesus mesenchymal stem cells (MSCs) from adult bone marrow and to characterize functionally their abilities to differentiate along diverse lineages. Adherent cells from adult rhesus macaque bone marrow were characterized for their growth characteristics, lineage differentiation, cell-surface antigen expression, telomere length, chromosome content, and transcription factor gene expression. Rhesus bone marrow MSCs (BMSCs) are very heterogeneous, composed of primarily long, thin cells and some smaller, round cells. The cells are capable of differentiating along osteogenic, chondrogenic, and adipogenic lineages in vitro. The cell morphology and multipotential differentiation capabilities are maintained throughout extended culture. They express CD59, CD90 (Thy-1), CD105, and HLA-1 and were negative for hematopoietic markers such as CD3, CD4, CD8, CD11b, CD13, CD34, and platelet endothelial cell adhesion molecule-1 (CD31). BMSCs were also demonstrated to express the mRNA for important stem cell-related transcription factors such as Oct-4, Sox-2, Rex-1, and Nanog. Rhesus BMSCs have a normal chromosome content, and the shortening of telomeres is minimal during early passages. These data demonstrate that BMSCs isolated from rhesus macaques have a high degree of commonality with MSCs isolated from other species. Therefore, isolation of these cells provides an effective and convenient method for rapid expansion of pluripotent rhesus MSCs.

[From bench to bedside: should we believe in the efficacy of stem cells in cerebral ischaemia?]

Stroke is the third cause of mortality and the leading cause of morbidity in industrialized countries. At the present time, ischaemic stroke is treated at the acute phase by thrombolysis with a recombinant of the tissular-plasminogen activator, which must be administered within the first 3 hours. Cell therapy, while using the self-renewal and differentiation potentials of stem cells, brings new hope for the long-term care of ischaemic stroke. Animal studies show that stem cells improve functional deficit without reduction of infarct volume and with very rare differentiation of the stem cell. These experimental studies suggest that stem cells would support cerebral plasticity via growth factor production and stimulation of endogenous mechanisms of local repair. Assessment of effectiveness and safety in the use of stem cells in cerebral ischaemia still require thorough investigation before clinical trials in humans can be developed.

Cell therapy for stroke

Increasing experimental evidence suggests that cell transplantation can enhance recovery from stroke in animal models of focal cerebral ischemia. Clinical trials have been investigating the effects of a human immortalized neuronal cell line and porcine fetal neurons in stroke victims with persistent and stable deficits. Preclinical studies are focusing on the effects of human stem cells from various sources including brain, bone marrow, umbilical cord, and adipose tissue. This review presents an overview of preclinical and clinical studies on cell therapy for stroke. We emphasize the current, limited knowledge about the biology of implant sources and discuss special conditions in stroke that will impact the potential success of neurotransplantation in clinical trials.

Magnetic resonance tracking of human CD34+ progenitor cells separated by means of immunomagnetic selection and transplanted into injured rat brain

Magnetic resonance imaging (MRI) provides a noninvasive method for studying the fate of transplanted cells in vivo. We studied whether superparamagnetic nanoparticles (CD34 microbeads), used clinically for specific magnetic sorting, can be used as a magnetic cell label for in vivo cell visualization. Human cells from peripheral blood were selected by CliniMACS CD34 Selection Technology (Miltenyi). Purified CD34+ cells were implanted into rats with a cortical photochemical lesion, contralaterally to the lesion. Twenty-four hours after grafting, the implanted cells were detected in the contralateral hemisphere as a hypointense spot on T2 weighted images; the hypointensity of the implant decreased during the first week. At the lesion site we observed a hypointensive signal 10 days after grafting that persisted for the next 3 weeks, until the end of the experiment. Prussian blue and anti-human nuclei staining confirmed the presence of magnetically labeled human cells in the corpus callosum and in the lesion 4 weeks after grafting. CD34+ cells were also found in the subventricular zone (SVZ). Human DNA (a human-specific 850 base pair fragment of alpha-satellite DNA from human chromosome 17) was detected in brain tissue sections from the lesion using PCR, confirming the presence of human cells. Our results show that CD34 microbeads superparamagnetic nanoparticles can be used as a magnetic cell label for in vivo cell visualization. The fact that microbeads coated with different commercially available antibodies can bind to specific cell types opens extensive possibilities for cell tracking in vivo.

Protective effects of bone marrow stromal cell transplantation in injured rodent brain: synthesis of neurotrophic factors

Several groups have suggested that transplantation of marrow stromal cells (MSCs) promotes functional recovery in animal models of brain trauma. Recent studies indicate that tissue replacement by this method may not be the main source of therapeutic benefit, as transplanted MSCs have only limited ability to replace injured central nervous system (CNS) tissue. To gain insight into the mechanisms responsible for such effects, we systematically investigated the therapeutic potential of MSCs for treatment of brain injury. Using in vitro studies, we detected the synthesis of various growth factors, including nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), glial cell line-derived neurotrophic factor (GDNF), and neurotrophin-3 (NT-3). Enzyme-linked immunosorbent assay (ELISA) demonstrated that MSCs cultured in Dulbecco's modified Eagle medium (DMEM) produced substantial amounts of NGF for at least 7 weeks, whereas the levels of BDNF, GDNF and NT-3 remained unchanged. In studies in mice, after intraventricular injection of MSCs, NGF levels were increased significantly in cerebrospinal fluid by ELISA, confirming our cell culture results. Further studies showed that treatment of traumatic brain injury with MSCs could attenuate the loss of cholinergic neuronal immunostaining in the medial septum of mice. These studies demonstrate for the first time that by increasing the brain concentration of NGF, intraventricularly transplanted MSCs might play an important role in the treatment of traumatic brain injury.

Autologous mesenchymal stem cell transplantation in stroke patients

Mesenchymal stem cell (MSC) transplantation improves recovery from ischemic stroke in animals. We examined the feasibility, efficacy, and safety of cell therapy using culture-expanded autologous MSCs in patients with ischemic stroke. We prospectively and randomly allocated 30 patients with cerebral infarcts within the middle cerebral arterial territory and with severe neurological deficits into one of two treatment groups: the MSC group (n = 5) received intravenous infusion of 1 x 10(8) autologous MSCs, whereas the control group (n = 25) did not receive MSCs. Changes in neurological deficits and improvements in function were compared between the groups for 1 year after symptom onset. Neuroimaging was performed serially in five patients from each group. Outcomes improved in MSC-treated patients compared with the control patients: the Barthel index (p = 0.011, 0.017, and 0.115 at 3, 6, and 12 months, respectively) and modified Rankin score (p = 0.076, 0.171, and 0.286 at 3, 6, and 12 months, respectively) of the MSC group improved consistently during the follow-up period. Serial evaluations showed no adverse cell-related, serological, or imaging-defined effects. In patients with severe cerebral infarcts, the intravenous infusion of autologous MSCs appears to be a feasible and safe therapy that may improve functional recovery.

Resuscitation from experimental heatstroke by transplantation of human umbilical cord blood cells

OBJECTIVE

Human umbilical cord blood cells (HUCBCs) are effective in the treatment of conventional stroke in experimental models. In the study described herein, we administered HUCBCs into the femoral vein or directly into the cerebral ventricular system and assessed their effects on circulatory shock, cerebral ischemia, and damage during heatstroke.

DESIGN

Controlled, prospective study.

SETTING

Hospital medical research laboratory.

SUBJECTS

Sprague-Dawley rats (287 +/- 16 g body weight, males).

INTERVENTIONS

Anesthetized rats, immediately after the onset of heatstroke, were divided into four major groups and given the following: a) normal saline or AIM-V medium intravenously (0.3 mL) or intracerebroventricularly (10 microL); b) peripheral blood mononuclear cells (5 x 10 in 0.3 mL AIM-V medium, intravenously, or 5 x 10 in 10 microL AIM-V medium, intracerebroventricularly); or c) HUCBCs (5 x 10 in 0.3 mL AIM-V medium, intravenously, or 5 x 10 in 10 microL AIM-V medium, intracerebroventricularly). Another group of rats, under urethane anesthesia, were exposed to room temperature (26 degrees C) and used as normothermic controls. Urethane-anesthetized animals were exposed to an ambient temperature of 43 degrees C to induce heatstroke. Their physiologic and biochemical parameters were continuously monitored.

MEASUREMENTS AND MAIN RESULTS

When the vehicle-treated rats underwent heat exposure, their survival time values were found to be 21-23 mins. Resuscitation with intravenous or intracerebroventricular doses of HUCBCs, but not peripheral blood mononuclear cells, immediately at the onset of heatstroke significantly improved survival during heatstroke (61-148 mins). As compared with values for normothermic controls, the vehicle-treated heatstroke rats had lower mean arterial pressure, cerebral blood flow, and brain PO2 values but higher intracranial pressure and cerebral ischemia values and more injury markers. The circulatory shock, intracranial hypertension, cerebral hypoperfusion and hypoxia, increment of cerebral ischemia, and damage markers during heatstroke were all significantly attenuated by intravenous or intracerebroventricular delivery of HUCBCs but not peripheral blood mononuclear cells.

CONCLUSIONS

We successfully demonstrate that HUCBC therapy may resuscitate heatstroke victims by reducing circulatory shock and cerebral ischemic injury; central delivery of HUCBCs seems superior to systemic delivery of HUCBCs in resuscitating patients with heatstroke.

Transplantation of cultured bone marrow stromal cells to improve peripheral nerve regeneration

The role of cultured bone marrow stromal cells (BMSCs) in peripheral nerve regeneration was examined using an established rabbit peroneal nerve regeneration model. A 15-mm peroneal nerve defect was bridged with a vein filled with BMSCs (1 x 10(6)), which had been embedded in collagen gel. On the contralateral side, the defect was bridged with a vein filled with collagen gel alone. When the regenerated tissue was examined 4, 8 and 12 weeks after grafting, the number and diameter of the myelinated fibers in the side with the BMSCs were significantly higher than in the control side without the BMSCs. This demonstrates the potential of using cultured BMSCs in peripheral nerve regeneration.

Glial nitric oxide and ischemia

One of the responses to cerebral ischemia is an increase in the production of nitric oxide, catalyzed by enzymes expressed in both resident and infiltrating cells. The nitric oxide that is generated does contribute to the ensuing pathology, but it can also be beneficial. The effects of nitric oxide depend on the cell site of production, the amount generated, and the chemical nature of the products of further oxidation. Understanding how nitric oxide production from microglia and astrocytes contributes to ischemic pathology is important for the development and application of future therapeutics based on inhibiting or amplifying its production in the injured brain.

Human bone marrow-derived mesenchymal stem cells in the treatment of gliomas

The poor survival of patients with human malignant gliomas relates partly to the inability to deliver therapeutic agents to the tumor. Because it has been suggested that circulating bone marrow-derived stem cells can be recruited into solid organs in response to tissue stresses, we hypothesized that human bone marrow-derived mesenchymal stem cells (hMSC) may have a tropism for brain tumors and thus could be used as delivery vehicles for glioma therapy. To test this, we isolated hMSCs from bone marrow of normal volunteers, fluorescently labeled the cells, and injected them into the carotid artery of mice bearing human glioma intracranial xenografts (U87, U251, and LN229). hMSCs were seen exclusively within the brain tumors regardless of whether the cells were injected into the ipsilateral or contralateral carotid artery. In contrast, intracarotid injections of fibroblasts or U87 glioma cells resulted in widespread distribution of delivered cells without tumor specificity. To assess the potential of hMSCs to track human gliomas, we injected hMSCs directly into the cerebral hemisphere opposite an established human glioma and showed that the hMSCs were capable of migrating into the xenograft in vivo. Likewise, in vitro Matrigel invasion assays showed that conditioned medium from gliomas, but not from fibroblasts or astrocytes, supported the migration of hMSCs and that platelet-derived growth factor, epidermal growth factor, or stromal cell-derived factor-1alpha, but not basic fibroblast growth factor or vascular endothelial growth factor, enhanced hMSC migration. To test the potential of hMSCs to deliver a therapeutic agent, hMSCs were engineered to release IFN-beta (hMSC-IFN-beta). In vitro coculture and Transwell experiments showed the efficacy of hMSC-IFN-beta against human gliomas. In vivo experiments showed that treatment of human U87 intracranial glioma xenografts with hMSC-IFN-beta significantly increase animal survival compared with controls (P < 0.05). We conclude that hMSCs can integrate into human gliomas after intravascular or local delivery, that this engraftment may be mediated by growth factors, and that this tropism of hMSCs for human gliomas can be exploited to therapeutic advantage.

Potential stem cell therapy and application in neurotrauma

Traumatic brain injury results from a sudden and external physical insult to the head, which is often accompanied by motor and cognitive impairment. Neurotrauma is characterized not only by focal abnormalities, but rather by multifocal, or even global structural and functional disturbances of the brain network. The impact initially causes necrotic cell death in the underlying tissue, followed by apoptotic cell death in the surrounding tissue due to multiple subsequent events, such as ischemia, excitotoxicity and altered gene expression. These pathological conditions are associated with high morbidity and mortality. Despite the high medical and economical relevance of neurotrauma there are currently no sufficient treatments. Supplementary therapeutic strategies have to be established. Many types of stem cells have the ability to engraft diffusely and become integral members of structures throughout the host CNS. Intrinsic factors appear to derive spontaneously from stem cells and seem to be capable of neuroprotective and/or neuroregenerative functions. Furthermore stem cells can be readily engineered to express specific genes. Such observations suggest that stem cells might participate in reconstructing the molecular and cellular milieu of traumatized brains. In this paper, the state of stem cell research is reviewed and its possible application in neurotrauma will be discussed.

Plasticity of bone marrow-derived stem cells

Stem cell plasticity refers to the ability of adult stem cells to acquire mature phenotypes that are different from their tissue of origin. Adult bone marrow cells (BMCs) include two populations of bone marrow stem cells (BMCs): hematopoietic stem cells (HSCs), which give rise to all mature lineages of blood, and mesenchymal stem cells (MSCs), which can differentiate into bone, cartilage, and fat. In this article, we review the literature that lends credibility to the theory that highly plastic BMCs have a role in maintenance and repair of nonhematopoietic tissue. We discuss the possible mechanisms by which this may occur. Also reviewed is the possibility that adult BMCs can change their gene expression profile after fusion with a mature cell, which has brought into question whether this stem cell plasticity is real.

Neural Cell Differentiation In Vitro from Adult Human Bone Marrow Mesenchymal Stem Cells

Bone marrow (BM) mesenchymal stem cells (MSCs) are cells capable of expanding and differentiating in vitro into nonhematopoietic cells. Neurotrophic cytokines, such as human epidermal growth factor (hEGF) and bovine fibroblast growth factor (bFGF) can induce differentiation into neural cells (NCs). When BM MSCs were cultured with hEGF and bFGF, RNA expression of neuronal specific markers Nestin, MAP-2, and tyrosine hydroxylase (TH) were observed. We tested a new cytokine combination to generate mature NCs. The plastic-adherent cells were collected and then split when they were 90% confluent from an enriched mononuclear cell layer. At passage 3, MSCs were cultured in neural differentiation media (dbcAMP, IBMX, FGF-8, BDNF, hEGF, and bFGF in NEUROBASAL media plus B27). Cells were counted on day 6. Immunofluorescent staining and reverse transcriptase (RT)-PCR were performed to evaluate the expression of neural markers. On day 6, 66% of cells developed dendrites and presented typical neural cell morphology. Some cells were positive for early neural markers Nestin and beta-tubulin III. Cells expressing mature neuronal markers (NF, NeuN, Tau, Nurr1, GABA, oligodendryte GalC, and glial GFAP) were also seen. By adding hEGF, bFGF, dbcAMP, IBMX, BDNF, and bFGF-8 into NEUROBASAL media plus B27, BM MSCs were directed toward becoming early and mature NCs.

Atorvastatin induction of VEGF and BDNF promotes brain plasticity after stroke in mice

Molecular mechanisms underlying the role of statins in the induction of brain plasticity and subsequent improvement of neurologic outcome after treatment of stroke have not been adequately investigated. Here, we use both in vivo and in vitro studies to investigate the potential roles of two prominent factors, vascular endothelial growth factor (VEGF) and brain-derived neurotrophic factor (BDNF), in mediating brain plasticity after treatment of stroke with atorvastatin. Treatment of stroke in adult mice with atorvastatin daily for 14 days, starting at 24 hours after MCAO, shows significant improvement in functional recovery compared with control animals. Atorvastatin increases VEGF, VEGFR2 and BDNF expression in the ischemic border. Numbers of migrating neurons, developmental neurons and synaptophysin-positive cells as well as indices of angiogenesis were significantly increased in the atorvastatin treatment group, compared with controls. In addition, atorvastatin significantly increased brain subventricular zone (SVZ) explant cell migration in vitro. Anti-BDNF antibody significantly inhibited atorvastatin-induced SVZ explant cell migration, indicating a prominent role for BDNF in progenitor cell migration. Mouse brain endothelial cell culture expression of BDNF and VEGFR2 was significantly increased in atorvastatin-treated cells compared with control cells. Inhibition of VEGFR2 significantly decreased expression of BDNF in brain endothelial cells. These data indicate that atorvastatin promotes angiogenesis, brain plasticity and enhances functional recovery after stroke. In addition, VEGF, VEGFR2 and BDNF likely contribute to these restorative processes.

Bone marrow transplants provide tissue protection and directional guidance for axons after contusive spinal cord injury in rats

Contusive spinal cord injury (SCI) produces large fluid-, debris- and inflammatory cell-filled cystic cavities that lack structure to support significant axonal regeneration. The recent discovery of stem cells capable of generating central nervous system (CNS) tissues, coupled with success in neurotransplantation strategies, has renewed hope that repair and recovery from CNS trauma is possible. Based on results from several studies using bone marrow stromal cells (MSCs) to promote CNS repair, we transplanted MSCs into the rat SCI lesion cavity to further investigate their effects on functional recovery, lesion morphology, and axonal growth. We found that transplanted MSCs induced hindlimb airstepping--a spontaneous locomotor movement associated with activation of the stepping control circuitry--but did not alter the time course or extent of overground locomotor recovery. Using stereological techniques to describe spinal cord anatomy, we show that MSC transplants occupied the lesion cavity and were associated with preservation of host tissue and white matter (myelin), demonstrating that these cells exert neuroprotective effects. The tissue matrix formed by MSC grafts supported greater axonal growth than that found in specimens without grafts. Moreover, uniform random sampling of axon profiles revealed that the majority of neurites in MSC grafts were oriented with their long axis parallel to that of the spinal cord, suggesting longitudinally directed growth. Together, these studies support further investigation of marrow stromal cells as a potential SCI repair strategy.

Tissue-engineering approaches for axonal guidance

Owing to the profound impact of nervous system damage, extensive studies have been carried out aimed at facilitating axonal regeneration following injury. Tissue engineering, as an emerging and rapidly growing field, has received extensive attention for nervous system axonal guidance. Numerous engineered substrates containing oriented extracellular matrix molecules, cells or channels have displayed potential of supporting axonal regeneration and functional recovery. Most attempts are focused on seeking new biomaterials, new cell sources, as well as novel designs of tissue-engineered neuronal bridging devices, to generate safer and more efficacious neuronal tissue repairs.

Intraspinal transplantation of CD34+ human umbilical cord blood cells after spinal cord hemisection injury improves functional recovery in adult rats

The present study was designed to compare the functional outcome of the intraspinal transplantation of CD34+ human umbilical cord blood (CB) cells with that of human bone marrow stromal (BMS) cells in adult rats with spinal cord injury. Sixty adult Wistar rats were subjected to left spinal cord hemisection, and then divided into three groups randomly. The control group received an injection of PBS without cells, while the two other groups of rats received a transplantation of 5 x 10(5) CD34+ CB or BMS cells, respectively. Functional outcome was measured using the modified Tarlov score at days 1, 7, 14, 21, and 28 after transplantation. A statistically significant improvement in functional outcome and survival rate in the experimental groups of rats was observed compared with the control group. Rats that received CD34+ CB cells achieved a better improvement in functional score than those that received BMS cells at days 7 and 14 after transplantation. Histological evaluation revealed that bromodeoxyuridine (BrdU)-labeled CD34+ CB and BMS cells survived and migrated into the injured area. Some of these cells expressed glial fibriliary acidic protein (GFAP) or neuronal nuclear antigen (NeuN). Our data demonstrate for the first time that intraspinal transplantation of human CD34+ CB cells provides benefit in function recovery after spinal cord hemisection in rats and suggest that CD34+ CB cells may be an excellent choice of cells as routine starting material of allogenic and autologous transplantations for the treatment of spinal cord injury.

A pre-clinical assessment model of rat autogeneic bone marrow stromal cell transplantation into the central nervous system

In order to verify the biological aspects of 'autogeneic' bone marrow stromal cells (BMSC) transplantation for neurological disorders, we aimed our study towards the assessment of the survival, distribution, and differentiation of autologous BMSC in the central nervous system (CNS). We harvested rat BMSC from femur bones, and the nuclei were then fluorescently labeled by a 24-h co-culture with bis-benzimide. These BMSC were stereotactically injected into the striatum (n=6) or thoracic cord (n=8) of each animal. We evaluated the distribution and differentiation of 'autogeneic' BMSC in the brain and spinal cord after 4 weeks, using the immunohistochemistry technique. We found some injected cells in the ipsilateral striatum, hippocampus, neocortex, and bilateral corpus callosum, and approximately 20% and 15% of the engrafted cells expressed neuronal and astrocytic markers, respectively. Other injected cells were distributed in the dorsal funiculus and adjacent gray matter, and about 10% and 15% of these cells expressed neuronal and astrocytic markers, respectively. Although the precise mechanism of BMSC transdifferentiation still remains unclear, the present results show that 'autogeneic' BMSC could highly differentiate into their own CNS neural cells, suggesting that they are surrounded by favorable conditions.

A Review and Rationale for the Use of Cellular Transplantation as a Therapeutic Strategy for Traumatic Brain Injury

Experimental research during the past decade has greatly increased our understanding of the pathophysiology of traumatic brain injury (TBI) and allowed us to develop neuroprotective pharmacological therapies. Encouraging results of experimental pharmacological interventions, however, have not been translated into successful clinical trials, to date. Traumatic brain injury is now believed to be a progressive degenerative disease characterized by cell loss. The limited capacity for self-repair of the brain suggests that functional recovery following TBI is likely to require cellular transplantation of exogenous cells to replace those lost to trauma. Recent advances in central nervous system transplantation techniques involve technical and experimental refinements and the analysis of the feasibility and efficacy of transplantation of a range of stem cells, progenitor cells and postmitotic cells. Cellular transplantation has begun to be evaluated in several models of experimental TBI, with promising results. The following is a compendium of these new and exciting studies, including a critical discussion of the rationale and caveats associated with cellular transplantation techniques in experimental TBI research. Further refinements in future research are likely to improve results from transplantation-based treatments for TBI.

Recovery and rehabilitation in stroke: stem cells

The recent demonstration that neurons for transplantation can be generated from stem cells and that the adult brain produces new neurons in response to stroke has raised hope for the development of a stem cell therapy for patients affected with this disorder. In this review we propose a road map to the clinic and describe the different scientific tasks that need to be accomplished to move stem cell-based approaches toward application in stroke patients.

Bone marrow grafts restore cerebral blood flow and blood brain barrier in stroke rats

We monitored alterations in cerebral blood flow (CBF) and blood-brain barrier (BBB) permeability following middle cerebral artery occlusion (MCAo) and intrastriatal transplantation of mouse bone marrow stromal cells (BMSCs) or saline infusion in adult Sprague-Dawley rats. Laser Doppler and Evans Blue assay revealed that BMSC grafts dose-dependently restored CBF and BBB to near normal levels at a much earlier period (Days 4-5 post-MCAo) in transplanted stroke animals compared to stroke animals that received saline infusion (Days 11-14 post-MCAo). Xenografted BMSCs survived in the absence of immunosuppression, and elevated levels of transforming growth factor-beta superfamily of neurotrophic factors were detected in transplanted stroke animals. These data suggest that early restoration of CBF and BBB following transplantation of BMSCs could mediate the reported functional outcomes in stroke animals.

Bone marrow stromal cell implantation for peripheral nerve repair

Cell therapy using bone marrow stromal cells is a new promising therapy for regenerative medicine. Previous studies demonstrated that local bone marrow stromal cells implantation in the distal stump of transected sciatic nerve of rats promotes early functional recovery. The purpose of this study was to expand on the preliminary research by investigating the long-term efficacy of bone marrow stromal cells using the same experimental setting. Functional test and histological studies demonstrate that bone marrow stromal cell-treated rats exhibit significant improvement on a walking tract test at day 180 after surgery compared with control rats. Taken together, these data suggest that bone marrow stromal cell therapy is a safe and effective strategy for peripheral nerve injuries.