Human cord blood transplantation in a neonatal rat model of hypoxic-ischemic brain damage: functional outcome related to neuroprotection in the striatum

Cell therapy for neonatal hypoxia-ischemia and cerebral palsy

Perinatal hypoxic-ischemic brain injury remains a major cause of cerebral palsy. Although therapeutic hypothermia is now established to improve recovery from hypoxia-ischemia (HI) at term, many infants continue to survive with disability, and hypothermia has not yet been tested in preterm infants. There is increasing evidence from in vitro and in vivo preclinical studies that stem/progenitor cells may have multiple beneficial effects on outcome after hypoxic-ischemic injury. Stem/progenitor cells have shown great promise in animal studies in decreasing neurological impairment; however, the mechanisms of action of stem cells, and the optimal type, dose, and method of administration remain surprisingly unclear, and some studies have found no benefit. Although cell-based interventions after completion of the majority of secondary cell death appear to have potential to improve functional outcome for neonates after HI, further rigorous testing in translational animal models is required before randomized controlled trials should be considered.

Transplantation of human umbilical cord blood cells mediated beneficial effects on apoptosis, angiogenesis and neuronal survival after hypoxic-ischemic brain injury in rats

Transplantation of human umbilical cord blood (hucb) cells in a model of hypoxic-ischemic brain injury led to the amelioration of lesion-impaired neurological and motor functions. However, the mechanisms by which transplanted cells mediate functional recovery after brain injury are largely unknown. In this study, the effects of hucb cell transplantation were investigated in this experimental paradigm at the cellular and molecular level. As the pathological cascade in hypoxic-ischemic brain injury includes inflammation, reduced blood flow, and neuronal cell death, we analyzed the effects of peripherally administered hucb cells on these detrimental processes, investigating the expression of characteristic marker proteins. Application of hucb cells after perinatal hypoxic-ischemic brain injury correlated with an increased expression of the proteins Tie-2 and occludin, which are associated with angiogenesis. Lesion-induced apoptosis, determined by expression of cleaved caspase-3, decreased, whereas the number of vital neurons, identified by counting of NeuN-positive cells, increased. In addition, we observed an increase in the expression of neurotrophic and pro-angiogenic growth factors, namely BDNF and VEGF, in the lesioned brain upon hucb cell transplantation. The release of neurotrophic factors mediated by transplanted hucb cells might cause a lower number of neurons to undergo apoptosis and result in a higher number of living neurons. In parallel, the increase of VEGF might cause growth of blood vessels. Thus, hucb transplantation might contribute to functional recovery after brain injury mediated by systemic or local effects.

Long-lasting paracrine effects of human cord blood cells on damaged neocortex in an animal model of cerebral palsy

Neonatal asphyxia is an important contributor to cerebral palsy (CP), for which there is no effective treatment to date. The administration of human cord blood cells (hUCBCs) is emerging as a therapeutic strategy for the treatment of neurological disorders. However, there are few studies on the application of hUCBCs to the treatment of neonatal ischemia as a model of CP. Experiments and behavioral tests (mainly motor tests) performed on neonatal hypoxia/ischemia have been limited to short-term effects of hUCBCs, but mechanisms of action have not been investigated. We performed a study on the use of hUCBCs in a rat model of neonatal hypoxia/ischemia and investigated the underlying mechanism for therapeutic benefits of hUCBC treatment. hUCBCs were intravenously transplanted into a rat model of neonatal hypoxia ischemia. hUCBCs increased microglia temporarily in the periventricular striatum in the early phase of disease, protected mature neurons in the neocortex from injury, paved the way for the near-normalization of brain damage in the subventricular zone (SVZ), and, in consequence, significantly improved performance in a battery of behavioral tests compared to the vehicle-treated group. Although the transplanted cells were rarely observed in the brain 3 weeks after transplantation, the effects of the improved behavioral functions persisted. Our preclinical findings suggest that the long-lasting positive influence of hUCBCs is derived from paracrine effects of hUCBCs that stimulate recovery in the injured brain and protect against further brain damage.

Umbilical cord blood mononuclear cell transplantation for neonatal hypoxic-ischemic encephalopathy

Despite recent advances in the treatment of neonatal hypoxic-ischemic encephalopathy (HIE) using therapeutic hypothermia, at least 30% of the cooled infants will die or have moderate/severe neurological disability. Umbilical cord blood cells (UCBCs), which are readily available at birth, have been shown to reduce sensorimotor and/or cognitive impairments in several models of brain damage, representing a promising option for the treatment of neurological diseases. In this review, we discuss recent preclinical studies that assessed the effects of UCBC transplantation in the Rice-Vannucci animal model of HIE. We also review the possible cell types and mechanisms involved in the therapeutic effect of UCBC transplantation, including neuroprotection, immunomodulation, and stimulation of neural plasticity and regeneration. In addition, we discuss how neuroimaging methods, such as bioluminescence imaging, nuclear-medicine imaging, or magnetic resonance imaging, could be used to evaluate the biodistribution of UCBCs in both preclinical and clinical studies.

Human cord blood for the hypoxic-ischemic neonate

Autologous umbilical cord blood (UCB) is a possible, but unproven, treatment for acute neonatal brain damage. Mesenchymal stem cells (MSCs), which are present in UCB, are likely to be the treating cell type. UCB is effective in the treatment of neonatal rodent hypoxic-ischemic injury (HI) and other types of brain injury when the cells are delivered acutely. Other types of adult stem cells are similarly effective. However, several negative studies have been reported. The most likely mechanisms of action are participation in blood vessel regeneration, improvement of survival of intrinsic cells, perhaps via neurotrophic factors, or suppression of the release of inflammatory cells from the spleen. In the latter case, the splenic inflammatory cells released at the time of injury are thought to have an adverse effect on brain injury. The timing of the administration of the UCB with respect to the time of the injury appears to be the most important issue: the earlier the better. The risks of autologous administration of UCB are minimal. Current clinical trials with UCB are in progress, but there are no peer-reviewed reports as yet. A multicenter trial with specific inclusion criteria is needed.

The dose-response effect of acute intravenous transplantation of human umbilical cord blood cells on brain damage and spatial memory deficits in neonatal hypoxia-ischemia

Despite the beneficial effects of cell-based therapies on brain repair shown in most studies, there has not been a consensus regarding the optimal dose of human umbilical cord blood cells (HUCBC) for neonatal hypoxia-ischemia (HI). In this study, we compared the long-term effects of intravenous administration of HUCBC at three different doses on spatial memory and brain morphological changes after HI in newborn Wistar rats. In addition, we tested whether the transplanted HUCBC migrate to the injured brain after transplantation. Seven-day-old animals underwent right carotid artery occlusion and were exposed to 8% O(2) inhalation for 2 h. After 24 h, randomly selected animals were assigned to four different experimental groups: HI rats administered with vehicle (HI+vehicle), HI rats treated with 1×10(6) (HI+low-dose), 1×10(7) (HI+medium-dose), and 1×10(8) (HI+high-dose) HUCBC into the jugular vein. A control group (sham-operated) was also included in this study. After 8 weeks of transplantation, spatial memory performance was assessed using the Morris water maze (MWM), and subsequently, the animals were euthanized for brain morphological analysis using stereological methods. In addition, we performed immunofluorescence and polymerase chain reaction (PCR) analyses to identify HUCBC in the rat brain 7 days after transplantation. The MWM test showed a significant spatial memory recovery at the highest HUCBC dose compared with HI+vehicle rats (P<0.05). Furthermore, the brain atrophy was also significantly lower in the HI+medium- and high-dose groups compared with the HI+vehicle animals (P<0.01; 0.001, respectively). In addition, HUCBC were demonstrated to be localized in host brains by immunohistochemistry and PCR analyses 7 days after intravenous administration. These results revealed that HUCBC transplantation has the dose-dependent potential to promote robust tissue repair and stable cognitive improvement after HI brain injury.

Stem cell therapy for neonatal brain injury: perspectives and challenges

Cerebral palsy is a major health problem caused by brain damage during pregnancy, delivery, or the immediate postnatal period. Perinatal stroke, intraventricular hemorrhage, and asphyxia are the most common causes of neonatal brain damage. Periventricular white matter damage (periventricular leukomalacia) is the predominant form in premature infants and the most common antecedent of cerebral palsy. Stem cell treatment has proven effective in restoring injured organs and tissues in animal models. The potential of stem cells for self-renewal and differentiation translates into substantial neuroprotection and neuroregeneration in the animal brain, with minimal risks of rejection and side effects. Stem cell treatments described to date have used neural stem cells, embryonic stem cells, mesenchymal stem cells, umbilical cord stem cells, and induced pluripotent stem cells. Most of these treatments are still experimental. In this review, we focus on the efficacy of stem cell therapy in animal models of cerebral palsy, and discuss potential implications for current and future clinical trials.

Hypoxic Ischemic Encephalopathy: Pathophysiology and Experimental Treatments

Hypoxic ischemic encephalopathy (HIE) is a serious birth complication affecting full term infants: 40-60% of affected infants die by 2 years of age or have severe disabilities. The majority of the underlying pathologic events of HIE are a result of impaired cerebral blood flow and oxygen delivery to the brain with resulting primary and secondary energy failure. In the past, treatment options were limited to supportive medical therapy. Currently, several experimental treatments are being explored in neonates and animal models to ameliorate the effects of secondary energy failure. This review discusses the underlying pathophysiologic effects of a hypoxic-ischemic event and experimental treatment modalities being explored to manage infants with HIE. Further research is needed to better understand if the long-term impact of the experimental treatments and whether the combinations of experimental treatments can improve outcomes in infants with HIE.

Homing of placenta-derived mesenchymal stem cells after perinatal intracerebral transplantation in a rat model

OBJECTIVE

The aim of this study is to assess early homing of placenta-derived stem cells after perinatal intracerebral transplantation in rats.

STUDY DESIGN

Neonatal Wistar rats (2-4 days old) were anesthetized, and 250,000 human placenta-derived mesenchymal stem cells (MSC) injected into the lateral ventricle or the paraventricular white matter using a stereotactic frame. Donor MSC were detected by immunohistochemistry using an antihuman HLA-ABC antibody.

RESULTS

In all, 84% of the animals survived the transplantation. Donor cells were detected in the brain ventricle 1-2 hours posttransplantation. After 4 hours, donor cells migrated throughout the ventricular system. At 1-4 weeks after transplantation, some cells had migrated into the periventricular white matter.

CONCLUSION

Human placenta-derived MSC were successfully transplanted into the lateral ventricles of neonatal rats. Donor cells survived, homed, and migrated in the recipient brains. Proliferation and differentiation analysis and functional tests will assess the therapeutic effects of stem cell transplantation.

Pathophysiology of perinatal asphyxia: can we predict and improve individual outcomes?

Perinatal asphyxia occurs still with great incidence whenever delivery is prolonged, despite improvements in perinatal care. After asphyxia, infants can suffer from short- to long-term neurological sequelae, their severity depend upon the extent of the insult, the metabolic imbalance during the re-oxygenation period and the developmental state of the affected regions. Significant progresses in understanding of perinatal asphyxia pathophysiology have achieved. However, predictive diagnostics and personalised therapeutic interventions are still under initial development. Now the emphasis is on early non-invasive diagnosis approach, as well as, in identifying new therapeutic targets to improve individual outcomes. In this review we discuss (i) specific biomarkers for early prediction of perinatal asphyxia outcome; (ii) short and long term sequelae; (iii) neurocircuitries involved; (iv) molecular pathways; (v) neuroinflammation systems; (vi) endogenous brain rescue systems, including activation of sentinel proteins and neurogenesis; and (vii) therapeutic targets for preventing or mitigating the effects produced by asphyxia.

Treatment advances in neonatal neuroprotection and neurointensive care

Knowledge of the nature, prognosis, and ways to treat brain lesions in neonatal infants has increased remarkably. Neonatal hypoxic-ischaemic encephalopathy (HIE) in term infants, mirrors a progressive cascade of excito-oxidative events that unfold in the brain after an asphyxial insult. In the laboratory, this cascade can be blocked to protect brain tissue through the process of neuroprotection. However, proof of a clinical effect was lacking until the publication of three positive randomised controlled trials of moderate hypothermia for term infants with HIE. These results have greatly improved treatment prospects for babies with asphyxia and altered understanding of the theory of neuroprotection. The studies show that moderate hypothermia within 6 h of asphyxia improves survival without cerebral palsy or other disability by about 40% and reduces death or neurological disability by nearly 30%. The search is on to discover adjuvant treatments that can further enhance the effects of hypothermia.

Human umbilical cord blood cells restore brain damage induced changes in rat somatosensory cortex

Intraperitoneal transplantation of human umbilical cord blood (hUCB) cells has been shown to reduce sensorimotor deficits after hypoxic ischemic brain injury in neonatal rats. However, the neuronal correlate of the functional recovery and how such a treatment enforces plastic remodelling at the level of neural processing remains elusive. Here we show by in-vivo recordings that hUCB cells have the capability of ameliorating the injury-related impairment of neural processing in primary somatosensory cortex. Intact cortical processing depends on a delicate balance of inhibitory and excitatory transmission, which is disturbed after injury. We found that the dimensions of cortical maps and receptive fields, which are significantly altered after injury, were largely restored. Additionally, the lesion induced hyperexcitability was no longer observed in hUCB treated animals as indicated by a paired-pulse behaviour resembling that observed in control animals. The beneficial effects on cortical processing were reflected in an almost complete recovery of sensorimotor behaviour. Our results demonstrate that hUCB cells reinstall the way central neurons process information by normalizing inhibitory and excitatory processes. We propose that the intermediate level of cortical processing will become relevant as a new stage to investigate efficacy and mechanisms of cell therapy in the treatment of brain injury.

Umbilical cord blood cell transplantation after brain ischemia--from recovery of function to cellular mechanisms

Cell transplantation has been proposed as a potential approach to the treatment of neurological disorders. One cell population of interest consists of human umbilical cord blood (hUCB) cells, which have previously been shown to be useful for reparative medicine in haematological diseases. However, hUCB cells are also capable of differentiating into various non-haematopoietic cells, including those of the neural lineage. Moreover, hUCB cells can secrete numerous neurotrophic factors and modulate immune function and inflammatory reaction. Several studies on animal models of ischemic brain injury have demonstrated the potential of hUCB cells to minimize damage and promote recovery after ischemic brain injury.This review focuses on the treatment of both stroke and perinatal hypoxic-ischemic brain injury using hUCB cells. We discuss the therapeutic effects demonstrated after hUCB cell transplantation and emphasize possible mechanisms counteracting pathophysiological events of ischemia, thus leading to the generation of a regenerative environment that allows neural plasticity and functional recovery. The therapeutic functional effects of hUCB cells observed in animal models make the transplantation of hUCB cells a promising experimental approach in the treatment of ischemic brain injury. Together with its availability, low risk of transplantation, immaturity of cells, and simple route of application, hUCB transplantation may stand a good chance of being translated into a clinical setting for the therapy of ischemic brain injury.

Update on stem cell therapy for cerebral palsy

INTRODUCTION

Due to the publicity about stem cell transplantation for the treatment of cerebral palsy, many families seek information on treatment, and many travel overseas for cell transplantation. Even so, there is little scientific confirmation of benefit, and therefore existing knowledge in the field must be summarized.

AREAS COVERED

This paper addresses the clinical protocols examining the problem, types of stem cells available for transplant, experimental models used to test the benefit of the cells, possible mechanisms of action, potential complications of cell treatment and what is needed in the field to help accelerate cell-based therapies.

EXPERT OPINION

While stem cells may be beneficial in acute injuries of the CNS the biology of stem cells is not well enough understood in chronic injuries or disorders such as cerebral palsy. More work is required at the basic level of stem cell biology, in the development of animal models, and finally in well-conceived clinical trials.

Could autologous cord blood stem cell transplantation treat cerebral palsy?

The young human brain is highly plastic and thus early brain lesions can lead to aberrant development of connectivity and mapping of functions. This is why initially in cerebral palsy only subtle changes in spontaneous movements are seen after the time of lesion, followed by a progressive evolution of a movement disorder over many months and years. Thus we propose that interventions to treat cerebral palsy should be initiated as soon as possible in order to restore the nervous system to the correct developmental trajectory. One such treatment might be autologous stem cell transplantation either intracerebrally or intravenously. All babies come with an accessible supply of stem cells, the umbilical cord, which can supply cells that could theoretically replace missing neural cell types, or act indirectly by supplying trophic support or modulating inflammatory responses to hypoxia/ischaemia. However, for such radical treatment to be proposed, it is necessary to be able to detect and accurately predict the outcomes of brain injury from a very early age. This article reviews our current understanding of perinatal injuries that lead to cerebral palsy, how well modern imaging might predict outcomes, what stem cells are yielded from umbilical cord blood and experimental models of brain repair using stem cells.

The treatment of neurodegenerative disorders using umbilical cord blood and menstrual blood-derived stem cells

Stem cell transplantation is a potentially important means of treatment for a number of disorders. Two different stem cell populations of interest are mononuclear umbilical cord blood cells and menstrual blood-derived stem cells. These cells are relatively easy to obtain, appear to be pluripotent, and are immunologically immature. These cells, particularly umbilical cord blood cells, have been studied as either single or multiple injections in a number of animal models of neurodegenerative disorders with some degree of success, including stroke, Alzheimer's disease, amyotrophic lateral sclerosis, and Sanfilippo syndrome type B. Evidence of anti-inflammatory effects and secretion of specific cytokines and growth factors that promote cell survival, rather than cell replacement, have been detected in both transplanted cells.

Repeated mesenchymal stem cell treatment after neonatal hypoxia-ischemia has distinct effects on formation and maturation of new neurons and oligodendrocytes leading to restoration of damage, corticospinal motor tract activity, and sensorimotor function

Birth asphyxia is a frequent cause of perinatal morbidity and mortality with limited therapeutic options. We show that a single mesenchymal stem cell treatment at 3 d (MSC-3) after neonatal hypoxia-ischemia (HI) in postnatal day 9 mice improved sensorimotor function and reduced lesion size. A second MSC treatment at 10 d after HI (MSC-3+10) further enhanced sensorimotor improvement and recovery of MAP2 and MBP (myelin basic protein) staining. Ipsilateral anterograde corticospinal tract tracing with biotinylated dextran amine (BDA) showed that HI reduced BDA labeling of the contralateral spinal cord. Only MSC-3+10 treatment partially restored contralateral spinal cord BDA staining, indicating enhanced axonal remodeling. MSC-3 enhanced formation of bromodeoxyuridine-positive neurons and oligodendrocytes. Interestingly, the second gift at day 10 did not further increase new cell formation, whereas only MSC-10 did. These findings indicate that increased positive effect of MSC-3+10 compared with MSC-3 alone is mediated via distinct pathways. We hypothesize that MSCs adapt their growth and differentiation factor production to the needs of the environment at the time of intracranial injection. Comparing the response of MSCs to in vitro culture with HI brain extracts obtained at day 10 from MSC-3- or vehicle-treated animals by pathway-focused PCR array analysis revealed that 29 genes encoding secreted factors were indeed differentially regulated. We propose that the function of MSCs is dictated by adaptive specific signals provided by the damaged and regenerating brain.

Human umbilical cord blood cells decrease microglial survival in vitro

When human umbilical cord blood (HUCB) cells are systemically administered following middle cerebral artery occlusion (MCAO) in rats, they produce a reduction in infarct size resulting in recovery of motor function. Rats receiving HUCB cells have a less severe inflammatory response compared to MCAO stroke rats. The purpose of this study was to determine the interaction between HUCB cells and the main resident immune cells of the brain (microglia) under normoxic and hypoxic conditions in vitro. Primary microglial cultures were incubated for 2 h in no oxygen (95% N, 5% CO(2)) and low glucose (1%) media. Mononuclear HUCB cells were added to half the cultures at the beginning of the hypoxia conditions. Microglial viability was determined using fluorescein diacetate/propidium iodide (FDA/PI) labeling and cytokine expression using ELISA. In some studies, CD11b+ or CD19+ cells isolated from the HUCB mononuclear fraction with magnetic antibody cell sorting (MACS) were used instead of the mononuclear fraction. Co-culturing mononuclear HUCB cells with microglia decreased viability of the microglia during hypoxia. In the microglial monocultures, hypoxia significantly increased release of IL-1beta compared to normoxia, while adding HUCB cells in the hypoxia condition decreased IL-1beta concentrations to the same level as in the normoxia monocultures. Both CD11b+ and CD19+ HUCB cells decreased microglial viability during normoxia and hypoxia. Our data suggest that HUCB cells may produce a soluble factor that decreases viability of microglia.

Monocyte transplantation for neural and cardiovascular ischemia repair

Neovascularization is an integral process of inflammatory reactions and subsequent repair cascades in tissue injury. Monocytes/macrophages play a key role in the inflammatory process including angiogenesis as well as the defence mechanisms by exerting microbicidal and immunomodulatory activity. Current studies have demonstrated that recruited monocytes/macrophages aid in regulating angiogenesis in ischemic tissue, tumours and chronic inflammation. In terms of neovascularization followed by tissue regeneration, monocytes/macrophages should be highly attractive for cell-based therapy compared to any other stem cells due to their considerable advantages: non-oncogenic, non-teratogenic, multiple secretary functions including pro-angiogenic and growth factors, straightforward cell harvesting procedure and non-existent ethical controversy. In addition to adult origins such as bone marrow or peripheral blood, umbilical cord blood (UCB) can be a potential source for autologous or allogeneic monocytes/macrophages. Especially, UCB monocytes should be considered as the first candidate owing to their feasibility, low immune rejection and multiple characteristic advantages such as their anti-inflammatory properties by virtue of their unique immune and inflammatory immaturity, and their pro-angiogenic ability. In this review, we present general characteristics and potential of monocytes/macrophages for cell-based therapy, especially focusing on neovascularization and UCB-derived monocytes.