Long-Term Recovery After Endothelial Colony-Forming Cells or Human Umbilical Cord Blood Cells Administration in a Rat Model of Neonatal Hypoxic-Ischemic Encephalopathy

Mononuclear cell therapy of neonatal hypoxic-ischemic encephalopathy in preclinical versus clinical studies: a systematic analysis of therapeutic efficacy and study design

Background

Hypoxic-ischemic encephalopathy (HIE) is a devastating condition affecting around 8.5 in 1000 newborns globally. Therapeutic hypothermia (TH) can reduce mortality and, to a limited extent, disability after HIE. Nevertheless, there is a need for new and effective treatment strategies. Cell based treatments using mononuclear cells (MNC), which can be sourced from umbilical cord blood, are currently being investigated. Despite promising preclinical results, there is currently no strong indicator for clinical efficacy of the approach. This analysis aimed to provide potential explanations for this discrepancy.

Methods

A systematic review and meta-analysis was conducted according to the Preferred Reporting Items for Systematic reviews and Meta-Analysis (PRISMA) guidelines. Preclinical and clinical studies were retrieved from PubMed, Web of Science, Scopus, and clinicaltrials.gov using a predefined search strategy. A total of 17 preclinical and 7 clinical studies were included. We analyzed overall MNC efficacy in preclinical trials, the methodological quality of preclinical trials and relevant design features in preclinical versus clinical trials.

Results

There was evidence for MNC therapeutic efficacy in preclinical models of HIE. The methodological quality of preclinical studies was not optimal, and statistical design quality was particularly poor. However, methodological quality was above the standard in other fields. There were significant differences in preclinical versus clinical study design including the use of TH as a baseline treatment (only in clinical studies) and much higher MNC doses being applied in preclinical studies.

Conclusions

Based on the analyzed data, it is unlikely that therapeutic effect size is massively overestimated in preclinical studies. It is more plausible that the many design differences between preclinical and clinical trials are responsible for the so far lacking proof of efficacy of MNC treatments in HIE. Additional preclinical and clinical research is required to optimize the application of MNC for experimental HIE treatment.

Stem cell-based interventions for the treatment of stroke in newborn infants

BACKGROUND

Perinatal stroke refers to a diverse but specific group of cerebrovascular diseases that occur between 20 weeks of fetal life and 28 days of postnatal life. Acute treatment options for perinatal stroke are limited supportive care, such as controlling hypoglycemia and seizures. Stem cell-based therapies offer a potential therapeutic approach to repair, restore, or regenerate injured brain tissue. Preclinical findings have culminated in ongoing human neonatal studies.

OBJECTIVES

To evaluate the benefits and harms of stem cell-based interventions for the treatment of stroke in newborn infants compared to control (placebo or no treatment) or stem-cell based interventions of a different type or source.

SEARCH METHODS

We searched CENTRAL, PubMed, Embase, and three trials registries in February 2023. We planned to search the reference lists of included studies and relevant systematic reviews for studies not identified by the database searches.

SELECTION CRITERIA

We attempted to include randomized controlled trials, quasi-randomized controlled trials, and cluster trials that evaluated any of the following comparisons. • Stem cell-based interventions (any type) versus control (placebo or no treatment) • Mesenchymal stem/stromal cells (MSCs) of a specifictype (e.g. number of doses or passages) or source (e.g. autologous/allogeneic or bone marrow/cord) versus MSCs of another type or source • Stem cell-based interventions (other than MSCs) of a specific type (e.g. mononuclear cells, oligodendrocyte progenitor cells, neural stem cells, hematopoietic stem cells, or induced pluripotent stem cell-derived cells) or source (e.g. autologous/allogeneic or bone marrow/cord) versus stem cell-based interventions (other than MSCs) of another type or source • MSCs versus stem cell-based interventions other than MSCs We planned to include all types of transplantation regardless of cell source (bone marrow, cord blood, Wharton's jelly, placenta, adipose tissue, peripheral blood), type of graft (autologous or allogeneic), and dose.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. Our primary outcomes were all-cause neonatal mortality, major neurodevelopmental disability, and immune rejection or any serious adverse event. Our secondary outcomes included all-cause mortality prior to first hospital discharge, seizures, adverse effects, and death or major neurodevelopmental disability at 18 to 24 months of age. We planned to use GRADE to assess the certainty of evidence for each outcome.

MAIN RESULTS

We identified no completed or ongoing randomized trials that met our inclusion criteria. We excluded three studies: two were phase 1 trials, and one included newborn infants with conditions other than stroke (i.e. cerebral ischemia and anemia). Among the three excluded studies, we identified the first phase 1 trial on the use of stem cells for neonatal stroke. It reported that a single intranasal application of bone marrow-derived MSCs in term neonates with a diagnosis of perinatal arterial ischemic stroke (PAIS) was feasible and apparently not associated with severe adverse events. However, the trial included only 10 infants, and follow-up was limited to three months.

AUTHORS' CONCLUSIONS

No evidence is currently available to evaluate the benefits and harms of stem cell-based interventions for treatment of stroke in newborn infants. We identified no ongoing studies. Future clinical trials should focus on standardizing the timing and method of cell delivery and cell processing to optimize the therapeutic potential of stem cell-based interventions and safety profiles. Phase 1 and large animal studies might provide the groundwork for future randomized trials. Outcome measures should include all-cause mortality, major neurodevelopmental disability and immune rejection, and any other serious adverse events.

Progress in the treatment of neonatal hypoxic-ischemic encephalopathy with umbilical cord blood mononuclear cells

Neonatal hypoxic-ischemic encephalopathy (HIE) is a common disease among newborns, which is a leading cause of neonatal death and permanent neurological sequelae. Therapeutic hypothermia (TH) is the only method for the treatment of HIE that has been recognized effective clinically at home and abroad, but the efficacy is limited. Recent research suggests that the cord blood-derived mononuclear cells (CB-MNCs), which the refer to blood cells containing one nucleus in the cord blood, exert anti-oxidative, anti-inflammatory, anti-apoptotic effects and play a neuroprotective role in HIE. This review focuses on safety and efficacy, the route of administration, dose, timing and combination treatment of CB-MNCs in HIE.

Factors Influencing the Efficacy of Umbilical Cord Blood-Derived Cell Therapy for Perinatal Brain Injury

INTRODUCTION

We have previously described preclinical literature which supports umbilical cord blood-derived cell (UCBC) therapy as an efficacious treatment for perinatal brain injury. However, efficacy of UCBCs may be influenced by different patient population and intervention characteristics.

OBJECTIVES

To systematically review the effects of UCBCs on brain outcomes in animal models of perinatal brain injury across subgroups to better understand the contribution of model type (preterm versus term), brain injury type, UCB cell type, route of administration, timing of intervention, cell dosage, and number of doses.

METHODS

A systematic search of MEDLINE and Embase databases was performed to identify studies using UCBC therapy in animal models of perinatal brain injury. Subgroup differences were measured by chi2 test where possible.

RESULTS

Differential benefits of UCBCs were seen across a number of subgroup analyses including intraventricular hemorrhage (IVH) vs. hypoxia ischemia (HI) model (apoptosis white matter (WM): chi2 = 4.07; P = .04, neuroinflammation-TNF-α: chi2 = 5.99; P = .01), UCB-derived mesenchymal stromal cells (MSCs) vs. UCB-derived mononuclear cells (MNCs) (oligodendrocyte WM: chi2 = 5.01; P = .03, neuroinflammation-TNF-α: chi2 = 3.93; P = .05, apoptosis grey matter (GM), astrogliosis WM), and intraventricular/intrathecal vs. systemic routes of administration (microglial activation GM: chi2 = 7.51; P = .02, astrogliosis WM: chi2 = 12.44; P = .002). We identified a serious risk of bias and overall low certainty of evidence.

CONCLUSIONS

Preclinical evidence suggests UCBCs to show greater efficacy in the injury model of IVH compared to HI, the use of UCB-MSCs compared to UCB-MNCs and the use of local administrative routes compared to systemic routes in animal models of perinatal brain injury. Further research is needed to improve certainty of evidence and address knowledge gaps.

Umbilical Cord Blood-Derived Cell Therapy for Perinatal Brain Injury: A Systematic Review & Meta-Analysis of Preclinical Studies

Perinatal brain injury is a major contributor to long-term adverse neurodevelopment. There is mounting preclinical evidence for use of umbilical cord blood (UCB)-derived cell therapy as potential treatment. To systematically review and analyse effects of UCB-derived cell therapy on brain outcomes in preclinical models of perinatal brain injury. MEDLINE and Embase databases were searched for relevant studies. Brain injury outcomes were extracted for meta-analysis to calculate standard mean difference (SMD) with 95% confidence interval (CI), using an inverse variance, random effects model. Outcomes were separated based on grey matter (GM) and white matter (WM) regions where applicable. Risk of bias was assessed using SYRCLE, and GRADE was used to summarise certainty of evidence. Fifty-five eligible studies were included (7 large, 48 small animal models). UCB-derived cell therapy significantly improved outcomes across multiple domains, including decreased infarct size (SMD 0.53; 95% CI (0.32, 0.74), p < 0.00001), apoptosis (WM, SMD 1.59; 95%CI (0.86, 2.32), p < 0.0001), astrogliosis (GM, SMD 0.56; 95% CI (0.12, 1.01), p = 0.01), microglial activation (WM, SMD 1.03; 95% CI (0.40, 1.66), p = 0.001), neuroinflammation (TNF-α, SMD 0.84; 95%CI (0.44, 1.25), p < 0.0001); as well as improved neuron number (SMD 0.86; 95% CI (0.39, 1.33), p = 0.0003), oligodendrocyte number (GM, SMD 3.35; 95 %CI (1.00, 5.69), p = 0.005) and motor function (cylinder test, SMD 0.49; 95 %CI (0.23, 0.76), p = 0.0003). Risk of bias was determined as serious, and overall certainty of evidence was low. UCB-derived cell therapy is an efficacious treatment in pre-clinical models of perinatal brain injury, however findings are limited by low certainty of evidence.

Stem cell‐based interventions for the treatment of stroke in newborn infants

This is a protocol for a Cochrane Review (intervention). The objectives are as follows:

To evaluate the benefits and harms of stem cell‐based interventions for the treatment of stroke in newborn infants compared to control (placebo or no treatment) or stem‐cell based interventions of a different type or source.

Neonatal asphyxia as an inflammatory disease: Reactive oxygen species and cytokines

Neonatologists resuscitate asphyxiated neonates by every available means, including positive ventilation, oxygen therapy, and drugs. Asphyxiated neonates sometimes present symptoms that mimic those of inflammation, such as fever and edema. The main pathophysiology of the asphyxia is inflammation caused by hypoxic-ischemic reperfusion. At birth or in the perinatal period, neonates may suffer several, hypoxic insults, which can activate inflammatory cells and inflammatory mediator production leading to the release of larger quantities of reactive oxygen species (ROS). This in turn triggers the production of oxygen stress-induced high mobility group box-1 (HMGB-1), an endogenous damage-associated molecular patterns (DAMPs) protein bound to toll-like receptor (TLR) -4, which activates nuclear factor-kappa B (NF-κB), resulting in the production of excess inflammatory mediators. ROS and inflammatory mediators are produced not only in activated inflammatory cells but also in non-immune cells, such as endothelial cells. Hypothermia inhibits pro-inflammatory mediators. A combination therapy of hypothermia and medications, such as erythropoietin and melatonin, is attracting attention now. These medications have both anti-oxidant and anti-inflammatory effects. As the inflammatory response and oxidative stress play a critical role in the pathophysiology of neonatal asphyxia, these drugs may contribute to improving patient outcomes.

Hypothermia Does Not Boost the Neuroprotection Promoted by Umbilical Cord Blood Cells in a Neonatal Hypoxia-Ischemia Rat Model

Neonatal hypoxic-ischemic encephalopathy (HIE) is one of the leading causes of death and long-term disability in the perinatal period. Currently, therapeutic hypothermia is the standard of care for this condition with modest efficacy and strict enrollment criteria. Therapy with umbilical cord blood cells (UCBC) has come forward as a strong candidate for the treatment of neonatal HIE, but no preclinical studies have yet compared the action of UCBC combined with hypothermia (HT) with the action of each therapy by itself. Thus, to evaluate the potential of each therapeutic approach, a hypoxic-ischemic brain lesion was induced in postnatal day ten rat pups; two hours later, HT was applied for 4 h; and 24, 48, and 72 h post-injury, UCBC were administered intravenously. The neonatal hypoxic-ischemic injury led to a brain lesion involving about 48% of the left hemisphere that was not improved by HT (36%) or UCBC alone (28%), but only with the combined therapies (25%; p = 0.0294). Moreover, a decrease in glial reactivity and improved functional outcomes were observed in both groups treated with UCBC. Overall, these results support UCBC as a successful therapeutic approach for HIE, even when treatment with therapeutic hypothermia is not possible.

Human umbilical cord blood mononuclear cells transplantation for perinatal brain injury

Perinatal brain injury is a leading cause of death and disability in children. Hypoxic-ischemic encephalopathy in full term infants, and white matter injury in premature infants are most known brain injury in perinatal period. Human umbilical cord blood mononuclear cells contain hematopoietic stem cells, mesenchymal stem cells, endothelial progenitor cells, lymphocytes, monocytes, and so on. Human umbilical cord blood mononuclear cells have many biological functions, such as nerve and vascular regeneration, anti-apoptosis, anti-inflammation, and immune regulation. Human umbilical cord blood mononuclear cells transplantation has achieved significant efficacy and safety in animal and clinical trials for the treatment of perinatal brain injury. We will review human umbilical cord blood mononuclear cells transplantation for perinatal brain injury in this review.

The alternative 3' splice site of GPNMB may promote neuronal survival after neonatal hypoxic-ischemic encephalopathy injury

This study aimed to decipher the effect of glycoprotein nonmetastatic melanoma protein B (GPNMB) on neonatal hypoxic-ischemic encephalopathy (NHIE) and its potential molecular mechanism. The hypoxic-ischemic (HI) model was established in 7-day-old rats, and then, Zea-Longa scores and Nissl staining were performed to measure brain damage post-HI. In addition, gene sequencing was used to detect the differential expression genes (DEGs), and then, Gene Ontology and Kyoto Encyclopedia of Genes and Genomes databases were used to determine the function of DEGs. Furthermore, an oxygen-glucose deprivation (OGD) model was developed in SY5Y cells and human fetal neurons, and then, the level of GPNMB was verified by quantitative real-time polymerase chain reaction. In addition, methyl thiazolyl tetrazolium and cell counting kit-8 assays were applied after GPNMB interference. Finally, the alternative splicing of GPNMB expression was analyzed using Splice Grapher software. The results indicated that HI induced marked neurological impairment and neuron injury in rats. Also, GPNMB was the most obviously upregulated gene in DEGs. Additionally, GPNMB was upregulated significantly in SY5Y and fetal neurons after OGD, and GPNMB-si promoted an increase in cell viability and number. Moreover, we found that the GPNMB alternative splicing type was the Alternative 3' splice site, with the alternative splicing site in 143382985:143404102. Herein, GPNMB promotes a crucial regulatory mechanism with alternative splicing for neuronal survival after NHIE.

Rationale for the Use of Cord Blood in Hypoxic-Ischaemic Encephalopathy

Hypoxic-ischaemic encephalopathy (HIE) is a severe complication of asphyxia at birth. Therapeutic hypothermia, the standard method for HIE prevention, is effective in only 50% of the cases. As the understanding of the immunological basis of these changes increases, experiments have begun with the use of cord blood (CB) because of its neuroprotective properties. Mechanisms for the neuroprotective effects of CB stem cells include antiapoptotic and anti-inflammatory actions, stimulation of angiogenesis, production of trophic factors, and mitochondrial donation. In several animal models of HIE, CB decreased oxidative stress, cell death markers, CD4+ T cell infiltration, and microglial activation; restored normal brain metabolic activity; promoted neurogenesis; improved myelination; and increased the proportion of mature oligodendrocytes, neuron numbers in the motor cortex and somatosensory cortex, and brain weight. These observations translate into motor strength, limb function, gait, and cognitive function and behaviour. In humans, the efficacy and safety of CB administration were reported in a few early clinical studies which confirmed the feasibility and safety of this intervention for up to 10 years. The results of these studies showed an improvement in the developmental outcomes over hypothermia. Two phase-2 clinical studies are ongoing under the United States regulations, namely one controlled study and one blinded study.

Xenograft of Human Umbilical Mesenchymal Stem Cells Promotes Recovery from Chronic Ischemic Stroke in Rats

Stroke is a leading cause of adult disability. In our previous study, transplantation of human umbilical mesenchymal stem cells (HUMSCs) in Wharton’s jelly in the acute phase of ischemic stroke promotes recovery in rats. Unfortunately, there is no cure for chronic stroke. Patients with chronic stroke can only be treated with rehabilitation or supportive interventions. This study aimed to investigate the potential of xenograft of HUMSCs for treating chronic stroke in rats. Rats were subjected to 90 min middle cerebral artery occlusion and then reperfusion to mimic ischemic cerebral stroke. On day 14 following stroke, HUMSCs were transplanted into the damaged cerebral cortex. The motor function in rats of the Stroke + HUMSCs group exhibited significant improvement compared to that of the Stroke + Saline group, and the trend persisted until day 56 post stroke. The cerebral cortex changes were tracked using magnetic resonance imaging, showing that cerebral atrophy was found starting on day 7 and was reduced significantly in rats receiving HUMSCs compared to that in the Stroke + Saline group from day 21 to day 56. HUMSCs were found to be existed in the rats’ cerebral cortex on day 56, with signs of migration. The grafted HUMSCs did not differentiate into neurons or astrocytes and may release cytokines to improve neuroprotection, decrease inflammation and increase angiogenesis. Our results demonstrate that xeno-transplantation of HUMSCs has therapeutic benefits for chronic ischemic stroke. Most importantly, patients do not need to use their own HUMSCs, which is a gospel thing for clinical patients.

Stem cells in neonatal diseases: An overview

Preterm birth and its common complications are major causes of infant mortality and long-term morbidity. Despite great advances in understanding the pathogenesis of neonatal diseases and improvements in neonatal intensive care, effective therapies for the prevention or treatment for these conditions are still lacking. Stem cell (SC) therapy is rapidly emerging as a novel therapeutic tool for several diseases of the newborn with encouraging pre-clinical results that hold promise for translation to the bedside. The utility of different types of SCs in neonatal diseases is being explored. SC therapeutic efficacy is closely associated with its secretome-conditioned media and SC-derived extracellular vesicles, and a subsequent paracrine action in response to tissue injuries. In the current review, we summarize the pre-clinical and clinical studies of SCs and its secretome in diverse preterm and term birth-related diseases, thereby providing new insights for future therapies in neonatal medicine.

Placental tissue stem cells and their role in neonatal diseases

Neonatal diseases such as hypoxic ischemic encephalopathy, diseases of prematurity and congenital disorders carry increased morbidity and mortality. Despite technological advancements, their incidence remains largely unabated. Stem cell (SC) interventions are novel therapies in the neonatal world. In pre-clinical models of neonatal diseases, SC applications have shown encouraging results. SC sources vary, with the bone marrow being the most utilized. However, the ability to harvest bone marrow SCs from neonates is limited. Placental-tissue derived SCs (PTSCs), provide an alternative and highly attractive source. Human placentas, the cornerstone of fetal survival, are abundant with such cells. Comparing to adult pools, PTSCs exhibit increased potency, decreased immunogenicity and stronger anti-inflammatory effects. Several types of PTSCs have been identified, with mesenchymal stem cells being the most utilized population. This review will focus on PTSCs and their pre-clinical and clinical applications in neonatology.

Combination of human endothelial colony-forming cells and mesenchymal stromal cells exert neuroprotective effects in the growth-restricted newborn

The foetal brain is particularly vulnerable to the detrimental effects of foetal growth restriction (FGR) with subsequent abnormal neurodevelopment being common. There are no current treatments to protect the FGR newborn from lifelong neurological disorders. This study examines whether pure foetal mesenchymal stromal cells (MSC) and endothelial colony-forming cells (ECFC) from the human term placenta are neuroprotective through modulating neuroinflammation and supporting the brain vasculature. We determined that one dose of combined MSC-ECFCs (cECFC; 10⁶ ECFC 10⁶ MSC) on the first day of life to the newborn FGR piglet improved damaged vasculature, restored the neurovascular unit, reduced brain inflammation and improved adverse neuronal and white matter changes present in the FGR newborn piglet brain. These findings could not be reproduced using MSCs alone. These results demonstrate cECFC treatment exerts beneficial effects on multiple cellular components in the FGR brain and may act as a neuroprotectant.

Umbilical cord blood therapy modulates neonatal hypoxic ischemic brain injury in both females and males

Preclinical and clinical studies have shown that sex is a significant risk factor for perinatal morbidity and mortality, with males being more susceptible to neonatal hypoxic ischemic (HI) brain injury. No study has investigated sexual dimorphism in the efficacy of umbilical cord blood (UCB) cell therapy. HI injury was induced in postnatal day 10 (PND10) rat pups using the Rice-Vannucci method of carotid artery ligation. Pups received 3 doses of UCB cells (PND11, 13, 20) and underwent behavioural testing. On PND50, brains were collected for immunohistochemical analysis. Behavioural and neuropathological outcomes were assessed for sex differences. HI brain injury resulted in a significant decrease in brain weight and increase in tissue loss in females and males. Females and males also exhibited significant cell death, region-specific neuron loss and long-term behavioural deficits. Females had significantly smaller brains overall compared to males and males had significantly reduced neuron numbers in the cortex compared to females. UCB administration improved multiple aspects of neuropathology and functional outcomes in males and females. Females and males both exhibited injury following HI. This is the first preclinical evidence that UCB is an appropriate treatment for neonatal brain injury in both female and male neonates.

Long-term administration of resveratrol at low doses improves neurocognitive performance as well as cerebral blood flow and modulates the inflammatory pathways in the brain

There is an increasing prevalence of coincident cerebrovascular deficiency and cognitive dysfunction with aging. Increased oxidative stress as well as inflammation that occurs with aging are associated with the impairment of cerebral vascularization. Interestingly, Resveratrol (RSV), a natural phytoalexin, is known to be a strong antioxidant and possesses anti-inflammatory properties. Collectively, these observations strongly suggest that RSV could protect against cerebral vascularization defect and then improves the decline cognitive function associated with aging. In order to test this hypothesis, we investigated the effect of a long-term RSV treatment (1.25 mg/day for 5 months) on cognitive performances of animals that we have allowed to age normally. Then, we further analyzed the gene expression profile and the cerebral blood flow in the brain. By means of novel object recognition (NOR) test, we observed that RSV enhanced NOR performances of aged rats. In addition, RSV enhanced cerebral blood flow during NOR task in aged rats. Using microarrays experiments, we also showed that several pathways related to inflammation and oxidative stress (Eicosanoid signaling, MIF-mediated innate immunity, NF-kB signaling, TNFR2 signaling, IL6 signaling, Production of nitric oxide and ROS) were down-regulated in the brain of RSV treatments rats compared to control rats. In conclusion, these results support that a long-term treatment with RSV improves cognitive performance in the elderly male rat model. This effect is associated with an increase in cerebral blood flow and a decrease in the expression of several pro-inflammatory pathways in the brain.

Diverse actions of cord blood cell therapy for hypoxic-ischemic encephalopathy

Perinatal hypoxic-ischemic encephalopathy (HIE) is a major cause of neonatal death and permanent neurological deficits. However, effective treatments have not yet been established, except therapeutic hypothermia, which is not effective for severe HIE; therefore, developing a novel therapy for HIE is of the utmost importance. Stem cell therapy has recently been identified as a novel therapy for HIE. Among the various stem cell sources, ethical hurdles can be avoided by using stem cells that originate from non-embryonic or non-neural tissues, such as umbilical cord blood cells (UCBCs), which are readily available and can be exploited for autologous transplantations. Human UCBs are a rich source of stem and progenitor cells. Many recent studies have reported the treatment effect of UCBCs. Additionally, phase I clinical trials have already been conducted, showing this therapy's safety and feasibility. One advantage of stem cell therapies, including UCBC administration, is that they exert treatment effects through multifaceted mechanisms. According to the findings of several publications, replacement of lost cells, namely, engraftment and differentiation into neuronal cells, is not likely to be the main mechanism. However, the association between UCBCs and various mechanism of action, such as neurogenesis, angiogenesis, and anti-inflammation, has been suggested in many studies, and most mechanisms are due to growth factors secreted from UCBCs. These diverse actions of UCBC treatment are expected to exert a substantial effect on HIE, which has a complex injury mechanism.

Optimization of behavioral testing in a long-term rat model of hypoxic ischemic brain injury

BACKGROUND

Hypoxic ischemic (HI) brain injury is a significant cause of childhood neurological deficits. Preclinical rodent models are often used to study these deficits; however, no preclinical study has determined which behavioral tests are most appropriate for long-term follow up after neonatal HI.

METHODS

HI brain injury was induced in postnatal day (PND) 10 rat pups using the Rice-Vannucci method of unilateral carotid artery ligation. Rats underwent long-term behavioral testing to assess motor and cognitive outcomes between PND11-50. Behavioral scores were transformed into Z-scores and combined to create composite behavioral scores.

RESULTS

HI rats showed a significant deficit in three out of eight behavioral tests: negative geotaxis analysis, the cylinder test and the novel object recognition test. These individual test outcomes were transformed into Z-scores and combined to create a composite Z-score. This composite z-score showed that HI rats had a significantly increased behavioral burden over the course of the experiment.

CONCLUSION

In this study we have identified tests that highlight specific cognitive and motor deficits in a rat model of neonatal HI. Due to the high variability in this model of neonatal HI brain injury, significant impairment is not always observed in individual behavioral tests, but by combining outcomes from these individual tests, long-term behavioral burden can be measured.

Stem Cell Therapy for Neonatal Hypoxic-Ischemic Encephalopathy: A Systematic Review of Preclinical Studies

Neonatal hypoxic-ischemic encephalopathy (HIE) is an important cause of mortality and morbidity in the perinatal period. This condition results from a period of ischemia and hypoxia to the brain of neonates, leading to several disorders that profoundly affect the daily life of patients and their families. Currently, therapeutic hypothermia (TH) is the standard of care in developing countries; however, TH is not always effective, especially in severe cases of HIE. Addressing this concern, several preclinical studies assessed the potential of stem cell therapy (SCT) for HIE. With this systematic review, we gathered information included in 58 preclinical studies from the last decade, focusing on the ones using stem cells isolated from the umbilical cord blood, umbilical cord tissue, placenta, and bone marrow. Outstandingly, about 80% of these studies reported a significant improvement of cognitive and/or sensorimotor function, as well as decreased brain damage. These results show the potential of SCT for HIE and the possibility of this therapy, in combination with TH, becoming the next therapeutic approach for HIE. Nonetheless, few preclinical studies assessed the combination of TH and SCT for HIE, and the existent studies show some contradictory results, revealing the need to further explore this line of research.

Brief inhalation of sevoflurane can reduce glial scar formation after hypoxic-ischemic brain injury in neonatal rats

Previous studies have demonstrated that sevoflurane postconditioning can provide neuroprotection after hypoxic-ischemic injury and improve learning and memory function in developing rodent brains. The classical Rice-Vannucci model was used to induce hypoxic-ischemic injury, and newborn (postnatal day 7) rats were treated with 2.4% sevoflurane for 30 minutes after hypoxic-ischemic injury. Our results showed that sevoflurane postconditioning significantly improved the learning and memory function of rats, decreased astrogliosis and glial scar formation, increased numbers of dendritic spines, and protected the histomorphology of the hippocampus. Mechanistically, sevoflurane postconditioning decreased expression of von Hippel-Lindau of hypoxia-inducible factor-1α and increased expression of DJ-1. Injection of 1.52 μg of the hypoxia-inducible factor-1α inhibitor YC-1 (Lificiguat) into the left lateral ventricle 30 minutes before hypoxic-ischemic injury reversed the neuroprotection induced by sevoflurane. This finding suggests that sevoflurane can effectively alleviate astrogliosis in the hippocampus and reduce learning and memory impairments caused by glial scar formation after hypoxic-ischemic injury. The underlying mechanism may be related to upregulated DJ-1 expression, reduced ubiquitination of hypoxia-inducible factor-1α, and stabilized hypoxia-inducible factor-1α expression. This study was approved by the Laboratory Animal Care Committee of China Medical University, China (approval No. 2016PS337K) on November 9, 2016.

LXA4 protects against hypoxic-ischemic damage in neonatal rats by reducing the inflammatory response via the IκB/NF-κB pathway

Hypoxia and the resultant decreases in cerebral blood flow in the perinatal period can lead to neonatal hypoxic-ischemic (HI) brain injury, which can, in turn, cause severe disability or even death. However, the efficacy of current treatment strategies remains limited. Several studies have demonstrated that lipoxin A4 (LXA4), as one of the earliest types of endogenous lipid mediators, can inhibit the accumulation of neutrophils, arrest inflammation, and promote the resolution of inflammation. However, research on LXA4 in the nervous system has rarely been carried out. In the present study, we sought to investigate the protective effect of LXA4 on HI brain damage in neonatal rats, as well as the underlying mechanisms. Through experiments conducted using an HI animal model, we found that the LXA4 intervention promoted the recovery of neuronal function and tissue structure following brain injury while maintaining the integrity of the blood-brain barrier in addition to reducing cerebral edema, infarct volume, and inflammatory responses. Our results suggest that LXA4 interfered with neuronal oxygen-glucose deprivation insults, reduced the expression of inflammatory factors, inhibited apoptosis, and promoted neuronal survival in vitro. Finally, the LXA4 intervention attenuated HI-induced activation of inhibitor kappa B (IκB) and degradation of nuclear factor-κB (NF-κB). In conclusion, our data suggest that LXA4 exerts a neuroprotective effect against neonatal HI brain damage through the IκB/NF-κB pathway. Our findings will help inform future studies regarding the effects of LXA4 on neuroinflammation, blood-brain barrier integrity, and neuronal apoptosis.

Stem cell-based interventions for the prevention of morbidity and mortality following hypoxic-ischaemic encephalopathy in newborn infants

BACKGROUND

Hypoxic-ischaemic encephalopathy (HIE) is a leading cause of mortality and long-term neurological sequelae, affecting thousands of children worldwide. Current therapies to treat HIE are limited to cooling. Stem cell-based therapies offer a potential therapeutic approach to repair or regenerate injured brain tissue. These preclinical findings have now culminated in ongoing human neonatal trials.

OBJECTIVES

To determine the efficacy and safety of stem cell-based interventions for the treatment of hypoxic-ischaemic encephalopathy (HIE) in newborn infants.

SEARCH METHODS

We used the standard search strategy of Cochrane Neonatal to search the Cochrane Central Register of Controlled Trials (CENTRAL; 2020, Issue 5), MEDLINE via PubMed (1966 to 8 June 2020), Embase (1980 to 8 June 2020), and CINAHL (1982 to 8 June 2020). We also searched clinical trials databases, conference proceedings, and the reference lists of retrieved articles for randomised controlled trials and quasi-randomised trials.

SELECTION CRITERIA

Randomised controlled trials, quasi-randomised controlled trials and cluster trials comparing 1) stem cell-based interventions (any type) compared to control (placebo or no treatment); 2) use of mesenchymal stem/stromal cells (MSCs) of type (e.g. number of doses or passages) or source (e.g. autologous versus allogeneic, or bone marrow versus cord) versus MSCs of other type or source; 3) use of stem cell-based interventions other than MSCs of type (e.g. mononuclear cells, oligodendrocyte progenitor cells, neural stem cells, hematopoietic stem cells, and inducible pluripotent stem cells) or source (e.g. autologous versus allogeneic, or bone marrow versus cord) versus stem cell-based interventions other than MSCs of other type or source; or 4) MSCs versus stem cell-based interventions other than MSCs.

DATA COLLECTION AND ANALYSIS

For each of the included trials, two authors independently planned to extract data (e.g. number of participants, birth weight, gestational age, type and source of MSCs or other stem cell-based interventions) and assess the risk of bias (e.g. adequacy of randomisation, blinding, completeness of follow-up). The primary outcomes considered in this review are all-cause neonatal mortality, major neurodevelopmental disability, death or major neurodevelopmental disability assessed at 18 to 24 months of age. We planned to use the GRADE approach to assess the quality of evidence.

MAIN RESULTS

Our search strategy yielded 616 references. Two review authors independently assessed all references for inclusion. We did not find any completed studies for inclusion. Fifteen RCTs are currently registered and ongoing. We describe the three studies we excluded.

AUTHORS' CONCLUSIONS

There is currently no evidence from randomised trials that assesses the benefit or harms of stem cell-based interventions for the prevention of morbidity and mortality following hypoxic-ischaemic encephalopathy in newborn infants.

Multiple doses of umbilical cord blood cells improve long-term brain injury in the neonatal rat

BACKGROUND

Hypoxic ischemic (HI) insults during pregnancy and birth can result in neurodevelopmental disorders, such as cerebral palsy. We have previously shown that a single dose of umbilical cord blood (UCB) cells is effective at reducing short-term neuroinflammation and improves short and long-term behavioural outcomes in rat pups. A single dose of UCB was not able to modulate long-term neuroinflammation or brain tissue loss. In this study we examined whether multiple doses of UCB can modulate neuroinflammation, decrease cerebral tissue damage and improve behavioural outcomes when followed up long-term.

METHODS

HI injury was induced in postnatal day 10 (PND10) rat pups using the Rice-Vannucci method of carotid artery ligation. Pups received either 1 dose (PND11), or 3 doses (PND11, 13, 20) of UCB cells. Rats were followed with behavioural testing, to assess both motor and cognitive outcomes. On PND50, brains were collected for analysis.

RESULTS

HI brain injury in rat pups caused significant behavioural deficits. These deficits were significantly improved by multiple doses of UCB. HI injury resulted in a significant decrease in brain weight and left hemisphere tissue, which was improved by multiple doses of UCB. HI resulted in increased cerebral apoptosis, loss of neurons and upregulation of activated microglia. Multiple doses of UCB modulated these neuropathologies. A single dose of UCB at PND11 did not improve behavioural or neuropathological outcomes.

CONCLUSIONS

Treatment with repeated doses of UCB is more effective than a single dose for reducing tissue damage, improving brain pathology and restoring behavioural deficits following perinatal brain injury.

The Development of Stem Cell-Based Treatment for Acute Ischemic Cerebral Injury

Acute ischemic brain injury is a serious disease that severely endangers the life safety of patients. Such disease is hard to predict and highly lethal with very limited effective treatments currently. Although currently, there exist treatments like drug therapy, hyperbaric oxygen therapy, rehabilitation therapy and other treatments in clinical practice, these are not significantly effective for patients when the situation is severe. Thus scientists must explore more effective treatments. Stem cells are undifferentiated cells with a strong potential of self-renewal and differentiate into various types of tissues and organs. Their emergence has brought new hopes for overcoming difficult diseases, further improving medical technology and promoting the development of modern medicine. Some combining therapies and genetically modified stem cell therapy have also been proven to produce obvious neuroprotective function for acute ischemic brain injury. This review is an introduction to the current research findings and discusses the definition, origin and classification of stem cells, as well as the future prospects of the stem cell-based treatment for acute ischemic cerebral injury.

Stem cell therapy for preventing neonatal diseases in the 21st century: Current understanding and challenges

Diseases of the preterm newborn such as bronchopulmonary dysplasia, necrotizing enterocolitis, cerebral palsy, and hypoxic-ischemic encephalopathy continue to be major causes of infant mortality and long-term morbidity. Effective therapies for the prevention or treatment for these conditions are still lacking as recent clinical trials have shown modest or no benefit. Stem cell therapy is rapidly emerging as a novel therapeutic tool for several neonatal diseases with encouraging pre-clinical results that hold promise for clinical translation. However, there are a number of unanswered questions and facets to the development of stem cell therapy as a clinical intervention. There is much work to be done to fully elucidate the mechanisms by which stem cell therapy is effective (e.g., anti-inflammatory versus pro-angiogenic), identifying important paracrine mediators, and determining the timing and type of therapy (e.g., cellular versus secretomes), as well as patient characteristics that are ideal. Importantly, the interaction between stem cell therapy and current, standard-of-care interventions is nearly completely unknown. In this review, we will focus predominantly on the use of mesenchymal stromal cells for neonatal diseases, highlighting the promises and challenges in clinical translation towards preventing neonatal diseases in the 21st century.

FGF21 promotes functional recovery after hypoxic-ischemic brain injury in neonatal rats by activating the PI3K/Akt signaling pathway via FGFR1/β-klotho

Perinatal asphyxia often results in neonatal cerebral hypoxia-ischemia (HI), which is associated with high mortality and severe long-term neurological deficits in newborns. Currently, there are no effective drugs to mitigate the functional impairments post-HI. Previous studies have shown that fibroblast growth factor 21 (FGF21) has a potential neuroprotective effect against brain injury. However, the effect of FGF21 on neonatal HI brain injury is unclear. In the present study, both in vivo and in vitro models were used to assess whether recombinant human FGF21 (rhFGF21) could exert a neuroprotective effect after HI and explore the associated mechanism. The results showed that the rhFGF21 treatment remarkably reduced the infarct volume, ameliorated the body weight and improved the tissue structure after HI in neonatal rats. In addition, the rhFGF21 treatment lengthened the running endurance times in the rotarod test and decreased the mean escape latencies and increased the number of platform crossings in the Morris water maze test at 21 d post-HI insult. In contrast, the FGFR1 inhibitor PD173074 and PI3K inhibitor LY294002 partially reversed these therapeutic effects. In isolated primary cortical neurons, the rhFGF21 treatment protected primary neurons from oxygen-glucose deprivation (OGD) insult by inhibiting neuronal apoptosis and promoting neuronal survival. Both our in vivo and in vitro results reveal that rhFGF21 could inhibit neuronal apoptosis by activating the PI3K/Akt signaling pathway via FGF21/FGFR1/β-klotho complex formation. Therefore, rhFGF21 may be a promising therapeutic agent for promoting functional recovery after HI-induced neonatal brain injury.

Endothelial colony-forming cell therapy for heart morphological changes after neonatal high oxygen exposure in rats, a model of complications of prematurity

Very preterm birth is associated with increased cardiovascular diseases and changes in myocardial structure. The current study aimed to investigate the impact of endothelial colony-forming cell (ECFC) treatment on heart morphological changes in the experimental model of neonatal high oxygen (O2 )-induced cardiomyopathy, mimicking prematurity-related conditions. Sprague-Dawley rat pups exposed to 95% O2 or room air (RA) from day 4 (P4) to day 14 (P14) were randomized to receive (jugular vein) exogenous human cord blood ECFC or vehicle at P14 (n = 5 RA-vehicle, n = 8 RA-ECFC, n = 8 O2 -vehicle and n = 7 O2 -ECFC) and the hearts collected at P28. Body and heart weights and heart to body weight ratio did not differ between groups. ECFC treatment prevented the increase in cardiomyocyte surface area in both the left (LV) and right (RV) ventricles of the O2 group (O2 -ECFC vs. O2 -vehicle LV: 121 ± 13 vs. 179 ± 21 μm2 , RV: 118 ± 12 vs. 169 ± 21 μm2 ). In O2 rats, ECFC treatment was also associated with a significant reduction in interstitial fibrosis in both ventricles (O2 -ECFC vs. O2 -vehicle LV: 1.07 ± 0.47 vs. 1.68 ± 0.41% of surface area, RV: 1.01 ± 0.74 vs. 1.77 ± 0.67%) and in perivascular fibrosis in the LV (2.29 ± 0.47 vs. 3.85 ± 1.23%) but in not the RV (1.95 ± 0.95 vs. 2.74 ± 1.14), and with increased expression of angiogenesis marker CD31. ECFC treatment had no effect on cardiomyocyte surface area or on tissue fibrosis of RA rats. Human cord blood ECFC treatment prevented cardiomyocyte hypertrophy and myocardial and perivascular fibrosis observed after neonatal high O2 exposure. ECFC could constitute a new regenerative therapy against cardiac sequelae caused by deleterious conditions of prematurity.

Building Blood Vessels with Vascular Progenitor Cells

Vascular progenitor cells have been identified from perivascular cell fractions and peripheral blood and bone marrow mononuclear fractions. These vascular progenitors share the ability to generate some of the vascular lineages, including endothelial cells, smooth muscle cells, and pericytes. The potential therapeutic uses for vascular progenitor cells are broad and relate to stroke, ischemic disease, and to the engineering of whole organs and tissues that require a vascular component. This review summarizes the best-characterized sources of vascular progenitor cells and discusses advances in 3D printing and electrospinning using blended polymers for the creation of biomimetic vascular grafts. These advances are pushing the field of regenerative medicine closer to the creation of small-diameter vascular grafts with long-term clinical utility.