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

Neuroprotection for neonatal hypoxic-ischemic encephalopathy: A review of novel therapies evaluated in clinical studies

Therapeutic hypothermia is an effective therapy for moderate-to-severe hypoxic-ischemic encephalopathy (HIE) in infants born at term or near-term in high-resource settings. Yet there remains a substantial proportion of infants who do not benefit or who will have significant disability despite therapeutic hypothermia. Novel investigational therapies that may confer additional neuroprotection by targeting known pathogenic mechanisms of hypoxic-ischemic brain injury are under development. This review focuses on putative neuroprotective agents that have shown promise in animal models of HIE, and that have been translated to clinical studies in neonates with HIE. We include agents that have been studied both with and without concurrent therapeutic hypothermia. Our review therefore addresses not just neonatal HIE in high-resource countries where therapeutic hypothermia is the standard of care, but also neonatal HIE in low- and middle-income countries where therapeutic hypothermia has been shown to be ineffective, and where the greatest burden of HIE-related morbidity and mortality exists.

Hypoxic Preconditioning Enhances the Potential of Mesenchymal Stem Cells to Treat Neonatal Hypoxic-Ischemic Brain Injury

BACKGROUND

Neonatal hypoxic-ischemic (HI) brain injury is one of the leading causes of long-term neurological morbidity in newborns. Current treatment options for HI brain injury are limited, but mesenchymal stem cell (MSC) therapy is a promising strategy to boost neuroregeneration after injury. Optimization strategies to further enhance the potential of MSCs are under development. The current study aimed to test the potency of hypoxic preconditioning of MSCs to enhance the therapeutic efficacy in a mouse model of neonatal HI injury.

METHODS

HI was induced on postnatal day 9 in C57Bl/6 mouse pups. MSCs were cultured under hypoxic (hypoxic-preconditioned MSCs [HP-MSCs], 1% O2) or normoxic-control (normoxic-preconditioned MSCs, 21% O2) conditions for 24 hours before use. At 10 days after HI, HP-MSCs, normoxic-preconditioned MSCs, or vehicle were intranasally administered. Gold nanoparticle-labeled MSCs were used to assess MSC migration 24 hours after intranasal administration. At 28 days post-HI, lesion size, sensorimotor outcome, and neuroinflammation were assessed by hematoxylin and eosin staining, cylinder rearing task, and IBA1 staining, respectively. In vitro, the effect of HP-MSCs was studied on transwell migration, neural stem cell differentiation and microglia activation, and the MSC intracellular proteomic content was profiled using quantitative LC-MS/ms.

RESULTS

Intranasally administered HP-MSCs were superior to normoxic-preconditioned MSCs in reducing lesion size and sensorimotor impairments post-HI. Moreover, hypoxic preconditioning enhanced MSC migration in an in vitro set-up, and in vivo to the lesioned hemisphere after intranasal application. In addition, HP-MSCs enhanced neural stem cell differentiation into more complex neurons in vitro but had similar anti-inflammatory effects compared with normoxic-preconditioned MSCs. Lastly, hypoxic preconditioning led to elevated abundances of proteins in MSCs related to extracellular matrix remodeling.

CONCLUSIONS

This study shows for the first time that hypoxic preconditioning enhanced the therapeutic efficacy of MSC therapy in a mouse model of neonatal HI brain injury by increasing the migratory and neuroregenerative capacity of MSCs.

Transplanted deep-layer cortical neuroblasts integrate into host neural circuits and alleviate motor defects in hypoxic-ischemic encephalopathy injured mice

BACKGROUND

Hypoxic-ischemic encephalopathy (HIE) is a major cause of neonatal disability and mortality. Although intensive studies and therapeutic approaches, there are limited restorative treatments till now. Human embryonic stem cell (hESCs)-derived cortical neural progenitors have shown great potentials in ischemic stroke in adult brain. However, it is unclear whether they are feasible for cortical reconstruction in immature brain with hypoxic-ischemic encephalopathy.

METHODS

By using embryonic body (EB) neural differentiation method combined with DAPT pre-treatment and quantitative cell transplantation, human cortical neuroblasts were obtained and transplanted into the cortex of hypoxic-ischemic injured brain with different dosages 2 weeks after surgery. Then, immunostaining, whole-cell patch clamp recordings and behavioral testing were applied to explore the graft survival and proliferation, fate commitment of cortical neuroblasts in vitro, neural circuit reconstruction and the therapeutic effects of cortical neuroblasts in HIE brain.

RESULTS

Transplantation of human cortical neural progenitor cells (hCNPs) in HIE-injured cortex exhibited long-term graft overgrowth. DAPT pre-treatment successfully synchronized hCNPs from different developmental stages (day 17, day 21, day 28) to deep layer cortical neuroblasts which survived well in HIE injured brain and greatly prevented graft overgrowth after transplantation. Importantly, the cortical neuroblasts primarily differentiated into deep-layer cortical neurons and extended long axons to their projection targets, such as the cortex, striatum, thalamus, and internal capsule in both ipsilateral and contralateral HIE-injured brain. The transplanted cortical neurons established synapses with host cortical neurons and exhibited spontaneous excitatory or inhibitory post-synaptic currents (sEPSCs or sIPSCs) five months post-transplantation. Rotarod and open field tests showed greatly improved animal behavior by intra-cortex transplantation of deep layer cortical neuroblasts in HIE injured brain.

CONCLUSIONS

Transplanted hESCs derived cortical neuroblasts survive, project to endogenous targets, and integrate into host cortical neural circuits to rescue animal behavior in the HIE-injured brain without graft overgrowth, providing a novel and safe cell replacement strategy for the future treatment of HIE.

Protopine Exerts Neuroprotective Effects on Neonatal Hypoxic-Ischemic Brain Damage in Rats via Activation of the AMPK/PGC1α Pathway

Introduction

Neonatal hypoxic-ischemic encephalopathy (HIE), caused by perinatal asphyxia, is characterized by high morbidity and mortality, but there are still no effective therapeutic drugs. Mitochondrial biogenesis and apoptosis play key roles in the pathogenesis of HIE. Protopine (Pro), an isoquinoline alkaloid, has anti-apoptotic and neuro-protective effects. However, the protective roles of Pro on neonatal hypoxic-ischemic brain injury remain unclear.

Methods

In this study, we established a CoCl2-induced PC12 cell model in vitro and a neonatal rat hypoxic-ischemic (HI) brain damage model in vivo to explore the neuro-protective effects of Pro and try to elucidate the potential mechanisms.

Results

Our results showed that Pro significantly reduced cerebral infarct volume, alleviated brain edema, inhibited glia activation, improved mitochondrial biogenesis, relieved neuron cell loss, decreased cell apoptosis and reactive oxygen species (ROS) after HI damage. In addition, Pro intervention upregulated the levels of p-AMPK/AMPK and PGC1α as well as the downstream mitochondrial biogenesis related factors, such as nuclear respiratory factor 1 (NRF1) and mitochondrial transcription factor A (TFAM), but the AMPK inhibitor compound c (CC) could significantly reverse these effects of Pro.

Discussion

Pro may exert neuroprotective effects on neonatal hypoxic-ischemic brain damage via activation of the AMPK/PGC1α pathway, suggesting that Pro may be a promising therapeutic candidate for HIE, and our study firstly demonstrate the neuro-protective roles of Pro in HIE models.

Neonatal encephalopathy due to suspected hypoxic ischemic encephalopathy: pathophysiology, current, and emerging treatments

BACKGROUND

Neonatal encephalopathy (NE) due to suspected hypoxic-ischemic encephalopathy (HIE), referred to as NESHIE, is a clinical diagnosis in late preterm and term newborns. It occurs as a result of impaired cerebral blood flow and oxygen delivery during the peripartum period and is used until other causes of NE have been discounted and HIE is confirmed. Therapeutic hypothermia (TH) is the only evidence-based and clinically approved treatment modality for HIE. However, the limited efficacy and uncertain benefits of TH in some low- to middle-income countries (LMICs) and the associated need for intensive monitoring have prompted investigations into more accessible and effective stand-alone or additive treatment options.

DATA SOURCES

This review describes the rationale and current evidence for alternative treatments in the context of the pathophysiology of HIE based on literatures from Pubmed and other online sources of published data.

RESULTS

The underlining mechanisms of neurotoxic effect, current clinically approved treatment, various categories of emerging treatments and clinical trials for NE are summarized in this review. Melatonin, caffeine citrate, autologous cord blood stem cells, Epoetin alfa and Allopurinal are being tested as potential neuroprotective agents currently.

CONCLUSION

This review describes the rationale and current evidence for alternative treatments in the context of the pathophysiology of HIE. Neuroprotective agents are currently only being investigated in high- and middle-income settings. Results from these trials will need to be interpreted and validated in LMIC settings. The focus of future research should therefore be on the development of inexpensive, accessible monotherapies and should include LMICs, where the highest burden of NESHIE exists.

Improving the future of clinical trials and translation of mesenchymal stromal cell therapies for neonatal disorders

Despite recent advances in neonatal intensive care medicine, neonatal disorders such as (bronchopulmonary dysplasia [BPD], intraventricular hemorrhage [IVH], and hypoxic ischemic encephalopathy [HIE]) remain major causes of death and morbidity in survivors, with few effective treatments being available. Recent preclinical studies have demonstrated the pleiotropic host injury-responsive paracrine protective effects of cell therapy especially with mesenchymal stromal cells (MSCs) against BPD, IVH, and HIE. These findings suggest that MSCs therapy might emerge as a novel therapeutic modality for these currently devastating neonatal disorders with complex multifactorial etiologies. Although early-phase clinical trials suggest their safety and feasibility, their clinical therapeutic benefits have not yet been proven. Therefore, based on currently available preclinical research and clinical trial data, we focus on critical issues that need to be addressed for future successful clinical trials and eventual clinical translation such as selecting the right patient and optimal cell type, route, dose, and timing of MSCs therapy for neonatal disorders such as BPD, HIE, and IVH.

2,3-Diphosphoglyceric Acid Alleviating Hypoxic-Ischemic Brain Damage through p38 MAPK Modulation

Neonatal hypoxic-ischemic encephalopathy (HIE) is a critical condition characterized by significant brain damage due to insufficient blood flow and oxygen delivery at birth, leading to high rates of neonatal mortality and long-term neurological deficits worldwide. 2,3-Diphosphoglyceric acid (2,3-DPG), a small molecule metabolite prevalent in erythrocytes, plays an important role in regulating oxygen delivery, but its potential neuroprotective role in hypoxic-ischemic brain damage (HIBD) has yet to be fully elucidated. Our research reveals that the administration of 2,3-DPG effectively reduces neuron damage caused by hypoxia-ischemia (HI) both in vitro and in vivo. We observed a notable decrease in HI-induced neuronal cell apoptosis, attributed to the downregulation of Bax and cleaved-caspase 3, alongside an upregulation of Bcl-2 expression. Furthermore, 2,3-DPG significantly alleviates oxidative stress and mitochondrial damage induced by oxygen-glucose deprivation/reperfusion (OGD/R). The administration of 2,3-DPG in rats subjected to HIBD resulted in a marked reduction in brain edema and infarct volume, achieved through the suppression of neuronal apoptosis and neuroinflammation. Using RNA-seq analysis, we validated that 2,3-DPG offers protection against neuronal apoptosis under HI conditions by modulating the p38 MAPK pathway. These insights indicated that 2,3-DPG might act as a promising novel therapeutic candidate for HIE.

Advances in Cerebral Palsy Treatment

Background:

Cerebral palsy is a complex neurodevelopmental disorder with various etiological factors and treatment options. This narrative review aimed to summarize the causes of cerebral palsy, identify areas needing additional research in treatment approaches, and highlight areas requiring further investigation. In order to provide a thorough overview of management techniques to lessen the effects of the illness and its consequences, this review has drawn data from a number of studies.

Introduction:

Prematurity increases the risk of brain damage during the developing stage and accounts for a sizable fraction of cerebral palsy cases. In a sizable portion of cases, maternal diabetes and hypertension are listed as the main causes. Damage to the brain tissue results from hypoxic-ischemic injuries sustained during pregnancy that upset the equilibrium of oxidants and antioxidants. To alter the oxidative stress pathway and ease related issues, pharmacological treatments, such as therapeutic hypothermia, free radical inhibition therapy, and mitochondrial therapy, have been proposed. Therapeutic strategies, such as physiotherapy, occupational therapy, speech therapy, and surgical interventions, have added quality to the lives of the children. Some of the most recent developments in this area include the development of biomarkers for muscle activity detection, machine learning to predict the types of cerebral palsy and abnormal movements, disease prediction with eye images, wireless inertia measuring unit for spasticity detection, computerbased video analysis of typical and atypical infants, identification of intellectual disabilities with algorithms, and deep learning methods for predicting cerebral palsy.

Methods:

This narrative review is based on a careful analysis of numerous researches conducted on cerebral palsy, which have served as the basis for statistical distribution. It reviews the causes of cerebral palsy, available treatments, and ongoing research with the goal of providing physicians and researchers in the field with useful information. The objectives, study questions, inclusion criteria, and search approach have all been outlined in a thorough protocol. To find pertinent research published up to September 2021, a literature search was carried out using electronic databases, including Google Scholar, PubMed, Cochrane Library, Scopus, and Web of Science. A combination of pertinent keywords, such as "cerebral palsy," "management," "technology," "wearable technology," "prematurity," and "artificial intelligence," has been used in the search approach.

Results:

Recent advances in the field include the discovery of biomarkers for the detection of muscle activity, machine learning algorithms to predict the types of cerebral palsy and abnormal movements, disease prediction using eye images, wireless inertia measuring units for the detection of spasticity, computer-based video analysis for the detection of atypical infants, and algorithms to identify intellectual disabilities. Additionally, employing technologies, like virtual reality systems, electrical stimulators, activity trackers, machine learning, and deep learning approaches, has shown promise in evaluating, diagnosing, and predicting treatment outcomes linked to gait, upper limb, and lower limb function.

Conclusion:

Future research should examine the clinical application of nanomedicine, stem cell therapy, and cutting-edge therapeutic strategies to prevent hypoxic-ischemic damage in the developing brain. Additionally, research is required to effectively assist children with severe speech difficulties using alternate communication modalities and cutting-edge computational tools. The outcomes for people with cerebral palsy can be improved by combining interdisciplinary efforts with cutting-edge technological interventions.

Mesenchymal Stromal Cell therapy for Hypoxic Ischemic Encephalopathy: Future directions for combination therapy with hypothermia and/or melatonin

Hypoxic ischemic encephalopathy (HIE) remains a leading cause of neonatal mortality and lifelong disability across the world. While therapeutic hypothermia (HT) is beneficial, it is only partially protective and adjuvant treatments that further improve outcomes are urgently needed. In high-income countries where HT is standard care, novel treatments are tested in conjunction with HT. Mesenchymal stromal cells (MSC) represent a paradigm shift in brain protection, uniquely adapting to the host cellular microenvironment. MSC have low immunogenicity and potent paracrine effects stimulating the host tissue repair and regeneration and reducing inflammation and apoptosis. Preclinical studies in perinatal brain injury suggest that MSC are beneficial after hypoxia-ischemia (HI) and most preclinical studies of MSC with HT show protection. Preclinical and early phase clinical trials have shown that allogenic administration of MSC to neonates with perinatal stroke and HIE is safe and feasible but further safety and efficacy studies of HT with MSC in these populations are needed. Combination therapies that target all stages of the evolution of injury after HI (eg HT, melatonin and MSC) show promise for improving outcomes in HIE.

Dietary LPC-Bound n-3 LCPUFA Protects against Neonatal Brain Injury in Mice but Does Not Enhance Stem Cell Therapy

Neonatal hypoxic-ischemic (HI) brain injury is a prominent cause of neurological morbidity, urging the development of novel therapies. Interventions with n-3 long-chain polyunsaturated fatty acids (n-3 LCPUFAs) and mesenchymal stem cells (MSCs) provide neuroprotection and neuroregeneration in neonatal HI animal models. While lysophosphatidylcholine (LPC)-bound n-3 LCPUFAs enhance brain incorporation, their effect on HI brain injury remains unstudied. This study investigates the efficacy of oral LPC-n-3 LCPUFAs from Lysoveta following neonatal HI in mice and explores potential additive effects in combination with MSC therapy. HI was induced in 9-day-old C57BL/6 mice and Lysoveta was orally supplemented for 7 subsequent days, with or without intranasal MSCs at 3 days post-HI. At 21-28 days post-HI, functional outcome was determined using cylinder rearing, novel object recognition, and open field tasks, followed by the assessment of gray (MAP2) and white (MBP) matter injury. Oral Lysoveta diminished gray and white matter injury but did not ameliorate functional deficits following HI. Lysoveta did not further enhance the therapeutic potential of MSC therapy. In vitro, Lysoveta protected SH-SY5Y neurons against oxidative stress. In conclusion, short-term oral administration of Lysoveta LPC-n-3 LCPUFAs provides neuroprotection against neonatal HI by mitigating oxidative stress injury but does not augment the efficacy of MSC therapy.

Stem Cell Therapy in Neonatal Hypoxic-Ischemic Encephalopathy and Cerebral Palsy: a Bibliometric Analysis and New Strategy

The aim of this study was to identify related scientific outputs and emerging topics of stem cells in neonatal hypoxic-ischemic encephalopathy (NHIE) and cerebral palsy (CP) through bibliometrics and literature review. All relevant publications on stem cell therapy for NHIE and CP were screened from websites and analyzed research trends. VOSviewer and CiteSpace were applied to visualize and quantitatively analyze the published literature to provide objective presentation and prediction. In addition, the clinical trials, published articles, and projects of the National Natural Science Foundation of China associated with stem cell therapy for NHIE and CP were summarized. A total of 294 publications were associated with stem cell therapy for NHIE and CP. Most publications and citations came from the USA and China. Monash University and University Medical Center Utrecht produced the most publications. Pediatric research published the most studies on stem cell therapy for NHIE and CP. Heijnen C and Kavelaars A published the most articles. Cluster analyses show that current research trend is more inclined toward the repair mechanism and clinical translation of stem cell therapy for NHIE and CP. By summarizing various studies of stem cells in NHIE and CP, it is indicated that this research direction is a hot topic at present. Furthermore, organoid transplantation, as an emerging and new therapeutic approach, brings new hope for the treatment of NHIE and CP. This study comprehensively summarized and analyzed the research trend of global stem cell therapy for NHIE and CP. It has shown a marked increase in stem cell therapy for NHIE and CP research. In the future, more efforts will be made on exploring stem cell or organoid therapy for NHIE and CP and more valuable related mechanisms of action to achieve clinical translation as soon as possible.

Targeting the Multiple Complex Processes of Hypoxia-Ischemia to Achieve Neuroprotection

Hypoxic-ischemic encephalopathy (HIE) is a major cause of newborn brain damage stemming from a lack of oxygenated blood flow in the neonatal period. Twenty-five to fifty percent of asphyxiated infants who develop HIE die in the neonatal period, and about sixty percent of survivors develop long-term neurological disabilities. From the first minutes to months after the injury, a cascade of events occurs, leading to blood-brain barrier (BBB) opening, neuronal death and inflammation. To date, the only approach proposed in some cases is therapeutic hypothermia (TH). Unfortunately, TH is only partially protective and is not applicable to all neonates. This review synthesizes current knowledge on the basic molecular mechanisms of brain damage in hypoxia-ischemia (HI) and on the different therapeutic strategies in HI that have been used and explores a major limitation of unsuccessful therapeutic approaches.

CXCL10 is a crucial chemoattractant for efficient intranasal delivery of mesenchymal stem cells to the neonatal hypoxic-ischemic brain

BACKGROUND

Hypoxic-Ischemic Encephalopathy (HIE) is a leading cause of mortality and morbidity in newborns. Recent research has shown promise in using intranasal mesenchymal stem cell (MSC) therapy if administered within 10 days after Hypoxia-Ischemia (HI) in neonatal mice. MSCs migrate from the nasal cavity to the cerebral lesion in response to chemotactic cues. Which exact chemokines are crucial for MSC guidance to the HI lesion is currently not fully understood. This study investigates the role of CXCL10 in MSC migration towards the HI-injured brain.

METHODS

HI was induced in male and female 9-day-old C57BL/6 mice followed by intranasal MSC treatment at day 10 or 17 post-HI. CXCL10 protein levels, PKH26-labeled MSCs and lesion size were assessed by ELISA, immunofluorescent imaging and MAP2 staining respectively. At day 17 post-HI, when CXCL10 levels were reduced, intracranial CXCL10 injection and intranasal PKH26-labeled MSC administration were combined to assess CXCL10-guided MSC migration. MSC treatment efficacy was evaluated after 18 days, measuring lesion size, motor outcome (cylinder rearing task), glial scarring (GFAP staining) and neuronal density (NeuN staining) around the lesion. Expression of the receptor for CXCL10, i.e. CXCR3, on MSCs was confirmed by qPCR and Western Blot. Moreover, CXCL10-guided MSC migration was assessed through an in vitro transwell migration assay.

RESULTS

Intranasal MSC treatment at day 17 post-HI did not reduce lesion size in contrast to earlier treatment timepoints. Cerebral CXCL10 levels were significantly decreased at 17 days versus 10 days post-HI and correlated with reduced MSC migration towards the brain. In vitro experiments demonstrated that CXCR3 receptor inhibition prevented CXCL10-guided migration of MSCs. Intracranial CXCL10 injection at day 17 post-HI significantly increased the number of MSCs reaching the lesion which was accompanied by repair of the HI lesion as measured by reduced lesion size and glial scarring, and an increased number of neurons around the lesion.

CONCLUSIONS

This study underscores the crucial role of the chemoattractant CXCL10 in guiding MSCs to the HI lesion after intranasal administration. Strategies to enhance CXCR3-mediated migration of MSCs may improve the efficacy of MSC therapy or extend its regenerative therapeutic window.

Neonatal Necrotizing Enterocolitis: An Update on Pathophysiology, Treatment, and Prevention

Necrotizing enterocolitis (NEC) is a life-threatening disease predominantly affecting premature and very low birth weight infants resulting in inflammation and necrosis of the small bowel and colon and potentially leading to sepsis, peritonitis, perforation, and death. Numerous research efforts have been made to better understand, treat, and prevent NEC. This review explores a variety of factors involved in the pathogenesis of NEC (prematurity, low birth weight, lack of human breast milk exposure, alterations to the microbiota, maternal and environmental factors, and intestinal ischemia) and reports treatment modalities surrounding NEC, including pain medications and common antibiotic combinations, the rationale for these combinations, and recent antibiotic stewardship approaches surrounding NEC treatment. This review also highlights the effect of early antibiotic exposure, infections, proton pump inhibitors (PPIs), and H2 receptor antagonists on the microbiota and how these risk factors can increase the chances of NEC. Finally, modern prevention strategies including the use of human breast milk and standardized feeding regimens are discussed, as well as promising new preventative and treatment options for NEC including probiotics and stem cell therapy.

Brain Maturation as a Fundamental Factor in Immune-Neurovascular Interactions in Stroke

Injuries in the developing brain cause significant long-term neurological deficits. Emerging clinical and preclinical data have demonstrated that the pathophysiology of neonatal and childhood stroke share similar mechanisms that regulate brain damage, but also have distinct molecular signatures and cellular pathways. The focus of this review is on two different diseases-neonatal and childhood stroke-with emphasis on similarities and distinctions identified thus far in rodent models of these diseases. This includes the susceptibility of distinct cell types to brain injury with particular emphasis on the role of resident and peripheral immune populations in modulating stroke outcome. Furthermore, we discuss some of the most recent and relevant findings in relation to the immune-neurovascular crosstalk and how the influence of inflammatory mediators is dependent on specific brain maturation stages. Finally, we comment on the current state of treatments geared toward inducing neuroprotection and promoting brain repair after injury and highlight that future prophylactic and therapeutic strategies for stroke should be age-specific and consider gender differences in order to achieve optimal translational success.

Mesenchymal stem cell therapy in perinatal arterial ischemic stroke: systematic review of preclinical studies

BACKGROUND

Perinatal arterial ischemic stroke (PAIS) is a neurologic disorder leading to long-term complications. Mesenchymal stem cells (MSCs) have emerged as a novel therapeutic agent. This systematic review aims to determine the effects of stem cell-based interventions for the treatment of PAIS in preclinical studies.

METHODS

We included all controlled studies on MSCs in neonatal animals with PAIS. Functional outcome was the primary outcome. The literature search was performed in February 2021.

RESULTS

In the 20 included studies, MSCs were most frequently delivered via intracerebral injection (n = 9), 3 days after the induction of PAIS (n = 8), at a dose ranging from 5 × 104 to 5 × 106 cells. The meta-analysis showed an improvement on the cylinder rearing test (MD: -10.62; 95% CI: -14.38 to -6.86) and on the water maze test (MD: 1.31 MD; 95% CI: 0.80 to 1.81) in animals treated with MSCs compared to the control group animals.

CONCLUSION

MSCs appear to improve sensorimotor and cognitive performance in PAIS-injured animals; however, the certainty of the evidence is low. Registration of the protocol of preclinical studies, appropriate sample size calculation, rigorous randomization, and reporting of the data on animal sex and survival are warranted. PROSPERO registration number: CRD42021239642.

IMPACT

This is the first systematic review and meta-analysis of preclinical studies investigating the effects of MSCs in an experimental model of PAIS. MSCs appear to improve sensorimotor and cognitive performance in PAIS-injured neonatal animals. The certainty of the evidence is low due to high or unclear risk of bias in most domains.

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.

Advances in Therapies to Treat Neonatal Hypoxic-Ischemic Encephalopathy

Neonatal hypoxic-ischemic encephalopathy (HIE) is a condition that results in brain damage in newborns due to insufficient blood and oxygen supply during or after birth. HIE is a major cause of neurological disability and mortality in newborns, with over one million neonatal deaths occurring annually worldwide. The severity of brain injury and the outcome of HIE depend on several factors, including the cause of oxygen deprivation, brain maturity, regional blood flow, and maternal health conditions. HIE is classified into mild, moderate, and severe categories based on the extent of brain damage and resulting neurological issues. The pathophysiology of HIE involves different phases, including the primary phase, latent phase, secondary phase, and tertiary phase. The primary and secondary phases are characterized by episodes of energy and cell metabolism failures, increased cytotoxicity and apoptosis, and activated microglia and inflammation in the brain. A tertiary phase occurs if the brain injury persists, characterized by reduced neural plasticity and neuronal loss. Understanding the cellular and molecular aspects of the different phases of HIE is crucial for developing new interventions and therapeutics. This review aims to discuss the pathophysiology of HIE, therapeutic hypothermia (TH), the only approved therapy for HIE, ongoing developments of adjuvants for TH, and potential future drugs for HIE.

A narrative review on treatment strategies for neonatal hypoxic ischemic encephalopathy

Background and Objective

Hypoxic-ischemic encephalopathy (HIE) is a leading cause of death and disability worldwide. Therapeutic hypothermia (TH) represents a significant achievement in the translation of scientific research to clinical application, but it is currently the only neuroprotective treatment for HIE. This review aims to revisit the use of TH for HIE and its longitudinal impact on patient outcomes to readers new to the field of HIE. We discuss how emerging therapies address the broader pathophysiology of injury progression in the neonatal brain days to years after HIE.

Methods

We included full articles and book chapters published in English on PubMed with references to "hypoxic ischemic encephalopathy", "birth asphyxia", "therapeutic hypothermia", or "neonatal encephalopathy". We limited our review to outcomes on term infants and to new therapeutics that are in the second phase of clinical trials.

Key Content and Findings

Despite the use of TH for HIE, mortality remains high. Analysis of longitudinal studies reveals a high incidence of ongoing disability even with the implementation of TH. New therapeutics addressing the secondary phase and the less understood tertiary phase of brain injury are in clinical trials as adjunctive treatments to TH to support additional neurological repair and regeneration.

Conclusions

TH successfully improves outcomes after HIE, and it continues to be optimized. Larger studies are needed to understand its use in mild cases of HIE and if certain factors, such as sex, affect long term outcomes. TH primarily acts in the initial phases of injury, while new pharmaceutical therapies target additional injury pathways into the tertiary phases of injury. This may allow for more effective approaches to treatment and improvement of long-term functional outcomes after HIE.

Barriers in translating stem cell therapies for neonatal diseases

Over the last 20 years, stem cells of varying origin and their associated secretome have been investigated as a therapeutic option for a myriad of neonatal models of disease, with very promising results. Despite the devastating nature of some of these disorders, translation of the preclinical evidence to the bedside has been slow. In this review, we explore the existing clinical evidence for stem cell therapies in neonates, highlight the barriers faced by researchers and suggest potential solutions to move the field forward.

MicroRNA therapeutic targets in neonatal hypoxic-ischemic brain injury: a narrative review

Neonatal hypoxic-ischemic brain injury (HIBI) is a devastating injury resulting from impaired blood flow and oxygen delivery to the brain at or around the time of birth. Despite the use of therapeutic hypothermia, more than one in four survivors suffer from major developmental disabilities-an indication of the critical need for more effective therapies. MicroRNAs (miRNA) have the potential to act as biomarkers and/or therapeutic targets in neonatal HIBI as a step toward improving outcomes in this high-risk population. This review summarizes the current literature around the use of cord blood and postnatal circulating blood miRNA expression for diagnosis or prognosis in human infants with hypoxic-ischemic encephalopathy, as well as animal studies assessing endogenous brain miRNA expression and potential for therapeutic targeting of miRNA expression for neuroprotection. Ultimately, the lack of knowledge regarding brain specificity of circulating miRNAs and the temporal variability in expression currently limit the use of miRNAs as biomarkers. However, given their broad effect profile, ease of administration, and small size allowing for effective blood-brain barrier crossing, miRNAs represent promising therapeutic targets for improving brain injury and reducing developmental impairments in neonates after HIBI. IMPACT: The high morbidity and mortality of neonatal hypoxic-ischemic brain injury (HIBI) despite current therapies demonstrates a need for developing more sensitive biomarkers and superior therapeutic options. MicroRNAs have been evaluated both as biomarkers and therapeutic options after neonatal HIBI. The limited knowledge regarding brain specificity of circulating microRNAs and temporal variability in expression currently limit the use of microRNAs as biomarkers. Future studies comparing the neuroprotective effects of modulating microRNA expression must consider temporal changes in the endogenous expression to determine appropriate timing of therapy, while also optimizing techniques for delivery.

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 combined with neuroprotective adjuvants shortens the duration of hospitalization in infants with hypoxic ischemic encephalopathy: Meta-analysis

Objective: Therapeutic hypothermia (TH) is the current standard of care for neonatal hypoxic-ischemic encephalopathy (HIE), yet morbidity and mortality remain significant. Adjuvant neuroprotective agents have been suggested to augment hypothermic-mediated neuroprotection. This analysis aims to identify the classes of drugs that have been used in combination with hypothermia in the treatment of neonatal HIE and determine whether combination therapy is more efficacious than TH alone. Methods: A systematic search of PubMed, Embase and Medline from conception through December 2022 was conducted. Randomized- and quasi-randomized controlled trials, observational studies and retrospective studies evaluating HIE infants treated with combination therapy versus TH alone were selected. Primary reviewers extracted information on mortality, neurodevelopmental impairment and length of hospitalization for meta-analyses. Effect sizes were pooled using a random-effects model and measured as odds ratio (OR) or mean difference (MD) where applicable, and 95% confidence intervals (CI) were calculated. Risk of bias was assessed using the tool from the Cochrane Handbook for Systematic Reviews of Interventions. Results: The search strategy collected 519 studies, 16 of which met analysis inclusion criteria. HIE infants totaled 1,288 infants from included studies, 646 infants received some form of combination therapy, while 642 received TH alone. GABA receptor agonists, NMDA receptor antagonists, neurogenic and angiogenic agents, stem cells, glucocorticoids and antioxidants were identified as candidate adjuvants to TH that have been evaluated in clinical settings compared to TH alone. Length of hospitalization was significantly reduced in infants treated with combination therapy (MD -4.81, 95% CI [-8.42. to -1.19], p = .009) compared to those treated with TH alone. Risk of mortality and neurodevelopmental impairment did not differ between combination therapy and TH alone groups. Conclusion: Compared to the current standard of care, administration of neuroprotective adjuvants with TH reduced the duration of hospitalization but did not impact the risk of mortality or neurodevelopmental impairment in HIE infants. Meta-analysis was limited by a moderate risk of bias among included studies and small sample sizes. This analysis highlights the need for preclinical trials to conduct drug development studies in hypothermic settings to identify relevant molecular targets that may offer additive or synergistic neuroprotection to TH, and the need for larger powered clinical trials to determine the dose and timing of administration at which maximal clinical benefits are observed for adjuvant neuroprotectants.

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.

Neonatal Hypoxic-Ischemic Encephalopathy: Perspectives of Neuroprotective and Neuroregenerative Treatments

Hypoxic-ischemic encephalopathy (HIE) is a serious condition that could have deleterious neurological outcomes, such as cerebral palsy, neuromotor disability, developmental disability, epilepsy, and sensitive or cognitive problems, and increase the risk of death in severe cases. Once HIE occurs, molecular cascades are triggered favoring the oxidative stress, excitotoxicity, and inflammation damage that promote cell death via apoptosis or necrosis. Currently, the therapeutic hypothermia is the standard of care in HIE; however, it has a small window of action and only can be used in children of more than 36 gestational weeks; for this reason, it is very important to develop new therapies to prevent the progression of the hypoxic-ischemic injury or to develop neuroregenerative therapies in severe HIE cases. The objective of this revision is to describe the emerging treatments for HIE, either preventing cell death for oxidative stress, excitotoxicity, or exacerbated inflammation, as well as describing a new therapeutic approach for neuroregeneration, such as mesenchymal stem cells, brain-derived neurotrophic factor, and gonadotropin realizing hormone agonists.

Stem Cells in Clinical Trials on Neurological Disorders: Trends in Stem Cells Origins, Indications, and Status of the Clinical Trials

Neurological diseases can significantly reduce the quality and duration of life. Stem cells provide a promising solution, not only due to their regenerative features but also for a variety of other functions, including reducing inflammation and promoting angiogenesis. Although only hematopoietic cells have been approved by the FDA so far, the number of trials continues to expand. We analyzed 492 clinical trials and illustrate the trends in stem cells origins, indications, and phase and status of the clinical trials. The most common neurological disorders treated with stem cells were injuries of brain, spinal cord, and peripheral nerves (14%), stroke (13%), multiple sclerosis (12%), and brain tumors (11%). Mesenchymal stem cells dominated (83%) although the choice of stem cells was highly dependent on the neurological disorder. Of the 492 trials, only two trials have reached phase 4, with most of all other trials being in phases 1 or 2, or transitioning between them (83%). Based on a comparison of the obtained results with similar works and further analysis of the literature, we discuss some of the challenges and future directions of stem cell therapies in the treatment of neurological diseases.

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.

Experimental Models for Testing the Efficacy of Pharmacological Treatments for Neonatal Hypoxic-Ischemic Encephalopathy

Representing an important cause of long-term disability, term neonatal hypoxic-ischemic encephalopathy (HIE) urgently needs further research aimed at repurposing existing drug as well as developing new therapeutics. Since various experimental in vitro and in vivo models of HIE have been developed with distinct characteristics, it becomes important to select the appropriate preclinical screening cascade for testing the efficacy of novel pharmacological treatments. As therapeutic hypothermia is already a routine therapy for neonatal encephalopathy, it is essential that hypothermia be administered to the experimental model selected to allow translational testing of novel or repurposed drugs on top of the standard of care. Moreover, a translational approach requires that therapeutic interventions must be initiated after the induction of the insult, and the time window for intervention should be evaluated to translate to real world clinical practice. Hippocampal organotypic slice cultures, in particular, are an invaluable intermediate between simpler cell lines and in vivo models, as they largely maintain structural complexity of the original tissue and can be subjected to transient oxygen-glucose deprivation (OGD) and subsequent reoxygenation to simulate ischemic neuronal injury and reperfusion. Progressing to in vivo models, generally, rodent (mouse and rat) models could offer more flexibility and be more cost-effective for testing the efficacy of pharmacological agents with a dose-response approach. Large animal models, including piglets, sheep, and non-human primates, may be utilized as a third step for more focused and accurate translational studies, including also pharmacokinetic and safety pharmacology assessments. Thus, a preclinical proof of concept of efficacy of an emerging pharmacological treatment should be obtained firstly in vitro, including organotypic models, and, subsequently, in at least two different animal models, also in combination with hypothermia, before initiating clinical trials.

Delivery of Stem Cell Secretome for Therapeutic Applications

Intensive studies on stem cell therapy reveal that benefits of stem cells attribute to the paracrine effects. Hence, direct delivery of stem cell secretome to the injured site shows the comparative therapeutic efficacy of living cells while avoiding the potential limitations. However, conventional systemic administration of stem cell secretome often leads to rapid clearance in vivo. Therefore, a variety of different biomaterials are developed for sustained and controllable delivery of stem cell secretome to improve therapeutic efficiency. In this review, we first introduce current approaches for the preparation and characterization of stem cell secretome as well as strategies to improve their therapeutic efficacy and production. The up-to-date delivery platforms are also summarized, including nanoparticles, injectable hydrogels, microneedles, and scaffold patches. Meanwhile, we discuss the underlying therapeutic mechanism of stem cell secretome for the treatment of various diseases. In the end, future opportunities and challenges are proposed.

New possibilities for neuroprotection in neonatal hypoxic-ischemic encephalopathy

Around 0.75 million babies worldwide suffer from moderate or severe hypoxic-ischemic encephalopathy (HIE) each year resulting in around 400,000 babies with neurodevelopmental impairment. In 2010, neonatal HIE was associated with 2.4% of the total Global Burden of Disease. Therapeutic hypothermia (TH), a treatment that is now standard of care in high-income countries, provides proof of concept that strategies that aim to improve neurodevelopment are not only possible but can also be implemented to clinical practice. While TH is beneficial, neonates with moderate or severe HIE treated with TH still experience devastating complications: 48% (range: 44-53) combined death or moderate/severe disability. There is a concern that TH may not be effective in low- and middle-income countries. Therapies that further improve outcomes are desperately needed, and in high-income countries, they must be tested in conjunction with TH. We have in this review focussed on pharmacological treatment options (e.g. erythropoietin, allopurinol, melatonin, cannabidiol, exendin-4/exenatide). Erythropoietin and allopurinol show promise and are progressing towards the clinic with ongoing definitive phase 3 randomised placebo-controlled trials. However, there remain global challenges for the next decade. Conclusion: There is a need for more optimal animal models, greater industry support/sponsorship, increased use of juvenile toxicology, dose-ranging studies with pharmacokinetic-pharmacodynamic modelling, and well-designed clinical trials to avoid exposure to harmful medications or abandoning putative treatments. What is Known: • Therapeutic hypothermia is beneficial in neonatal hypoxic-ischemic encephalopathy. • Neonates with moderate or severe hypoxic-ischemic encephalopathy treated with therapeutic hypothermia still experience severe sequelae. What is New: • Erythropoietin, allopurinol, melatonin, cannabidiol, and exendin-4/exenatide show promise in conjunction with therapeutic hypothermia. • There is a need for more optimal animal models, greater industry support/sponsorship, increased use of juvenile toxicology, dose-ranging studies with pharmacokinetic-pharmacodynamic modelling, and well-designed clinical trials.

Childhood stroke

Stroke is an important cause of neurological morbidity in children; most survivors have permanent neurological deficits that affect the remainder of their life. Stroke in childhood, the focus of this Primer, is distinguished from perinatal stroke, defined as stroke before 29 days of age, because of its unique pathogenesis reflecting the maternal-fetal unit. Although approximately 15% of strokes in adults are haemorrhagic, half of incident strokes in children are haemorrhagic and half are ischaemic. The causes of childhood stroke are distinct from those in adults. Urgent brain imaging is essential to confirm the stroke diagnosis and guide decisions about hyperacute therapies. Secondary stroke prevention strongly depends on the underlying aetiology. While the past decade has seen substantial advances in paediatric stroke research, the quality of evidence for interventions, such as the rapid reperfusion therapies that have revolutionized arterial ischaemic stroke care in adults, remains low. Substantial time delays in diagnosis and treatment continue to challenge best possible care. Effective primary stroke prevention strategies in children with sickle cell disease represent a major success, yet barriers to implementation persist. The multidisciplinary members of the International Pediatric Stroke Organization are coordinating global efforts to tackle these challenges and improve the outcomes in children with cerebrovascular disease.

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.

Microglia and Stem-Cell Mediated Neuroprotection after Neonatal Hypoxia-Ischemia

Neonatal hypoxia-ischemia encephalopathy (HIE) refers to a brain injury in term infants that can lead to death or lifelong neurological deficits such as cerebral palsy (CP). The pathogenesis of this disease involves multiple cellular and molecular events, notably a neuroinflammatory response driven partly by microglia, the brain resident macrophages. Treatment options are currently very limited, but stem cell (SC) therapy holds promise, as beneficial outcomes are reported in animal studies and to a lesser degree in human trials. Among putative mechanisms of action, immunomodulation is considered a major contributor to SC associated benefits. The goal of this review is to examine whether microglia is a cellular target of SC-mediated immunomodulation and whether the recruitment of microglia is linked to brain repair. We will first provide an overview on microglial activation in the rodent model of neonatal HI, and highlight its sensitivity to developmental age. Two complementary questions are then addressed: (i) do immune-related treatments impact microglia and provide neuroprotection, (ii) does stem cell treatment modulates microglia? Finally, the immune-related findings in patients enrolled in SC based clinical trials are discussed. Our review points to an impact of SCs on the microglial phenotype, but heterogeneity in experimental designs and methodological limitations hamper our understanding of a potential contribution of microglia to SC associated benefits. Thorough analyses of the microglial phenotype are warranted to better address the relevance of the neuroimmune crosstalk in brain repair and improve or advance the development of SC protocols in humans.

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.

Therapeutic Potential of Astrocyte Transplantation

Cell transplantation is an attractive treatment strategy for a variety of brain disorders, as it promises to replenish lost functions and rejuvenate the brain. In particular, transplantation of astrocytes has come into light recently as a therapy for amyotrophic lateral sclerosis (ALS); moreover, grafting of astrocytes also showed positive results in models of other conditions ranging from neurodegenerative diseases of older age to traumatic injury and stroke. Despite clear differences in etiology, disorders such as ALS, Parkinson's, Alzheimer's, and Huntington's diseases, as well as traumatic injury and stroke, converge on a number of underlying astrocytic abnormalities, which include inflammatory changes, mitochondrial damage, calcium signaling disturbance, hemichannel opening, and loss of glutamate transporters. In this review, we examine these convergent pathways leading to astrocyte dysfunction, and explore the existing evidence for a therapeutic potential of transplantation of healthy astrocytes in various models. Existing literature presents a wide variety of methods to generate astrocytes, or relevant precursor cells, for subsequent transplantation, while described outcomes of this type of treatment also differ between studies. We take technical differences between methodologies into account to understand the variability of therapeutic benefits, or lack thereof, at a deeper level. We conclude by discussing some key requirements of an astrocyte graft that would be most suitable for clinical applications.

Ambient Temperature Is Correlated With the Severity of Neonatal Hypoxic-Ischemic Brain Injury via Microglial Accumulation in Mice

BACKGROUND

The pathophysiology of neonatal hypoxic-ischemic encephalopathy (HIE) has been studied in several rodent models to develop novel treatments. Although it is well known that high ambient temperature results in severe HIE, the effect of subtle changes in ambient temperature during a hypoxic-ischemic (HI) insult has not been studied. Therefore, in order to clarify the difference of pathophysiological change among the HIE models due to the influence of small changes in chamber temperature, three-step gradual change of 0.5°C each were prepared in ambient temperature during hypoxic exposure.

METHODS

Blood flow in the left common carotid artery (CCA) of neonatal mice was interrupted using bipolar electronic forceps under general and local anesthesia. The mice were subsequently subjected to 10% hypoxic exposure for 50 min at 36.0, 36.5, or 37.0°C. A control group was also included in the study. The size of the striatum and hippocampus and the volume reduction rate of the hemisphere in the section containing them on the ischemic side were evaluated using microtubule associated protein 2 (MAP2) immunostaining. The accumulation of Iba1-positive cells was investigated to assess inflammation. Additionally, rotarod and open-field tests were performed 2 weeks after HI insult to assess its effect on physiological conditions.

RESULTS

MAP2 staining revealed that the higher the temperature during hypoxia, the more severe the volume reduction rate in the hemisphere, striatum, and hippocampus. The number of Iba1-positive cells in the ipsilateral lesion gradually increased with increasing temperature, and there was a significant difference in motor function in the 36.5 and 37.0°C groups compared with the sham group. In the open-field tests, there was a significant decrease in performance in the 37.0°C groups compared with the 36.0°C and sham groups.

CONCLUSIONS

Even a small gradual change of 0.5°C produced a significant difference in pathological and behavioral changes and contributed to the accumulation of Iba1-positive cells. The arrangement of ambient temperature is useful for creating a rodent model with the appropriate severity of the targeted neuropsychological symptoms to establish a novel therapy for HIE.

Neuroprotection and Axonal Regeneration Induced by Bone Marrow Mesenchymal Stromal Cells Depend on the Type of Transplant

Mesenchymal stromal cell (MSC) therapy to treat neurodegenerative diseases has not been as successful as expected in some preclinical studies. Because preclinical research is so diverse, it is difficult to know whether the therapeutic outcome is due to the cell type, the type of transplant or the model of disease. Our aim here was to analyze the effect of the type of transplant on neuroprotection and axonal regeneration, so we tested MSCs from the same niche in the same model of neurodegeneration in the three transplantation settings: xenogeneic, syngeneic and allogeneic. For this, bone marrow mesenchymal stromal cells (BM-MSCs) isolated from healthy human volunteers or C57/BL6 mice were injected into the vitreous body of C57/BL6 mice (xenograft and syngraft) or BALB/c mice (allograft) right after optic nerve axotomy. As controls, vehicle matched groups were done. Retinal anatomy and function were analyzed in vivo by optical coherence tomography and electroretinogram, respectively. Survival of vision forming (Brn3a⁺) and non-vision forming (melanopsin⁺) retinal ganglion cells (RGCs) was assessed at 3, 5 and 90 days after the lesion. Regenerative axons were visualized by cholera toxin β anterograde transport. Our data show that grafted BM-MSCs did not integrate in the retina but formed a mesh on top of the ganglion cell layer. The xenotransplant caused retinal edema, detachment and folding, and a significant decrease of functionality compared to the murine transplants. RGC survival and axonal regeneration were significantly higher in the syngrafted retinas than in the other two groups or vehicle controls. Melanopsin⁺RGCs, but not Brn3a⁺RGCs, were also neuroprotected by the xenograft. In conclusion, the type of transplant has an impact on the therapeutic effect of BM-MSCs affecting not only neuronal survival but also the host tissue response. Our data indicate that syngrafts may be more beneficial than allografts and, interestingly, that the type of neuron that is rescued also plays a significant role in the successfulness of the cell therapy.

Mitochondrial dysfunction in perinatal asphyxia: role in pathogenesis and potential therapeutic interventions

Perinatal asphyxia (PA)-induced brain injury may present as hypoxic-ischemic encephalopathy in the neonatal period, and long-term sequelae such as spastic motor deficits, intellectual disability, seizure disorders and learning disabilities. The brain injury is secondary to both the hypoxic-ischemic event and oxygenation-reperfusion following resuscitation. Following PA, a time-dependent progression of neuronal insult takes place in terms of transition of cell death from necrosis to apoptosis. This transition is the result of time-dependent progression of pathomechanisms which involve excitotoxicity, oxidative stress, and ultimately mitochondrial dysfunction in developing brain. More precisely mitochondrial respiration is suppressed and calcium signalling is dysregulated. Consequently, Bax-dependent mitochondrial permeabilization occurs leading to release of cytochrome c and activation of caspases leading to transition of cell death in developing brain. The therapeutic window lies within this transition process. At present, therapeutic hypothermia (TH) is the only clinical treatment available for treating moderate as well as severe asphyxia in new-born as it attenuates secondary loss of high-energy phosphates (ATP) (Solevåg et al. in Free Radic Biol Med 142:113-122, 2019; Gunn et al. in Pediatr Res 81:202-209, 2017), improving both short- and long-term outcomes. Mitoprotective therapies can offer a new avenue of intervention alone or in combination with therapeutic hypothermia for babies with birth asphyxia. This review will explore these mitochondrial pathways, and finally will summarize past and current efforts in targeting these pathways after PA, as a means of identifying new avenues of therapeutic intervention.

Clinical and imaging outcomes after intrathecal injection of umbilical cord tissue mesenchymal stem cells in cerebral palsy: a randomized double-blind sham-controlled clinical trial

BACKGROUND

This study assessed the safety and efficacy of intrathecal injection of umbilical cord tissue mesenchymal stem cells (UCT-MSC) in individuals with cerebral palsy (CP). The diffusion tensor imaging (DTI) was performed to evaluate the alterations in white-matter integrity.

METHODS

Participants (4-14 years old) with spastic CP were assigned in 1:1 ratio to receive either UCT-MSC or sham procedure. Single-dose (2 × 107) cells were administered in the experimental group. Small needle pricks to the lower back were performed in the sham-control arm. All individuals were sedated to prevent awareness. The primary endpoints were the mean changes in gross motor function measure (GMFM)-66 from baseline to 12 months after procedures. The mean changes in the modified Ashworth scale (MAS), pediatric evaluation of disability inventory (PEDI), and CP quality of life (CP-QoL) were also assessed. Secondary endpoints were the mean changes in fractional anisotropy (FA) and mean diffusivity (MD) of corticospinal tract (CST) and posterior thalamic radiation (PTR).

RESULTS

There were 36 participants in each group. The mean GMFM-66 scores after 12 months of intervention were significantly higher in the UCT-MSC group compared to baseline (10.65; 95%CI 5.39, 15.91) and control (β 8.07; 95%CI 1.62, 14.52; Cohen's d 0.92). The increase was also seen in total PEDI scores (vs baseline 8.53; 95%CI 4.98, 12.08; vs control: β 6.87; 95%CI 1.52, 12.21; Cohen's d 0.70). The mean change in MAS scores after 12 months of cell injection reduced compared to baseline (-1.0; 95%CI -1.31, -0.69) and control (β -0.72; 95%CI -1.18, -0.26; Cohen's d 0.76). Regarding CP-QoL, mean changes in domains including friends and family, participation in activities, and communication were higher than the control group with a large effect size. The DTI analysis in the experimental group showed that mean FA increased (CST 0.032; 95%CI 0.02, 0.03. PTR 0.024; 95%CI 0.020, 0.028) and MD decreased (CST -0.035 × 10-3; 95%CI -0.04 × 10-3, -0.02 × 10-3. PTR -0.045 × 10-3; 95%CI -0.05 × 10-3, -0.03 × 10-3); compared to baseline. The mean changes were significantly higher than the control group.

CONCLUSIONS

The UCT-MSC transplantation was safe and may improve the clinical and imaging outcomes.

TRIAL REGISTRATION

The study was registered with ClinicalTrials.gov ( NCT03795974 ).

Microarray and qPCR Analysis of Mitochondrial Metabolism Activation during Prenatal and Early Postnatal Development in Rats and Humans with Emphasis on CoQ10 Biosynthesis

At the end of the mammalian intra-uterine foetal development, a rapid switch from glycolytic to oxidative metabolism must proceed. Using microarray techniques, qPCR, enzyme activities and coenzyme Q content measurements, we describe perinatal mitochondrial metabolism acceleration in rat liver and skeletal muscle during the perinatal period and correlate the results with those in humans. Out of 1546 mitochondrial genes, we found significant changes in expression in 1119 and 827 genes in rat liver and skeletal muscle, respectively. The most remarkable expression shift occurred in the rat liver at least two days before birth. Coenzyme Q-based evaluation in both the rat model and human tissues showed the same trend: the total CoQ content is low prenatally, significantly increasing after birth in both the liver and skeletal muscle. We propose that an important regulator of rat coenzyme Q biosynthesis might be COQ8A, an atypical kinase involved in the biosynthesis of coenzyme Q. Our microarray data, a total of 16,557 RefSeq (Entrez) genes, have been deposited in NCBI's Gene Expression Omnibus and are freely available to the broad scientific community. Our microarray data could serve as a suitable background for finding key factors regulating mitochondrial metabolism and the preparation of the foetus for the transition to extra-uterine conditions.

Bone marrow mesenchymal stem cells overexpressing hepatocyte growth factor ameliorate hypoxic-ischemic brain damage in neonatal rats

Objectives

Hypoxic–ischemic brain damage (HIBD) is a major cause of brain injury in neonates. Bone marrow mesenchymal stem cells (BMSCs) show therapeutic potential for HIBD, and genetic modification may enhance their neuroprotective effects. The goal of this study was to investigate the neuroprotective effects of hepatocyte growth factor (HGF)-overexpressing BMSCs (BMSCs-HGF) against HIBD and their underlying mechanisms.

Methods:

BMSCs were transfected with HGF using adenoviral vectors. HIBD models were established and then BMSCs were transplanted into the brains of HIBD rats via intraventricular injection. 2,3,5-Triphenyltetrazolium chloride (TTC) staining was used to measure cerebral infarction volumes. In vitro, primary cultured cortical neurons were co-cultured with BMSCs in a Transwell plate system. Oxygen–glucose deprivation (OGD) was applied to imitate hypoxic–ischemic insult, and PD98059 was added to the culture medium to block the phosphorylation of extracellular signal-regulated kinase (ERK). Cell apoptosis was determined using TUNEL staining. The expression of HGF was measured by immunofluorescence, real-time quantitative PCR (RT-qPCR), and western blots. The expression of phosphorylated ERK (p-ERK) and B-cell lymphoma-2 (Bcl-2) was measured by western blots.

Results

HGF-gene transfection promoted BMSC proliferation. Moreover, BMSCs-HGF decreased HIBD-induced cerebral infarction volumes and enhanced the protective effects of the BMSCs against HIBD. BMSCs-HGF also increased expression of HGF, p-ERK, and Bcl-2 in brain tissues. In vitro, BMSC-HGF protected neurons against OGD-induced apoptosis. Inhibition of ERK phosphorylation abolished the neuroprotective effect of BMSCs-HGF against OGD.

Conclusions

BMSCs-HGF is a potential treatment for HIBD and that the ERK/Bcl-2 pathway is involved in the underlying neuroprotective mechanism.