Stem cell therapies for perinatal brain injuries

The Role of Extracellular Vesicles in the Developing Brain: Current Perspective and Promising Source of Biomarkers and Therapy for Perinatal Brain Injury

This comprehensive review focuses on our current understanding of the proposed physiological and pathological functions of extracellular vesicles (EVs) in the developing brain. Furthermore, since EVs have attracted great interest as potential novel cell-free therapeutics, we discuss advances in the knowledge of stem cell- and astrocyte-derived EVs in relation to their potential for protection and repair following perinatal brain injury. This review identified 13 peer-reviewed studies evaluating the efficacy of EVs in animal models of perinatal brain injury; 12/13 utilized mesenchymal stem cell-derived EVs (MSC-EVs) and 1/13 utilized astrocyte-derived EVs. Animal model, method of EV isolation and size, route, timing, and dose administered varied between studies. Notwithstanding, EV treatment either improved and/or preserved perinatal brain structures both macroscopically and microscopically. Additionally, EV treatment modulated inflammatory responses and improved brain function. Collectively this suggests EVs can ameliorate, or repair damage associated with perinatal brain injury. These findings warrant further investigation to identify the optimal cell numbers, source, and dosage regimens of EVs, including long-term effects on functional outcomes.

Current proceedings of cerebral palsy

Cerebral palsy (CP) is a complicated disease with varying causes and outcomes. It has created significant burden to both affected families and societies, not to mention the quality of life of the patients themselves. There is no cure for the disease; therefore, development of effective therapeutic strategies is in great demand. Recent advances in regenerative medicine suggest that the transplantation of stem cells, including embryonic stem cells, neural stem cells, bone marrow mesenchymal stem cells, induced pluripotent stem cells, umbilical cord blood cells, and human embryonic germ cells, focusing on the root of the problem, may provide the possibility of developing a complete cure in treating CP. However, safety is the first factor to be considered because some stem cells may cause tumorigenesis. Additionally, more preclinical and clinical studies are needed to determine the type of cells, route of delivery, cell dose, timing of transplantation, and combinatorial strategies to achieve an optimal outcome.

Effect of cerebral hypothermia and asphyxia on the subventricular zone and white matter tracts in preterm fetal sheep

Prolonged, moderate cerebral hypothermia is consistently neuroprotective after experimental hypoxia-ischemia. We have previously shown that hypothermia is also protective after profound asphyxia in the preterm brain. However, there is a concern whether hypothermia could suppress the proliferative response to injury in the white matter or subventricular zone (SVZ). Preterm (0.7 gestation) fetal sheep received complete umbilical cord occlusion for 25 min followed by cerebral hypothermia (extradural temperature reduced from 39.4±0.3 to 29.5±2.6°C) from 90 min to 70h after the end of occlusion or sham cooling. Occlusion-normothermia was associated with no effect on CNPase+ cells, but loss of O4+ oligodendrocytes, induction of cleaved caspase-3, and IB4+ microglia in the gyral and periventricular white matter compared to sham-occlusion (p < 0.05), with a significant increase in KI67+ cells in the periventricular white matter (p < 0.05). Hypothermia was associated with significant protection of O4+ cells, with suppression of IB4+ microglia and KI67+ cells in the periventricular white matter. There was no significant change in astrocytes, microglia, KI67+, or caspase-3+ cells in the SVZ after asphyxia. In conclusion, this study provides strong support for the selective vulnerability of immature oligodendrocytes to a highly relevant insult in the fetal sheep. Although white matter protection with cerebral hypothermia was associated with reduced proliferation in the white matter tracts, it did not impair proliferation in the SVZ.

Cellular treatments for spinal cord injury: the time is right for clinical trials

More than 1 million people in the United States live with a spinal cord injury (SCI). Despite medical advances, many patients with SCIs still experience substantial neurological disability, with loss of motor, sensory, and autonomic function. Cell therapy is ideally suited to address the multifactorial nature of the secondary events following SCI. Remarkable advances in our understanding of the pathophysiology of SCI, structural and functional magnetic resonance imaging, image-guided micro-neurosurgical techniques, and transplantable cell biology have enabled the use of cell-based regenerative techniques in the clinic. It is important to note that there are more than a dozen recently completed, ongoing, or recruiting cell therapy clinical trials for SCI that reflect the views of many key stakeholders. The field of regenerative neuroscience has reached a stage in which the clinical trials are scientifically and ethically justified. Although experimental models and analysis methods and techniques continue to evolve, no model will completely replicate the human condition. It is recognized that more work with cervical models of contusive/compressive SCI are required in parallel with clinical trials. It is also important that the clinical translation of advances made through well-established and validated experimental approaches in animal models move forward to meet the compelling needs of individuals with SCI and to advance the field of regenerative neuroscience. However, it is imperative that such efforts at translation be done in the most rigorous and informed fashion to determine safety and possible efficacy, and to provide key information to clinicians and basic scientists, which will allow improvements in regenerative techniques and the validation and refinement of existing preclinical animal models and research approaches. The field of regenerative neuroscience should not be stalled at the animal model stage, but instead the clinical trials need to be focused, safe, and ethical, backed up by a robust, translationally relevant preclinical research strategy.

Neural differentiation potential of rat amniotic epithelial cells

Amniotic epithelial cells (AEC) are thought to represent a stem-like cell population and to be an attractive cell source for regenerative medicine, because abundant cells can be obtained noninvasively at delivery. The authors investigated the neural differentiation potential of rat AEC. Rat AEC expressed vimentin and nestin, but not c-kit, oct-4, or nanog. The expression of the neural lineage markers, including betaIII-tubulin, neuron specific enolase (NSE), neurofilament-M, neuroD, glial fibrillary acidic protein (GFAP), myelin basic protein (MBP), tyrosine hydroxylase (TH), acetylcholinesterase (AChE), cholin acetyltransferase (ChAT), and mammalian achaete-scute homolog1 (MASH1), was detected by RT-PCR in the cultured rat AEC. After neural induction, rat AEC dramatically changed their shapes, projecting dendrite-like structures. Immunocytochemically, approximately 20% of the induced cells expressed an immature neuronal marker, betaIII-tubulin. Our findings suggested that rat AEC might be already committed to differentiate to various neural lineages and that they could differentiate to immature neurons in vitro.

Impairment of perinatal hypoxia-ischemia to the preterm brainstem

Hypoxia-ischemia is a major perinatal problem that results in severe damage to the newborn brain. This study assessed functional integrity of the brainstem at term in preterm infants after perinatal hypoxia-ischemia to shed light on the influence of hypoxia-ischemia on the preterm brainstem. We recruited sixty-eight preterm infants after perinatal hypoxia-ischemia, ranging in gestation 28-35 weeks. Brainstem evoked response was studied at term age (37-42 weeks postconceptional age) with 91-910/s clicks using the maximum length sequence technique. Compared with healthy preterm infants, the preterm infants after perinatal hypoxia-ischemia showed a significant increase in I-V interval at very high rates 455 and 910/s of clicks (P<0.05, 0.05). III-V interval and III-V/I-III interval ratio also increased significantly at 455 and 910/s (P<0.05-0.01). The slope of III-V interval-rate function was significantly steeper than in the healthy preterm infants (P<0.05). Compared with normal term controls, the preterm infants after hypoxia-ischemia showed similar, but slightly more significant, abnormalities. The differences between the preterm infants after hypoxia-ischemia and the healthy preterm and term infants generally increased with increasing click rate. These results demonstrated that central components of brainstem auditory evoked response were abnormal at very high click rates in the preterm infants after perinatal hypoxia-ischemia. Click rate-dependent change in the more central part of the brainstem is also abnormal. Apparently, functional integrity of the brainstem, mainly in the more central part, is impaired. Hypoxic-ischemic damage to the preterm brainstem is unlikely to completely recover within a relatively short period after the insult, which is of clinical importance.

Evaluation and management of stroke in the neonate

Ischemic perinatal stroke (IPS) occurs in 1 of 2300 to 5000 live births. It is an under-recognized cause of significant long-term disabilities, including hemiplegic cerebral palsy, epilepsy, cognitive delays, and behavioral impairments. The pathophysiology is complex and multifactorial, involving maternal, fetal, placental, and neonatal factors. Knowledge and interventions are emerging to facilitate early diagnosis and treatment of IPS. Early treatment may translate into improved long-term neurodevelopmental outcomes.

Embryonic stem cell biology

ES cell research represents an exploding field of exploration. Initially predicted to provide rapid cures for numerous human diseases, the clinical usefulness of ES cell-derived cells remains untested in humans. However, ES cells have rapidly expanded our knowledge of human development and the molecular details of differentiation. Our ability to generate relatively pure populations of specifically differentiated cells for transplantation has markedly improved. It is hoped that soon researchers will overcome the biologic impediments to successful treatment of human disease with ES cell-derived cells.