The aim of the present study has been to obtain high yields of oligodendrocyte precursor cells (OPCs) in culture. This is a first step in facilitation of myelin repair. We show that, in addition to factors, known to promote proliferation, such as basic fibroblast growth factor (FGF-2) and platelet derived growth factor (PDGF) the choice of the basal medium exerts a significant influence on the yield of OPCs in cultures from newborn rats. During a culture period of up to 9 days we observed larger numbers of surviving cells in Dulbecco’s Modified Eagle Medium (DMEM) and Roswell Park Memorial Institute Medium (RPMI) compared with Neurobasal Medium (NB). A larger number of A2B5-positive OPCs was found after 6 days in RPMI based media compared with NB. The percentage of bromodeoxyuridine (BrdU)-positive cells was largest in cultures maintained in DMEM and RPMI. The percentage of caspase-3 positive cells was largest in NB, suggesting that this medium inhibits OPC proliferation and favors apoptosis. A difference between NB and DMEM as well as RPMI is the reduced Na+-content. The addition of equiosmolar supplements of mannitol or NaCl to NB medium rescued the BrdU-incorporation rate. This suggested that the osmolarity influences the proliferation of OPCs. Plating density as well as residual microglia influence OPC survival, BrdU incorporation and caspase-3 expression. We found, that high density cultures secrete factors that inhibit BrdU incorporation whereas the presence of additional microglia induces an increase in caspase-3 positive cells, indicative of enhanced apoptosis. An enhanced number of microglia could thus also explain the stronger inhibition of OPC differentiation observed in high density cultures in response to treatment with the cytokines TNF-a and IFN-g.We conclude that a maximal yield of OPCs is obtained in a medium of an osmolarity higher than 280 mOsm plated at a relatively low density in the presence of as little microglia as technically achievable.

The consumption of energy drinks is continuously rising, particularly in children and adolescents. While risks for adverse health effects, like arrhythmia, have been described, effects on neural cells remain elusive. Considering that neurodevelopmental processes like myelination and neuronal network formation peak in childhood and adolescence we hypothesized that developing oligodendrocytes and neurons are particularly vulnerable to main energy drink components. Immature oligodendrocytes and hippocampal neurons were isolated from P0-P1 Wistar rats and were incubated with 0.3 mg/mL caffeine and 4 mg/mL taurine alone or in combination for 24 h. Analysis was performed immediately after treatment or after additional three days under differentiating conditions for oligodendrocytes and standard culture for neurons. Oligodendrocyte degeneration, proliferation, and differentiation were assessed via immunocytochemistry and immunoblotting. Neuronal integrity was investigated following immunocytochemistry by analysis of dendrite outgrowth and axonal morphology. Caffeine and taurine induced an increased degeneration and inhibited proliferation of immature oligodendrocytes accompanied by a decreased differentiation capacity. Moreover, dendritic branching and axonal integrity of hippocampal neurons were negatively affected by caffeine and taurine treatment. The negative impact of caffeine and taurine on developing oligodendrocytes and disturbed neuronal morphology indicates a high risk for disturbed neurodevelopment in children and adolescents by excessive energy drink consumption.

Exposure to N-methyl-d-aspartate (NMDA) receptor antagonists has been demonstrated to induce neurodegeneration in newborn rats. However, in clinical practice the use of NMDA receptor antagonists as anesthetics and sedatives cannot always be avoided. The present study investigated the effect of the indirect cholinergic agonist physostigmine on neurotrophin expression and the extracellular matrix during NMDA receptor antagonist induced injury to the immature rat brain. The aim was to investigate matrix metalloproteinase (MMP)-2 activity, as well as expression of tissue inhibitor of metalloproteinase (TIMP)-2 and brain-derived neurotrophic factor (BDNF) after co-administration of the non-competitive NMDA receptor antagonist MK801 (dizocilpine) and the acetylcholinesterase (AChE) inhibitor physostigmine. The AChE inhibitor physostigmine ameliorated the MK801-induced reduction of BDNF mRNA and protein levels, reduced MK801-triggered MMP-2 activity and prevented decreased TIMP-2 mRNA expression. Our results indicate that AChE inhibition may prevent newborn rats from MK801-mediated brain damage by enhancing neurotrophin-associated signaling pathways and by modulating the extracellular matrix.

Despite improved neonatal intensive care, the risk of premature-born infants developing bronchopulmonary dysplasia (BPD) and encephalopathy of prematurity (EoP) remains high. With hyperoxia being a major underlying factor, both preterm-birth-related complications are suggested to be closely interrelated. However, experimental models are lacking for the assessment of the potentially close interplay between both organs. To establish a model, suitable for the assessment of both affected organs, Wistar rats were exposed to 80% oxygen from postnatal day 2 (P2) for seven days. Brain and lung tissues were analysed via histomorphometry, immunohistochemistry, real-time PCR, and western blot at term P11. In the brain, hyperoxia induced significant hypomyelination accompanied by a reduction in oligodendrocytes and CD68 expression on microglia cells. These changes correlate with arrested alveolarisation and an increased number of macrophages in the lung. Interestingly, in contrast to the reduced formation of pulmonary microvessels, an increased vascular density was detected in the brain. Seven days of hyperoxia induces typical characteristics of BPD and EoP in neonatal rats, thereby linking impaired alveolarisation with disturbed myelination in the brain and providing an experimental model for understanding pathophysiological mechanisms and identifying organ-spanning novel therapeutic interventions targeting both diseases.

Preterm infants often require oxygen supplementation, resulting in high risk for bronchopulmonary dysplasia (BPD) and neurodevelopmental deficits. Despite a growing number of studies, there is still little knowledge about brain injury in BPD models. Therefore, we exposed neonatal C57BL/6 mice to 85% oxygen from birth to postnatal day (P) 14. At P28, two weeks after recovery under normoxic conditions, right hemisphere was used for the analysis of mRNA and the left hemisphere for protein expression of neuronal cells, neuroinflammatory and vascularisation markers, analysed by real-time PCR and Western blot, respectively. Hyperoxia led to an altered expression of markers associated with neuronal and oligodendrocyte maturation and neuroinflammation such as Dcx, Nestin, Il-1β, Il-6, NG2, and YM1/2. These changes were accompanied by an increased expression of genes involved in angiogenesis and vascular remodelling, e.g., Vegf-a, Nrp-1, and Icam-1. Together, 14 days of hyperoxia triggered a phenotypic response, resembling signs of encephalopathy of prematurity (EoP).

Preterm infants are at high risk of developing long-term brain injury such as encephalopathy of prematurity (EoP). Hyperoxia is a major contributor to EoP, affecting white and grey matter, with immature oligodendrocytes and hippocampal neurons being particularly vulnerable. While no causal therapy is available, mesenchymal stromal cells (MSCs) show therapeutic potential and are considered a promising candidate, although their effector mechanisms remain incompletely understood. Primary oligodendrocytes were isolated from mixed glial cultures of P0–P2 rats and hippocampal neurons from E16 rat embryos. On day 3 (oligodendrocytes) and day 5 (neurons) after isolation, cells were exposed to hyperoxia for 8 h and subsequently co-cultured indirectly with naive or hypoxic-preconditioned human MSCs (hMSCs) for 48 h under standard culture conditions. Degeneration, proliferation, differentiation and mitochondrial respiration were assessed in both cell types. Both naive and hypoxic-preconditioned hMSCs attenuated hyperoxia-induced degeneration, reduced proliferation and mitochondrial respiration failure. Although oligodendrocyte differentiation, assessed by myelin basic protein (MBP) expression, was modulated neither by hyperoxia nor by hMSC treatment, the dendritic structure in hippocampal neurons was impaired by hyperoxia and improved by hMSC treatment. Notably, hypoxic-preconditioned hMSCs showed a stronger therapeutic effect than naive hMSCs on hyperoxia-damaged hippocampal neurons. These findings indicate that indirect hMSC co-culture mitigates hyperoxia-induced impairment of immature oligodendrocytes and hippocampal neurons and that hypoxic preconditioning may modulate this effect in a cell type-specific manner.