Zika virus (ZiKV) has been extensively studied since it was linked to congenital malformations, and recent research has revealed that astrocytes are targets of ZiKV. However, the consequences of ZiKV infection, especially to this cell type, remain largely unknown, particularly considering integrative studies aiming to understand the crosstalk among key cellular mechanisms and fates involved in the neurotoxicity of the virus. Here, the consequences of ZiKV infection in ipSc-derived astrocytes are presented. our results show RoS imbalance, mitochondrial defects and DnA breakage, which have been previously linked to neurological disorders. We have also detected glial reactivity, also present in mice and in post-mortem brains from infected neonates from the northeast of Brazil. Given the role of glia in the developing brain, these findings may help to explain the observed effects in congenital Zika syndrome related to neuronal loss and motor deficit.

The northeast (NE) region of Brazil commonly goes through drought periods, which favor cyanobacterial blooms, capable of producing neurotoxins with implications for human and animal health. The most severe dry spell in the history of Brazil occurred between 2012 and 2016. Coincidently, the highest incidence of microcephaly associated with the Zika virus (ZIKV) outbreak took place in the NE region of Brazil during the same years. In this work, we tested the hypothesis that saxitoxin (STX), a neurotoxin produced in South America by the freshwater cyanobacteria Raphidiopsis raciborskii, could have contributed to the most severe Congenital Zika Syndrome (CZS) profile described worldwide. Quality surveillance showed higher cyanobacteria amounts and STX occurrence in human drinking water supplies of NE compared to other regions of Brazil. Experimentally, we described that STX doubled the quantity of ZIKV-induced neural cell death in progenitor areas of human brain organoids, while the chronic ingestion of water contaminated with STX before and during gestation caused brain abnormalities in offspring of ZIKV-infected immunocompetent C57BL/6J mice. Our data indicate that saxitoxin-producing cyanobacteria is overspread in water reservoirs of the NE and might have acted as a co-insult to ZIKV infection in Brazil. These results raise a public health concern regarding the consequences of arbovirus outbreaks happening in areas with droughts and/or frequent freshwater cyanobacterial blooms.

Here a novel technique for engineering neural tissue consisting of motor neurons by combining human‐induced pluripotent stem cells (hiPSCs) with small molecules releasing microspheres is demonstrated. First, the small molecule purmorphamine (puro) is successfully encapsulated into poly ε‐caprolactone (PCL) microspheres using a single emulsion oil‐in‐water (o/w) method for the first time with an efficiency of (84% ± 2.12%). These microspheres release 91% ± 1.7% of the encapsulated puro in a controlled fashion over 46 days. Puro microspheres, along with previously characterized retinoic acid (RA) releasing microspheres, are then incorporated into hiPSC aggregates to engineer neural tissue. The combination of puro and RA microspheres promotes hiPSC differentiation as indicated by the expression of multiple neural markers, including the neuronal marker β‐tubulin III (βT‐III), and the transcription factor Olig2 (7.69 ± 8.38%) on day 28. These tissues express the motor neuron marker HB9 (24.85 ± 4.51%) on day 35, and the mature motor neuron marker ChaT (12.35 ± 4.17%) on day 60. These engineered tissues can be used for regenerative medicine applications such as treating spinal cord injury (SCI), disease modeling, and drug screening.

Background Neurological and other systemic complications occur in adults with severe COVID-19. Here we describe SARS-CoV-2 infection complicated by neuroinvasion in the post-mortem tissues of a child. Methods We performed a complete autopsy of a 14-month-old child who died of COVID-19 pneumonitis. Histological sections of multiple organs were stained with haematoxylin and eosin. Luxol fast blue staining for myelin and immunohistochemistry were performed in selected areas of the brain. The presence of SARS-CoV-2 was investigated by immunostaining with anti-spike protein antibody and by RT-qPCR. Findings Lesions included microthrombosis, pulmonary congestion, interstitial oedema, lymphocytic infiltrates, bronchiolar injury, collapsed alveolar spaces, cortical atrophy, and severe neuronal loss. SARS-CoV-2 staining was observed along the apical region of the choroid plexus (ChP) epithelium and in ependymal cells of the lateral ventricle, but was restricted to ChP capillaries and vessels in some regions. SARS-CoV-2 infection of brain tissue was confirmed by RT-qPCR in fragments of the ChP, lateral ventricle, and cortex. Interpretation Our results show multisystemic histopathological alterations caused by SARS-CoV-2 infection and contribute to knowledge regarding the course of fatal COVID-19 in children. Furthermore, our findings of ChP infection and viral neurotropism suggest that SARS-CoV-2 may invade the central nervous system by blood-cerebrospinal fluid barrier disruption. Funding Carlos Chagas Filho Foundation for Supporting Research in the State of Rio de Janeiro (FAPERJ); the National Council for Scientific and Technological Development (CNPq) and Coordination for the Improvement of Higher Education Personnel (CAPES), in addition to intramural grants from D'Or Institute for Research and Education. Resumo Complicações sistêmicas e neurológicas foram descritas em adultos com COVID-19 grave. Neste trabalho, descrevemos a infecção por SARS-CoV-2, incluindo sua neuroinvasão, nos tecidos post-mortem de uma criança. Métodos Realizamos a autópsia completa de uma criança de 14 meses que morreu de pneumonite por COVID-19. Cortes histológicos de múltiplos órgãos foram corados com Hematoxilina e Eosina. A coloração de Luxol Fast Blue para mielina e imuno-histoquímica foram realizadas em áreas selecionadas do cérebro. A presença de SARS-CoV-2 foi investigada por imunomarcação com anticorpo anti-proteína spike e por RT-qPCR. Achados As lesões incluíram microtrombose, congestão pulmonar, edema intersticial, infiltrados linfocíticos, lesão bronquiolar, colapso dos espaços alveolares, atrofia cortical e perda neuronal grave. A presença de SARS-CoV-2 foi observada ao longo da região apical do epitélio do plexo coróide (PC) e nas células ependimárias do ventrículo...

31The northeast (NE) region of Brazil commonly goes through drought periods, which 32 favor cyanobacterial blooms, capable of producing neurotoxins with implications for human 33 and animal health. The most severe dry spell in the history of Brazil occurred between 2012 34 and 2016. Coincidently, the highest incidence of microcephaly associated with the Zika virus 35 (ZIKV) outbreak was described in the NE region of Brazil during the same years. In this 36 work, we tested the hypothesis that saxitoxin (STX), a neurotoxin produced in South America 37 by the freshwater cyanobacteria Raphidiopsis raciborskii, could have contributed to the most 38 severe Congenital Zika Syndrome (CZS) profile described worldwide. Quality surveillance 39 showed higher cyanobacteria amounts and STX occurrence in human drinking water supplies 40 of NE compared to other regions of Brazil. Experimentally, we described that STX doubled 41 the amount of ZIKV-induced neural cell death in progenitor areas of human brain organoids, 42 while the chronic ingestion of water contaminated with STX before and during gestation 43 caused brain abnormalities in offspring of ZIKV-infected immunocompetent C57BL/6J mice. 44Our data indicate that saxitoxin-producing cyanobacteria is overspread in water reservoirs of 45 the NE and might have acted as a co-insult to ZIKV infection in Brazil. These results raise a 46 public health concern regarding the consequences of arbovirus outbreaks happening in areas 47 with droughts and/or frequent freshwater cyanobacterial blooms. 48Author summary 49 The uncontrolled spreading of cyanobacteria in drinking water reservoirs has been the 50 cause of serious public health problems worldwide. Toxin-producing cyanobacterial blooms 51 commonly occur during drought periods in the northeast (NE) region of Brazil. During Zika 52Virus (ZIKV) outbreak in 2015-16, Brazilian NE showed disproportionately higher 53 microcephaly incidence. Here, we test the hypothesis that the cyanotoxin saxitoxin (STX) 54 3 may act as a co-insult for ZIKV. Water quality surveillance data showed increased 55 cyanobacteria population and higher STX amount in NE region during 2014-2018 we observed that neural progenitor cell death was doubled after STX exposure to ZIKV-57 infected brain organoids. In vivo, chronic ingestion of STX during gestational period 58 potentiated ZIKV-derived brain abnormalities in newborn mice. Our study provides new 59 insights that may explain the discrepancies among Brazilian regions regarding CZS severity. 60Moreover, the data highlight the importance of cyanobacteria and cyanotoxin freshwater 61 monitoring for future arbovirus outbreaks. 62

Coronavirus disease 2019 (COVID-19) was initially characterized as a respiratory illness. Neurological manifestations were reported mostly in severely affected patients. Routes for brain infection and the presence of virus particles in situ have not been well described, raising controversy about how the virus causes neurological symptoms. Here, we report the autopsy findings of a 1-year old infant with COVID-19. In addition to pneumonitis, meningitis and multiple organ damage related to thrombosis, a previous encephalopathy may have contributed to additional cerebral damage. SARS-CoV-2 infected the choroid plexus, ventricles, and cerebral cortex. This is the first evidence of SARS-CoV-2 detection in an infant post-mortem brain.

Graphical abstract

Neural development represents a dynamic process where mitochondrial integrity is decisive for neuronal activity. Structural changes in these organelles may be related to neurological disorders. Valproic acid (VPA) is an anticonvulsive drug commonly used for epilepsy treatment and its use is associated to increased risk of neuropsychiatric disorders. Recently we showed changes in shape and membrane potential in mitochondria from human neural progenitor cells (NPCs) exposed to VPA (da Costa et al. 2015). Here, we applied transmission electron microscopy and electron tomography to evaluate mitochondrial damage caused by VPA in NPCs. Results showed mitochondrial cristae disorganization in a dose dependent manner. Disturbance in mitochondrial ultrastructure may influence metabolism, leading to synaptic plasticity and neurogenesis impairment. These data contribute to understanding VPA exposure potential effects on brain development.