Immunocompetent Brain Organoids with Microglia Allow Advanced Aging Research.

Aging is a complex and multifactorial process that significantly affects brain function and health, since it is commonly associated with the emergence of neurodegenerative diseases. Recent advances in stem cell technology have facilitated the development of brain organoids, three-dimensional structures that mimic key aspects of brain architecture and functionality. By incorporating microglia, the resident monocyte-derived immune cells of the central nervous system, immunocompetent brain organoids can provide a more physiologically relevant model for studying brain aging. This chapter explores the methodology of immunocompetent brain organoids for advanced aging research, detailing protocols for their generation from a co-culture of neural stem cells and primitive macrophage progenitors.

Congenital Zika Virus Infection Impairs Corpus Callosum Development.

Congenital Zika syndrome (CZS) is a set of birth defects caused by Zika virus (ZIKV) infection during pregnancy. Microcephaly is its main feature, but other brain abnormalities are found in CZS patients, such as ventriculomegaly, brain calcifications, and dysgenesis of the corpus callosum. Many studies have focused on microcephaly, but it remains unknown how ZIKV infection leads to callosal malformation. To tackle this issue, we infected mouse embryos in utero with a Brazilian ZIKV isolate and found that they were born with a reduction in callosal area and density of callosal neurons. ZIKV infection also causes a density reduction in PH3+ cells, intermediate progenitor cells, and SATB2+ neurons. Moreover, axonal tracing revealed that callosal axons are reduced and misrouted. Also, ZIKV-infected cultures show a reduction in callosal axon length. GFAP labeling showed that an in utero infection compromises glial cells responsible for midline axon guidance. In sum, we showed that ZIKV infection impairs critical steps of corpus callosum formation by disrupting not only neurogenesis, but also axon guidance and growth across the midline.

Effect of Serial Systemic and Intratumoral Injections of Oncolytic ZIKVBR in Mice Bearing Embryonal CNS Tumors.

The Zika virus (ZIKV) has shown a promising oncolytic effect against embryonal CNS tumors. However, studies on the effect of different administration routes and the ideal viral load in preclinical models are highly relevant aiming for treatment safety and efficiency. Here, we investigated the effect and effectiveness of different routes of administration, and the number of ZIKVBR injections on tumor tropism, destruction, and side effects. Furthermore, we designed an early-stage human brain organoid co-cultured with embryonal CNS tumors to analyze the ZIKVBR oncolytic effect. We showed that in the mice bearing subcutaneous tumors, the ZIKVBR systemically presented a tropism to the brain. When the tumor was located in the mice's brain, serial systemic injections presented efficient tumor destruction, with no neurological or other organ injury and increased mice survival. In the human cerebral organoid model co-cultured with embryonal CNS tumor cells, ZIKVBR impaired tumor progression. The gene expression of cytokines and chemokines in both models suggested an enhancement of immune cells recruitment and tumor inflammation after the treatment. These results open new perspectives for virotherapy using the ZIKVBR systemic administration route and multiple doses of low virus load for safe and effective treatment of embryonal CNS tumors, an orphan disease that urges new effective therapies.