Functional and developmental analysis of the blood–brain barrier in zebrafish

Developing a Novel Embryo–Larval Zebrafish Xenograft Assay to Prioritize Human Glioblastoma Therapeutics

“…At this time, minimal mortality was observed due to injection (*1% and *20% for 2 and 3 DPF, respectively) and most major organ systems are fully developed during this time period, including a rudimentary blood-brain barrier allowing us to more closely simulate tests conducted in mammalian models. 18,25 Based on work by others, we maintained our xenografts at 33°C, which is lower than the standard 37°C for culturing glioblastoma cells, but higher than the typical 28°C for zebrafish maintenance. 6,15 This temperature caused no observable zebrafish toxicity, yet resulted in adequate human glioblastoma growth and migration/invasion over the 3-4 day assay period to detect exposure-dependent differences between treatment groups.…”

“…4 By transplanting glioblastoma cells into the 48-72 h postfertilization zebrafish brain, which possess a functioning blood-brain barrier similar to mammalian models, our laboratory has developed an efficient and relevant assay using high-content imaging to study glioblastoma progression and prioritize the development of new glioblastoma therapies. 18 Our previous studies revealed that genetic knockdown of a protein important in glioblastoma invasion (calpain 2) reduces glioblastoma invasion by *90%. 19 Implanting these modified cells in the zebrafish brain microenvironment further demonstrated that knockdown of calpain 2 reduced glioblastoma invasion by 2.9-fold, which was similar to the reduction observed in organotypic mouse brain tissues (2.3-fold).…”

Zebrafish as a Model for Developmental Neurotoxicity Assessment: The Application of the Zebrafish in Defining the Effects of Arsenic, Methylmercury, or Lead on Early Neurodevelopment

“…While the exact timing of complete maturation of zebrafish BBB is unclear, it has been revealed that two tight junction proteins, Claudin-5 and ZO-1, in zebrafish brain endothelial cells are expressed as early as 72 hpf [27]. As visualized by Jeong et al [27], the BBB of zebrafish is functional at 72 hpf as the leakage of an injected large molecular weight tracer, rhodamine-dextran (10 kDa) was restricted in microvessels of brain parenchyma.…”

“…While the exact timing of complete maturation of zebrafish BBB is unclear, it has been revealed that two tight junction proteins, Claudin-5 and ZO-1, in zebrafish brain endothelial cells are expressed as early as 72 hpf [27]. As visualized by Jeong et al [27], the BBB of zebrafish is functional at 72 hpf as the leakage of an injected large molecular weight tracer, rhodamine-dextran (10 kDa) was restricted in microvessels of brain parenchyma. The zebrafish BBB may undergo further maturation to exclude small molecules after completion of embryogenesis, as shown in Fleming et al [102] with the inclusion of Evans blue (961 Da) and sodium fluorescein (376 Da), restricted through 5 and 10 days after fertilization, respectively.…”

“…The embryonic developmental stages of zebrafish are well documented, which provides a guide for researchers to identify major physiological alterations occurring during developmental toxicity assays [24]. Moreover, there is continuous progress on uncovering the developmental processes of the CNS and blood-brain-barrier (BBB) of the zebrafish [25][26][27][28][29][30]. Overall development of the zebrafish CNS and patterning of brain sub-regions are completed within three days after fertilization during which neurogenesis and formation of pioneer axons initiate (Figure 1).…”