[Construction of zebrafish models for screening intracranial hemorrhage associated genes]

Objective: To construct zebrafish models for the screening of intracranial hemorrhage (ICH) associated genes. Methods: ICH zebrafish models were constructed through morpholino oligonucleotides (MOs) technique and microinjection technique, and multiple verification was performed from macro and micro perspectives. First, the normal wild-type AB strain zebrafish injected with control MO was used as the control group, and AB zebrafish embryos microinjected with MOs of genes related to development of neural crest-derived cells (NCDCs) were used as the study group, such as col8a1 MO, tfap2α MO, msx1a MO, msx2 MO, and dkk1a MO. Preliminary verification of the model was conducted under a white-light optical microscope. Then, the model was verified by Tg (flk1: gfp; gata1: dsRed) double transgenic zebrafish, with vascular endothelial cells labeled by green fluorescent protein (GFP) and red blood cell labeled by fluorescent protein (dsRed), and thus the location of cerebral hemorrhage can be observed more clearly. Specifically, zebrafish embryos were microinjected with Control MO as the control group and those microinjected with col8a1 MO as the study group. Then the embryos were cultured until 48 hours post-fertilization to observe the leakage of red blood cells under the confocal laser scanning microscope. Finally, Tg (flk1: gfp) transgenic zebrafish was used to verify the model based on the blood-brain barrier (BBB). Through the leakage of dextran-rhodamine and DAPI dyes, the destruction of BBB and the occurrence of cerebral hemorrhage in zebrafish were further clarified, and quantitative statistics were carried out to verify the relationship between NCDCs development related genes and cerebral hemorrhage phenotype, which proved that the modeling was effective. Results: The zebrafish with col8a1, tfap2α, and msx1 mutations in the study group had apparent ICH compared with wildtype zebrafish, and the prevalence of ICH was 18.18% (52/286), 23.04% (62/251), and 35.94% (23/64), respectively. While, the zebrafish with msx2 and dkk1a mutations rarely had ICH, with the ICH prevalence of 1.03% (1/97) and 1.15% (1/87), respectively. The prevalence of red blood cells leakage in Tg (flk1:gfp; gata1:dsred) double transgenic zebrafish injected with Control Mo and col8a1 Mo was 0.37% (1/273) and 18.18% (52/286) (P<0.001). The number of DAPI positive nuclei of Tg (flk1: gfp) transgenic zebrafish injected with Control Mo and col8a1 Mo was 10.05±5.27 and 60.35±3.96 (P<0.001), and the fluorescent intensity of midbrain parenchymal induced by dextran-rhodamin leakage was 2.54±4.70 and 5.13±3.52 (P<0.001). Conclusion: This study successfully constructs the ICH zebrafish models, and ICH-related genes are screened out, such as col8a1, tfap2α, msx1, and so on.