The ~50% of ccm2 CRISPR fish that survived developed highly penetrant CCMs (A and C). Arrows indicate superficial lesions on dorsal (A) and ventral (C) surface of the brain. Note hemorrhage into the ventricles. Lesions are absent in control embryos (E and G). Clear, unobstructed brain imaging cocktails and computational analysis (CUBIC) clearing (B, D, F, H) enables visualization of CCM burden by light sheet microscopy. Arrows indicate the lesions that corresponded to those seen in bright field, and arrowhead indicates a deeper lesion. L: left, R: right. Scale bar: 1 mm. (I) Cavernomas were dispersed throughout the central nervous system including cerebrum, cerebellum, brain stem, and spinal cord. (J) Hematoxylin and eosin (H&E) stained brain section reveals nucleated erythrocytes filling a dilated vessel with adjacent Prussian blue stained iron deposition (K) in ccm2 CRISPR fish and the absence of lesions or iron deposition in control fish (L, M). (N, O) A CCM from a patient stained with H&E (N) or Prussian blue (O). Note similar appearance to the zebrafish lesion shown in (J, K). Arrow indicates dilated vessel. Scale bar: 50 µm. (P) CCMs were significantly reduced in ccm2 CRISPR adult fish on klf2a-/- background compared to that on klf2a+/+ background. Total number of embryos in each group is indicated. p=0.0076. Two-tailed Fisher’s exact test was used for comparison.
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