Using Nuclear Magnetic Resonance (NMR) Microscopy to Quantify Kidney and Cyst Volume in Adult Zebrafish

Background: While the murine models have been instrumental for our understanding of the pathogenesis of cystic kidney diseases, large scale genetic screen and pharmacological drug screen are prohibitively expensive in these models. We recently developed renal cyst models in adult zebrafish, opening the possibility of conducting larger scale genetic screens and compound testings. However, adult zebrafish are opaque, methods for assessing phenotypes of adult zebrafish kidney are limited, which motivated us to further develop new phenotyping tools. The current NMR method has been carried in a whole fish. While accurate measurement of total kidney volume, a crucial biomarker for predicting disease progression rates, can be obtained, quantification of the volume in cystic kidneys is difficult because of altered kidney morphology. Methods: NMR scan was performed using an Avance III 300 MHz with microimaging accessories (Bruker BioSpin). Here, we choose to use zebrafish ift140 CRISPRants as an adult kidney cyst model and present a new method via scanning trimmed samples, in which unrelated tissues were removed while the kidney remained intact and were attached to the dorsal body wall. Results: Kidney shape can be better visualized, enabling reliable quantification of total kidney volume of cystic kidneys. Because of improved resolution, kidney cysts can be reliably detected, which is validated via conventional histological staining on paraffin sections. Cyst in 3D can now be imaged and quantification in the whole kidney, overcoming the biasness of the current method, i.e. quantifying cysts in individual slides from histological sections. Conclusion: In conclusion, our new NMR phenotyping method enables reliable quantification of kidney total volume and cysts in 3D, which would significantly promote the use of adult zebrafish for the study of renal cystic diseases. Funding: Other NIH Support - R56