Human Kidney Slice Cultures Are a Flexible Platform to Study Drug Mechanisms and Glomerular Diseases

Background: Short term human kidney slice cultures represent a tractable experimental system for studying kidney structure and responses to drugs since they remain viable in vitro while retaining key structures such as the glomerular slit diaphragm. We leveraged this system to study tissue responses to cytokine and drug treatment. Methods: 6mm cores of kidney cortex were harvested from human nephrectomy specimens. After embedding in agarose, 250µm vibratome slices were generated and cultured in transwell inserts for various timepoints. Slice viability was assessed using the MTT assay. Slice morphology was assessed using conventional histology and 3D lightsheet microscopy. Bulk gene expression was assessed using quantitative RT-PCR. For treatments, replicate slices were incubated for 16 hours in 100ng/ml human IFNγ ± 10µM baricitinib. Whole transcriptome spatial gene expression profiling was performed using the GeoMx digital spatial profiler. Results: Kidney slice cultures exhibited good viability in short term (<72 hours) in vitro culture. When exposed to IFNγ, RT-PCR revealed upregulation of the APOL1 gene (Fig. 1A). This upregulation was completely blocked by baricitinib. Spatial transcriptomic profiling of individual glomeruli recapitulated APOL1 induction by IFNγ and suppression by baricitinib (Fig. 1B,C). APOL1 induction was validated using RNA in situ hybridization (Fig. 1D). Pathway analysis revealed baricitinib suppression of additional targets affecting development and vascular biology. Conclusion: Kidney slice cultures are biologically responsive and amenable to advanced imaging and hi-plex -omic profiling. This system can be leveraged to understand kidney disease mechanisms and to identify on- and off-target effects of drugs. Funding: NIDDK Support