Small Animal Internal Medicine Resident Colorado State University Fort Collins, CO, United States
Abstract:
Background: The liver transcriptome can be assessed to identify gene expression patterns, but liver biopsy is invasive. Little is known about whether fine needle aspirate (FNA) samples provide comparable information to biopsies.
Hypothesis/
Objectives: To define the liver transcriptome of cats using RNA sequencing from liver biopsy and FNA samples obtained from healthy cats and compare findings between the two sample types.
Animals: Four healthy purpose-bred adult cats.
Methods: Surgical liver biopsies were obtained during routine ovariectomy with IACUC approval. Fine needle liver aspirates were collected using a 22-gauge needle from a liver lobe adjacent to the liver biopsy site. RNA was extracted and subjected to Illumina sequencing. Sequence files were aligned to the reference cat genome and assembled using Partek Flow software. Differential analysis was performed with DESeq2, and gene set enrichment analysis (GSEA) was conducted for comparison.
Results: A total of 18,502 protein-coding genes were sequenced. Hepatocyte gene signatures were identified in both biopsies and FNA samples, with high similarity between biological replicates. However, 1,508 genes were significantly upregulated and 1,596 downregulated in FNA samples compared to biopsies. Upregulated pathways were associated with metabolic processes.
Conclusions and Clinical Importance: RNA sequencing allows for comprehensive characterization of the feline liver transcriptome. Although hepatocyte gene signatures were detectable in FNAs, significant differential expression suggests potential limitations. Further research, including samples from healthy cats and those with different hepatic disease syndromes, is needed to determine the reliability of FNAs as a less invasive alternative to biopsies.
