Infarction of Paratesticular Inflammatory Myofibroblastic Tumor Mimicking Testicular Torsion.

This report describes a 14-year-old male with a rare paratesticular inflammatory myofibroblastic tumor that presented atypically with acute unilateral scrotal pain and swelling. This presentation, which raised suspicion for testicular torsion, contrasts with the typical presentation of a slow-growing scrotal mass. Scrotal exploration revealed an infarcted right testis, demonstrating this locally aggressive tumor can undergo vascular invasion and occlude testicular blood supply. Thus, inflammatory myofibroblastic tumor should be considered in the differential diagnosis when evaluating patients with acute scrotal pain suspicious for testicular infarction.

HepaRG cells undergo increased levels of post-differentiation patterning in physiologic conditions when maintained as 3D cultures in paper-based scaffolds.

Monolayer cultures of hepatocytes lack many aspects of the liver sinusoid, including a tissue-level organization that results from extracellular matrix interactions and gradients of soluble molecules that span from the portal triad to the central vein. We measured the activity and transcript levels of drug-metabolizing enzymes in HepaRG cells maintained in three different culture configurations: as monolayers, seeded onto paper scaffolds that were pre-loaded with a collagen matrix, and when seeded directly into the paper scaffolds as a cell-laden gel. Drug metabolism was significantly decreased in the presence of the paper scaffolds compared to monolayer configurations when cells were exposed to standard culture conditions. Despite this decreased function, transcript levels suggest the cells undergo increased polarization and adopt a biliary-like character in the paper scaffolds, including the increased expression of transporter proteins (e.g., ABCB11 and SLOC1B1) and the KRT19 cholangiocyte marker. When exposed to representative periportal or perivenous culture conditions, we observed in vivo zonal-like patterns, including increased cytochrome P450 (CYP) activity and transcript levels in the perivenous condition. This increased CYP activity is more pronounced in the laden configuration, supporting the need to include multiple aspects of the liver microenvironment to observe the post-differentiation processing of hepatocytes.

HepaRG cells undergo increased levels of post-differentiation patterning in physiologic conditions when maintained as 3D cultures in paper-based scaffolds.

Monolayer cultures of hepatocytes lack many aspects of the liver sinusoid, including a tissue-level organization that results from extracellular matrix interactions and gradients of soluble molecules that span from the portal triad to the central vein. We measured the activity and transcript levels of drug-metabolizing enzymes in HepaRG cells maintained in three different culture configurations: as monolayers, seeded onto paper scaffolds that were pre-loaded with a collagen matrix, and when seeded directly into the paper scaffolds as a cell-laden gel. Drug metabolism was significantly decreased in the presence of the paper scaffolds compared to monolayer configurations when cells were exposed to standard culture conditions. Despite this decreased function, transcript levels suggest the cells undergo increased polarization and adopt a biliary-like character in the paper scaffolds, including the increased expression of transporter proteins (e.g., ABCB11 and SLOC1B1) and the KRT19 cholangiocyte marker. When exposed to representative periportal or perivenous culture conditions, we observed in vivo zonal-like patterns, including increased cytochrome P450 (CYP) activity and transcript levels in the perivenous condition. This increased CYP activity is more pronounced in the laden configuration, supporting the need to include multiple aspects of the liver microenvironment to observe the post-differentiation processing of hepatocytes.

HepaRG cells adopt zonal-like drug-metabolizing phenotypes under physiologically relevant oxygen tensions and Wnt/ß-catenin signaling.

The cellular microenvironment plays an important role in liver zonation, the spatial distribution of metabolic tasks amongst hepatocytes lining the sinusoid. Standard tissue culture practices provide an excess of oxygen and a lack of signaling molecules typically found in the liver. We hypothesized that incorporating physiologically relevant environments would promote post-differentiation patterning of hepatocytes and result in zonal-like characteristics. To test this hypothesis, we evaluated the transcriptional regulation and activity of drug-metabolizing enzymes in HepaRG cells exposed to three different oxygen tensions, in the presence or absence of Wnt/ß-catenin signaling. The drug-metabolizing activity of cells exposed to representative periportal (11% O2) or perivenous (5% O2) oxygen tensions were significantly less than cells exposed to ambient oxygen. A comparison of cytochrome P450 (CYP) 1A2, 2D6, and 3A4 activity at PP and PV oxygen tensions showed significant increases at the lower oxygen tension. The activation of the Wnt/ß-catenin pathway only modestly impacted CYP activity at PV oxygen tension, despite a significant increase in CYP expression under this condition. Our results suggest oxygen tension is the major contributor to zonal patterning in HepaRG cells, with the Wnt/ß-catenin signaling pathway playing a lesser albeit important role. Our datasets also highlight the importance of including activity-based assays, as transcript data alone does not provide an accurate picture of metabolic competence. Significance Statement This work investigates the post-differentiation patterning of HepaRG cells cultured at physiologically relevant oxygen tensions, in the presence and absence of Wnt/ß-catenin signaling. HepaRG cells exposed to periportal (11% O2) or perivenous (5% O2) oxygen tensions display zonation-like patterning of both cytochrome P450 (CYP) and glucuronosyltransferase (UGT) enzymes. These datasets also suggest that oxygen is a primary regulator of post-differentiation patterning, with Wnt/ß-catenin having a lesser effect on activity but a significant effect on transcriptional regulation of these enzymes.