Speaker
Description
Background: In vitro models of human liver development are crucial for studying the impact of xenobiotic exposure on the developing fetus and neonate. However, the limited availability of fetal and neonatal primary human hepatocytes (PHHs) makes it difficult to conduct these studies, leaving these populations vulnerable to empirical drug dosing and possible related toxicities.
Methods: Induced pluripotent stem cells (iPSCs) derived from adult cells were differentiated into fetal/neonatal hepatocyte-like cells (fnHLCs) over a 26-day period to mimic in utero hepatocyte development. The gene expression profiles (via qPCR) and metabolic capabilities of the fnHLCs were compared to those of 1-day old neonatal PHHs and adult PHHs. In addition, induction (using rifampicin and betamethasone) and hepatotoxicant bioactivation assays (using aflatoxin B1) were conducted to assess model robustness.
Results: The fnHLC model displayed a mix of fetal and neonatal gene expression markers - including high levels of CYP3A7, AFP, and GSTP1 - distinct from adult PHHs. Functionally, fnHLCs demonstrated the ability to metabolize DHEA to 16αOH DHEA, which is produced by fetal/neonatal CYP3A7. Additionally, fnHLCs metabolized midazolam (MDZ) with 1’OH/4OH metabolite ratios (~1.04) that closely resembled those observed in neonatal PHHs (~1.82), contrasting sharply with adult PHHs (~5.97). fnHLCs successfully modeled neonatal drug responses by lacking significant CYP3A7 mRNA induction upon rifampicin treatment and by demonstrating CYP-mediated bioactivation of aflatoxin B1 to the AFQ1 metabolite.
Conclusions: iPSC-derived fnHLCs successfully recapitulate important drug-metabolizing gene expression and enzymatic functions characteristic of the developing human liver. This model provides highly valuable in vitro platform for investigating xenobiotic metabolism and toxicity during the critical fetal and neonatal developmental stages.
Acknowledgments:
This was generously supported by the NIH National Institute of Allergy and Infectious Diseases, grant No. AI183687 to JNL.
