July 20, 2021
**< .01 and ***< .001 between the indicated culture formats. Discussion In this study, we developed the first-of-its-kind cell culture platform that induces high and stable levels of phenotypic functions in both PHHs and primary human LSECs over the course of several weeks. contrast, both PHHs and endothelial cells displayed stable phenotype for 3 weeks in PHH/fibroblast/endothelial cell tricultures; furthermore, layered tricultures in which PHHs and endothelial cells were separated by a protein gel to mimic the space of Disse displayed similar functional levels as the coplanar tricultures. Conclusions PHH/fibroblast/endothelial tricultures constitute a robust platform to elucidate reciprocal interactions between PHHs and endothelial cells in physiology, disease, and?after drug exposure. assays for drug development.11 Given their physiological relevance, isolated primary human hepatocytes (PHHs) are widely considered to be ideal for building human liver models. However, when cultured in the presence of ECM proteins (eg, collagen) alone, PHHs rapidly (hours to days) decline in critical phenotypic functions, such as cytochrome P-450 (CYP450) enzyme activities,12 insulin responsiveness,13 and expression of the master liver transcription factor, hepatocyte nuclear factor 4.14 Similarly, when cultured alone, LSECs lose their characteristic fenestrations and undergo apoptosis within a few days.15 In contrast to hepatocyte monocultures, coculture with both liver- and nonliver-derived NPC types can enhance hepatocyte functions in culture.16 Endothelial cells have been previously explored toward transiently enhancing hepatocyte functions in cocultures relative to declining hepatocyte monocultures. However, many such hepatocyte-endothelial coculture studies use rodent cells17, 18, 19, 20, 21 that do not completely suffice for modeling human liver biology. Furthermore, the use of abnormal cancerous cell lines22, 23, 24 and/or nonliver endothelial cells17, 19, 21, 25 may provide a first approximation of hepatocyte-endothelial interactions but needs to be complemented with the use of primary cells from human liver?tissue to Bisoprolol fumarate determine similarities and differences in observed cell responses. Indeed, the Yarmush group has created cocultures of PHHs and primary human LSECs, which showed high level of low-density lipoprotein uptake in PHHs in the presence of LSECs,26 and increased (1.3-fold) hepatic CYP1A activity in serum-free coculture with endothelial cells under high (95%) oxygen levels.27 However, it is not clear from these short-term (24 hours) data sets whether LSECs can induce high levels of phenotypic functions in PHHs over long-term (weeks) culture as compared with PHH monocultures. Bisoprolol fumarate Additionally, the differential effects of LSECs on PHH functions relative to?nonliver vascular endothelial cells remain to be elucidated. To address the Bisoprolol fumarate limitations with the previously mentioned hepatocyte-endothelial coculture studies, here we sought to first elucidate the effects of primary human LSECs on the long-term functions of PHHs with comparisons to nonliver endothelial cells (human umbilical vein endothelial cells [HUVECs]) and PHH monocultures. We benchmarked the effects of endothelial cells on PHHs to the effects of 3T3-J2 murine embryonic fibroblasts, a cell type?that expresses hepatocyte-supporting molecules present in the liver28 and is known to induce high levels of functions in PHHs for 4C6 weeks as the housekeeping gene. Statistical significance was determined with a 1- or 2-way analysis of?variance followed by a Bonferroni pair-wise post hoc test?(< .05). Results Comparison of Primary Human Hepatocytes/Endothelial and Primary Human Hepatocytes/Fibroblast Cocultures LIFR Primary human LSECs and primary HUVECs displayed prototypical endothelial morphology for up to 6 passages (Figure?1) and could be subsequently used for cocultivation with PHHs. Micropatterned cocultures of PHHs?and endothelial cells (either LSECs or HUVECs) were compared with cocultures of PHHs and 3T3-J2 fibroblasts (Figure?2(all culture models shown contained micropatterned PHHs).