Hormone and Drug-Mediated Modulation of Glucose Metabolism in a Microscale Model of the Human Liver.

Due to its central role in glucose homeostasis, the liver is an important target for drug development efforts for type 2 diabetes mellitus (T2DM). Significant differences across species in liver metabolism necessitate supplementation of animal data with assays designed to assess human-relevant responses. However, isolated primary human hepatocytes (PHHs) display a rapid decline in phenotypic functions in conventional monolayer formats. Cocultivation of PHHs with specific stromal cells, especially in micropatterned configurations, can stabilize some liver functions for ~4 weeks in vitro. However, it remains unclear whether coculture approaches can stabilize glucose metabolism that can be modulated with hormones in PHHs. Thus, in this study, we compared commonly employed conventional culture formats and previously developed micropatterned cocultures (MPCCs) of cryopreserved PHHs and stromal fibroblasts for mRNA expression of key glucose metabolism genes (i.e., phosphoenolpyruvate carboxykinase-1 [PCK1]) and sensitivity of gluconeogenesis to prototypical hormones, insulin and glucagon. We found that only MPCCs displayed high expression of all transcripts tested for at least 2 weeks and robust gluconeogenesis with responsiveness to hormones for at least 3 weeks in vitro. Furthermore, MPCCs displayed glycogen storage and lysis, which could be modulated with hormones under the appropriate feeding and fasting states, respectively. Finally, we utilized MPCCs in proof-of-concept experiments where we tested gluconeogenesis inhibitors and evaluated the effects of stimulation with high levels of glucose as in T2DM. Gluconeogenesis in MPCCs was decreased after stimulation with drugs (i.e., metformin) and the PHHs accumulated significant amount of lipids following incubation with excess glucose (i.e., 340% in 50 mM glucose relative to physiologic 5 mM glucose controls). In conclusion, MPCCs provide a platform to study glucose metabolism and hormonal responsiveness in cryopreserved PHHs from multiple donors for several weeks in vitro. This model is also useful to study the effects of drugs and overnutrition for applications in T2DM.