Comparative analysis of cell lineage differentiation during hepatogenesis in humans and mice at the single-cell transcriptome level

Abstract

During embryogenesis, the liver is the site of hepatogenesis and hematopoiesis and contains many cell lineages derived from the endoderm and mesoderm. However, the characteristics and developmental programs of many of these cell lineages remain unclear, especially in humans. Here, we performed single-cell RNA sequencing of whole human and mouse fetal livers throughout development. We identified four cell lineage families of endoderm-derived, erythroid, non-erythroid hematopoietic, and mesoderm-derived non-hematopoietic cells, and defined the developmental pathways of the major cell lineage families. In both humans and mice, we identified novel markers of hepatic lineages and an ID3+ subpopulation of hepatoblasts as well as verified that hepatoblast differentiation follows the “default-directed” model. Additionally, we found that human but not mouse fetal hepatocytes display heterogeneity associated with expression of metabolism-related genes. We described the developmental process of erythroid progenitor cells during human and mouse hematopoiesis. Moreover, despite the general conservation of cell differentiation programs between species, we observed different cell lineage compositions during hematopoiesis in the human and mouse fetal livers. Taken together, these results reveal the dynamic cell landscape of fetal liver development and illustrate the similarities and differences in liver development between species, providing an extensive resource for inducing various liver cell lineages in vitro.

Integrating Spatial Transcriptomics and Single-Cell RNA-seq Reveals the Gene Expression Profling of the Human Embryonic Liver

“…However, Wang and co-workers found the opposite results. They found that, in both humans and mice, the proliferation rate of hepatoblasts/hepatocytes decreased throughout development ( Wang et al, 2020 ). These differences between studies may be related to both the selection of embryonic stage and the methods.…”

“…The liver consists of greater than 20 cell types, including hepatocytes, liver endothelial cells, biliary ductal cells (cholangiocytes), mesothelial cells, Kupffer cells, and various circulatory immune cells, which are all organized to form the foundation for liver functions, including glycolytic and urea metabolism, immune responses, and drug detoxification ( Wang et al, 2020 ). In the development of human fetus, liver is an essential hemopoietic organ.…”

Signaling molecules orchestrating liver regenerative medicine

“…The specification of hepatoblasts toward hepatocytes has shown to be a default‐directed progressive process in which the transition is characterized by gradual changes in gene expression. However, this is not the case for cholangiocytes which the transition requires regulated signaling and also requires to escape from the default‐directed hepatoblast‐hepatocyte transition (Wang et al, 2020). Differentiation of hepatoblasts into cholangiocytes is promoted by FGF, BMP, and dominantly TGF‐β (through notch signaling) gradients, whereas other signaling molecules such as HGF, OSM, and glucocorticoids induce hepatocyte differentiation (Shin and Monga, 2013; Snykers, De Kock, Rogiers, & Vanhaecke, 2009).…”

“…Although the main phases of liver regeneration were discussed separately in previous sections, mechanistically, numerous investigations have indicated a complex array of interactive signaling factors between these phases, which shows an orchestrated operation of these phases with highly overlapping functions. During early hepatogenesis where the differentiation of progenitor cells toward specified hepatocytes is pursued, not only the proliferation of progenitor cells along with progressive gene specialization (toward hepatocytes) occurs, but also, simultaneously, the proliferation of highly specified hepatocytes is followed where a mixture of proliferating hepatoblast and hepatocytes is detectable in the developing tissue (Butler, Hoffman, Smibert, Papalexi, & Satija, 2018; Michalopoulos & DeFrances, 1997; Wang et al, 2020). In fact, as the tissue development proceeds, the ratio of hepatoblast/hepatocytes is decreased until the time in which the regeneration is further followed only by hepatocyte proliferation (Butler et al, 2018; Wang et al, 2020).…”

“…During early hepatogenesis where the differentiation of progenitor cells toward specified hepatocytes is pursued, not only the proliferation of progenitor cells along with progressive gene specialization (toward hepatocytes) occurs, but also, simultaneously, the proliferation of highly specified hepatocytes is followed where a mixture of proliferating hepatoblast and hepatocytes is detectable in the developing tissue (Butler, Hoffman, Smibert, Papalexi, & Satija, 2018; Michalopoulos & DeFrances, 1997; Wang et al, 2020). In fact, as the tissue development proceeds, the ratio of hepatoblast/hepatocytes is decreased until the time in which the regeneration is further followed only by hepatocyte proliferation (Butler et al, 2018; Wang et al, 2020). Similarly, in the regeneration process after partial hepatectomy of mice liver, if no delay in hepatocyte proliferation occurs, a rough simultaneous specification of hepatic resident progenitors and cell cycle activity of parenchymal hepatocytes proceeds, whereas if the hepatocytes proliferation impaired or delayed, the hepatoblast specification precedes, and they invade the adjacent tissue as they proliferate (Li et al, 2013).…”