Developmental insights from early mammalian embryos and core signaling pathways that influence human pluripotent cell growth and differentiation

Abstract

Human pluripotent stem cells (hPSCs) have two potentially attractive applications: cell replacement-based therapies and drug discovery. Both require the efficient generation of large quantities of clinical-grade stem cells that are free from harmful genomic alterations. The currently employed colony-type culture methods often result in low cell yields, unavoidably heterogeneous cell populations, and substantial chromosomal abnormalities. Here, we shed light on the structural relationship between hPSC colonies/embryoid bodies and early-stage embryos in order to optimize current culture methods based on the insights from developmental biology. We further highlight core signaling pathways that underlie multiple epithelial-to-mesenchymal transitions (EMTs), cellular heterogeneity, and chromosomal instability in hPSCs. We also analyze emerging methods such as non-colony type monolayer (NCM) and suspension culture, which provide alternative growth models for hPSC expansion and differentiation. Furthermore, based on the influence of cell-cell interactions and signaling pathways, we propose concepts, strategies, and solutions for production of clinical-grade hPSCs, stem cell precursors, and miniorganoids, which are pivotal steps needed for future clinical applications.

An expandable embryonic stem cell-derived Purkinje neuron progenitor population that exhibits in vivo maturation in the adult mouse cerebellum

“…Once specification of the MHB-region was reached, neuronal and glial cell progenitor populations were born spontaneously and required no further treatment other than isolation by replating on laminin in NPC medium 29 . Laminin, which can act as a key maintenance component of the basement membrane surrounding epithelial cells during early stages of embryonic development 55 , served as an effective surface coating following neural differentiation 25 , 56 , 57 . FGF2, which can induce rhombomere-1 activity 58 , was also critical in that it helped NPCs to maintain their neuronal progenitor functionality, probably by keeping the population mitotically active and by preventing the initiation of terminal differentiation 59 .…”

Capturing the ephemeral human pluripotent state

“…It has been hypothesized that colonies of hPSC grown on fibroblast‐like cells lose their pluripotent identity and acquire mesenchymal characteristics because the hPSC interact with fibroblasts at the periphery where there is no ECAD‐mediated cell–cell contact. In contrast, a noncolony monolayer of hPSC will have continuous intercellular adhesions mediated by ECAD and a more stable pluripotent phenotype (Chen et al, ).…”

Lost in Translation: Regulation of ABCG2 Expression in Human Embryonic Stem Cells

“…In particular, hESC experiments could be greatly influenced by growth media containing various growth factors, extracellular matrices, environmental cues, and various growth patterns (9). Suboptimal growth factors may definitely result in alterations of core signaling pathways, which underlie epithelial-to-mesenchymal transitions (EMTs), cellular heterogeneity, and chromosomal instability in hESCs (10). All the above conditions would alter ABCG2 expression and localization.…”