efficient-differentiation-human-pluripotent-stem-cells-into-liver

Efficient Differentiation of Human Pluripotent Stem Cells into Liver Cells

The liver detoxifies harmful substances, secretes vital proteins, and executes key metabolic activities, thus sustaining life. Consequently, liver ...

Stanford University School of Medicine

Liver diseases afflict millions of patients worldwide. Currently, the only long-term treatment for liver failure is the transplantation of a new liver. However, intravenously transplanting a suspension of human hepatocytes might be a less-invasive approach to partially reconstitute lost liver functions in human patients as evinced by promising outcomes in clinical trials. The purpose of this essay is to emphasize outstanding questions that continue to surround hepatocyte transplantation. While adult primary human hepatocytes are the gold standard for transplantation, hepatocytes are heterogeneous. Whether all hepatocytes engraft equally and what specifically defines an "engraftable" hepatocyte capable of long-term liver reconstitution remains unclear. To this end, mouse models of liver injury enable the evaluation of human hepatocytes and their behavior upon transplantation into a complex injured liver environment. While mouse models may not be fully representative of the injured human liver and human hepatocytes tend to engraft mice less efficiently than mouse hepatocytes, valuable lessons have nonetheless been learned from transplanting human hepatocytes into mouse models. With an eye to the future, it will be crucial to eventually detail the optimal biological source (whether in vivo- or in vitro-derived) and presumptive heterogeneity of human hepatocytes and to understand the mechanisms through which they engraft and regenerate liver tissue in vivo.

Evaluating the regenerative potential and functionality of human liver cells in mice.

Multiple adult tissues are maintained by stem cells of restricted developmental potential which can only form a subset of lineages within the tissue. For instance, the two adult lung epithelial compartments (airways and alveoli) are separately maintained by distinct lineage-restricted stem cells. A challenge has been to obtain multipotent stem cells and/or progenitors that can generate all epithelial cell types of a given tissue. Here we show that mouse Sox9 multipotent embryonic lung progenitors can be isolated and expanded long term in 3D culture. Cultured Sox9 progenitors transcriptionally resemble their in vivo counterparts and generate both airway and alveolar cell types in vitro. Sox9 progenitors that were transplanted into injured adult mouse lungs differentiated into all major airway and alveolar lineages in vivo in a region-appropriate fashion. We propose that a single expandable embryonic lung progenitor population with broader developmental competence may eventually be used as an alternative for region-restricted adult tissue stem cells in regenerative medicine.

Isolation and 3D expansion of multipotent Sox9 mouse lung progenitors.

How are closely related lineages, including liver, pancreas, and intestines, diversified from a common endodermal origin? Here, we apply principles learned from developmental biology to rapidly reconstitute liver progenitors from human pluripotent stem cells (hPSCs). Mapping the formation of multiple endodermal lineages revealed how alternate endodermal fates (e.g., pancreas and intestines) are restricted during liver commitment. Human liver fate was encoded by combinations of inductive and repressive extracellular signals at different doses. However, these signaling combinations were temporally re-interpreted: cellular competence to respond to retinoid, WNT, TGF-β, and other signals sharply changed within 24 hr. Consequently, temporally dynamic manipulation of extracellular signals was imperative to suppress the production of unwanted cell fates across six consecutive developmental junctures. This efficiently generated 94.1% ± 7.35% TBX3HNF4A human liver bud progenitors and 81.5% ± 3.2% FAH hepatocyte-like cells by days 6 and 18 of hPSC differentiation, respectively; the latter improved short-term survival in the FahRag2Il2rg mouse model of liver failure.

Article	Year
Evaluating the regenerative potential and functionality of human liver cells in mice. Differentiation; research in biological diversity\| PubMed ID: 29078082	2017
Isolation and 3D expansion of multipotent Sox9 mouse lung progenitors. Nature methods\| PubMed ID: 29106405	2017
A Roadmap for Human Liver Differentiation from Pluripotent Stem Cells. Cell reports\| PubMed ID: 29466743	2018

Lay Teng Ang

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