Research

Generating human artery and vein cells from pluripotent stem cells reveals the arterial tropism of Nipah and Hendra viruses.

Blood vessels have wide-ranging roles in health and disease, and include multiple subtypes (e.g. arteries and veins). We differentiated human pluripotent stem cells into artery and vein endothelial cells at >90% purity in 3-4 days, mapping changes in extracellular signals, gene expression, chromatin state, and cell-surface markers at each differentiation step. Next, we applied these artery and vein cells to study deadly infection of the human vasculature by biosafety level 4 (BSL4) viruses, specifically Nipah and Hendra viruses (which have ~57-59% fatality rates). Both viruses preferentially infected artery cells in vitro and created multinucleated arterial syncytia, consistent with arterially-biased expression of their entry receptor. This illuminates origins of human endothelial subtype diversity; reveals specific endothelial subtypes targeted by BSL4 viruses; and delineates for the first time a stem cell-based toolkit for BSL4 virology. 

Ang LT*^,y, Nguyen A^y, Liu KJ^y, Chen A, Xiong XC, Curtis M, Martin RM, Raftry BC, Ng CY,  Vogel U, Lander A, Lesch BJ, Fowler J, Holman AR, Chai T,  Yang Y, Vijayakumar S, Suchy FP, Nishimura T, Bhadury J, Porteus MH, Nakauchi H, Cheung C, George SC, Red-Horse K, Prescott JB* & Loh KM* (2022) Generating human artery and vein cells from pluripotent stem cells reveals the arterial tropism of Nipah and Hendra viruses. Cell 185, 1–19

Efficient generation of endodermal cell-types from human pluripotent stem cells

We identified signals driving the stepwise differentiation of hPSCs into anterior primitive streak, and subsequently, definitive endoderm while concomitantly inhibiting the formation of unwanted cell-types (mesoderm and ectoderm). We consistently generated ~94% pure endoderm from 9 distinct hPSC lines, showing that we could minimize line-to-line variability in differentiation by specifically inhibiting formation of unwanted cell-types. These pure endoderm populations allowed us to generate downstream liver, pancreatic, and intestinal progenitors from hPSCs and enabled molecular analysis of endoderm differentiation.

Loh KM^y,*, Ang LT^y,*, Zhang J, Kumar V, Ang J, Auyeong JQ, Lee KL, Choo SH, Lim CYY, Nichane M, Tan J, Noghabi MS, Azzola L, Ng ES, Durruthy-Durruthy J, Sebastiano V, Poellinger L, Elefanty AG, Stanley EG, Chen Q, Prabhakar S, Weissman IL, Lim B (2014). Efficient endoderm induction from human pluripotent stem cells by logically directing signals controlling lineage bifurcations. Cell Stem Cell 14: 237-52.

Efficient generation of liver progenitors from human pluripotent stem cells and their use to treat liver failure

It is a challenge to generate pure populations of human hepatocytes from hPSCs. To address this, we mapped liver development from hPSCs and defined signalling pathways that regulate multiple consecutive stages of liver differentiation, including patterning of human endoderm into foregut; liver bud specification; and segregation of hepatocyte vs. biliary fates. This roadmap enabled us to generate >80% pure hepatocytes by day 18 of differentiation, which could engraft in the Fah^-/- Rag2^-/- Il2rg^-/- mouse model of chronic liver failure.

Ang LT*, Tan AKY, Autio MI, Goh SH, Choo SH, Lee KL, Tan JM, Pan B, Lee JH, Lum JJ, Lim YY, Yeo KX, Wong JY, Liu M, Oh LL, Chia PL, Loh CH, Chen A, Chen QF, Weissman, IL, Loh KM, Lim B* (2018). A roadmap for human liver differentiation from pluripotent stem cells. Cell Reports Feb 20;22(8):2190-2205.

Efficient generation of mesodermal cell-types from human pluripotent stem cells

How do different mesodermal cell-types emerge? We 1) mapped the sequence of pairwise lineage choices through which distinct mesodermal precursors are formed and 2) determined the positively- and negatively-acting extracellular signals that promote or repress mesodermal cell fates at each lineage juncture. This knowledge helped us efficiently differentiate hPSCs into 12 human mesodermal lineages, including bone and heart progenitors, each of which could engraft mouse models and regenerate their respective human tissue in vivo.

Loh KM^y, Chen A^y, Koh PW, Deng T, Sinha R, Tsai JM, Barkal AA, Shen KY, Jain R, Morganti RM, Ng SC, Morganti RM, Fernhoff NB, George BM, Wernig G, Salomon RAE, Chen Z, Vogel H, Epstein JA, Kundaje A, Talbot WS, Beachy PA, Ang LT*, Weissman IL* (2016). Mapping the pairwise choices and leading from pluripotency to human bone, heart and other mesoderm cell-types. Cell 166: 451-467