Dr Wei Cui - Stem Cell Differentiation
Background
Embryonic stem (ES) cells are derived from the inner cell mass of pre-implantation embryos and can be expanded to large numbers whilst maintaining their differentiation potentials of embryonic founder cells, being able to differentiate into all the cell types of an organism. Therefore, ES cells have important implications for providing insight into basic developmental biology.
The study of ES cell biology has become more intriguing by the establishment of human ES cells (hESCs) because it provides unlimited resources not only for studying basic human developmental biology but also for their potential clinical applications. Our group is interested in identifying and characterizing signalling pathways controlling ES cell differentiation to specific lineage fates.
Aim
The overall aim of our research is to understand the molecular mechanism controlling efficient differentiation of ES cells, particularly hESCs, to neural lineage and hepatic cell fate.
Research projects
- Characterisation of Neural Progenitors/Stem Cells Derived From Human Embryonic Stem Cells
- Using human embryonic stem cell as model system to study telomere and telomerase biology
- Generation of functional hepatocytes from human embryonic stem cells
Characterisation of Neural Progenitors/Stem Cells Derived From Human Embryonic Stem Cells
We have previously developed a procedure in which hESCs can be differentiated efficiently to neural progenitors (Figure 1). The hESC-derived neural progenitors can be cultured extensively and still express certain neural progenitor markers. However, the cells do not have the same characteristics throughout. It is possible that these changes reflect the process during in vivo neural development. Therefore, it is important to understand the molecular mechanisms underlie these changes.
The objectives of this project are:
- to characterise hESC-derived neural progenitors at various differentiation stages for their molecular signature as well as their developmental potentials;
- to explore molecular mechanisms that regulate cell differentiation at various time points.
Fig.1 Schematic illustration of neural differentiation of hESCs.
Using human embryonic stem cell as model system to study telomere and telomerase biology
Telomeres are specialized DNA-protein structures at each chromosome ends of eukaryotes and play a critical role in the maintenance of chromosomal integrity and genome stability. Telomerase is a nucleoprotein complex for the de novo synthesis of telomeres.
Telomerase consists of two important core components: a catalytic telomerase reverse transcriptase (TERT), a RNA unit (TR). During human development, expression of hTERT is restricted in germ cells, early embryos and certain adult progenitor/stem cells and is low or absent in somatic cells.
However, hTERT is expressed in over 90% cancers and contributes to the immortalisation of cancer cells. Human embryonic stem cells (hESCs) express high levels of telomerase in their undifferentiated status and have stable telomere lengths. However, upon differentiation, hTERT is dramatically downregulated which results in telomere shortening when cells divide.
Therefore, hESCs provide a unique in vitro model to study the regulation of telomerase and telomeres and their function. In this work, we intend to use hESCs and their neural derivatives as model system to investigate the impact of hTERT expression on hESC self-renewal and differentiation and to understand molecular mechanisms that regulate telomerase expression and telomere lengths.
Generation of functional hepatocytes from human embryonic stem cells
Distinct properties of hESCs make them not only a potential cell resource for clinical application but also a valuable cell source for biomedical applications, particularly in drug discovery and toxicology studies. In this project, we seek to improve our culture and differentiation conditions in order to improve functions of hESC-derived hepatocytes.
Selected publications:
1. Wu,JQ, Habegger L, Noisa P, Szekely A, Qiu C, Hutchison S, Raha D, Egholm M, Lin H, Weissman S, Cui W, Gerstein M, Snyder M. (2010). Dynamic transcriptomes during neural differentiation of human embryonic stem cells revealed by short, long, and paired-end sequencing. Proc.Natl.Acad.Sci.U.S.A. 107, 5254-5259.
2. Narva E, Autio R, Rahkonen N, Kong L, Harrison N, Kitsberg D, Borghese L. Itskovitz-Eldor J, Rasool O. Dvorak P, Hovatta O, Otonkoski T, Tuuri T, Cui W, Brustle O, Baker D, Maltby E, Moore HD, Benvenisty N, Andrews PW, Yli-Harja O, Lahesmaa R. (2010). High-resolution DNA analysis of human embryonic stem cell lines reveals culture-induced copy number changes and loss of heterozygosity. Nat.Biotechnol. 28, 371-377
3. Rahman R, Forsyth NR, Cui W. (2008). Telomeric 3'-overhang length is associated with the size of telomeres. Exp. Gerontol. 43, 258-265.
4. Hay DC, Zhao D, Fletcher J, Hewitt ZA, McLean D, Urruticoechea-Uriguen A, Black JR, Elcombe C, Ross JA, Wolf R, Cui W. (2008). Efficient differentiation of hepatocytes from human embryonic stem cells exhibiting markers recapitulating liver development in vivo. Stem Cells 26, 894-902.
5. Hay DC, Zhao D, Ross A, Mandalam R. Lebkowski J, Cui W. (2007) Direct Differentiation of Human Embryonic Stem Cells to Hepatocyte-Like Cells Exhibiting Functional Activities. Cloning Stem Cells 9: 51-62.
6. Guillot PV, Cui W, Fisk NM, Polak DJ. (2007) Stem cell differentiation and expansion for clinical applications of tissue engineering. J Cell Mol Med. 11:935-944.
7. Gerrard L, Rodgers L, Cui W. (2005) Differentiation of Human Embryonic Stem Cells to Neural Lineages in Adherent Culture by Blocking Bone Morphogenetic Protein Signaling. Stem Cells 23: 1234-1241.
8. Gerrard L, Zhao D, Clark AJ, Cui W. (2005) Stably transfected human embryonic stem cell clones express OCT4-specific green fluorescent protein and maintain self-renewal and pluripotency. Stem Cells 23:124-33.
9. Clark AJ, Ferrier P, Aslam S, Burl S, Denning C, Wylie D, Ross A, de Sousa P, Wilmut I, Cui W. (2003) Proliferative lifespan is conserved after nuclear transfer. Nat Cell Biol 5:535-8.
10. Cui W., Wylie D, Aslam S, Dinnyes A, King T, Wilmut I, Clark AJ (2003) Telomerase-immortalized sheep fibroblasts can be reprogrammed by nuclear transfer to undergo early development. Biol Reprod 69:15-21.
11. Cui W, Aslam S, Fletcher J, Wylie D, Clinton M, Clark AJ (2002) Stabilization of Telomere Length and Karyotypic Stability Are Directly Correlated with the Level of hTERT Gene Expression in Primary Fibroblasts. J Biol Chem 277:38531-8.
12. Cui W, Allen ND, Skynner M, Gusterson B, Clark AJ (2001) Inducible ablation of astrocytes shows that these cells are required for neuronal survival in the adult brain. Glia 34:272-82.
13. Cui W, Gusterson B, Clark AJ (1999) Nitroreductase-mediated cell ablation is very rapid and mediated by a p53-independent apoptotic pathway. Gene Ther 6:764-70.
14. Cui W, Fowlis DJ, Bryson S, Duffie E, Ireland H, Balmain A, Akhurst RJ (1996) TGFbeta1 inhibits the formation of benign skin tumors, but enhances progression to invasive spindle carcinomas in transgenic mice. Cell 86:531-42.
15. Cui W, Fowlis DJ, Cousins FM, Duffie E, Bryson S, Balmain A, Akhurst RJ (1995) Concerted action of TGF-beta 1 and its type II receptor in control of epidermal homeostasis in transgenic mice. Genes Dev 9:945-55.
