Programming and re-programming of haemopoietic cell fate

Lead Research Organisation: University of Oxford

Abstract

The blood is composed of a variety of different types of cells that each have specialised and distinct functions. As these cells die they are replenished by a small pool of long-lived cells known as stem cells which have the capacity both to produce more stem cells (a process termed self-renewal) or give rise to all the specialized blood cell types of the blood (a process termed differentiation). Our research programme attempts to understand, at the molecular level, how stem cells decide whether to self-renew, or to differentiate and in the latter case, into which cell type (a process termed lineage-specification). These working decisions that stem cells make are ultimately effected at the level of differential gene activity or usage, and gaining an understanding of how this process works is an important problem in developmental biology, transplantation medicine, stem cell based gene therapy and haematological malignancy. We study this process by genetically altering the activities of candidate molecular regulators of these processes. We anticipate that these studies will illuminate how normal cell fate decisions are instigated and inform approaches aimed at manipulating the expansion, directed-differentiation or reprogramming of stem cell fate for therapeutic or commercial advantage.

Technical Summary

All the different specialised cell types that constitute the blood are derived from a multipotential haemopoietic stem cell (HSC). HSCs are long-lived and in addition to having the capacity to give rise, through differentiation, to all blood lineages, HSC are capable of extensive self-renewal. It remains unclear at the molecular level how the balance between self-renewal and differentiation is regulated and how the different blood lineages are specified. However we can presume that the process of cell type restriction involves the formation of stable transcription factor complexes that initiate and consolidate (or repress) exclusive programmes of gene expression. Transcription factors have therefore been intensively studied as candidate instigators of cell fate decisions. This capacity has been emphasised by recent studies that indicate that individual transcription factors can reprogramme the development fate of already committed cell types. In our own laboratory we have shown that the erythroid-affiliated transcription factor GATA-1 can re-specify the fate of freshly isolated, bone marrow-derived, committed neutrophil-monocyte progenitors. In response to exogenous GATA-1 activity these cells adopt erythroid or other GATA-1-affiliated cell fates. These observations provide a mechanism for reprogramming of committed haematopoietic progenitors and an experimental entry point for directly identifying the key loci involved. Since manipulation of GATA-1 activity can also alter cell fate in multipotential progenitors that express endogenous GATA-1 and retain both erythroid and neutrophil monocyte potential, the same mechanisms and loci are likely to also be directly involved in normal uni-lineage differentiation from multipotent progenitor cells. Thus our approach is to examine transcription factor-mediated alterations in cell fate primarily in the experimental context of reprogramming and apply our results to the more normal context of cell fate programming from the multipotential uncommitted state. We will ask the following questions: 1) Which cells can be reprogrammed (lineage/stage of differentiation) by a single transcription factor. 2) Which transcription factors can reprogram. 3) What is the mechanism of reprogramming, is it de-differentiation or trans-differentiation? 4) How complete is the reprogramming i.e. do the cells show residual features of their original lineage and are they fully functional? 5) To what extent is the mechanism the same regardless of the lineage/stage being reprogrammed and to what extent is it lineage/stage specific? 6) What is the detailed mechanism of reprogramming in respect of target genes, chromatin re-modelling etc. 7) Does reprogramming require cell division. 8) Can human cells be reprogrammed? 9) To what extent to the processes which mediate reprogramming also function to programme the cell fate output of multipotent cells. We anticipate that these studies will contribute to our understanding of how normal cell fate decisions are instigated and inform approaches aimed at manipulating the expansion, directed-differentiation or reprogramming of stem cell fate for therapeutic or commercial advantage.
 
Description Cord Blood
Geographic Reach National 
Policy Influence Type Participation in advisory committee
 
Description ESTOOLs - EU Framework6 integrated Project to examine mechanisms of human ES cell self renewal and differentiation
Amount € 205,854 (EUR)
Funding ID 18739 
Organisation Sixth Framework Programme (FP6) 
Sector Public
Country European Union (EU)
Start  
 
Description EUROCSC - "STREP" Consortium for the study of Cancer Stem Cells
Amount £148,170 (GBP)
Funding ID 37632 
Organisation European Commission 
Sector Public
Country European Union (EU)
Start  
 
Description EuroSystem European Federation for Systematic Stem Cell Biology
Amount £394,168 (GBP)
Funding ID 200720 
Organisation European Commission 
Sector Public
Country European Union (EU)
Start  
 
Description STEMEXPAND - Stem Cell Expansion - Expansion and engraftment of haematopoietic and mesenchymal stem cells
Amount £384,233 (GBP)
Funding ID 222989 
Organisation European Commission 
Sector Public
Country European Union (EU)
Start  
 
Description Transcriptional programming of pre-leukaemia and leukaemia stem and progenitor cells in childhood ALL
Amount £1,451,548 (GBP)
Organisation Leukaemia and Lymphoma Research 
Sector Charity/Non Profit
Country United Kingdom
Start  
 
Title Network Database 
Description A database of gene expression profiles and transcription factor targets throughout blood lineage development. 
Type Of Material Biological samples 
Year Produced 2009 
Provided To Others? Yes  
Impact This database is serving to foster collaborative interactions with European colleagues including Gerald de Haan - University of Gronigen, Netherlands, Carsten Petersen, University of Lund, Sweden, Ingo Roeder University of Leipzig, Germany and Ruud Delwel Erasmus University, The Netherlands 
 
Description Micro Array Development 
Organisation Oxford Gene Technology
Country United Kingdom 
Sector Private 
PI Contribution We have provided consultation about stem cell biology. We have provided stem cells and cell lines and identified gene targets for technology validation.
Collaborator Contribution OGT have provided my laboratory with state of the art micro array platforms and assisted in design of array based experiments.
Impact Interactions with Oxford Gene Technology have lead to partnership in a new Eu framework 7 programme EuroSYSTEM. They have resulted in on going development of novel array based methods for analysis of gene expression in single cells.
 
Description Network reconstruction 
Organisation Lund University
Country Sweden 
Sector Academic/University 
PI Contribution We have provided data sets and in depth knowledge of the biology of blood based stem cell systems.
Collaborator Contribution This partnership has provided a PhD student based in the department of theoretical physics in Lund University under the direction of Carsten Petersen. This student's project is solely based on mathematical analysis of data produced by our MRC programme.
Impact Co-authored publication in PLOS Computational Biology PubMed ID 19165316 There has been an exchange of my MRC funded bioinformatician (Shamit Soneji) between sites. Additionally we have received bioinformatical support from other members of the theoretical physics department.
 
Description Stem cell expansion 
Organisation Lund University
Country Sweden 
Sector Academic/University 
PI Contribution We have provided candidate genes involved in self renewal and molecular biology expertise.
Collaborator Contribution Stefan Karlsson's laboratory has assisted us with in-depth knowledge of short hair pin RNA vectors and gene therapy approaches for our studies of human blood stem cell self renewal.
Impact We have achieved funding through the Haemato Linne Programme in Sweden to support a joint post doctoral fellow based in Sweden.
Start Year 2007
 
Description Bryanstone School 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? Yes
Geographic Reach Local
Primary Audience Schools
Results and Impact Prof Enver accompanied by Dr Emma Kemp from Public Outreach Division of EuroSystem (EU Framework 7) showed a movie (stem cell story) to students from the Bryanstone School Science Society - approx 70 children. Prof Enver then presented his own research in an accessible form and hosted a question and answer session on both topics. The event took approximately 2 hours.

Several school children requested laboratory placements in Prof Enver's lab and they were directed to Emma Kemp at EuroSystem for further information.
Year(s) Of Engagement Activity 2009
 
Description Geoff Thomas 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Policymakers/politicians
Results and Impact Prof Enver attended House of Commons to brief parliamentarians and representatives of charitable and pharmasuitacle sectors on break throughs in cancer stem cell science. This presentation was in support of the activities of the Geoff Thomas Foundation.which is raising funds for Leukaemia Research. http://www.geoffthomasfoundation.org/site/index.php?option=com_content&view=article&id=20&Itemid=68

Raised awareness.
Year(s) Of Engagement Activity 2008
 
Description ISSCR - Barcelona 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? Yes
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact Prof Enver assembled a panel of scientists, ethisists and health care professionals to assist in a panel discussion based around short movies describing stem cells. The event was entitled "Everything you wanted to know about Stem cells but were afraid to ask" and took place at Bosmo Caixa Museum, Barcelona. It was attended by a range of scientists, patient advocate, patients, policy makers, lay public and journalists. In addition through the offices of ESTOOLS we put on a photographic exhibit entitled "Smile of a Stem Cell" which was displayed at the Cosmo Caixa Museum and open to public and scientists alike.

This is part of on-going public engagement and out reach by the ISSCR but most importantly this served as a platform for high lighting the activities of two major European networks focused on stem cell research namely EuroSystem and ESTOOLS.
Year(s) Of Engagement Activity 2009
 
Description Leukaemia Research Fund Golf Charity Day, Ashridge 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Public/other audiences
Results and Impact Prof Enver described his research to approx 100 members of the public who had participated in a charitable golf event.

This event raised approx £10k for Leukaemia Research and enhanced the scientific understanding of patients and their families in respect of the diseases which afflict them.
Year(s) Of Engagement Activity 2009
 
Description Lord Patel 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Policymakers/politicians
Results and Impact Prof Enver described the state of the art in stem cell biology to an assembly and parliamentarians and policymakers at the invitation of Lord Narendra Patel.

This was part of informing opinion around the issue of stem cells and there by helping to maintain progressive legislation and competitiveness in the stem cell area within the UK.
Year(s) Of Engagement Activity 2006
 
Description Twins with Leukaemia 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Media (as a channel to the public)
Results and Impact Prof Enver attended the Science Media Centre and presented findings recently published in Science Magazine, Hong et al 'Initiating and cancer-propagating cells in TEL-AML10 associated childhood leukaemia", which pertained to the origins of childhood leukaemia.

This story was widely covered in national and international news media including the front page of The Independent and major tv coverage.
Year(s) Of Engagement Activity 2008