title: Small molecule regulation of normal and leukemic stem cells.
abstract: OBJECTIVE
  Hematopoietic stem and progenitor cell (HSPC) transplantation is frequently used in the treatment of hematological diseases. The outcome of the procedure is strongly influenced by the quantity of injected cells, especially if low cell numbers are infused as frequently encountered with cord blood transplants. Ex-vivo expansion of cord blood HSPCs would increase cell numbers, thus accelerating engraftment and reducing infectious complications and transplant-related mortality. In addition, expansion would maximize accessibility to better HLA-matched units, further improving patients' outcome. Similarly, in-vitro maintenance or expansion of leukemic stem cells (LSCs) would enable research into the much awaited targeted therapies that spare normal hematopoietic stem cells (HSCs). Here, we review recent findings on small molecules (excluding biologicals) regulating the activity of normal and leukemic stem cells and provide insights into basic science and clinical implications.
  
  
  RESULTS
  High-throughput screening of small molecules active on primary hematopoietic cells has led to the identification of two potent series of chemical compounds, best exemplified by StemRegenin1 and UM171, that both expand HSPCs. Current data suggest that the aryl hydrocarbon receptor antagonist StemRegenin1 is most active on primitive normal hematopoietic progenitors and LSCs and that UM171 expands long-term normal HSCs.
  
  
  CONCLUSIONS
  Small molecules are clinically useful and powerful tools for expanding HSPCs. They are also of potential value for dissecting the still elusive regulatory networks that govern self-renewal of human HSCs.
authors.affiliation: aMolecular Genetics of Stem Cells Laboratory, Institute for Research in Immunology and Cancer (IRIC), University of Montreal bDivision of Hematology, Maisonneuve-Rosemont Hospital cDepartment of Medicine, Faculty of Medicine, University of Montreal, Montreal, QC, Canada.
authors.forename: Iman
authors.initials: I
authors.lastname: Fares
authors.forename: Laura
authors.initials: L
authors.lastname: Rivest-Khan
authors.forename: Sandra
authors.initials: S
authors.lastname: Cohen
authors.forename: Guy
authors.initials: G
authors.lastname: Sauvageau
mesh_terms: D002452:Cell Count; D018929:Cell Culture Techniques; D049109:Cell Proliferation / Q000187:drug effects; D005312:Fetal Blood / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D005786:Gene Expression Regulation; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D057166:High-Throughput Screening Assays; D006801:Humans; D007211:Indoles / Q000494:pharmacology*; D007938:Leukemia / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D014411:Neoplastic Stem Cells / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D011687:Purines / Q000494:pharmacology*; D011743:Pyrimidines / Q000494:pharmacology*; D018336:Receptors, Aryl Hydrocarbon / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D007211:Indoles; D011687:Purines; D011743:Pyrimidines; D018336:Receptors, Aryl Hydrocarbon; C552240:StemRegenin 1; C000592665:UM171 compound