title: New approaches to expand hematopoietic stem and progenitor cells.
abstract: BACKGROUND
  Hematopoietic stem cells (HSCs) are defined by their capacity to self-renew and to differentiate into all blood cell lineages, and are currently the foundation of HSC transplantation therapy. A variety of methods have recently been explored to find a way to expand hematopoietic stem and progenitor cells (HSCs/PCs) ex vivo in order to improve the efficiency and outcome of HSC transplantation.
  
  
  METHODS
  Recent studies of HSCs/PCs have led to the development of new ways to detect and purify HSCs/PCs and have also revealed several intrinsic and extrinsic factors that control the molecular signals fundamental to self-renewal and differentiation of HSCs. These findings have provided new approaches for expanding HSCs/PCs ex vivo utilizing protein factors and small-molecule compounds (SMCs) and have also demonstrated promising outcomes in clinical trials.
  
  
  CONCLUSIONS
  Although further technical innovation is still needed, elucidation of the whole picture of signaling pathways critical to HSCs/PCs and manipulation of such pathways by SMCs could establish efficient, cost-effective, riskless and robust methods for ex vivo expansion of HSCs/PCs. With these efforts, more sophisticated HSC transplantation would be possible in the near future.
authors.affiliation: Nissan Chemical Industries, Research Planning Department, 3-7-1 Kanda-nishiki-cho, Chiyoda-ku, Tokyo 101-0054, Japan.
authors.forename: Taito
authors.initials: T
authors.lastname: Nishino
authors.forename: Mitsujiro
authors.initials: M
authors.lastname: Osawa
authors.forename: Atsushi
authors.initials: A
authors.lastname: Iwama
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D018929:Cell Culture Techniques; D002454:Cell Differentiation / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002469:Cell Separation / Q000379:methods*; D002478:Cells, Cultured; D018380:Hematopoietic Stem Cell Transplantation; D006412:Hematopoietic Stem Cells / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D015398:Signal Transduction
chemical_list: D015415:Biomarkers