title: All-trans retinoic acid (ATRA) enhances maintenance of primitive human hematopoietic progenitors and skews them towards myeloid differentiation in a stroma-noncontact culture system.
abstract: OBJECTIVE
  We have previously shown that hematopoietic progenitor cells (HPCs) from umbilical cord blood (UCB) can be maintained in a cytokine-supplemented stroma-noncontact (SNC) system. Here, we tested if all-trans retinoic acid (ATRA), known to improve expansion of murine hematopoietic stem cells, would enhance human HPC maintenance in a SNC culture system.
  
  
  METHODS
  CD34+CD38-Lin- cells from UCB were cultured in transwells above AFT024 in the presence of Flt-3 ligand (FLT) and thrombopoietin (TPO), with or without ATRA. Total nucleated cells (TNC), colony-forming units (CFUs), long-term culture-initiating cells (LTC-ICs), myeloid-lymphoid initiating cells (ML-ICs) and SCID repopulating cells (SRCs) were evaluated 1 to 5 weeks after culture.
  
  
  RESULTS
  All-trans retinoic acid (1 mumol/L) reduced expansion of CD34+CD38-Lin- TNC and CFUs after 2 to 5 weeks of culture. However, it significantly increased LTC-IC expansion after 1 to 3 and, even more so, 5 weeks of culture. ATRA also increased recovery of more primitive ML-ICs and SRCs. Increased HPC recovery appeared dependent on the presence of stromal cells, as LTC-IC expansion was significantly reduced when ATRA was added to stroma-free cultures.
  
  
  CONCLUSIONS
  All-trans retinoic acid increases expansion of early HPCs in a stromal cell-dependent fashion.
authors.affiliation: Department of Medicine, University of Hong Kong, Hong Kong.
authors.forename: Anskar Y H
authors.initials: AY
authors.lastname: Leung
authors.forename: Catherine M
authors.initials: CM
authors.lastname: Verfaillie
mesh_terms: D000818:Animals; D018952:Antigens, CD34; D018929:Cell Culture Techniques; D002454:Cell Differentiation; D002460:Cell Line; D049109:Cell Proliferation; D002478:Cells, Cultured; D018920:Coculture Techniques; D005312:Fetal Blood; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000187:drug effects*; D006801:Humans; D051379:Mice; D038042:Myelopoiesis / Q000187:drug effects*; D017154:Stromal Cells / Q000166:cytology / Q000502:physiology; D013997:Time Factors; D014212:Tretinoin / Q000494:pharmacology*
chemical_list: D018952:Antigens, CD34; D014212:Tretinoin