title: IL-6 precludes the differentiation induced by IL-3 on expansion of CD34+ cells from cord blood.
abstract: OBJECTIVE
  Ex vivo expansion of hematopoietic progenitor cells (HPC) from umbilical cord blood (UCB) is an interesting strategy to obtain a sufficient number of transplantable cells for adults. To define the optimal culture conditions allowing the generation of HPC that retain their proliferative capacity without loss of long-term culture-initiating cells (LTC-IC), the effect of different cytokine combinations on the expansion of CD34+ cells from UCB was assessed.
  
  
  METHODS
  CD34+ cells were cultured in serum-free culture medium with four cytokine combinations: stem cell factor plus thrombopoietin plus flk2/flt3 ligand (STF), STF plus interleukin-3 (IL-3), STF plus interleukin-6 (IL-6) and STF plus IL-6 plus IL-3. After a 1-week culture, the number of CD34+ and CD133+ cells, colony forming units (CFU), LTC-IC and telomerase activity were determined.
  
  
  RESULTS
  The addition of IL-6 or IL-3 to the combination of STF significantly enhanced the expansion of CD34+, CD133+ cells and CFU. All cytokine combinations tested induced a slight increase in LTC-IC number except that composed by STF plus IL-3. The greatest induction of telomerase activity was observed with the combination of STF plus IL-3 or plus IL-3 plus IL-6. Decay of the activity along time was observed when the combination of STF plus IL-3 was used, and this effect was reverted by the addition of IL-6.
  
  
  CONCLUSIONS
  Our results demonstrate that the inclusion of IL-6 in a serum-free short-term culture has a beneficial effect on HPC expansion from UCB, and precludes the negative effects induced by IL-3 on LTC-IC expansion and telomerase activity.
authors.affiliation: Instituto de Biología Celular, Organismo Público Valenciano de Investigación, Valencia, Spain.
authors.forename: Araceli
authors.initials: A
authors.lastname: Encabo
authors.forename: Emilia
authors.initials: E
authors.lastname: Mateu
authors.forename: Francisco
authors.initials: F
authors.lastname: Carbonell-Uberos
authors.forename: Maria Dolores
authors.initials: MD
authors.lastname: Miñana
mesh_terms: D018952:Antigens, CD34; D018929:Cell Culture Techniques / Q000379:methods; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D016207:Cytokines / Q000494:pharmacology; D004336:Drug Antagonism; D005312:Fetal Blood / Q000166:cytology*; D006801:Humans; D007377:Interleukin-3 / Q000494:pharmacology*; D015850:Interleukin-6 / Q000494:pharmacology*; D019098:Telomerase / Q000378:metabolism
chemical_list: D018952:Antigens, CD34; D016207:Cytokines; D007377:Interleukin-3; D015850:Interleukin-6; D019098:Telomerase