title: Low-dose insulin-like growth factor binding proteins 1 and 2 and angiopoietin-like protein 3 coordinately stimulate ex vivo expansion of human umbilical cord blood hematopoietic stem cells as assayed in NOD/SCID gamma null mice.
abstract: BACKGROUND
  Insulin-like growth factors (IGFs), IGF binding proteins (IGFBPs) and angiopoietin-like proteins (ANGPTLs) can enhance the ex vivo expansion of hematopoietic stem cells (HSCs) when used with a standard cytokine cocktail of stem cell factor (SCF), thrombopoietin (TPO) and FLT3 ligand (FL). In order to determine the optimal dose and combination of IGFs, IGFBPs and ANGPTLs, serial dilution and full permutation of IGFBP1, IGFBP2, IGF2 and ANGPTL3 were applied on a cryopreserved umbilical cord blood mononuclear cell (UCB-MNC) ex vivo expansion system.
  
  
  METHODS
  In this system, 4 × 105 cells/ml of UCB-MNCs were inoculated in serum-free Stemspan® medium (Stemcell technologies, vancouver, BC, Canada) supplied with standard basal cytokine combination of 100 ng/ml SCF, 50 ng/ml FL and 100 ng/ml TPO and supported by a bone marrow mesenchymal stromal cell layer.
  
  
  RESULTS
  Paradoxically, experiment results showed that the highest expansion of CD34+CD38-CD90+ primitive progenitor was stimulated by cytokine combination of SCF + TPO + FL + IGFBP1 + IGFBP2 + ANGPTL3 at a low dose of 15 ng/ml IGFBP1 and 20 ng/ml IGFBP2 and ANGPTL3. This ex vivo expansion was further validated in 8-week-old to 10-week-old nonobese diabetic/severe combined immunodeficiency interleukin 2 gamma chain null (NOD/SCID-IL2Rγ-/-) mice. Limiting dilution assay showed excellent correlation between the HSC ex vivo surface marker of CD34+CD38-CD90+ and the in vivo competitive repopulating unit (CRU) functional assay.
  
  
  CONCLUSIONS
  IGFBP1, IGFBP2, IGF2 and ANGPTL3 can stimulate the expansion of CD34+CD38-CD90+ primitive progenitor at low dose. The optimal combination comprises IGFBP1, IGFBP2 and ANGPTL3 together with the standard cytokine cocktail of SCF, FL and TPO. The CD34+CD38-CD90+ phenotype can serve as a surrogate ex vivo surface marker for HSCs due to consistency with the in vivo CRU functional assay.
authors.forename: Xiubo
authors.initials: X
authors.lastname: Fan
authors.forename: Florence Ph
authors.initials: FP
authors.lastname: Gay
authors.forename: Francesca Wi
authors.initials: FW
authors.lastname: Lim
authors.forename: Justina Ml
authors.initials: JM
authors.lastname: Ang
authors.forename: Pat Py
authors.initials: PP
authors.lastname: Chu
authors.forename: Sudipto
authors.initials: S
authors.lastname: Bari
authors.forename: William Yk
authors.initials: WY
authors.lastname: Hwang
mesh_terms: D000091303:Angiopoietin-Like Protein 3; D000075802:Angiopoietin-like Proteins; D042682:Angiopoietins / Q000494:pharmacology*; D000818:Animals; D018929:Cell Culture Techniques / Q000379:methods*; D005312:Fetal Blood / Q000166:cytology; D018380:Hematopoietic Stem Cell Transplantation / Q000379:methods; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000187:drug effects; D006801:Humans; D018970:Insulin-Like Growth Factor Binding Protein 1 / Q000494:pharmacology*; D018971:Insulin-Like Growth Factor Binding Protein 2 / Q000494:pharmacology*; D007335:Insulin-Like Growth Factor II / Q000494:pharmacology*; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID
chemical_list: C479896:ANGPTL3 protein, human; D000091303:Angiopoietin-Like Protein 3; D000075802:Angiopoietin-like Proteins; D042682:Angiopoietins; C035170:IGF2 protein, human; C032231:IGFBP1 protein, human; C577903:IGFBP2 protein, human; D018970:Insulin-Like Growth Factor Binding Protein 1; D018971:Insulin-Like Growth Factor Binding Protein 2; D007335:Insulin-Like Growth Factor II