Cotransplantation of ex vivo expanded and unexpanded cord blood units in immunodeficient mice using insulin growth factor binding protein-2-augmented mesenchymal cell cocultures

Biol Blood Marrow Transplant. 2012 May;18(5):674-82. doi: 10.1016/j.bbmt.2012.01.001. Epub 2012 Jan 9.


Ex vivo expansion of cord blood (CB) hematopoietic stem cells and cotransplantation of 2 CB units (CBUs) could enhance the applicability of CB transplantation in adult patients. We report an immunodeficient mouse model for cotransplantation of ex vivo expanded and unexpanded human CB, showing enhanced CB engraftment and provide proof of concept for this transplantation strategy as a means of overcoming the limiting cell numbers in each CBU. CBUs were expanded in serum-free medium supplemented with stem cell factor, Flt-3 ligand, thrombopoietin, and insulin growth factor binding protein-2 together with mesenchymal stromal cell coculture. Unexpanded and expanded CB cells were cotransplanted by tail vein injection into 45 sublethally irradiated nonobese diabetic SCID-IL2γ(-/-) (NSG) mice. Submandibular bleeding was performed monthly, and mice were sacrificed 4 months after transplantation to analyze for human hematopoietic engraftment. Expansion of non-CD34(+) selected CB cells yielded 40-fold expansion of CD34(+) cells and 3.1-fold expansion of hematopoietic stem cells based on limiting dilution analysis of NSG engraftment. Mice receiving expanded grafts exhibited 4.30% human cell repopulation, compared with 0.92% in mice receiving only unexpanded grafts at equivalent starting cell doses, even though the unexpanded graft predominated in long-term hematopoiesis (P = .07). Ex vivo expanded grafts with lower initiating cell doses also showed equivalent engraftment to unexpanded grafts with higher cell dose (8.0% versus 7.9%; P = .93). In conclusion, ex vivo expansion resulted in enhanced CB engraftment despite eventual rejection by the unexpanded CBU.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antigens, CD34 / biosynthesis
  • Antigens, CD34 / immunology
  • Cell Proliferation / drug effects
  • Cells, Cultured
  • Coculture Techniques
  • Fetal Blood / cytology
  • Fetal Blood / immunology
  • Fetal Blood / transplantation*
  • Graft Survival / immunology
  • Hematopoietic Stem Cell Transplantation / methods*
  • Hematopoietic Stem Cells / cytology
  • Hematopoietic Stem Cells / drug effects*
  • Hematopoietic Stem Cells / immunology
  • Humans
  • Injections, Intravenous
  • Insulin-Like Growth Factor Binding Protein 2 / pharmacology*
  • Membrane Proteins / pharmacology
  • Mesenchymal Stem Cell Transplantation
  • Mesenchymal Stem Cells / cytology
  • Mesenchymal Stem Cells / drug effects*
  • Mesenchymal Stem Cells / immunology
  • Mice
  • Mice, SCID
  • Stem Cell Factor / pharmacology
  • Thrombopoietin / pharmacology
  • Transplantation, Heterologous
  • Whole-Body Irradiation


  • Antigens, CD34
  • Insulin-Like Growth Factor Binding Protein 2
  • Membrane Proteins
  • Stem Cell Factor
  • flt3 ligand protein
  • Thrombopoietin