Human CD34(+)CXCR4(-) sorted cells harbor intracellular CXCR4, which can be functionally expressed and provide NOD/SCID repopulation

Blood. 2002 Oct 15;100(8):2778-86. doi: 10.1182/blood-2002-02-0564.

Abstract

Homing and repopulation of nonobese diabetic/severe combined immunodeficient (NOD/SCID) mice by enriched human CD34(+) stem cells from cord blood, bone marrow, or mobilized peripheral blood are dependent on stromal cell-derived factor 1 (SDF-1)/CXCR4 interactions. Recently, human cord and fetal blood CD34(+)CD38(-)CXCR4(-) and CXCR4(+) cells, sorted with neutralizing anti-CXCR4 monoclonal antibody (mAb), were shown to have similar NOD/SCID repopulation potential. Herein we report that human cord blood CD34(+)CXCR4(+) (R4(+)) and CD34(+)CXCR4(-) (R4(-)) subsets, sorted with neutralizing anti-CXCR4 mAb, engrafted NOD/SCID mice with significantly lower levels of human cells compared with nonsorted and SDF-1-migrated CD34(+) cells. Coinjection of purified cells with 10 microg anti-CXCR4 mAb significantly reduced engraftment of all CD34(+) subsets, and 50 microg completely abrogated engraftment by R4(-) and CD34(+) cells. Importantly, R4(-) cells harbor intracellular CXCR4, which can be rapidly induced to cell surface expression within a few hours. Moreover, 48 hours of cytokine stimulation resulted in up-regulation of both cell surface and intracellular CXCR4, restoring migration capacities toward a gradient of SDF-1 and high-level NOD/SCID repopulation potential. In addition, homing of sorted R4(-) cells into the murine bone marrow and spleen was significantly slower and reduced compared to CD34(+) cells but yet CXCR4 dependent. In conclusion, R4(-) cells express intracellular CXCR4, which can be functionally expressed on the cell membrane to mediate SDF-1-dependent homing and repopulation. Our results suggest dynamic CXCR4 expression on CD34(+) stem and progenitor cells, regulating their motility and repopulation capacities.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antigens, CD / analysis*
  • Antigens, CD34 / analysis*
  • Cell Division / immunology
  • Cell Division / physiology
  • Fetal Blood / cytology*
  • Hematopoietic Stem Cells / cytology*
  • Hematopoietic Stem Cells / immunology
  • Hematopoietic Stem Cells / physiology*
  • Humans
  • Infant, Newborn
  • Mice
  • Mice, Inbred NOD
  • Mice, SCID
  • Receptors, CXCR4 / analysis*
  • Receptors, CXCR4 / genetics
  • Receptors, CXCR4 / physiology
  • Stem Cell Transplantation / methods*
  • Transplantation, Heterologous / physiology*

Substances

  • Antigens, CD
  • Antigens, CD34
  • Receptors, CXCR4