Ex vivo expansion of umbilical cord blood (UCB) CD34(+) cells alters the expression and function of alpha 4 beta 1 and alpha 5 beta 1 integrins.
We have investigated the influence of ex vivo expansion of human CD34(+) cord blood cells on the expression and function of adhesion molecules involved in the homing and engraftment of haematopoietic progenitors. Ex vivo expansion of umbilical cord blood CD34(+) cells for 6 d in the presence of interleukin 3 (IL-3), IL-6 and stem cell factor (SCF) or IL-11, SCF and Flt-3L resulted in increased expression of alpha 4, alpha 5, beta 1, alpha M and beta 2 integrins. However, a significant decrease in the adhesion of progenitor cells to fibronectin was observed after the ex vivo culture (adhesion of granulocyte-macrophage colony-forming units (CFU-GM) was 22 +/- 4% in fresh cells versus 5 +/- 2% and 2 +/- 2% in each combination of cytokines). Incubation with the beta 1 integrin-activating antibody TS2/16 restored adhesion to fibronectin. Transplantation of ex vivo expanded umbilical cord blood CD34(+) cells was associated with an early delayed engraftment in non-obese diabetic/severe combined immunodeficient (NOD/SCID) mice. Incubation of cells with the monoclonal antibody TS2/16 before transplantation almost completely abrogated NOD/SCID repopulating ability of both fresh and expanded CD34(+) cells. The seeding efficiency of fresh and expanded CD34(+) cells was similar, but markedly reduced after incubation with the TS2/16 monoclonal antibody. Our results show that functional activation of beta 1 integrins could overcome the decreased very late antigen (VLA)-4- and VLA-5-mediated adhesion observed after ex vivo expansion of haematopoietic progenitors. However, in vivo, these effects induced an almost complete abrogation of the homing and repopulating ability of CD34(+) UCB cells.
Ramírez
M
M
Unidad de Biología Molecular y Celular y Terapia Génica, CIEMAT, Madrid, Spain.
Segovia
J C
JC
Benet
I
I
Arbona
C
C
Güenechea
G
G
Blaya
C
C
García-Conde
J
J
Bueren
J A
JA
Prosper
F
F
D000818:Animals; D018952:Antigens, CD34; D002455:Cell Division; D002478:Cells, Cultured; D005312:Fetal Blood / Q000276:immunology / Q000378:metabolism; D005353:Fibronectins / Q000378:metabolism; D005434:Flow Cytometry / Q000379:methods; D006801:Humans; D039041:Integrin alpha4beta1; D016023:Integrins / Q000378:metabolism*; D007963:Leukocytes, Mononuclear / Q000502:physiology* / Q000637:transplantation; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D017469:Receptors, Fibronectin / Q000378:metabolism; D016201:Receptors, Lymphocyte Homing / Q000378:metabolism
D018952:Antigens, CD34; D005353:Fibronectins; D039041:Integrin alpha4beta1; D016023:Integrins; D017469:Receptors, Fibronectin; D016201:Receptors, Lymphocyte Homing