Functionally Distinct Subpopulations of Cord Blood CD34+ Cells Are Transduced by Adenoviral Vectors with Serotype 5 or 35 Tropism

Adenovirus serotype 5 (Ad5)-based vectors can be retargeted with fiber receptor specificity of serotype 35 adenovirus (Ad5F35) and thereby bypass the paucity of the coxsackie and adenovirus receptor (CAR) on hematopoietic cells by utilizing CD46 as cellular receptor. The gene transfer efficiency into NOD/SCID repopulating cells by an Ad5F35-GFP vector was investigated in comparison with its corresponding Ad5-GFP vector. Cord blood CD34+ cells were transduced following overnight culture under serum-free conditions supported by early acting cytokines. In agreement with previous findings, the Ad5F35-GFP vector showed significant superiority to the Ad5-GFP vector in gene transfer into cells with primitive immunophenotype. However, the Ad5F35-GFP vector allowed efficient gene transfer into both dividing and nondividing CD34+ cells, whereas the Ad5-GFP vector preferentially allowed gene transfer into dividing cells expressing lower levels of CD34 antigen, which correlated with high levels of CAR expression. The sorted GFP+ cells following Ad5F35-GFP transduction at relatively low multiplicity of infection consistently reconstituted the NOD/SCID mouse bone marrow with multilineage differentiation. In contrast, the GFP+ cells following Ad5-GFP transduction were nearly devoid of reconstitution capacity. Thus, Ad5F35 vectors encoding functional genes can facilitate transient genetic manipulation of human NOD/SCID repopulating cells.