Adenoviral-mediated gene transfer into ex vivo expanded human bone marrow mesenchymal progenitor cells

Objective. Based on their differentiation properties and facilely of ex viv o expansion, human bone marrow mesenchymal progenitor cells (MPC), are cons idered as attractive targets to deliver foreign genes to the hone marrow or other mesenchymal tissues. In this study we investigated the feasibility o f transduce MPC with adenoviral vectors (Adv), Methods. MPC were expanded ex vivo and transduced with replication-defectiv e Adv-containing reporter genes (lacZ or GFP) under the control of CMV prom oter. Transfection efficiency was assessed by microscopical scoring or by n ow cytometry, Expression and involvement of Adv-attachment (CAR) and Adv-in ternalization (integrins alpha v) receptors were evaluated by flow cytometr ic studies. Results, Transgene expression analysis showed that only 19% +/- 3% of cells expressed the transgenes at high levels, MPC express the attachment and in ternalization receptors required for Adv infection. While integrins alpha v beta 3 and alpha v beta 5 are expressed by all MPC, CAR is solely expresse d by a fraction of low size cells. Antibodies against CAR and alpha v beta 5, but not against alpha v beta 3, blocked Adv-mediated gene transfer into MPC, showing that CAR and alpha v beta 4 are required for infection, Becaus e alpha v beta 5, as compared with CAR, is overexpressed in MPC, the result s suggest that the efficiency of Adv-mediated gene transfer into MPC depend s on the level of CAR expression, Conclusion. These findings demonstrate that Adv may be useful to engineer a subpopulation of ex vivo expanded human mesenchymal progenitors, with a hi gh level of transgene expression. (C) 2000 International Society for Experi mental Nematology. Published by Elsevier Science Inc.