Cryopreservation of Human Adipose-Derived Stem Cells for Use in Ex Vivo Regional Gene Therapy for Bone Repair

The development of an ex vivo regional gene therapy clinical pathway using adipose-derived stem cells (ASCs) may require cryopreservation for cell culture, storage, and transport prior to clinical use. ASCs isolated from five donors were transduced with a lentiviral vector containing BMP-2. Three groups were assessed: transduction without cell freezing (group 1), freezing of cells for 3 weeks followed by transduction (group 2), and cell transduction prior to freezing (group 3). Nontransduced cells were used as a control. The cluster of differentiation (CD) marker profiles, cell number, BMP-2 production, and osteogenic potential were measured. The CD marker profile (CD44, CD73, CD90, and CD105) was unchanged after cryopreservation. Cell number was equivalent among cryopreservation protocols in transduced and nontransduced cells. There was a trend toward decreased BMP-2 production in group 3 compared to groups 1 and 2. Osteogenic potential based on Alizarin red concentration was higher in group 2 compared to group 3, with no difference compared to group 1. Freezing ASCs prior to transduction with a lentiviral vector containing BMP-2 has no detrimental effect on cell number, BMP-2 production, osteogenic potential, or immunophenotype. Transduction prior to freezing, however, may limit the BMP-2 production and potential osteogenic differentiation of the ASCs.