Lentivirus transduction of human osteoclast precursor cells and differentiation into functional osteoclasts

Gene transfer into stem cells has been an ongoing priority as a treatment for genetic disease and cancer for more than two decades. Methods described herein, form the basis for providing the cell source to determine if osteoclast precursor cells (OcP) can be used as therapeutic gene delivery systems in vivo. Osteoclasts and tumor associated macrophages or OcP, support survival, tumor progression and osteolysis in bone cancers. Two sources of precursor cells are compared: CD14+ cells, the standard OcP, found abundantly in peripheral blood and CD34+ cells, hematopoietic stem cells that are rare, but which can be expanded into OcP. Our findings characterize cell yield at each step of the transduction process and thus provide essential data for planning future in vivo experiments. In addition we demonstrate that essential functions of OcP are preserved following lentiviral transduction. Specifically, neither the transduction method nor the lentiviral transduction influence the OcP's ability to form osteoclasts, express the marker gene, EGFP, or resorb bone. Finally, we conclude that CD34+ cells yield significantly more transduced cells and form functionally superior osteoclasts in vitro. This study represents a step towards considering human gene therapy for bone cancer by demonstrating successful transduction of human OcP for use as cellular delivery vehicles to sites of bone cancer.