In vivo imaging of engraftment and enrichment of lentiviral transduced hematopoietic bone marrow cells under MGMT-P140K mediated selection.

摘要

Today hematopoietic cell transplantation (HCT) has become routine for treating patients with hematopoietic malignancies and bone marrow failure. Despite many successful preclinical and clinical studies for treating certain genetic defects by transplanting hematopoietic stem cells (HSC) containing one or more therapeutic genes, there have been limitations and complications with this approach. In our lab, we have been working to improve the efficiency of viral gene transfer and transgene expression in HSC. Due to the difficulties of culturing and enriching HSC ex vivo, we have developed a strategy to select and enrich transplanted HSC in vivo with the help of a mutant human alkylguanine DNA-transferase (MGMT-P140K). In order to monitor the fact of transduced and transplanted cells and to understand the dynamic selection process in vivo, we utilized a novel imaging technique, bioluminescence imaging (BLI). Developed in the past few years, genetic modification using the firefly luciferase gene allows researchers to non-invasively visualize transduced HSC homing, expansion, engraftment and in vivo selection over a long period of time. Periodical bioluminescence imaging revealed dramatic spatial and temporal shifting of transgene expression in early phase of engraftment, indicating a stochastic event of homing and expansion after HSC transplantation. Long-term monitoring of in vivo selection showed an effective MGMT-P140K mediated selection on lentiviral transduced bone marrow cells, resulting in persistent BLI foci, which represented long-lived transgene expressing HSC derived stem and progenitor cells. The results from these studies provided interesting and valuable information on the biology of bone marrow transplantation and the field of gene therapy.