Molecular purging of multiple myeloma cells by ex-vivo culture and retroviral transduction of mobilized-blood CD34+ cells
1 San Raffaele Telethon Institute for Gene Therapy (HSR-TIGET), Scientific Institute H.S. Raffaele, Milan, Italy
2 Hematology and BMT Unit, Scientific Institute H.S. Raffaele, Milan, Italy
3 Hematology and Bone Marrow Transplant Unit, Hospital S. Gerardo, Monza, Italy
4 Department of Transfusion Medicine, Clinical Center, National Institutes of Health, Bethesda, MD 20892, USA
5 Department of Biomedical Sciences and Human Oncology and Center for Experimental Research and Clinical Studies, University of Turin, Turin, Italy
6 Department of Human Morphology, University of Milan, Milan, Italy
Journal of Translational Medicine 2007, 5:35 doi:10.1186/1479-5876-5-35Published: 12 July 2007
Tumor cell contamination of the apheresis in multiple myeloma is likely to affect disease-free and overall survival after autografting.
To purge myeloma aphereses from tumor contaminants with a novel culture-based purging method.
We cultured myeloma-positive CD34+ PB samples in conditions that retained multipotency of hematopoietic stem cells, but were unfavourable to survival of plasma cells. Moreover, we exploited the resistance of myeloma plasma cells to retroviral transduction by targeting the hematopoietic CD34+ cell population with a retroviral vector carrying a selectable marker (the truncated form of the human receptor for nerve growth factor, ΔNGFR). We performed therefore a further myeloma purging step by selecting the transduced cells at the end of the culture.
Overall recovery of CD34+ cells after culture was 128.5%; ΔNGFR transduction rate was 28.8% for CD34+ cells and 0% for CD138-selected primary myeloma cells, respectively. Recovery of CD34+ cells after ΔNGFR selection was 22.3%. By patient-specific Ig-gene rearrangements, we assessed a decrease of 0.7–1.4 logs in tumor load after the CD34+ cell selection, and up to 2.3 logs after culture and ΔNGFR selection.
We conclude that ex-vivo culture and retroviral-mediated transduction of myeloma leukaphereses provide an efficient tumor cell purging.