Development of a gene therapy based bone marrow purging system for leukemias

Abstract

Although viable gene therapy based methods have been reported for the selective removal or purging of contaminating epithelial derived cancer cells from stem cell grafts, similar strategies for the purging of leukemia cells have been significantly less efficient. Hematopoietic cells are difficult targets for transduction with currently available vectors. Polylysine based molecular conjugate vectors (MCV) were previously found to effectively transduce both normal and malignant hematopoietic cells. A panel of human leukemia cell lines as well as CD34 þ selected primary human hematopoietic progenitor cells (HPC) were tested for differential gene expression utilizing different promoters. Reporter gene expression under the control of RSV and SV40 promoters showed a 6-log fold increase in leukemia cells when compared to primary HPC. Using a polylysine based recombinant molecular conglomerate vector (recMCV) encoding the HSV-tk suicide gene under control of RSV, we demonstrated effective and specific cell killing in all leukemia cell lines as well as in primary human leukemia cells derived from chemotherapy refractory patients, while HPC survived under the same conditions at approximately 20% viability. These proof of principle experiments demonstrate that gene therapy technology could be utilized to successfully purge leukemia cells from HPC.

Lentiviruses: Vectors for Cancer Gene Therapy

“…Small numbers of transduced tumor cells can also result in the killing of nontransduced surrounding tumor cells, a phenomenon called the "bystander effect" (Burrows et al 2002;Hamel et al 1996;Rubsam et al 1999). Recent developments have shown that using suicide gene therapy in stem cells can have an impact on killing surrounding cancer cells (Huang et al 2005;Rath et al 2009). Other suicide genes are also being developed.…”

Optimized Processing of Growth Factor Mobilized Peripheral Blood CD34+ Products by Counterflow Centrifugal Elutriation

“…Since it was first introduced in the 1970s [24–28], counterflow centrifugal elutriation (CCE) has been used extensively in research applications to separate cell products on the basis of size and density. More recently, a clinical elutriation device has been developed (Elutra; GambroBCT, Lakewood, CO, http://www.caridianbct.com) and has been successfully used to isolate monocytes from peripheral blood apheresis products for vaccine applications [29–36] and lymphocytes for adoptive immunotherapy [37]. During elutriation, platelets and red blood cells are efficiently separated from white blood cells with monocytes highly enriched in a single fraction.…”