Abstract:Pluripotent hematopoietic stem cells (PHSC) are rare cells capable of multilineage differentiation, long-term reconstituting activity and extensive self-renewal. Such cells are the logical targets for many forms of corrective gene therapy, but are poor targets for retroviral mediated gene transfer owing to their quiescence, as retroviral transduction requires that the target cells be cycling. To try and surmount this problem we have constructed a retroviral producer line that expresses the membrane-bound form … Show more
“…Retroviral transfections occur with low efficiency in non-dividing human hematopoietic stem cells, limiting their use as vectors for inserting multidrug resistance genes [54,55]. Attempts to circumvent this problem include exposure of the stem and progenitor cells to growth factors interleukin-1 (IL-1), IL-3, IL-6, kit-ligand, and/or stem cell factor (SCF) prior to transfection [42,45,56], or co-cultivation of stem cells with retroviral producers expressing surface bound SCF growth factor [57]. Other retroviruses, such as lentivirus and spumavirus, have the advantage of being able to undergo proviral integration into non-dividing cells [58,59].…”
Gene therapy offers new opportunities for cancer treatment and prevention through the use of targeted, relatively nontoxic treatments that can identify, disable, and destroy malignant cells. This article reviews the principles behind oncogene inactivation, tumor suppressor gene replacement, inhibition of angiogenesis, immunopotentiation, molecular chemotherapy, and addition of drug resistance genes. The adcantages and limitations of viral and nonviral vectors for delivery of the therapeutic genes are presented.
“…Retroviral transfections occur with low efficiency in non-dividing human hematopoietic stem cells, limiting their use as vectors for inserting multidrug resistance genes [54,55]. Attempts to circumvent this problem include exposure of the stem and progenitor cells to growth factors interleukin-1 (IL-1), IL-3, IL-6, kit-ligand, and/or stem cell factor (SCF) prior to transfection [42,45,56], or co-cultivation of stem cells with retroviral producers expressing surface bound SCF growth factor [57]. Other retroviruses, such as lentivirus and spumavirus, have the advantage of being able to undergo proviral integration into non-dividing cells [58,59].…”
Gene therapy offers new opportunities for cancer treatment and prevention through the use of targeted, relatively nontoxic treatments that can identify, disable, and destroy malignant cells. This article reviews the principles behind oncogene inactivation, tumor suppressor gene replacement, inhibition of angiogenesis, immunopotentiation, molecular chemotherapy, and addition of drug resistance genes. The adcantages and limitations of viral and nonviral vectors for delivery of the therapeutic genes are presented.
Expression of the membrane-bound form of human stem cell factor (mbSCF) on the surface of retroviral packaging cells allows its efficient incorporation into retrovirus particles in a biologically active form, opening up the possibility for the use of retroviral display in many therapeutic areas, such as in gene therapy, drug delivery and in the development of novel vaccines.
Gene therapy vectors based on murine retroviruses are strated that these cells, though quiescent, can still be sucunable to transduce non-dividing cells. This has proven a cessfully transduced. This approach was extended to tarparticular problem in the haematopoietic system where the geting of umbilical cord blood CD34 + cells, a predominantly target cells of choice, the pluripotent stem cells are quiescquiescent population that normally require the addition of ent. In an attempt to circumvent this difficulty we have concytokines for efficient transduction. Using the SCFstructed a retroviral producer line that expresses the memexpressing producer line in the absence of exogenously brane bound form of human recombinant stem cell factor added cytokines, we observed a marked stimulation in (SCF) on its cell surface. This should enable the retroviral transduction efficiency over that achieved using the parent producers to deliver a growth signal to the target cells simproducer line alone. Colonies derived from these cells arisultaneous with their exposure to retrovirus. We tested the ing in semi-solid media were also shown to be positive for ability of these modified producers to transduce a growth expression of a retrovirally encoded reporter gene. factor-starved, SCF-dependent cell line (TF-1) and demon-
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