In our recent report, a syringe pump was used to slowly infuse VSV-G pseudotyped SIN-LV vectors into the BM so that more vectors can be in better contact with the resident cells to achieve high levels of transduction [10] (Fig

In our recent report, a syringe pump was used to slowly infuse VSV-G pseudotyped SIN-LV vectors into the BM so that more vectors can be in better contact with the resident cells to achieve high levels of transduction [10] (Fig.?1a). the blood circulation. In contrast, a single IO delivery of G-FVIII-LV utilizing a megakaryocytic-specific GP1b promoter achieved platelet-specific FVIII expression, Thalidomide-O-amido-C6-NH2 (TFA) leading to prolonged, partial correction of HemA in treated animals. Most interestingly, comparable therapeutic benefit with G-F8-LV was obtained in HemA mice with pre-existing anti-FVIII inhibitors. Platelets is an ideal IO delivery vehicle since FVIII stored in -granules of platelets is usually guarded from high-titer anti-FVIII antibodies; and that even relatively small numbers of activated platelets that locally excrete FVIII may be sufficient to promote efficient clot formation during bleeding. Additionally, combination of pharmacological brokers improved transduction of LVs and persistence of transduced cells and transgene expression. Overall, a single IO infusion of G-F8-LV can generate long-term stable expression of hFVIII in platelets and correct hemophilia phenotype for long term. This approach has high potential to permanently treat FVIII deficiency with and without pre-existing anti-FVIII antibodies. strong class=”kwd-title” Keywords: Hemophilia A, Factor VIII, Gene therapy, Intraosseous delivery, Lentiviral vectors, Megakaryocyte-specific gene expression, Anti-FVIII inhibitory antibodies, Stem cell gene therapy Background Deficiency of blood clotting factor VIII (FVIII) results in hemophilia A (HemA), a serious bleeding disorder. Current treatment of HemA patients with repeated infusions of FVIII is usually costly, inconvenient, and incompletely effective [1]. In addition, approximately 25?% of treated patients develop anti-FVIII immune responses. Gene therapy that can accomplish long-term phenotypic correction without the complication of anti-FVIII antibody formation represents a highly desirable approach to treat HemA patients. Previous phase I gene therapy clinical trials [2C4], however, produced only transient, low-level FVIII expression due to inefficient gene delivery and induction of immune responses to FVIII and/or gene therapy vectors. The hematopoietic stem cells (HSCs) in bone marrow (BM) can serve as a significant target for stable integration of therapeutic genes into the genome. Therapeutic levels of FVIII have been obtained by ex lover vivo gene therapy using HSCs transduced by retroviral vectors transporting porcine FVIII combined with immune suppression and busulfan [5, 6]. However, it is highly undesirable to perform pre-conditioning for hemophilia patients. Rabbit Polyclonal to ARC It is exhibited recently that in vivo gene transfer can be successfully carried out by direct intraosseous (IO) injection using several different vectors including adeno-, retro-, and Thalidomide-O-amido-C6-NH2 (TFA) lenti-viral vectors (LVs) [7C10]. HSCs can be efficiently transduced by these vectors and the transgene expression was detected in both Thalidomide-O-amido-C6-NH2 (TFA) progenitors and differentiated cell lineages [7, 8, 11]. This in vivo protocol corrected BM defects for long-term in diseased animals with Fanconi anemia [11]. Many drawbacks of ex lover vivo gene therapy, including maintenance of stem cell properties, low levels of engraftment, and side effects of cytokine activation can be evaded [9, 10, 12]. Most importantly, no pre-conditioning of the subject is required for this approach, thus providing a novel strategy for treating HemA. In this concise review, we will Thalidomide-O-amido-C6-NH2 (TFA) discuss the recently developed novel approach of IO delivery of LVs to correct hemA [10]. The benefit and limitations of using LVs driven by ubiquitous and megakaryocyte-specific promoters will be compared. The potential of the development of this novel in vivo technology into clinically feasible gene transfer protocol to treat hemA patients, especially the clinically challenging patients with pre-existing inhibitory antibodies will be discussed. Review Gene therapy vs. protein alternative therapy and other therapies Current treatment of hemophilia entails repeated infusions of FVIII protein either as regular prophylaxis or treatment during bleeding episodes. For severe patients, the standard treatment consists of intravenous infusion of factor VIII concentrates three times per week or every other day [6, 7]. In addition, 25?% of the patients develop inhibitory antibodies to FVIII following repeated infusions of FVIII. In recent years, efforts have been made to improve the efficacy of protein alternative therapy. One of the major successes is usually to prolong the half-life of FVIII in blood circulation [13]. This is recently achieved by either attaching polyethylene glycol (PEG) to FVIII (PEGylated FVIII) [14, 15] or fusing a monomeric Fc fragment of immunoglobulin G [16] or albumin [17] to FVIII. Less frequent infusions of FVIII can be administered to patients with these long lasting.