Expression of human factor VIII under control of the platelet-specific αIIb promoter in megakaryocytic cell line as well as storage together with VWF

Shi, Qizhen; Wilcox, David A.; Fahs, Scot A.; Kroner, Philip A.; Montgomery, Robert R.

doi:10.1016/s1096-7192(03)00049-0

Cited by 48 publications

(61 citation statements)

References 46 publications

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“…FVIII normally circulates in plasma and is not present in platelets or other blood cells (22,23). Our laboratory has previously demonstrated in vitro costorage of FVIII with VWF in megakaryocyte α-granules (22,23) and endothelial Weibel-Palade bodies (21) when FVIII is ectopically expressed in these cells, and VWF enhances this expression. Clinically, 25-30% of hemophilia patients develop inhibitory antibodies in response to FVIII replacement therapy (43,44), and thus gene therapy by constitutive synthesis and release of recombinant FVIII into plasma (i.e., specifying gene therapy to liver or endothelial cells) might not be therapeutic in these patients in the presence of such inhibitory antibodies.…”

Section: Discussionmentioning

confidence: 99%

“…This failure may be attributed in part to the fact that none of these approaches directed FVIII synthesis to cells that synthesize and store VWF, even though VWF is known to stabilize FVIII in plasma (40) and in the commercial production of recombinant FVIII products (41,42). FVIII normally circulates in plasma and is not present in platelets or other blood cells (22,23). Our laboratory has previously demonstrated in vitro costorage of FVIII with VWF in megakaryocyte α-granules (22,23) and endothelial Weibel-Palade bodies (21) when FVIII is ectopically expressed in these cells, and VWF enhances this expression.…”

Section: Discussionmentioning

confidence: 99%

“…We have previously demonstrated that coexpression of FVIII in a cell that stores VWF results in the costorage, and release, of FVIII (4,21). More specifically, directing FVIII expression to megakaryocytes results in storage of FVIII with VWF in the α-granules of platelets (22,23). A megakaryocytic, lineage-specific promoter would direct FVIII expression only to that blood cell lineage where VWF is normally endogenously synthesized and stored (20,24).…”

Section: Introductionmentioning

confidence: 99%

“…In addition to platelets, GPIbα expression has been reportedly synthesized in endothelial (25)(26)(27) and breast tumor cells (28). Thus, we chose the platelet-specific GPIIb gene promoter (the αIIb promoter) that has been demonstrated to direct megakaryocyte-specific gene transcription (22,(29)(30)(31)(32)(33)(34)(35)(36)(37).…”

Section: Introductionmentioning

confidence: 99%

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Factor VIII ectopically targeted to platelets is therapeutic in hemophilia A with high-titer inhibitory antibodies

Shi

Wilcox

Fahs

et al. 2006

Journal of Clinical Investigation

167

276

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Inhibitory immune response to exogenously infused factor VIII (FVIII) is a major complication in the treatment of hemophilia A. Generation of such inhibitors has the potential to disrupt gene therapy for hemophilia A.We explore what we believe to be a novel approach to overcome this shortcoming. Human B-domain-deleted FVIII (hBDDFVIII) was expressed under the control of the platelet-specific αIIb promoter in platelets of hemophilic (FVIII null ) mice to create 2bF8 trans mice. The FVIII transgene product was stored in platelets and released at the site of platelet activation. In spite of the lack of FVIII in the plasma of 2bF8 trans mice, the bleeding phenotype of FVIII null mice was corrected. More importantly, the bleeding phenotype was corrected in the presence of high inhibitory antibody titers introduced into the mice by infusion or by spleen cell transfer from recombinant hBDDFVIII-immunized mice. Our results demonstrate that this approach to the targeted expression of FVIII in platelets has the potential to correct hemophilia A, even in the presence of inhibitory immune responses to infused FVIII. IntroductionMonogenic diseases, characterized by the loss of a specific plasma protein, are currently treated by repetitive replacement therapy and are choice candidates amenable to gene therapy. Hemophilia A, a severe congenital bleeding disorder caused by the loss of clotting factor VIII (FVIII) (1), is a prototype of such monogenic diseases. Currently, hemophilia A is treated by infusion of recombinant or plasma-derived FVIII (2). However, 25-30% of patients develop antibodies (FVIII inhibitors) that selectively inactivate the clotting activity of FVIII and negate its therapeutic efficacy (3). Hemophilia A is considered a strong candidate for gene therapy because the therapeutic window is broad and even a minimal plasma level of plasma FVIII is clinically advantageous. The development of inhibitory antibodies to the FVIII transgene product in plasma remains a significant barrier to some patient candidates. Many groups have developed various strategies for directing FVIII synthesis (4-15), although inadequacies of gene delivery and expression and inhibitor formation remain clinical problems (7,(16)(17)(18).The approach we investigated, which we believe to be novel, is based on the hypothesis that targeting the production of FVIII to a secreting cell type that acts in the immediate vicinity of sites where FVIII is needed could overcome the presence of inhibitory antibodies. Furthermore, by sequestering the FVIII, the generation of antibodies in naive individuals might be prevented or at least rendered less relevant.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Factor VIII ectopically targeted to platelets is therapeutic in hemophilia A with high-titer inhibitory antibodies

Shi

Wilcox

Fahs

et al. 2006

Journal of Clinical Investigation

167

276

View full text Add to dashboard Cite

show abstract

“…Chuah et al were inhibited bleeding in hemophilia A SCID mice using intravenous injection of adenovirus carrying BDD -FVIII gene (Chuah et al, 2003). Shi et al believed that platelet/ megakaryocyte is a target for hemophilia A gene therapy, they were transferred equipted specific platelet glycoprotein IIb promoter BDDhFVIII to Domi cells, hFVIII was biosynthesised (Shi et al, 2003). Sarkar and colleagues were transferred AAV carrying hFVIII to deficient FVIII mice through portal, intravenous and spleen injections, they observed secreted hFVIII in transgenic animals but no in neonatal animal .…”

Section: Gene Therapy Of Hemophilia Amentioning

confidence: 99%