Ex Vivo Gene Therapy for Hemophilia A That Enhances Safe Delivery and Sustained In Vivo Factor VIII Expression from Lentivirally Engineered Endothelial Progenitors

Abstract

ABSTRACT

Integration of Blood Outgrowth Endothelial Cells in Dermal Fibroblast Sheets Promotes Full Thickness Wound Healing

“…According to this definition, two EPC types are distinguished: the early outgrowing and initially nonadherent fraction, which is clonally related to hematopoietic stem cells and does not incorporate into vessels, and the late outgrowing and immediately adherent fraction that lacks hematopoietic markers and does incorporate into vessels [11]. The latter cells are also referred to as ''blood outgrowth endothelial cells'' (BOEC) and have been derived from peripheral and/or cord blood [13][14][15][16]. They have been used for restoring blood flow in peripheral vascular disease models [17,18], for prevascularization of decellularized skin or bone tissue-engineered constructs [19,20] and as a vehicle for gene therapy [15,21].…”

“…The latter cells are also referred to as ''blood outgrowth endothelial cells'' (BOEC) and have been derived from peripheral and/or cord blood [13][14][15][16]. They have been used for restoring blood flow in peripheral vascular disease models [17,18], for prevascularization of decellularized skin or bone tissue-engineered constructs [19,20] and as a vehicle for gene therapy [15,21]. Although the ability to infiltrate in vessels is a well-recognized feature of BOEC, their trophic effect on neovascularization is not well-documented and even doubted [12], neither have their paracrine interactions with non-EC been elaborately studied, certainly not in a wound context.…”

Storage and regulated secretion of factor VIII in blood outgrowth endothelial cells

“…Recent studies have suggested that it may be beneficial to express FVIII in cells that also express its natural carrier protein von Willebrand factor (VWF). [5][6][7][8][9][10][11] In the circulation, VWF protects FVIII from premature clearance and proteolytic degradation by virtue of its ability to bind to it with high affinity. [12][13][14] VWF is expressed in megakaryocytes and vascular endothelial cells.…”

“…Studies in hemophilia A mice have demonstrated that transplantation of liver sinusoidal endothelial cells can correct the hemophilic phenotype. 5,21 In addition, transplantation of genetically modified BOECs intravenously 10,22 or implanted subcutaneously in a Matrigel TM scaffold 10 results in long-term therapeutic levels of FVIII.…”

Non-hematopoietic stem cells as factories for in vivo therapeutic protein production

“…In a related study, and to avoid concerns about cell dissemination throughout the body, BOEC fVIII were implanted s.c. in Matrigel scaffolds in non-obese diabetic-severe combined immunodeficiency or in immunocompetent hemophilic mice, showing therapeutic fVIII expression for several months before the eventual return to baseline levels. 60 Using an MSC-based strategy for the treatment of hemophilia B, autologous factor IX-producing MSCs were loaded into sophisticated porous scaffolds specifically designed to maximize cell capacity and provide MSC with the appropriate adhesion cues. When implanted in hemophilic mice, these scaffolds supported long-term engraftment and systemic factor IX delivery by MSCs that corrected the hemophilic phenotype of most animals for up to 12 weeks.…”