AUTHOR=Qiu Liyan , Xie Mi , Zhou Miaojin , Liu Xionghao , Hu Zhiqing , Wu Lingqian 

TITLE=Restoration of FVIII Function and Phenotypic Rescue in Hemophilia A Mice by Transplantation of MSCs Derived From F8-Modified iPSCs

JOURNAL=Frontiers in Cell and Developmental Biology

VOLUME=Volume 9 - 2021

YEAR=2021

URL=https://www.frontiersin.org/journals/cell-and-developmental-biology/articles/10.3389/fcell.2021.630353

DOI=10.3389/fcell.2021.630353

ISSN=2296-634X

ABSTRACT=Hemophilia A (HA), an X-linked recessive congenital bleeding disorder, affects 80%–85% of patients with hemophilia. Nearly half of severe hemophiliacs are caused by a 0.6-Mb genomic inversion (Inv22) disrupting F8. Although viral-based gene therapy has showed therapeutic effects for hemophilia B (HB), such a promise approach is not applicable for HA at the present stage, mainly owing to the big size of F8 cDNA that far exceeds the AAV packaging capacity. We previously reported an in situ genetic correction of Inv22 in HA patient-specific induced pluripotent stem cells (HA-iPSCs) by using TALENs. Meanwhile, we investigated an alternative strategy for targeted gene addition, in which cDNA of the B-domain deleted F8 (BDDF8) was targeted at the rDNA locus of HA-iPSCs using TALENickases to restore the FVIII function. In this study, given their low immunogenicity and ability to secrete FVIII under physiological condition, mesenchymal stem cells (MSCs) were differentiated from F8-corrected iPSCs, BDDF8-iPSCs and HA-iPSCs, and were characterized and verified of FVIII expression efficacy in vitro. After the three types of MSCs were respectively infused into HA mice via intravenous injection, long-term engraftment was observed with restoration of FVIII function and phenotypic rescue in HA mice by transplantation of F8-corrected iMSCs and BDDF8-iMSCs. Our findings suggest that the ex vivo gene therapy by using iMSCs derived from F8-modified iPSCs could be feasible and effective, showing promise in clinical translation of therapeutic gene editing for HA and other genetic birth defects, particularly those involving large sequence variants.