Phenotypic correction of hemophilia A in sheep by postnatal intraperitoneal transplantation of FVIII-expressing MSC

Abstract

We recently re-established a line of sheep that accurately mimics the clinical symptoms and genetics of severe hemophilia A (HA). Herein, we tested a novel, non-ablative transplant therapy in 2 pediatric HA animals. Paternal mesenchymal stem cells (MSC) were transduced with a porcine FVIII-encoding lentivector, and transplanted via the intraperitoneal route, without preconditioning. At the time of transplantation, these animals had received multiple hFVIII treatments for various spontaneous bleeds, and had developed debilitating hemarthroses which produced severe defects in posture and gait. Transplantation of transduced MSC resolved all existent hemarthroses, and spontaneous bleeds ceased. Damaged joints recovered fully; the animals regained normal posture and gait and resumed normal activity. Despite achieving factor-independence, a sharp rise in pre-existent Bethesda titers occurred following transplantation, decreasing the effectiveness and duration of therapy. Post-mortem examination revealed widespread engraftment, with MSC present within the lung, liver, intestine, and thymus, but particularly within joints affected at the time of transplantation, suggesting MSC homed to sites of ongoing injury/inflammation to release FVIII, explaining the dramatic improvement in hemarthrotic joints. In summary, this novel, non-ablative MSC transplantation was straightforward, safe, and converted life-threatening, debilitating HA to a moderate phenotype in a large animal model.

Replacing bad (F)actors: hemophilia

“…Several groups of investigators are pursuing this approach and, of these, one particularly promising but preliminary study was conducted in an ovine model of hemophilia A. 26 In that study, Porada et al used adult BM-derived MSCs isolated from paternal donors that were genetically modified using HIV-based lentivector encoding a BDD p-FVIII transgene. Genetically modified MSCs were transplanted into the peritoneal cavity of 2 affected hemophilia A recipients, the first of which already harbored a low-titer inhibitor against h-FVIIII and received a dose of 3 ϫ 10 7 cells.…”

Potential of Mesenchymal Stem Cells for Liver Regeneration

“…In addition to the inherent properties of MSC that make them well suited for cellular therapy, it is important to realize that MSC can easily be genetically manipulated in vitro, with both viral and non-viral vectors, to enhance their immunosuppressive properties [86,87], to deliver a protein that is missing/defective in the patient, to induce apoptosis of tumor cells, to promote cell proliferation, to guide their migration to a specific site within the body, and even to direct their differentiation towards a specific cell lineage [88][89][90], making the range of clinical applications for which MSC could be used almost limitless.…”

Recent Advances and Future Perspectives in Lentiviral Gene Therapy for Hemophilia A and B

“…MSCs have mild immunogenic profile, they are able both to self-renew and differentiate into the osteogenic, adipogenic and chondrogenic lineages and to contribute to both the parenchyma and perivascular zones of the engrafted organs. In contrast to the use of HSCs, there is no evidence of clonal dominance or insertional oncogenesis when MSCs are used, though this has not been addressed as rigorously as with HSCs [78,94]. In addition, the expanded cells can be transplanted without the need for preconditioning and without evidence for any adverse effects [94][95][96][97].…”

“…In contrast to the use of HSCs, there is no evidence of clonal dominance or insertional oncogenesis when MSCs are used, though this has not been addressed as rigorously as with HSCs [78,94]. In addition, the expanded cells can be transplanted without the need for preconditioning and without evidence for any adverse effects [94][95][96][97]. In the context of MSC-based hemophilia gene therapy, LV transduced MSCs were reported to express FVIII for over a 5-month period in vitro.…”

“…MSCs have several characteristics that make them attractive targets for ex vivo gene therapy [91][92][93][94][95]. They are relatively easy to obtain, culture, expand into adequate numbers for clinical application and to transduce in vitro.…”