Activated factor X targeted stored in platelets as an effective gene therapy strategy for both hemophilia A and B.

Abstract

BACKGROUND:

Treatment of hemophiliacs with inhibitors remains challenging, and new treatments are in urgent need. Coagulation factor X plays a critical role in the downstream of blood coagulation cascade, which could serve as a bypassing agent for hemophilia therapy. Base on platelet-targeted gene therapy for hemophilia by our and other groups, we hypothesized that activated factor X (FXa) targeted stored in platelets might be effective in treating hemophilia A (HA) and B (HB) with or without inhibitors.

METHODS:

To achieve the storage of FXa in platelets, we constructed a FXa precursor and used the integrin αIIb promoter to control the targeted expression of FXa precursor in platelets. The expression cassette (2bFXa) was carried by lentivirus and introduced into mouse hematopoietic stem and progenitor cells (HSPCs), which were then transplanted into HA and HB mice. FXa expression and storage in platelets was examined in vitro and in vivo. We evaluated the therapeutic efficacy of platelet-stored FXa by tail bleeding assays and the thrombelastography. In addition, thrombotic risk was assessed in the recipient mice and the lipopolysaccharide induced inflammation mice.

RESULTS:

By transplanting 2bFXa lentivirus-transduced HSPCs into HA and HB mice, FXa was observed stably stored in platelet α-granules, the stored FXa is releasable and functional upon platelet activation. The platelet-stored FXa can significantly ameliorate bleeding phenotype in HA and HB mice as well as the mice with inhibitors. Meanwhile, no FXa leakage in plasma and no signs of increased risk of hypercoagulability were found in transplantation recipients and lipopolysaccharide induced septicemia recipients.

CONCLUSIONS:

Our proof-of-principle data indicated that target expression of the FXa precursor to platelets can generate a storage pool of FXa in platelet α-granules, the platelet-stored FXa is effective in treating HA and HB with inhibitors, suggesting that this could be a novel choice for hemophilia patients with inhibitors.

• Authors: Dawei Wang, Xiaohu Shao, Qiang Wang, Xiaohong Pan, Yujun Dai, Shuxian Yao, Tong Yin, Zhugang Wang, Jiang Zhu, Xiaodong Xi, Zhu Chen, Saijuan Chen, Guowei Zhang
• Journal: Clinical and translational medicine (Clin Transl Med) Vol. 11 Issue 3 Pg. e375 (03 2021) ISSN: 2001-1326 [Electronic] United States
• PMID: 33783994 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: © 2021 The Authors. Clinical and Translational Medicine published by John Wiley & Sons Australia, Ltd on behalf of Shanghai Institute of Clinical Bioinformatics.

Chemical References

• Factor Xa

Topics

• Animals
• Blood Platelets
• Disease Models, Animal
• Factor Xa (metabolism)
• Genetic Therapy (methods)
• Hemophilia A (therapy)
• Hemophilia B (therapy)
• Male
• Mice
• Mice, Inbred C57BL
• Mice, Knockout