Factor VIII with a 237 amino acid B‐domain has an extended half‐life in F8‐knockout mice
Author(s): ,
E. Bloem
Affiliations:
Novo Nordisk A/S, Novo Nordisk Park, Måløv, Denmark
Correspondence: Esther Bloem, Novo Nordisk Park, 2760 Måløv, Denmark|Tel.: +45 3079 6793|E‐mail: eblo@novonordisk.com
,
D. M. Karpf
Affiliations:
Novo Nordisk A/S, Novo Nordisk Park, Måløv, Denmark
,
P. L. Nørby
Affiliations:
Novo Nordisk A/S, Novo Nordisk Park, Måløv, Denmark
,
P. B. Johansen
Affiliations:
Novo Nordisk A/S, Novo Nordisk Park, Måløv, Denmark
,
M. Loftager
Affiliations:
Novo Nordisk A/S, Novo Nordisk Park, Måløv, Denmark
,
H. Rahbek‐Nielsen
Affiliations:
Novo Nordisk A/S, Novo Nordisk Park, Måløv, Denmark
,
H. H. Petersen
Affiliations:
Novo Nordisk A/S, Novo Nordisk Park, Måløv, Denmark
,
G. E. Blouse
Affiliations:
Novo Nordisk A/S, Novo Nordisk Park, Måløv, Denmark
,
L. Thim
Affiliations:
Novo Nordisk A/S, Novo Nordisk Park, Måløv, Denmark
,
M. Kjalke
Affiliations:
Novo Nordisk A/S, Novo Nordisk Park, Måløv, Denmark
G. Bolt
Affiliations:
Novo Nordisk A/S, Novo Nordisk Park, Måløv, Denmark
ISTH Academy. Bloem E. Feb 8, 2019; 273388
Esther Bloem
Esther Bloem
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Journal Abstract
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Background
Factor VIII consists of the A1‐domain, A2‐domain, B‐domain, A3‐domain, C1‐domain, and C2‐domain. FVIII with an intermediate‐length B‐domain of 226 amino acids (aa) has previously been evaluated in murine gene therapy studies.
Objective
To characterize FVIII with intermediate‐length B‐domains in vitro and in vivo in F8‐knockout (KO) mice.
Methods and results
FVIII molecules with B‐domains of 186–240aa had longer half‐lives in F8‐KO mice than FVIII molecules with shorter or longer B‐domains. FVIII with a B‐domain containing the 225 N‐terminal aa fused to the 12 C‐terminal aa of the wild‐type B‐domain (FVIII‐237) had a 1.6‐fold extended half‐life in F8‐KO mice as compared with FVIII with a 21aa B‐domain (FVIII‐21). The in vitro and in vivo activity of FVIII‐237 were comparable to those of FVIII‐21, as was binding to von Willebrand factor. Cell binding to LDL receptor‐related protein 1 (LRP‐1)‐expressing cells was markedly reduced for FVIII‐237 as compared with FVIII‐21, whereas the affinity for LRP‐1 was not reduced in surface plasmon resonance (SPR) studies. FVIII‐21 cell binding and internalization could be inhibited by a fragment consisting of the 226 N‐terminal aa of the FVIII B‐domain, and SPR analysis suggested that this B‐domain fragment might bind with weak affinity to FVIII‐21.
Conclusion
Reduced cell binding of FVIII‐237 might explain the observed extended half‐life in F8‐KO mice. This may contribute to the increased FVIII levels measured in murine gene therapy studies using FVIII constructs with similar B‐domain lengths.
Keyword(s)
factor VIII, half‐life, hemophilia A, LDL receptor‐related protein‐1, von Willebrand factor
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