Therapeutic potential of fetal liver cell transplantation in hemophilia A mice

Hemophilia A (HA) cell therapy approaches in pediatric individuals require suitable factor (F)VIII-producing cells for stable engraftment. Liver sinusoidal endothelial cells (LSEC) and hematopoietic stem cells (HSC) have been demonstrated to be suitable for the treatment of adult HA mice. However, after transplantation in busulfan (BU)-conditioned newborn mice, adult LSEC/HSC cannot efficiently engraft, while murine fetal liver (FL) hemato/vascular cells from embryonic day 11-13 of gestation (E11-E13), strongly engraft the hematopoietic and endothelial compartments while also secreting FVIII. Our aim was to investigate the engraftment of FL cells in newborn HA mice to obtain a suitable “proof of concept” for the development of a new HA treatment in neonates. Hence, we transplanted FL E11 or E13 cells and adult bone marrow (BM) cells into newborn HA mice with or without BU preconditioning. Engraftment levels and FVIII activity were assessed starting from 6 weeks after transplantation. FL E11-E13+ BU transplanted newborns reached up to 95% engraftment with stable FVIII activity levels observed for 16 months. FL E13 cells showed engraftment ability even in the absence of BU preconditioning, while FL E11 cells did not. BM BU transplanted newborn HA mice showed high levels of engraftment; nevertheless, in contrast to FL cells, BM cells cannot engraft HA newborns in BU non-conditioning regimen. Finally, none of the transplanted mice developed anti-FVIII antibodies. Overall, this study sheds some light on the therapeutic potential of healthy FL cells in the cure of HA neonatal/pediatric patients.AF was supported in part by Telethon grant no. GGP19201 and by Horizon 2020, HemAcure grant no. 667421, Vanguard grant no. 874700. SM was partially supported by the Università del Piemonte Orientale (FAR 2017) and by Bando Roche per la Ricerca 2019. The Junta de Andalucia Research Funding Program PAI-BIO295 supported the work of MJS. MJS also acknowledges financial support from the Maria de Maeztu-CABD MDM-2016-0687 and CEX-2020-001088-M grants and the Empleo Juvenil-JA 2018 program that supported the work of RG. LJS and AL were supported by the Andalusian Association of Hemophilia ASANHEMO FV2016-20.With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX-2020-001088-M).Peer reviewe