Neonatal bone marrow transplantation prevents liver disease in a murine model of erythropoietic protoporphyria.

Background & Aims: Erythropoietic protoporphyria (EPP) is an inherited disorder of heme biosynthesis caused by partial ferrochelatase deficiency, resulting in protoporphyrin IX (PPIX) accumulation in erythrocytes, responsible for skin photosensitivity. In some EPP patients, the development of cholestatic liver injury due to PPIX accumulation can lead to hepatic failure. In adult EPP mice, bone marrow transplantation (BMT) leads to skin photosensitivity correction but fails to reverse liver damages, probably because of the irreversible nature of liver fibrosis. Our aim was to determine the time course of liver disease progression in EPP mice and to evaluate the protective effect of BMT into neonates.

Methods: We studied the development of liver disease from birth in EPP mice, in relation with erythroid and hepatic PPIX accumulation. To prevent the development of liver disease, BMT was performed into newborn mice using a novel busulfan-mediated preconditioning assay.

Results: We showed that hepatic PPIX accumulates during the first 2 weeks and correlates with the onset of a progressive liver fibrosis in 12-day-old EPP mice. Transplantation of normal congenic hematopoietic stem cells into EPP neonates led to long-term donor hematopoiesis recovery. A full correction of erythroid PPIX accumulation and skin photosensitivity was obtained. Furthermore, five months after neonatal BMT, liver damage was almost completely prevented.

Conclusions: We demonstrated for the first time that BMT could be successfully used to prevent liver disease in EPP mice and suggested that BMT would be an attractive therapeutic option to prevent severe liver dysfunction in EPP patients.